Integrated Resources Management in Asian Cities: The Urban NEXUS South-East Asia

Transcription

1 Integrated Resources Management in Asian Cities: The Urban NEXUS South-East Asia Municipal wastewater treatment plant in Korat Innovative Wastewater Solutions Report on the surveys of September 2016, January and June 2017 in Korat (Nakhon Ratchasima), Thailand Prepared by Dr Wolfgang Kirchhof; Mr Bernhard Wöffen; Mr Charel Baumann, Research Institute for Water and Waste Management at RWTH Aachen University Dr. Chart Chiemchaisri, Kasertsart University, Bangkok with advisory notes by Mr Hermann Messmer, awt Umwelttechnik Eisleben and Mr Mihael Ketov, Institute of Power Systems and Power Economics, RWTH Aachen University PN GIZ Integrated Resources Management in Asian Cities: The Urban NEXUS Programme September 2017

2 Author with main contributions: Dipl.-Ing. Bernhard Wöffen Research Institute for Water and Waste Management at RWTH Aachen University (FiW) Kackertstr , D Aachen, Germany Supervising author: Dr.-Ing. Wolfgang Kirchhof (FiW) Tel.: Report_on_Korat 2

3 Table of contents Table of contents EXECUTIVE SUMMARY INTRODUCTION Overall Background Structure of the study Methodology of the study FINDINGS of SEPTEMBER 2016 SURVEY on the MUNICIPAL WWTP KORAT Basic data on Korat Observations and Results in September Calculation of the capacity of the wastewater treatment plant Korat Calculation of the aerobic sludge system s capacity RECOMMENDATIONS based on the findings of the visit in Sept Concept for the rehabilitation of the treatment plant Short-term measures Intermediate term measures Long-term measures FINDINGS of JUNE 2017 SURVEY on the MUNICIPAL WWTP KORAT General remarks Findings in pumping stations P 1, P 2.1 and P Findings in wwtp Findings at wwtp Findings at wwtp Findings at wwtp RECOMMENDATIONS to improve the Wastewater Treatment Plant Preamble and clarifications Improvement of the measuring and analysis system of the wwtp Improvement of safety and working conditions Improvement of the budget system Report_on_Korat 3

4 3.4.5 Reversal of wastewater flow Recommended action plan to restart the main wastewater treatment plant in Korat Active sludge management Options for a sustainable operation of the wastewater treatment plant operation Annotation for the repair of the travelling bridges of the rectangular tanks of wwtp 1 and wwtp Annotation to the change of flow direction and the new distributor to feed wwtp 1 / Annotation to the use of the pond area for the installation of a Photo voltaic plant FINDINGS of the September 2016 survey on the NEW DEVELOPMENT ZONE 7 KORAT Water management structures of Zone Conceptual recommendations for the wastewater management in Zone Short-term corrective measures of the combined sewer outfalls Short-term protection measures of the natural river against run-off water Intermediate term measures for the wastewater management Development of an integrated urban drainage plan (Master Plan) Recommendations for an integrated urban drainage plan for zone 7, focusing on decentralized measures ANNEXES Report_on_Korat 4

5 List of Figures Figure 1: Members of the survey team conducted the survey in September Figure 2: Members of the survey team that conducted the survey in June, Figure 3: Figure 4: Figure 5: Overview map of the main survey areas in Korat, 1 = wastewater treatment plant, 2 = new development zone Sewer network of Korat with location of the pumping stations to the wastewater treatment plant consisting of nine ponds and three aerated wastewater plants Wastewater treatment plant of Korat with main pumping stations (P 1, P 21,P 2.2), pond inlet structure (I 1 3) and aerated biological treatment systems (wwtp 1 3) Figure 6: Municipal wastewater treatment plant in Korat Figure 7: Plan of sewer sewerage system to the wwtp (left) and flow through scheme in the wwtp Figure 8: Aeration basin and sedimentation basin of wwtp line Figure 9: Travelling bridge with four suction scrapers of the first wwtp line Figure 10: Dimension of the wastewater treatment process, including aeration tank and sedimentation basin Figure 11: Korat Wastewater Treatment Plant with reversed wastewater flow Figure 12: Photos of the last two pumping stations before the pond system Figure 13: Photos of the geared guiding tracks from a functioning wwtp Figure 14: Photo of a correctly dimensioned travelling bridge from a functioning wwtp Figure 15: Field equipment for Analysis of sludge volume and settleable solid content Figure 16: Figure 17: Figure 18: Overview photo of Korat wwtp with indicated area for a vacuum sewer system Photo of a sludge humification system (Left), area of the korat wwtp area needed for sludge humidification (right) Overview of wastewater flow and main pipes and main pumping stations to the ponds Figure 19: Korat wastewater pumping station 1 at road Soi Taosura Figure 20: Example of performance curve for new Corman-Rupp pump Type T10C60SC-B (2017) Report_on_Korat 5

6 Figure 21: Electrodes for flow-measurement at the pipes to the collecting shaft Figure 22: Korat wastewater pumping stations to feed the ponds (P 2.2 left photos, P 2.1 right side photos) Figure 23: Corrosion at pipes and concrete in the collection shaft from P 2.1 and P 2.2 (photos from top) Figure 24: Principle aeration basin, recycle sludge pumps, surplus sludge pumps Figure 25: Principle sedimentation basin with traveling bridges Figure 26: Figure 27: Wwtp 1: Aeration basin, bubble test, damaged rail of sedimentation basin, automatic sensor, sampling equipment, broken stop switch Wwtp 2: Aeration basin, recycle sludge pumps, surplus sludge pumps, operstor with grease gun, sedimentation basin with traveling bridges Figure 28: 20 ml/l Biomass in the aeration basin after one day operation of wwtp Figure 29: Wwtp3: Main inlet power switch, sedimentation basin with traveling bridges, door of machinary house, broken rails, broken cable lift ffor of stirrer, damaged rail Figure 30: Wastewater Measurement electrode types Figure 31: Korat Wastewater Treatment Plant with reversed wastewater flow Figure 32: Example of a new distributor to Korat Wastewater Treatment Plant Figure 33: Hand drawing of the guding and rollng side of a traveling bridge Figure 34: Chronological order of changing flow direction Figure 35: Formal outline of the distributor for feed of wwtp Figure 36: Section A-A of the distributor Figure 37: Section B-B of the distributor Figure 38: Aerial view of the development zone 7 in Korat Figure 39: Sketch of development zone 7 with existing sewer net work Figure 40: Photos of various land uses, (agriculture) in the development zone Figure 41: Photos of various river sections (weir, natural river bank, level measuring device, information plate of RID8) in the development zone Figure 42: Wastewater facilities in Zone 7, left: decentralised treatment system, right: Waterflow under combined sewer overflow pipe Figure 43: Sketch of the Development Zone 7, with indicated spots of the combined sewer (drainage) overflows and the natural river (green belt) Report_on_Korat 6

7 Figure 44: Figure 45: Figure 46: Figure 47: Figure 48: Photo of a retention basin with filter unit at the outlet point (www Schemes of run-off water treatment systems using sand filtrations and constructed wet lands Photos of installed run-off water treatment systems using sand filtrations and constructed wet lands (Kirchhof, 2012) Core elements and topics of an integrated urban drainage planning by DWA Concept for developments in the Development Zone 7, with indicated development topics List of Tables Table 1 Measured electric currency for aerators and recycle pumps (as a hint for maintenance) Table 2 Hydraulic losses and needed length of the pipes from in the distributor...53 Table 3 Estimated masses and costs for changing the flow direction...57 Table 4 Technical input and output data for the PV plant on the wwtp area in Korat...59 Annexes Annex 1: Checklists of the pumping stations P1, P 2.1, P 2.2 and wwtp 1-3 Annex 2: Annex 3: Annex 4: General To Do List Special recommendations to traveling bridges from Mr. Messmer AWT Calculation matrix to calculate basic data for a PV-plant Report_on_Korat 7

8 List of Abbreviations Abbreviation AS BOD 5 COD DWA EPB FOG MBAS MLSS O&M ots SBR SS ToR TDS TKN TP VS WWTP Explanation Activated Sludge Biochemical Oxygen Demand within five days Chemical Oxygen Demand German Water Association Environmental Protection Bureau Fat, oil and grease Methylene blue active substances Mixed liquor suspended solids Operation and Maintenance Organic dry matter Sequencing Batch Reactor Suspended solids Terms of Reference Total Dissolved Solids Total Kjeldahl-Nitrogen is the sum of organic nitrogen and Ammonium (NH + 4 ) in an analysis sample total phosphor Vacuum station Wastewater Treatment Plant Report_on_Korat 8

