www.life-uftec.eu www.life-uftec.eu With the contribution of the Life financial instrument of the European Commission 1
PROJECT CHARACTERISTICS Coordinator CETaqua Associated beneficiaries SGAB, Pentair and Dow Duration 3 years (1 st September 2010-31 st August 2013) Budget 2.156 k Funding 1.051 k - LIFE+ Programme of the EC BENEFICIARIES STAKEHOLDERS COFINANCED BY 2
www.life-uftec.eu Outline 1 - Context and background...4 2 - The UFTEC project...6 3 - The case study: The Llobregat River (Spain)...7 4 - Goals...9 5 - Direct UF prototypes & RO pilot plant...10 Pentair technology: pressurised inside-out membranes Dow technology: pressurised outside-in membranes GE-Zenon technology: submerged outside-in membranes RO pilot plant 6 - Technical assessment of direct UF over conventional pre-treatment...15 Water quality Assessment of the impact of direct UF on RO membranes Technical comparison of direct UF and conventional pre-treatment 7 - Environmental and cost-effectiveness analysis of direct UF and conventional pre-treatment...20 Environmental impact assessment Cost-effectiveness analysis 8 - Communication activities...23 Final workshop and visits Technical events Publications Website and video 9 - Conclusions...26 3
1 Figure 1 Picture of a freshwater source in Castellar de n Hug (Barcelona) Context and background Freshwater accounts for only 2.5% of total water volume within the planet. The need to preserve it and make an efficient use of the resource is mandatory to ensure the life continuation. Drinking water treatment plants (DWTPs) will have to face significant challenges in the following decades: be able to supply an increasing water demand using lower quality resources under an increased stringency in legislation and sustainability framework. This context requires the application of leadingedge technologies combined with best operational practices, enabling a cost reduction and a risk minimization. 4
www.life-uftec.eu 1 Context and background The UFTEC project was started in 2010 as a response to DWTPs needs, in order to provide tools to drinking water plant s managers to better adapt them to the current and future context. The UFTEC concept relies on the application of direct ultrafiltration (UF) technology as a pre-treatment in DWTPs, as alternative to the conventional ones which typically include dioxichlorination, coagulation/flocculation, settling and sand filtration. Direct Ultrafiltration (UF) can be an appropriate technology to substitute and/or update conventional pretreatment for subsequent reverse osmosis (RO) stage in surface water treatment plants. However, its long-term efficiency needed to be assessed at demonstration scale (with real surface water) not only in technical terms but also in environmental and economic ones. Figure 2 Sant Joan Despí DWTP conventional pre-treatment (settlers) ULTRAFILTRATION Ultrafiltration is being increasingly used for drinking water production, gradually gaining acceptance as the preferred pre-treatment to reverse osmosis. Ultrafiltration (UF) is a technology where water is forced through a membrane, obtaining a permeate free of solids and pathogens such as viruses and bacteria, as can be seen in Figure 3. ULTRAFILTRATION 20-40 nm RAW WATER PERMEATE WATER Figure 3 Ultrafiltration principle Virus Bacteria Protein Suspended solids Salts + Dissolved matter Salts Dissolved organic matter 5
2 The UFTEC project The UFTEC project aimed at substituting conventional pre-treatment of raw river water by direct UF. As the demo site was Sant Joan Despí DWTP, the conventional pre-treatment compared consisted of dioxichlorination, coagulation, flocculation, settling and sand filtration, as shown in Figure 4. The approach adopted in this project was totally disruptive, pushing further the application of UF, since it was implemented just at the beginning of the treatment scheme. Demonstration site: Sant Joan Despí DWTP (Barcelona, Spain) (3 prototypes) (1 pilot plant) (not studied) (not studied) Conventional pre-treatment UFTEC concept Figure 4 Scheme of the UFTEC concept versus the conventional pre-treatment in the case study selected 6
www.life-uftec.eu 3 Figure 5 The Llobregat river, the case study selected The case study: The Llobregat River The surface water selected in the project was the Llobregat River, which represents a challenging scenario due to its high variability both in quality and quantity aspects. For instance, turbidity during the period studied (2011-2013) varied from less than 10 NTU to more than 1000 NTU. Sant Joan Despí DWTP (Spain), which is using Llobregat river water as a source for drinking water production for Barcelona area, was selected as a case study. This led to the possibility of testing a broad range of scenarios in terms of water quality and technical operation conditions. 7
3 The case study The Llobregat River Barcelona, Spain Length: 170 km Springs altitude: 1259 masl Figure 6 Pictures of the water intake of Sant Joan Despí DWTP in different periods of draught (up) and floods (down) Sant Joan Despí Barcelona, Spain Site location ZOOM UFTEC site Figure 7 Location of Sant Joan Despí DWTP and the UFTEC project site 8
www.life-uftec.eu 4 Goals To demonstrate at prototype scale that direct UF can be an efficient alternative to conventional pretreatment for RO in DWTPs (Sant Joan Despí as model plant). To assess the efficiency of 3 direct UF prototypes with different configurations and membrane materials. To evaluate reagents and energy consumption as well as water losses of conventional and UF pre-treatment. To perform Life Cycle Analysis (LCA) and Cost Efectiveness Analysis (CEA) for the environmental and economic comparison of direct UF and conventional pre-treatment. To disseminate results obtained and transfer the knowledge gathered to other DWTPs in Europe. Figure 8 Detail of Sant Joan Despí DWTP 9