9 0 EXECUTIVE SUMMARY The Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) is conducting the project Integrated Resource Management in Asian Cities The Urban Nexus, financed by the Federal German Ministry of Cooperation and Economic Development (BMZ). The Urban Nexus Project started in 2013 over a period of 3 years. The follow up phase started in 2016 to come to an end by December The Asian cities are provided with technical advice on urban planning and development approaches that include the interrelations and synergies of the sectors: water, energy and food security such as secure water supply and sanitation systems, energy security and efficiency, land use, physical planning and food security. Korat (Nakhon Ratchasima) Municipality is one of the partner cities requesting the GIZ Nexus project to conduct surveys on Nakhon Ratchasima areas to figure out solutions for decentralized options to improve the water and sanitation situation. A team of the Research Institute for Water and Waste Management at the RWTH Aachen University and of the Faculty of Civil Engineering of the Kasetsart University, Bangkok conducted surveys in September / October 2016, in January 2017 and in June The team inspected the main municipal wastewater treatment plant (wwtp) and visited various loctions in the zone, called zone 7 and in which households are not yet connected to the main drain to the wwtp, and presented their findings on meetings at the Korat municipality on 30 January 2017 and on June Wastewater treatment plant and short-term actions: The advisory team stated that the existing wwtp is well designed according to international design standards. The infrastructural concrete works are of adequate strength and quality. Based on these findings, the team expressed their opinion that it is economically expedient for Korat s municipality to rehabilate the wwtp in order to reduce health risks caused by untreated domestic waste water, released into the urban environment. The team found out that during the inspection many aggregates of the wwtp, including pumps, aerators, scrapers, blowers were mal-functioning or completely out of order. For the rehabilitation of the existing plant, detailed technical recommendations were formulated (Chap.2 and 3) and a detailed cost summary for the renewal and repair of the main aggregates, including scrapers, stirrers, aerators was formulated. Advisory services were delivered on how to modify the wastewater drain to the wwtp and the whole wastewater treatment system. It is sufficient to start the repair of only two (2 out of 3) treatment lines of the wwtp (One line exists fo one aeration and one sedimentation basin). If the wwtp will be repaired and correctly operated, the capacity will be big enough to treat the daily amount of about 70,000 m³ wastewater per day, equivalently of about the wastewater amount produced by 280,000 inhabitants Report_on_Korat 9

10 The cost for the repair works are estimated as follows: Wwtp line 1: 3,600,000 Baht (91,700 EUR) Wwtp line 2: 3,300,000 Baht (84,100 EUR) Good process control: The advisory team found out that the process control has severe faults and formulated recommendations on how to upgrade the technical analysis and monitoring systems (Chap.3). Beside the technical upgrade, it is advisable to improve knowledge and capabilities for the supervising and operational staff by a tailor-made training programme. Budget for Operation and Maintenance (O&M): The team found out that the fund allocation for the O&M is not sufficient, it is urgently necessary to install an annual budget for the O&M works in order to avoid severe damages. In cases of emergencies, this budget the plant operatorional staff will in time be enabled to start repair actions and to avoid interruptions of the wwtp operation. Wastewater treatment plant and middle-term actions: The team has noted that the existing wwtp is designed and capable to treat more hazardous substances as in the situation found during the survey The existing plant could be operated more efficiently: It is recommended to look on a measure on how the increase the wastewater load in the inlet drain. It is recommended to connect households directly to the wastewater treatment plant, e.g by connecting houses using a vacuum sewer system. Decentralized options for the development zone 7 : For the services of the city development zone 7 conceptual recommendations were formulated, pointing out high potentials for the development of decentralized wastewater systems in zone 7. The team found out that untreated wastewater from the main waste water collector could be discharged into the river. It is recommended to collect this wastewater in retension basins and treat it before the release into the river. Open and or agricultural areas are available and could be used to install nature-near wastewater treatment plants, such as vertically or horizontally flown-through root filter systems. After the treatment this water could be used as irrigation water for the agricultural areas.decentralized systems have to be maintained and monitored by operational staff of the municipality. It is advisable to conduct a study on how municipal waste water management and agricultural land management could be combined regarding the different responsibilities of the municipality and agricultural departments Report_on_Korat 10

11 Wastewater treatment plant and long-term actions: The team confirmed that after the rehabilitation of two out of three lines the wwtp will met the requirements and that there will be a significant part of the existing pond area, which will not be used for the treatment process. Estimately of about m² of the pond area that can be used for other city development projects. The team estimated the benefit of this idle area, if this area is used for the implementation and operation of a photovoltaic plant for the generation of electrical energy (Chap.3). Regarding the local physical and climatic conditions, the team assessed that it is technically and economically feasible to install a PV plant of 38 MWp and to produce about MWh/a of electrical power Report_on_Korat 11

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13 1 INTRODUCTION 1.1 Overall Background The German Agency for International Cooperation (GIZ) is conducting the project Integrated Resource Management in Asian Cities The Urban Nexus, starting from 2013 over a period of 3 years. Selected Asian cities are provided with technical advice on urban planning and development approaches that include the interrelations and synergies of the sectors: water, energy and food security such as secure water supply and sanitation systems, energy security and efficiency, land use, physical planning and food security. Moreover, knowledge and experience sharing and cooperation between public, private and civil-society stakeholders is essential. Strategically, the project focuses on two core elements. On the one hand, nexus initiatives demonstrate in an exemplary way how to integrate the nexus approach into urban planning and development processes. On the other hand, the regional exchange and dissemination of successful practical approaches to integrated resource management is undertaken through efficient networking. Nakhon Ratchasima (Korat) Municipality in Thailand is one of the Nexus Partner cities requesting the GIZ Nexus project to conduct a study on integrated wastewater management and waste management in Korat. The key objective was to analyze the situation and to find potentials for innovative improvements. Preliminary results and findings are summarized in the report Wastewater management and organic waste management in Korat/ Thailand, prepared by Fraunhofer IGB in March 2014 for the Regional NEXUS project. In July 2016 on behalf of GIZ, a follow-up study was commissioned to develop innovative semi and decentralized solutions for the wastewater treatment regarding water reuse options and energy saving option for the municipal wastewater treatment plant Korat and for the New Development zone in Korat. Main topics of this study were development of appropriate, innovative, semi and decentralized solutions for the treatment of municipal wastewater regarding options for the generation of alternative water resources, water reuse. The consultancy comprised a preparatory work phase in Germany, a short-term mission of an international and a national expert team from September 28 to September 30, 2016 to Nakhon Ratchasima, and an assessment work phase afterwards. On January 30, 2017, preliminary results of the study were presented at the municipality in Nakhon Ratchasima. Another study mission thereafter took place from June 13 to June 16, 2017 and was focused on the rehabilation of the waste water treatment plant and the assessment of potentials after the implementation of the recommended rehabilitation measures Report_on_Korat 13

14 1.2 Structure of the study The surveys were conducted by a team of the Research Institute for Water and Waste Management at the RWTH Aachen University (FiW) and of the Faculty of Engineering of the Kasetsart University in Bangkok as local partner (Figure 1 and 2). Figure 1: Members of the survey team conducted the survey in September 2016 Dr. Rawit, J Messmer, Hermann Wöffen, Bernhard Kasetsart University, Bangkok, Thailand AWT Umwelttechnik Eisleben GmbH, Germany FIW Aachen, Germany Figure 2: Members of the survey team that conducted the survey in June, 2017 Both survey teams were accompanied and supported by Mr. Ralph Trosse and Mr Rashane Sala-Ngarm, both GIZ Urban Nexus collaborators and partially also by Ms. Ruth Erlbeck, Project Director of the Urban Nexus Project. 1.3 Methodology of the study Two experts visits were conducted. Team 1 visited the city of Korat in September 2016, joined meetings at the municipality office and the department of sanitation. Under the guidance of the leading engineer of the dept. of sanitation various points of interest in the city of Korat were visited and inspected, including the municipal wastewater treatment plant (see Fig.3, 1.), the waste management plant, the new development zone, called zone 7 (2.) at the dept. of water supply. All requested data were made available, including design data, operational data, and water supply data Report_on_Korat 14

15 Figure 3: Overview map of the main survey areas in Korat, 1 = wastewater treatment plant, 2 = new development zone The team assessed the findings and re-calculated various rehabilitation options using international standards and guidelines, as follows: DWA- A 118 Hydraulic calculation of the sewerage systems, 2006 DIN EN 1091; DIN A 116 Vacuum sewer systems DWA-A131 Calculation of single step wastewater treatment plants, 2016 DWA-T4/20176 Calculation of wastewater treatment plants in warm and cold climate zones, 2016 Wastewater Engineering, Treatment and Reuse, 4 th edition, Metcalf & Eddy, 2004 Factors of the selection and assessment of the recommended concepts and actions are Use and re-use of existing infrastructure, as far as possible Low energy consumption Adapted to local man-power and capabilities Adapted to the local requirements Acceptance of the users Results of the study were presented at the municipality in Nakhon Ratchasima on January 30, Subsequently, team (Fig.2) conducted a visit to Korat and observed critical plant components of the wwtp, such as: Suction scrapers, travelling bridges of the sedimentation tanks, Sludge recycling pumps The last two pumping stations of the sewer network Roads and houses in the neighboring area of the wwtp and pond area Report_on_Korat 15

16 More details on the construction of the plant components were made available. Based on these information, the team discussed in more details on how to improve the performance of the wastewater treatment system Report_on_Korat 16

17 2 FINDINGS of SEPTEMBER 2016 SURVEY on the MUNICIPAL WWTP KORAT 2.1 Basic data on Korat Nakhon Ratchasima (Thai: นครราชส มา), commonly known as Korat (โคราช), is one of the four major cities of Isan, the central-eastern region of Thailand. Korat is at the western edge (elevation of about 200 m,) of the Korat Plateau, about 250 km north-east of Bangkok. It is the governmental seat of the Nakhon Ratchasima Province and Nakhon Ratchasima District. As of 2010, the municipal area had a population of 142,645. In 2013 Korat has 173,000 registered inhabitants. As many people lived as unregistered in the city, the total population is estimated with 250,000 inhabitants. The annual rainfall amount is about 1,500 mm. Most rainfall (rainy season) is seen from May to October (see diagrams in Annex 5). Korat has a dry period from December to February. On average, the warmest month is April, the coolest month is December. During rainy season flooding due to heavy rain occurs frequently. During the dry season water becomes scarce, limiting the agricultural production. About 90 % of the population is connected to a combined sewer system, the outer districts, including the zone 7 are not yet connected, (end of 2016). Private houses are equipped with septic tanks, overflows of which are connected by pipes to open sewer systems, which are connected to the main wastewater discharge pipe system. As by the sewer system already treated household wastewater and surface run-off water during the rainy season is collected, the pollution load of the wastewater is lower than in industrialized countries, such as Germany, where nearly only closed pipe systems are used for the sewage collection systems. 2.2 Observations and Results in September 2016 An overview plan of the sewer system of Korat, provided by the municipality, is shown in Figure 4. The information available is very scarce, as only the main pipes, overflows and pumping stations are shown Report_on_Korat 17

18 wastewater treatment plant (wwtp 1-3) P 1 P 2.1 P 2.2 main wastewater pumping stations Figure 4: Sewer network of Korat with location of the pumping stations to the wastewater treatment plant consisting of nine ponds and three aerated wastewater plants The wastewater from the connected parts of the city are planned to go to the main wastewater pumping station P 1. P 1 pumps the wastewater to P 2.1. P 2.2 pumps the wastewater coming from the nearer area in a tower. P 2.1 pumps the wastewater coming from P 1 in the same tower. From the tower the wastewater is let in a freeflow to three inlet structures (I 1 3, Figure 5) at the side of the ponds across the aeration and sedimentation buildings at the wastewater treatment plant. In Figure 5 shows the complete wastewater plant consisting of three parallel units. Each unit first has a pond system with 3 ponds in a line and one aerated sludge system. The aerated sludge system consists of one aerated basin and two sedimentation basins with a reverseand surplus sludge pumping station. The pond system has a total length in flow direction of the water of round 760 meter and a width of total round 700 m (see red lines in Figure 5). The pond system is divided into 9 ponds that first clean the wastewater by sedimentation and the aeration due to the oxygen that is captured from the surface of the ponds Report_on_Korat 18

19 wwtp 1 wwtp 2 wwtp 3 P 1 P 2.1 P 2.2 I 1 I 2 I 3 P 1, P2.1 and P.2.2: main wastewater pumping stations I 1, I2 and I3: inlet shafts Figure 5: Wastewater treatment plant of Korat with main pumping stations (P 1, P 21,P 2.2), pond inlet structure (I 1 3) and aerated biological treatment systems (wwtp 1 3) The municipal wwtp Korat is based on a pond system (with an overall area of 120,000 m², built in 1990 s and an activated sludge plant, which in 2009 was integrated into the pond area, designed for a flow of 75,000 m³/d. It is reported that during the rainy season the flow is about 60,000 m³ and during the dry season of about 30,000 m³/day. Figure 6: Municipal wastewater treatment plant in Korat The technical wwtp, designed for a flow of 75,000 m³/d, was foreseen to treat the effluent of the pond system. The collected waste water, coming from the city area is lifted by a pumping station into the pond system and flows through the pond system in three parallel lines before it is treated in the wwtp Report_on_Korat 19

20 Figure 7: Plan of sewer sewerage system to the wwtp (left) and flow through scheme in the wwtp The Municipal wastewater treatment plant in Korat is underloaded. As described in the preliminary studies, it is evident, that the organic load in the influent of the activated sludge system is not sufficient to generate enough biomass for the system to work properly. This is due to the degradation processes in the upstream treatment ponds and especially due to the septic tanks in use on most housing and commercial plots in the city.the water quality parameter measured in the influent and effluent of the wwtp system indicates that the technical wwtp is critically underloaded. BOD, COD and TKN were measured by the team in October: Inlet BOD mg/l Inlet COD mg/l Inlet TKN mg/l Due to the COD/BOD ratio of 2,0 2.2 (54,3/25,9) it could be stated that the incoming wastewater can be treated with the activated sludge process, but as the organic loaded, expressed as low COD-load, is very low, the bacterial degradation rate of the activated sludge process will be low. Due to this fact, the production of the activated sludge will remain low. So there should be taken some pre-caution measures to avoid the loss of the activated sludge in the basins, (if the process is running again) Report_on_Korat 20

21 The plant has technical faults: During the survey in 2016 the technical wwtp was not functioning and has obviously severe technical faults. The inflow was not evenly distributed to the three treatment lines. The travelling bridges for the sludge reflux were not working because of not appropriately synchronised engines, therefore the sludge reflux pumps were also not running. The wastewater in the aeration basins didn t contain any sludge. Figure 8: Aeration basin and sedimentation basin of wwtp line 1 The travelling bridges (Fig. 9) were not functioning. The bridge sag (durchhängen) in its middle causing uneven strains of its wheels at the ends of bridge. Figure 9: Travelling bridge with four suction scrapers of the first wwtp line Report_on_Korat 21

22 2.3 Calculation of the capacity of the wastewater treatment plant Korat The capacity of the existing wastewater treatment plant was calculated using international design standards and, if necessary, by chosing asumptions based on the team s experts experiences Calculation of the aerobic sludge system s capacity Using the as-built drawings, surface areas, volumes, and depths of the aeration and sedimentation tanks were calculated, as shown in Fig.10. Figure 10: Dimension of the wastewater treatment process, including aeration tank and sedimentation basin Sewage treatment capacity: Assuming a sludge volume index SVI of 150 l/kg, a sludge thickening time = 2 h, a return sludge pumping rate of 100 %, and a max. area loading of 460 l/(m²*h). the maximum treatable sewage flow is 35,000 m³/d and the maximum attainable sludge mass in AS-tank is about 14.5 t. COD and Nitrogen treatment capacity: Assuming an average wastewater temperature of 25 C, an solids retention time in the aerobic zone of 2.0 d (days), an overall solids retention time of 4.3 d, an excess sludge flow of kg/day is calculated. Based on these data the maximum treatable COD load is = 6000 kg/d and the maximum treatable Nitrogen load is 700 kg/d (per one treatment line). Biogas production capacity using an anaerobic sludge digester: Assuming a solids concentration after the sludge thickening of 4 %, a designed solids retention time of 30 days, a yield coefficient = 0,33 Nm³/kg organic_ss, a ratio of organic compounds in the excess sludge of 60 %, a digester with a volume of 2500 m³ is required, producing a volume of 650 Nm³ Biogas/day (per one treatment line) Report_on_Korat 22

23 If all components of the existing wastewater treatment plant will be repaired the total treatment capacity will be about 100,000 m³/d wastewater and a total amount of biogas will be almost m³ biogas 1 per day. 2.4 RECOMMENDATIONS based on the findings of the visit in Sept Concept for the rehabilitation of the treatment plant It is important to note that the underlying calculations are based on the full capacity of the existing activated sludge plant (with three treatment lines (trains)). However, it can be supposed that the actual inflow load is currently below the plant s capacity. Therefore, a step by step approach is highly recommended. With the data and experience from the first steps the reactivation of the first AS plant and the improved analysis plan, the planning of long-term measures should be adjusted accordingly. Furthermore, measures to increase the inflow load should be implemented to increase the plants efficiency and reduce the environmental impact of non-treated wastewater in the city. An optimal use of the wastewater treatment plants capacity should also play an important role in the recommended integrated urban drainage planning. The concept for the rehabilitation of the treatment plant contains short-term, intermediate and long-term measures, as follow: Short-term measures Corrective measures to use of existing infrastructure Direct repair measures of one scraper and one aeration system Measures to modify the wastewater in-flow Accompanying measures to improve control of operation Intermediate term measures Long-term measures Measures to increase the inlet waste load Assessment of the results of the short-term and intermediate term measures Measures for sludge treatment after successful new start of operation Sludge humification 1 Biogas contains about 60 % of Methane (CH 4 ), which is an important climate hazardous gas. About 1200 m³ Methane per day can be recycled Report_on_Korat 23

24 2.4.2 Short-term measures The short-term measures should be realized as a complete bundle of measures and be focused only on the rehabilitation of one wastewater treatment line, preferable of line 1, the most western line. If one measure is not implemented the other measures will not functioning or will have not the results as designed Reversal of wastewater flow To raise the amount of degradable organic matter in the activated sludge basins, the wastewater should be directly pumped into the AS plant without prior treatment in the pond system, as seen in Fig.11. Figure 11: Korat Wastewater Treatment Plant with reversed wastewater flow Pumping station (1) Upstream of pond PS Pumping station (2) at inlet of pond Figure 12: Photos of the last two pumping stations before the pond system Report_on_Korat 24

25 Re-check of capacity of two pumping stations Installation of a new pumping line Estimated cost expected: 2,250,000 Baht (60,000 EUR) Detailed calculation on the basis of the DWA A 131 (2016) in combination with the DWA- Topics T4/2016 (Design of wastewater treatment plant in warm and cold climate zones) show that the AS plant is capable of treating up to 100,000 m³/d wastewater and roughly 18 t/d of BOD load. To reverse the wastewater flow, the pressure pipe, coming from the pumping station and leading towards the inflow pumping station of the treatment plant, needs to be redirected towards the AS plant Repair of the travelling bridge of the sedimentation tank The first step in reactivating the AS plant should be the reparation of the scraper bridge over the clarifier basins of the AS system. To prevent the bridges from failing again because of not properly synchronised engines, the installation of a geared guiding track, as shown in figure 13, or another stabilising method (guided rail) is recommended Figure 13: Photos of the geared guiding tracks from a functioning wwtp Technical modification of scraper by the gear guiding tracks Function checks of installed sludge pumps for recycling and sludge withdrawals To re-start the aerobic process, activated sludge (feeding sludge) is recommended to be introduced., e.g. by sludge suction car by UBA Bangkok Estimation of cost expected: 7, Baht (200,000 EUR) Report_on_Korat 25

26 Figure 14: Photo of a correctly dimensioned travelling bridge from a functioning wwtp At the long term, the construction of a combined, aerated sand- and grease trap basin prior to the AS system is recommendable in order to keep sand from sedimenting in the AS basins. Furthermore, the collected sand can be used for example in road construction and the retained grease can later be cofermented in the digestion tank, which will lead to a higher biogas yield. However, the construction will be costly because of the AS systems locations in the last treatment ponds, which makes a more complicated pipe layout necessary to install an upstream basin Improvement of wastewater analysis The lack of reliable long term wastewater data from the treatment plant influent and effluent hamper the planning of sensible modifications. To further improve the assumptions made for the wastewater load calculations and enable the plant s staff and planners to react in case of changing influent, a regular sampling plan should be implemented. This is also necessary to enable the active sludge management presented. The key parameters BOD, TS, SS, ph and Ammonium, should be analysed at least on a weekly basis at varying weekdays and times of the day. The samples should be composite samples mixed out of at least five catch samples taken in a timeframe of two hours Report_on_Korat 26

27 Figure 15: Field equipment for Analysis of sludge volume and settleable solid content Sludge volume index Floatable sludge content Settlable solids Estimated cost expected: 380,000 Baht (10,000 EUR) For simple regular BOD measurements, chemical free measuring systems such as OxiTop are recommendable. Further parameters such as the COD, total nitrogen or phosphorus should be measured once a month in one of the weekly composite samples. In addition, the TS, ots, ph and Redox potential of the excess sludge should be analyzed on a weekly basis Report_on_Korat 27

28 2.4.3 Intermediate term measures Measures to increase the inlet wastewater load The connection of households which are located near to the wastewater treatment plant in Korat is technically feasible and can be realized in the next four to five years. The connection can be realized in a modular system which can be enlarged by a stepwise connection of the housing areas. Planned Vacuum station Pump station Pressure line Planned inlet Wastewatetr treatment plant 1 Pond after wwtp Vacuum line Pond for sludge humidification Vacuum service area Pump station (rec. To be shut down) Figure 16: Overview photo of Korat wwtp with indicated area for a vacuum sewer system Existing pipe systems can be used by modifiying pipe connections and flow directions. Existing free spaces of wwtp area can be used for new pumping stations for the sewer system. In case of a vacuum sewer system the housings for the vacuum suction pumps can be integrated into existing pump stations Report_on_Korat 28

29 2.4.4 Long-term measures Sludge humification As soon as the wastewater flow has been reversed and the AS plant is functional, the first and second treatment ponds of the current system should be emptied. A part of the thereby freed area should be converted into sludge humification beds (as shown in figure 17). Figure 17: Photo of a sludge humification system (Left), area of the korat wwtp area needed for sludge humidification (right) These flat beds will be filled continuously with the excess sludge. The planted reed plants help dewatering and stabilizing the sludge over a period of 5-7 years. After that, the sludge can be used as fertilizer in agriculture. According to first estimations, an area of (only) 30,000 m 2 is necessary for the humification beds Active sludge management Even with the flow direction reversed, the low content of degradable organic load in the wastewater influent will continue to be a challenge for the AS system. An active sludge management by the treatment plant staff, similar to the methods used at the Dindaeng Water Environment Control Plant in Bangkok, should be implemented. This means that in case of very low-loaded inflow, excess sludge from a storage tank should be pumped into the AS basins in order to provide enough organic matter to keep the bacterial processes going. This storage tank should have a volume of 250 m 3, which is roughly equal to the daily excess sludge production (thickened) Report_on_Korat 29

30 Excess sludge treatment using an anaerobic sludge digestion The excess sludge from the AS plant is a potential energy source and contains valuable nutrients. Anaerobic sludge digestion is used worldwide as an effective treatment technology which lowers significantly the bacterial activity while producing biogas at the same time. Calculations show that up to 10 t SS of sludge could be produced at the Korat wastewater treatment plant which can provide up to 2,000 Nm 3 /d of biogas. The digested sludge should subsequently be dried in a solar drying plant for the use as agricultural fertilizer. To implement this treatment chain, the following buildings are necessary: A gravity thickener with a volume of about 780 m 3 (height = 2,5 m, diameter = 20 m), one or several sludge digesters with a total volume of about 8000 m 3, a sludge dewatering plant (e.g. belt filter press, screw presses etc.) and a sludge drying plant As the construction of sludge digesters demands detailed planning and a big investment from the city or national budget, the implementation of an anaerobic sludge digestion is time consuming. To be able to implement these measures as soon as possible, a short-term solution for the sludge treatment is described below Report_on_Korat 30

31 3 FINDINGS of JUNE 2017 SURVEY on the MUNICIPAL WWTP KORAT 3.1 General remarks Based on the recommendations of the Septemebr 2016 survey, presented on January 2017 to the Vice-mayor of the Korat municipality, the municipality has expressed their strong will to improve the infrastructural works of the wwtp, including the misfunctioning scraper, sirrer and aerator systems. The consultant send a second team to conduct a survey in June 2017 and to formulate recommendations to support and guide the works intended by the Korat municipality. Overall, the wastewater treatment plant and the pumping stations seemed to be in good condition. However, some issues were raised by the staff and were also observed by the project team. The results of the check are listed in the Annexes. The things that should be undertaken to make the wastewater treatment plant running are described in Annex 2 and 3: Annex 1: Checklists of the pumping stations P1, P 2.1, P 2.2 and wwtp 1 3. Annex 2: General To Do List Annex 3: Special recommendations for traveling bridges from Mr. Messmer AWT. 3.2 Findings in pumping stations P 1, P 2.1 and P2.2 Pumping Station P 1 Pumping station P 1 has a coarse screen, a macerator for the screenings and five submersible pumps in the flow direction to the pump sump (see Figure 19). Data, such as 1. yearly flow (m³/a), 2. maximum flow capacity (m³/h), 3. pump characteristics/charts, manufacturer and pump type to know more about the design of the pumping station was not available during the visit. The functionality of screen, macerator and the five pumps (currency uptake) could not be tested. The pumping direction is to the 1.5 m x 1.5 m channel to pumping station P 2.2 at the wastewater pond (see Figure 18) Report_on_Korat 31

32 P 1 main wastewater pumping stations P 2.1 P 2.2 Figure 18: Overview of wastewater flow and main pipes and main pumping stations to the ponds Pumping station P 1 operating building (left) excavating units coarse screen and macerator Pump sump with five submersible pumps Non return valves and shut-off valves Figure 19: Korat wastewater pumping station 1 at road Soi Taosura Report_on_Korat 32

33 Pumping Stations P 2.1 and 2.2 In the flow direction to the pump sump, pumping station P 2.1 has a screen and two old (1989, Flygt) submersible pumps and two new dry mounted inline centrifugal pumps, Corman-Rupp (see Figure 22) with a suction high of approx. 3 m. Figure 20: Example of performance curve for new Corman-Rupp pump Type T10C60SC-B (2017) Pumping station P 2.2 has four submersible pumps but no screen (see Figure 22). Data, such as 1. yearly flow (m³/a), 2. maximum flow capacity (m³/h), 3. pump characteristics/charts, manufacturer and pump type for P 2.2 to know more of the design of the pumping station was not available during the visit. This data are important data and should be present for maintenance, decision makings and economic efficiency calculations. The functions of screen and the four pumps of P 2.1 were tested. A reserve pump for the two Flygt-pumps had just arrived from repair work (see Figure 22). One pump in P 2.2 was working. Excavating units are constructed as portal cranes and were in a good condition. The pumps P 2.1 and P 2.2 pump the water to the approx. 3 m high collecting shaft (see Figure 22 and Figure 23). From that collecting shaft the water flows by gravity to three approx. 5 m x 2 m inlet shafts at front the wastewater ponds (see Figure 5 and Figure 22) Report_on_Korat 33

34 At the two pipes coming from the pumping stations 2.1 and 2.2 there are flow-measure instruments (technical malfunction, see Figure 21). Figure 21: Electrodes at pipe from P 2.1 Electrodes at pipe from P 2.1 Electrodes for flow-measurement at the pipes to the collecting shaft Report_on_Korat 34

35 collecting shaft.operating building P 2.2 P 2.1, P 2.2 and operating building reserve unit (packed) and defect pump P 2.1 float switches, orange for new pumps P 2.2 from top of collecting shaft 2017 new installed 2 pumps at P 2.1 Pump sump and valves of four pumps in P 2.2 Pump sump for two old submerge pumps in P 2.1, the right two pumps are no more installed Figure 22: Korat wastewater pumping stations to feed the ponds (P 2.2 left photos, P 2.1 right side photos) Report_on_Korat 35

36 The concrete on top and in the collecting shaft and the pipes in this area are heavily corroded (see Figure 23). It could be renovated with Polyethylene plates or coatings. Figure 23: Corrosion at handrails and concrete Corrosion at pipe and concrete Corrosion at pipes and concrete in the collection shaft from P 2.1 and P 2.2 (photos from top) 3.3 Findings in wwtp 1 3 As described in the preliminary studies, it is evident, that the organic load in the influent of the activated sludge system is not sufficient to generate enough biomass for the system to work properly. Water quality parameter measured by FIW/KU-team, measured in October 2016 Inlet BOD: Inlet COD: Inlet TKN: mg/l mg/l mg/l. This is due to the degradation processes in the upstream treatment ponds and especially due to the septic tanks in use on most housing and commercial plots in the city, required by the national regulation for septic tanks. To solve the problem of the low inlet loads, the flow direction could be changed (see chapter 3.4.5) (this measure will avid the degradation in the ponds) and there could be generated higher concentrated wastewater in the inflow by adding higher wastewater, such as wastewater that is directly sucked by a vacuum system from households (by-passing the septic tanks and not using a septic tank before entering the wwtp. The construction of the three plants (wwtp 1 3) is identical and shown in Figure 24 (aeration basin) and Figure 25 (sedimentation basin). Each plant consists of one large aeration basin that is aerated by four aerators and 528 membrane diffusors at the ground of the basin. The inflow from the ponds flows by gravity Report_on_Korat 36

37 (water-level difference between aeration basin and ponds) to the non-aerated zone of the basin, just after the inflow of the recycled sludge. The aerated zone should have an oxygen concentration of 1.5 mg/l; sludge in the aeration basin should grow to 3-4 g/m³. 3 of the 4 installed stirrers have to operate continuously. The traveling bridges and two of the three recycle-sludge pumps should work for 24 h/d continuously. Surplus sludge should be pumped away, if the sludge concentration in the aeration basin is higher than 4 mg/l. In a first phase, regarding the low measured load, it will be sufficient to operate only two of the three plants. Inflow from pond 4 Stirrer/mixer 4 Aerators 3 Recycle sludge pumps Figure 24: 48 x 11 = 528 Membranes Outlet to sedimentation basin Principle aeration basin, recycle sludge pumps, surplus sludge pumps 3 Recycle sludge pumps 2 Surplus sludge pumps traveling bridge From aeration basin Effluent, cleaned wastewater Figure 25: Principle sedimentation basin with traveling bridges Report_on_Korat 37

38 3.3.1 Findings at wwtp 1 At wwtp 1 three of the rails at the sedimentation basin were severely damaged by the wheels of the traveling bridge. A converter in the switch cabinet of the bridge 2 was out of order. Converters for varying the speed of the bridges are not needed with an electric bridge the converter-problem was fixed and the bridge could run. The hints to fix the other problems at traveling bridges are given from Mr. Messmer, AWT. Bridge to aeration basin with not used room (laboratory?) bubble test for aerators, 10 burst membranes in wwtp 1 damaged rails sedimentation basin, traveling bridges ABB AX400, Temp. Redox, technical malfunction 2 ) 1 equipment for sampling 1,000 m (too far away from the point of sampling at the wwtp) Figure 26: 1) Limit switch at the Traveling bridge, 2) not at non driven axis mounted rotation control Wwtp 1: Aeration basin, bubble test, damaged rail of sedimentation basin, automatic sensor, sampling equipment, broken stop switch Report_on_Korat 38

39 Aeration basin The bubble test in the aeration basin showed approx. 10 damaged aeration membranes (see Figure 26). These membranes have to be changed by an industrial diver. The basin cannot be completely emptied, because the walls of the basin are not designed for more than 1 m difference of water level in and out of the basin. Control of wastewater temperature, oxygen (also recommended: Redox-potential, see chapter 3.4.2) is needed for economic operation. For safety of the workers there should be a life-belt at the railing of the aerated basin and the lights should operate correctly (approx. 10 lights of each wwtp are damaged). The long distance to the laboratory leads to false analytics because the sample react chemically in the hot climate. It is easier to analyze the samples just after taking them in the rooms that are near each bridge of the aeration basin. The data will be more accurately. Another technical option is the installation of automatic measurements of oxygen contents and nitrate concentrations at two points inside of each aeration basin. The switch cabinets must be cleaned. The evidence of breeding pigeons inside the service room and of geckos inside of the cabinets should be not tolerated Report_on_Korat 39

40 3.3.2 Findings at wwtp 2 The result of check of wwtp 2 is better than the wwtp 1. The bubble test showed no damaged membranes. All pumps worked well a little grease and oil was needed for the gear-boxes of the motors and the wheel bearings (see Figure 27). Aeration basin bubble test for aerators without defects recycle sludge pumps surplus sludge pumps Manual grease gun for wheel bearings sedimentation basin 1 with traveling bridge Figure 27: Wwtp 2: Aeration basin, recycle sludge pumps, surplus sludge pumps, operstor with grease gun, sedimentation basin with traveling bridges After changing one motor for the traveling bridge from wwtp 1 to wwtp 2 both traveling bridges of wwtp worked the full way (50 m) up and down the sedimentation basin under supervision. The sludge of the sedimentation basins was pumped to the aeration basin and in the short-time test seemed to work quite well (see Figure 28) Report_on_Korat 40

41 20 mg/l sludge Sludge in aeration basin wwtp 2 after one day operation Figure 28: 20 ml/l Biomass in the aeration basin after one day operation of wwtp 2 The measurement of currency of the aerators show differences (aerator 1 has the highest currency uptake of the 4 aerators / and pump 2 has a higher currency than pump 1 and 3.) This observation gives the hint to save energy by re-switching the pumps as follows:using Pump 1 and 3 or aerator 2 instead of aerator 1 can save up to 10 % of electric energy. Table 1 Measured electric currency for aerators and recycle pumps (as a hint for maintenance) Aerator 1 48 Amp Pump 1 36 Amp Aerator 2 42 Amp Pump 2 42 Amp Aerator 3 46 Amp Pump 3 35 Amp Aerator 4 45 Amp Safety and working conditions can be improved, for fixing of problems with the traveling bridges see Annex 3. The switch cabinets must be cleaned Report_on_Korat 41

42 3.3.3 Findings at wwtp 3 The condition of wwtp 3 was checked, although knowing that the plant was never in operation, in order to find hints how to use parts of wwtp for the support of the foreseen operations of wwtp1 and or wwtp 2. The main switch of the electric power supply of wwtp 3 was out of order. The main cable to this plant was disconnected. Operation of the stirrers, aerators, pumps and traveling bridges could not be checked. The rails of the traveling bridges at wwtp 3 were in a good condition. All the wheels of the traveling bridge and one grating were missing (used in wwtp 1 + 2). Main switch, does not operate, no power supply to wwtp 3 Approx. 10 diffuser luminaires are broken or lost in each wwtp Door aerator building, key is missing All 4 Rails wwtp3 are in good condition (not used), one grating is missing Figure 29: aeration basin excavating unit for stirrers sedimentation basin 1+2with traveling bridges without wheels Wwtp 3: Main inlet power switch, sedimentation basin with traveling bridges, door of machinary house, broken rails, broken cable lift ffor of stirrer, damaged rail Report_on_Korat 42

43 The four installed stirrers could not be lifted because the excavating unit was damaged. The door of the aerator room must be repaired a key for this room was missing. The switch cabinets must be cleaned because the dirt on the plates can cause a short circuit Report_on_Korat 43

44 3.4 RECOMMENDATIONS to improve the Wastewater Treatment Plant Preamble and clarifications It is important to note that the underlying calculations are based on the full capacity of the existing activated sludge plant. However, it can be supposed that the actual inflow load is currently below the plant s capacity. Therefore, a step by step approach is highly recommended. With the data and experience from the first steps i.e. the reactivation of the first two AS plants ( wwtp 1, wwtp 2) and the improved analysis plan, the planning of the long-term measures should be adjusted accordingly. Furthermore, measures to increase the inflow load should be implemented to increase the plant s efficiency and reduce the environmental impact of non-treated wastewater in the city. An optimal use of the wastewater treatment plant s capacity should also play an important role in the recommended integrated urban drainage planning Improvement of the measuring and analysis system of the wwtp The lack of reliable long term wastewater data from the treatment plant influent and effluent hamper the planning of sensible modifications. To further improve the assumptions made for the wastewater load calculations and enable the plant s staff and planners to react in case of changing influent, a regular sampling plan should be implemented. This is also necessary to enable an active sludge management. The key parameters BOD, TS, SS, ph and Ammonium and nitrate should be analyzed at least on a weekly basis at varying weekdays and times of the day. The samples should be composite samples mixed out of at least five catch samples taken in a timeframe of two hours. For simple regular BOD measurements, chemical free measuring systems such as OxiTop are recommendable. Further parameters such as the COD, total nitrogen or phosphorus should be measured once a month in one of the weekly composite samples. In addition, the TS, ots, ph and Redox potential of the excess sludge should be analyzed on a weekly basis. To analyze the process of wastewater treatment better and to save energy the wwtp 1-3 the plants should have continuous measure equipment for the following parameters 1. Flow (m³/h, m³/a), installed at the outlet of the clarifier basins 2. Oxygen (mg/l, g/m³), installed at the end of the aerated zone of the aeration basins 3. Nitrate (mg/l, g/m³), installed at the end of the not aerated zone of the aeration basins 4. Phosphorus, installed at the outlet of the last treatment unit (now outlet clarifier basin, later on when changed flow direction outlet of ponds) Report_on_Korat 44

45 For Nitrate and Phosphorus (3. and 4.), it is a matter of cost efficiency to measure these parameters twice a day for three plants in the laboratory or online with automatic datasampling. Information of distribution companies and types of measuring instruments Examples of distribution companies and types of measure equipment used for working in wastewater treatment plants are given here: Temperature, Nitrate-N (NO3-N), Phosphate (PO4-P) Flow, Oxygen with self-cleaning electrodes: 1. HACH LANGE GmbH, Willstätterstraße Düsseldorf, Germany Phone: +49 / (0)211 / Fax: +49 / (0)211 / Mail: info@hach-lange.ch, Internet: Flow, Temperature, Phosphate (PO4-P), Nitrate-N, Oxygen: 2. ABB, ABB Asea Brown Boveri Ltd CEO: Ulrich Spiesshofer Address: Affolternstrasse 44, 8050 Zurich, Switzerland Phone: Fax: The ABB Contact Directory ( helps you find local sales and services contacts for ABB products in your country. Temperature, Nitrate-N (NO3-N), Phosphate (PO4-P) Flow: 3. Xylem Analytics Germany Sales GmbH & Co. KG, WTW, Dr.-Karl-Slevogt- Straße Weilheim, Germany Phone: Fax: Info.WTW@Xyleminc.com, Web: Report_on_Korat 45

46 The electrode types are looking like shown in Figure 30. Controllers and interfaces for control and regulate are offered for serving up to 20 sensors and have a data-store on demand. Figure 30: Wastewater Measurement electrode types Improvement of safety and working conditions For the safety of the workers there should be a life belt mounted at the middle of the aeration basin, for its not possible to swim in aerated water. The lot of broken lights should be procured and mounted and improved cost-effectiveness of LED lights should be checked. Working conditions could be improved by pneumatic grease presses, pressure water cleaners and industrial vacuum cleaner. The daily needed equipment (Oil, grease, working tools, quick-tests measurement equipment like water sampler, beaker, Imhoff hoppers, portable measurement for ph-, oxygen, ) should be in the rooms at the wwtps Improvement of the budget system For a faster reaction to manage regular maintenance and repair of equipment of the wwtp 1-3 and to conduct the monitoring and analysis the staff responsible for the operation and maintenance of the wwtp should have their own budget. The allocation can be done on a yearly basis Reversal of wastewater flow To raise the amount of degradable organic matter in the activated sludge basins, the wastewater should be directly pumped into the AS plant without prior treatment in the pond system, as seen in Figure Report_on_Korat 46

47 Figure 31: Korat Wastewater Treatment Plant with reversed wastewater flow Detailed calculation on the basis of the DWA A 131 (2016) in combination with the DWA- Topics T4/2016 (Design of wastewater treatment plant in warm and cold climate zones) show that the AS plant is capable of treating up to 100,000 m³/d wastewater and roughly 18 t/d of BOD load. To reverse the wastewater flow, the pressure pipe, coming from the pumping station P 1 (Figure 5) and leading towards the pumping station P 2.1 of the treatment plant, needs to be redirected towards the AS plant. It has to be determined whether a new inflow pumping station is necessary or not. If the pumps at station number P1 have enough power to pump the wastewater directly into the new to build distributor to the AS basins, only a new flow separation unit (distributor like shown in Figure 32) needs to be installed. (Fig.32 shows a distributor system for a distribution starting from the middle of the wwtp system.) Figure 32: Example of a new distributor to Korat Wastewater Treatment Plant Report_on_Korat 47

48 3.4.6 Recommended action plan to restart the main wastewater treatment plant in Korat The first step in reactivating the wwtp 1 and wwtp 2 should be the repair of the travelling bridges over the clarifier basins of the AS system. To prevent the bridges from failing again it should be modified like shown in the recommendations of Mr. Messmer (see Annex 3). The second step is to get all things done due to the ToDo-List in Annex 2. The effects of this reparations and addition equipment should be checked by experts and The third step would be a planning for the new distribution building for a hydraulic distribution of Wastewater from P 1 and P 2.2 to wwtp 1 - (2) 3 the connecting pipes from pumping stations and to the aeration basins of wwtp 1 - (2) 3 Effluent from P1 and P 2.2 first into new distributor, from there to wwtp 1-3, from there to the ponds and out of the ponds to the outlet pipes of wwtp 1 - (2) 3. In the long term, the construction of a combined, aerated sand- and grease trap basin prior to the AS system is recommendable in order to keep sand from sedimenting in the AS basins. The collected sand can be used for example in road construction, for land-scaping and the retained grease can later be cofermented in the digestion tank (or the surplus sludge basin), which will lead to a higher biogas yield if treated in a digestion tank. However, the construction will be costly because of the AS systems locations in the last treatment ponds, which makes a more complicated pipe layout necessary to install an upstream basin Active sludge management Even with the flow direction reversed, the low content of degradable organic load in the wastewater influent will continue to be a challenge for the continuous operation of the AS system. A sludge management system has to eb installed to guarantee enough active bacteria mass (Activated sludge) even in cases of emergencies. An active sludge management by the treatment plant staff, similar to the methods used at the Dindaeng Water Environment Control Plant in Bangkok, should be implemented. This means that in case of very lowloaded inflow, excess sludge from a storage tank should be pumped into the AS basins in order to provide enough organic matter to keep the bacterial processes going. This storage tank should have a volume of 250 m 3, which is roughly equal to the daily excess sludge production (thickened) Report_on_Korat 48

49 3.4.8 Options for a sustainable operation of the wastewater treatment plant operation After setting into operation of the waste water treatment process at the wastewater treatment plant in Korat there should be taken some measures to guarantee a long-lasting operation. Among these options are the improvement of the technical equipment, the knowledge of the operational staff, the replacement of less effective instruments or machines, improvement of the knowledge of new technical developments Report_on_Korat 49

50 3.5 Annotation for the repair of the travelling bridges of the rectangular tanks of wwtp 1 and wwtp 2 (written by Mr. Messmer, awt Umwelttechnik Eisleben, Germany) The travelling bridges need one guiding side with two wheels with flanges moving on one rail. The guiding side will have contact to the top and to the sides of the rail head. The other side moves without guiding flanges only on the top of the rail head from the second rail. Figure 33: Hand drawing of the guding and rollng side of a traveling bridge Report_on_Korat 50

51 These are the non-guiding wheels. The guiding wheel should have a 5 mm wider running surface than the width of the rail head is. The guiding wheel must be align together. The non-guiding wheels must align together and must be parallel to the alignment of the guiding wheels. The guiding and non-guiding wheels must be fixed on the axles. There is no movement in direction of the axles allowed. This can be done by spacer sleeves to the bearings which are connected to the driving chassis. The non-guiding wheels must be wide enough to handle the wide-tolerances of one rail to the other rail. The tolerance in the wide of one rail to the other rail is for tank wides below 15 m max allowed to +- 5 mm. The tolerance in height is allowed to +-2mm for a 2m section. For the complete railway are +- 5 mm allowed. Rail joint must have a smooth top level without a noticeable height difference. Rail joints must be connected by rail joiners or must be welded to fix the height from one side to the other side while handling the wheel-loads. The drive motor can be installed in the middle of the bridge connected with transmissions to the driven wheels or every driven wheel can be directly connected with a drive motor. One non-driven wheel from a travelling bridge must be equipped with a sensor and a sensorplate to control the turning of the non-driven wheel if the drive motor is in operation. If the drive motor is operating and the sensor for monitoring the non-driven wheel shows 5sec no turning, the drive motor must immediately stop to prevent the travelling bridge and the wheels from damages and to prevent the bridge to come out of the railway. On each end of the rails there are sensor-plates or cushions to switch one of the end-position sensors. It s not necessary that both switches stop the bridge. It is allowed that one side of the bridge stops when the other side is up to 100 mm in front of the end position. This can vary from travel to travel depending on tolerances in the rails and in different sludge and wind-loads to the bridge. Further details are given in more detailed hand drawings fo the rail and wheels system in the annex Report_on_Korat 51

52 3.6 Annotation to the change of flow direction and the new distributor to feed wwtp 1 / 2 (written by Bernhard Wöffen, FiW) Remark: Assuming the repair of the wastewater treatment plant wwtp 1 and wwtp 2, the advisory team has agreed on the fact that the wastewater should first be treated by the wwtp and not by the pond system. The pond system will be foreseen as maturation of the treated wastewater effluent of the wwtp. The chapter 3 Annotation to the change of flow direction and the new distributor to feed wwtp 1 / 2 contains calculations and technical hints, that describe the necessary steps, followed by a cost estimation. The infrastructural works contain various tasks: A new distributor, new influent pipes have to be build, some openings for the new effluents and close the old effluents are necessary to change the flow direction. The temporal order of the changing of the flow direction is described as follows (see Figure 34: Chronological order of changing flow direction34). 1. Construction of the distributor on the existing pipeline from the pumping station P1 to the pumping station P 2.01 with the feed lines to the aeration basin of wwtp Preparation of the new settling tank effluents: drain openings 0.9mx0.9 m in the effluent channels opposite the current drain. 3. Production of the new pond flows through a shaft on the existing drainage line to the secondary sedimentation tank and new upstream drainage pipes (UK 1 m under current pond water level) a. Commissioning of the distributor by opening the pipeline and installing a slide valve on the side of the pipeline to the PW 2.02 (PW 2.02 goes out of operation) 4. Construction of the pumping line from PW 2.01 to the new distributer (use of the former pipeline PW1 to P 2.02 along the pond in the counter-flow direction) 4. 4.a Commissioning of the new (old) pump line to the new distributor bay (pressure line connection PW, opening of the built-in shut-off at the distributor) 5. Closure of the "old" drains of the settling tank. 6. Close "old" effluents of the aeration basin. 7. Emptying the no longer required ponds and closing the existing pond passages. 8. Reserved areas for sludge treatment Report_on_Korat 52

53 Figure 34: Chronological order of changing flow direction The technical information of the existing pipes (diameters, depth and materials) and the capacity of the pumping stations are not sufficient to construct the new distributor exactly. A formal outline of the distributor is given in Figure 35: Formal outline of the distributor for feed of wwtp Without the house for the vacuum system the building is 9.90 m x 4.00 m in length and width. Depending on the depth of the pipe from pumping station 1 to pumping station 2.02 at the edge of the ponds the depth of the distributor should be 3.50 m (see Figure 36 and The hydraulic losses for the needed pipes are calculated in Table 2 Hydraulic losses and needed length of the pipes from in the distributor. These losses are calculated on a basis of 2,500 m³/h for the pipes to wwtp 1 / 2. The estimation of the flow is based on 100,000 m³/d capacity of the plants (2 2,500 m³/h 24 h/d = 120,000 m³/d). Table 2 Hydraulic losses and needed length of the pipes from in the distributor from to di Länge L 0,02*L/Di v v2/2g hv Distributor wwtp1 1,000 mm 145 m m/s m m wwtp2 1,000 mm 371 m m/s m m emergency overflow pond 1,200 mm 10 m m/s m m The overflow height over the spillway of 4.50 m length is 0.30 m for 5,000 m³/h overflow and 0.19 m for the regular overflow of 2,500 m³/h Report_on_Korat 53

54 For the emergency overflow to the 1,200 mm pipe there is an overflow high of 0.34 m calculated. The most commonly used baffles are fixed baffles per DIN with a clearance between baffle and crest of 2 times the overflow head (2 x 0.19 = about 0.4 m, see Figure 35: Formal outline of the distributor for feed of wwtp 1 + 2) Report_on_Korat 54

55 0,80 m scum baffle knife gate valves 12,90 m top of spillway: max. top water aeration basin + losses pipe, + Innovative Wastewater Solutions for Korat (Nakhon Ratchasima), Thailand Pipe from P1, estimated DN 1.200, estimated depht 2,50 m B House for the Vacuum system 3,0 m effluent Vakuum system 0,3 m Layout of the distributor 4,5 m DN 1000 Pipe to wwtp 2, 371 m 0,3 m DN 1000 Pipe to wwtp 1, 145 m 4,5 m A emergency overflow DN 1200, to pond, 10 m A 0,3 m Estimated DN 1200 Pipe Valve for shut of to build connection to P ,3 m 1,4 m 0,4 0,3 m 1,3 m 0,3 m 4,0 m B Figure 35: Formal outline of the distributor for feed of wwtp Report_on_Korat 55

56 181 m +NN SECTION A-A 180 m +NN 179 m +NN House for the Vacuum system 178 m +NN Axis of knive gate valves 177 m +NN estimated level street 176,8 m +NN Top overflow 176,00 m +NN 0,80 m scum baffle DN 1000 Pipe to wwtp 2, 371 m 176 m +NN 175,80 m + NN DN 1000 Pipe to wwtp 1, 145 m 175,50 m + NN emergency overflow DN 1200, to pond, 10 m Level aeration basin m +NN Pond level 175,00 m cut off top of the pipe 174 m +NN Fill in concrete around the pipe 173 m +NN Estimated DN 1200 Pipe Figure 36: Section A-A of the distributor 181 m +NN SECTION B-B 180 m +NN House for the vacuum system 179 m +NN 178 m +NN cut off the top of the pipe for commission of the distributor 177 m +NN estimated level street emergency overflow ########## DN 1200, to pond, 10 m effluent Vakuum max. 176,30 m + NN 176 m +NN system normal water level 175,80 m + NN 0,80 m scum baffle Top 176,00 +NN bottom 175,20 +NN 175 m +NN Valve for commission distributor 174 m +NN 173 m +NN Estimated DN 1200 Pipe Figure 37: Section B-B of the distributor Report_on_Korat 56

57 Depending on the mentioned major uncertainties (flow, height and diameter of the pipes) the costs were calculated in Table 3. Table 3 Estimated masses and costs for changing the flow direction mass Description estimated TP Bath for each Total price 19.8 m³ concrete for the distributor base plate 500 9,900 19,000 THB 376,200 THB m³ concrete for the Distributor walls ,137 34,200 THB 955,206 THB m³ concrete for the distributor overflow walls 900 6,818 34,200 THB 259,065 THB 3 Slide Valves 1000 and 1200 mm 3,000 9, ,000 THB 342,000 THB 9.3 m scum baffle, stainless steel, 0.80 m high 600 5,580 22,800 THB 212,040 THB m² grate, with installation ,810 19,000 THB 600,780 THB 4.2 m emergency outlet DN ,200 5,040 45,600 THB 191,520 THB Total distributor (without, house for vacuum station) 115,417 2,936,811 THB 145 pipe DN 1000 to wwtp 1 1, ,000 38,000 THB 5,510,000 THB 371 pipe DN 1000 to wwtp 2 1, ,000 38,000 THB 14,098,000 THB 3 outlet pipes L= 10 m DN 800 from pond with new shaft 10,000 30, ,000 THB 1,140,000 THB 2 Closing outlet sedimentation basin, new outlet to the pond 4,500 9, ,000 THB 342,000 THB 2 Closing influent to aeration basin 1,500 3,000 57,000 THB 114,000 THB 1 Changing pumping station 2.01, effluent to new distributor can not be estimated without more knowlege Total 750,701 27,077,622 THB Report_on_Korat 57

58 3.7 Annotation to the use of the pond area for the installation of a Photo voltaic plant (calculated by the Mr Mihael Ketov, Institute for Electrical Plants and Energy Management, RWTH Aachen University (IAEW)) Remark: In case of a successful reactivation and renewal of the wastewater treatment and sewage sludge management in Korat there will be decisive change of the existing land used for the main waste water treatment plant in Korat. About half of the pond area will not be used for the waste water treatment process. There will be big potential for new land use by the municipality of Korat. Options already mentioned are the installation of a solar and wind park for the generation of electricity. Calculation of the possibilities of using PV and wind turbines on the land of 270,300 m² of the treatment plant area. Use of wind turbines Regarding the close distance to the military airport in Korat and the housing areas near to the wastewater treatment plant, it is very unlikely that a permit for the installation of wind mills will be issued. The height of suitable wind mills will be higher than150 m.there will be shadow effects, noise emissions, and adverse effects on the air traffic. Regarding the available wind velocities at that locations, the operation of wind mills will be positively assessed, but due to the other local limitiations no further evaluations were done. Calculation of the possibilities of using Photo voltaic plant Assumptions: Available land area of 270,300 m² (not used pond area). Only upfront investment without maintenance costs. Power grid extension costs not considered. Panels after investment period with no value. Constant over time: full load hours, efficiency, solar radiation, feed-in tariff, exchange rate and cost of capital Report_on_Korat 58

59 Table 4 Technical input and output data for the PV plant on the wwtp area in Korat Parameter Value Unit source Input data (Technical) average full load hours 1350 h/a pvest.php?lang=en&map=africa usable net area m² efficiency 14 % Solar_cell_efficiency average solar radiation at standard conditions 1 kw/m² Output data (Technical) total installed MWp calculated capacity average feed-in MWh/a calculated Parameter Value Unit source Input data (Financial) feed-in tariff 4.12 THB/kWh Projects phase 2, source: uploads/publication/ 384bf513d3c90d94c 609e 739be270b3den.pdf exchange rate =1/38.58 EUR/TBH total module price EUR/kWp ocuments/publications/ studies/ aktuelle -faktenzur- photovoltaik-in-deutschland.pdf cost of capital 8 %/a [C27] investment period 20 a [C30] present value factor for annuity 9,82 =(((1+(C27/100))^C30)- 1)/(((1+(C27/100))^C30)*(C27/100)) Output data (Financial) total upfront EUR calculated investment feed-in tariff EUR/a calculated payment total present value of EUR calculated feed-in tariff payment total present value EUR calculated of payments amortization 15.4 a calculated As the total present value of payments is positive, the potential of an installation and operation of a PV plant is assessed as high Report_on_Korat 59

60 4 FINDINGS of the September 2016 survey on the NEW DEVELOPMENT ZONE 7 KORAT 4.1 Water management structures of Zone 7 The new development zone of Korat, north of the Mittraphap road, is an area, which is still under construction. The land use is still diverse; agricultural uses dominate in the northern parts, the southern part is occupied by houses and department stores along the main road. In middle parts a mixed land uses with gated communities, single living houses, some workshops and shops were observed. Figure 38: Aerial view of the development zone 7 in Korat A sewer net is not laid. In the southern part seven combined sewer outlets (CSO) are installed, connected to the main sewer pipeline along the Mittraphap road to main wastewater treatment plant Korat. Figure 39: Sketch of development zone 7 with existing sewer net work Report_on_Korat 60

61 The area is dewatered by a small river, flowing from the eastern to the western part. The level is controlled by a weir (Fig.41) at the western border. The river is still meandering; the river bank is widely natural covered by brushes and single trees (Fig.42). The river is controlled by the regional irrigation department (RID8). Figure 40: Photos of various land uses, (agriculture) in the development zone 7 Figure 41: Photos of various river sections (weir, natural river bank, level measuring device, information plate of RID8) in the development zone 7 Wastewater treatment facilities were not installed. In the south-western part of zone 7 a small wastewater treatment plant consisting of two subsequently flown-through chambers was observed, which was constructed underground. The general condition of the inlet sewer pipes and pumping stations is unknown, however the visited facilities were not functioning due to no maintenance work, as can be seen in Fig Report_on_Korat 61

62 Given the suspected poor condition of at least parts of the sewer network, it cannot be guaranteed that all of the wastewater from the connected parts of the city arrives at the wastewater treatment plant. Figure 42: Wastewater facilities in Zone 7, left: decentralised treatment system, right: Waterflow under combined sewer overflow pipe The area of Zone 7 is still not fully developed. The already built housing areas are not connected to the centralized wastewater drain system. Agricultural areas are partly watered by the river and dewatered into an open drain system. The river water is polluted by the effluents of seven combined sewer overflows (CSO) (Figure 43). Figure 43: Sketch of the Development Zone 7, with indicated spots of the combined sewer (drainage) overflows and the natural river (green belt) Report_on_Korat 62

63 CSO are simple infrastructural works inside of a combined sewer or drain system. During periods of heavy rainfall, the additional volume in combined sewers system can exceed the capacity of the drain system. During these occasions combined sewer systems are designed to overflow and discharge the excess directly to the river without reaching the sewage treatment plant. These overflows contain not only land drainage (run-off rainwater), but also wastewater and debris. High levels of nutrients like Total Nitrogen and Total Phosphorous cause excessive algae and weed growth, which lowers wate quality, harms fish and other aquatic life as a result of lower oxygen levels. As the waste water management system is not well developed there are high potentials for the introduction of new energy-saving technologies, such as decentralized and or semidecentralized systems. 4.2 Conceptual recommendations for the wastewater management in Zone 7 The conceptual recommendations for the wastewater management in Zone 7 contains shortterm, intermediate and long-term measures, as follow: Short-term measures Corrective measures of the combined sewer outfalls strategy Protection of the natural river against pollution by surface run-off and storm water Intermediate term measures Integrated urban drainage planning (Master Plan), It is recommended to conduct an integrated urban drainage planning process.. Long-term measures In this phase of consultancy, long-term measures will not be described. More details on the city planning process should be made available. An integrated urban drainage plan (here categorized as intermediate-term measure) should be conducted to priorize future actions and to describe the interconnections of all water courses, drains, artificial reservoirs and treatment facililties Short-term corrective measures of the combined sewer outfalls The combined sewer system operation should be improved by measures, such as Developing a CSO Management strategy Implementing a monitoring program to identify and quantify CSO events Proactively eliminating wet weather flows from the Combined sewer district (zone 7) through infrastructural upgrades Report_on_Korat 63

64 Installing retention basins with filtration units (sand filter) (Figure 44) at the CSO. During an CSO event, the first flushes of the waste water can be collected in these retension basins and subsequently pumped back into the main sewer system. Figure 44: Photo of a retention basin with filter unit at the outlet point (www Short-term protection measures of the natural river against run-off water Land drainage from the city continuously pollute the river during wet weather events. This stormwater picks up pollutants as it flows across the land, whether it comes from streets, open areas, or rooftops. These river pollutions should be reduced by measures, such as Disposing of household chemicals and used oil properly, and not pouring them down the drain or in storm sewers on the street Fixing fluid leaks from vehicles, and Treatment of run-off water by installing filter systems, such as sand filter and weed root systems, installed along the river banks (Figure 45, 46) Figure 45: Schemes of run-off water treatment systems using sand filtrations and constructed wet lands Report_on_Korat 64

65 Figure 46: Photos of installed run-off water treatment systems using sand filtrations and constructed wet lands (Kirchhof, 2012) 4.3 Intermediate term measures for the wastewater management Development of an integrated urban drainage plan (Master Plan) It is recommended to develop an general integrated urban drainage plan. Many of the problems that the city wastewater authorities face are partly caused by the lack of an overall planning for the city s sewer network and water treatment facilities. One main problem is currently that the wastewater pumped into the main wastewater treatment plant is organically much lower loaded as designed. This fact is due to degradation processes in the drainage system and dilution processes due to wrong pipe connections or infiltration of surface or rain water to the sewer network. Apart from the main pipes, the exact location and condition of many combined sewers are mostly unknown. Extensions of the sewer network and new facilities are planned as reaction to local problems and taking little to no account of the rest of the downstream network or future developments. This can lead to various problems (overloaded sewers, not properly working pumping stations etc.) resulting in regular overflow from the sewers into nearby waterbodies Report_on_Korat 65

66 Figure 47: Core elements and topics of an integrated urban drainage planning by DWA In order to improve this situation, the elaboration of a master plan is highly recommendable. The DWA working paper A100 gives an overview on how to realize such a master plan, calling it an integrated urban drainage plan. It emphasizes the importance of an in-depth data acquisition from the target area (Step 3) as well as a functional and economical evaluation of the sewer network and treatment facility condition (Step 4) before elaborating a set of measures for the whole system (Step 5 and 6) and prioritization of these measures (Step 7). Given the suspected poor condition of at least parts of the sewer network, it cannot be guaranteed that all of the wastewater from the connected parts of the city arrives at the wastewater treatment plant Report_on_Korat 66

67 4.3.2 Recommendations for an integrated urban drainage plan for zone 7, focusing on decentralized measures It is recommended to develop an integrated urban drainage plan for zone 7, focusing on decentralized measures. Housing area Green bank river park Sand filter Housing area Agricultural production area (irrigated) Alternative Water reuse Wastewater treatment park VS Anaerob reactor with Biogas production Agriculture food processing Agricultural production area (irrigated) Alternative Alternative energy reuse fertilizer use Root filter Root filter Root filter Root filter Commercial area Root filter Figure 48: Concept for developments in the Development Zone 7, with indicated development topics A draft of a drain and wastewater treatment plan for zone 7 is shown in Figure 48 indicating following measures: River protection against pollution through run-off water o Creating a green bank and river park o Installing sand filter systems along the river course Sewage water collection and treatment o Construction of retention basins at the combined sewer outfalls o Connecting the commercial area directly to the main sewer system o Connecting housing areas to a wastewater treatment plant (wwtp) located in the zone 7, connected preferably by a vacuum sewer system, o Installation of a system to utilize the biogas derived from the sludge generated in the wastewater treatment process Options, which should be considered: Treated wastewater should be treated to such level that the water can be used as alternative source for the agricultural irrigation (such as vegetable production (urban farming). Sewage sludge should be treated to such a level that the sludge can be used as alternative natural fertilizer for the agricultural production. Surplus heat energy, which will be generated during the operation of combined heat and power plant (CHPs), can be used as alternative heat energy resources for agricultural productions, such as food drying. As zone 7 is less populated than the main city area and still used for agricultural productions, the local conditions are positively assessed and an installion of wind power plants should be regarded to generate alternative electricity sources Report_on_Korat 67

68 5 ANNEXES Report_on_Korat 68

69 Annex 1 a Checklists of the pumping stations P1, P 2.1, P 2.2 and wwtp Report_on_Korat 69

70 Annex 1 b Report_on_Korat 70

71 Annex 1 c Report_on_Korat 71

72 Annex 1 d Report_on_Korat 72

73 Annex 2 a General To Do List Report_on_Korat 73

74 Annex 2 b General To Do List Report_on_Korat 74

75 Annex 2 c General To Do List Report_on_Korat 75

76 Annex 3 a Recommendations for the repair of the traveling bridges from Mr. Messmer, awt Umwelttechnik Eisleben, Germany Report_on_Korat 76

77 Annex 3 b Recommendations for the repair of the traveling bridges from Mr. Messmer, awt Umwelttechnik Eisleben, Germany Report_on_Korat 77

78 Annex 3 c Recommendations for the repair of the traveling bridges from Mr. Messmer, awt Umwelttechnik Eisleben, Germany Report_on_Korat 78

79 Annex 4: Calculation matrix to calculate basic data for a PV-plant Report_on_Korat 79

80 Annex 5: Climate diagrams for the Korat area Average minimum and maximum temperature over the year Average monthly hours of sunshine over the year Average monthly precipitation over the year (rainfall) Report_on_Korat 80