5 Figure 9 Picture of the site with the UFTEC direct UF prototypes Direct UF prototypes & RO pilot plant Three direct UF prototypes with the three existing module configurations were operated continuously during 2 years (since May 2011 to April 2013), in Sant Joan Despí DWTP (Spain). Additionally, an experimental RO unit was also operated during one year to assess the impact of direct UF on a subsequent RO step. The sizes of the three UF prototypes were chosen in order to eliminate scaling up risks. An exhaustive monitoring program was applied in the direct UF process in terms of water quality and productivity, chemicals and energy consumption in order to carry out a technical, environmental and economic assessment of the process concept studied. 10
www.life-uftec.eu 5.1 PENTAIR PROTOTYPE Pressurised inside-out membranes Membrane Scheme: Figure 10 Scheme of the inside-out pressurised technology PENTAIR PROTOTYPE (Pressurised inside-out membranes) Technology Pentair (former Norit) Configuration Pressurised inside-out Membrane model Pentair X-Flow Aquaflex Pore size 20 nm (max. 22,5 nm) Material PES/PVP Filtration Area Pre-treatment possibilities Maximum capacity Aquaflex (55m 2 ) Strainer (300 μm) Coagulant dosing (in tank, in line) ph correction 7.7 m 3 /h (5.3 m 3 /h nominal capacity) Possible cleaning sequences Hydraulic: Backwash-Forward flush, airflush Chemical cleaning: NaOCl, NaOH;HCl Figure 11 Picture of Pentair prototype (PT1) Table 1 Characteristics of the Pentair prototype (PT1) 11
5.2 DOW PROTOTYPE Pressurised outside-in membranes Membrane Scheme: Figure 12 Scheme of the outside-in pressurised technology DOW PROTOTYPE (Pressurised outside-in membranes) Membranes DOW TM Ultrafiltration SFP-2880 Number of modules 2 Material PVDF Filtration Area 77 m 2 (each module) Pore size 30 nm Nominal capacity 5 m 3 /h (each module) Pre-treatment Hydrocyclon and ring filters (200 μm) Chemical Pretreatment No Cleaning sequences Table 2 BW: Backwash (including Air Scour and Forward Flush) CEB: Chemically Enhanced Backwash CIP: Cleaning in Place Characteristics of DOW prototype (PT2) Figure 13 Picture of DOW prototype (PT2) 12
www.life-uftec.eu 5.3 SGAB PROTOTYPE Pressurised outside-in membranes Membrane Scheme: Figure 14 Scheme of the outside-in submerged technology SGAB PROTOTYPE (Pressurised outside-in membranes) Membranes GE-Zenon ZW500D Number of trains 1 Number of modules per train 10 Material PVDF Filtration Area 40.9 m 2 (each module) Pore size Nominal capacity Pretreatment Cleaning sequences Other possible sequences Flux (fixed) 40 nm 10 m 3 /h (max. of 15 m 3 /h) Rotary screen (1mm), coagulation and additional ph control Backwash (BW) + Air Scour (AS) CEB: BW+AS+dosing of NaOCl/Citric acid CIP: dosing and soaking with NaOCl/Citric acid Relax - Air scour 24.5 LMH Figure 15 Picture of the SGAB prototype (GE-Zenon technology) (PT3) Table 3 Characteristics of GE-Zenon prototype (PT3) 13
5.4 RO PILOT PLANT Spiral-wound membranes Membrane Scheme: Figure 17 Scheme of RO technology RO PILOT PLANT (Spiral-wound membranes) Technology RO Configuration 4 lines with 1 membrane each: 1 for PT1 permeate, 1 for PT2 permeate, 1 for PT3 permeate and 1 for conventional pre-treated water Membrane model LE2540 (DOW) Size 4 inch modules Feed flow 1 m 3 /h per line Average conversion 15% Table 4 Characteristics of the RO pilot plant Figure 16 Picture of the RO pilot plant 14
www.life-uftec.eu 6 Figure 18 Detail of Sant Joan Despí DWTP conventional pre-treatment Technical assessment of direct UF over conventional pre-treatment The feasibility of direct UF has been assessed and operational conditions have been optimized for the different feed water quality scenarios faced. Water quality obtained by direct UF has been fairly constant in terms of turbidity, suspended solids content, fouling indexes and microbiological analysis, independently of the feed water fluctuations. Results obtained have been compared with the conventional pre-treatment water quality, as shown in this chapter. 15
6.1 ; Water quality Turbidity and Total Suspended Solids (TSS) Average values 100 144,1 147,0 TSS (mg/l) Turbidity (NTU) 10 1 0,1 0,01 0,28 Turbidity 0,04 1,39 TSS 0,35 Average turbidity and TSS of the UF permeate is lower than the water from the conventional pretreatment (Figure 19). Direct UF permeate turbidity is kept under the recommended value of 0.2NTU in almost all cases, whereas conventional exceeds in 50% of the samples. In addition, permeate turbidity is constant and independent of the feed water variability, as can be seen in Figure 20. Turbidity (NTU), TSS (mg/l) Raw water Conventional pre-treatment Direct UF Figure 19 Average turbidity in raw and pre-treated water Recommended turbidity for subsequent RO process is <0.2NTU, which is achieved with direct UF. Cumulative frequency (%) 100 80 % 60 40 20 0 0,01 0,1 1 10 100 1000 10000 Turbidity % Raw water Figure 20 Conventional pre-treatment Direct UF Turbidity frequency distribution in raw and pre-treated water. Figure 21 Detail of Cetaqua s laboratory 16
www.life-uftec.eu Fouling indexes: Silt Density Index (SDI) and Modified Fouling Index (MFI) MFI (s/l 2 ) 12 10 8 ; ; 13,21 Conventional pre-treated water exceeds the recommended value for subsequent RO stage. In consequence further pretreatment should be needed to meet the SDI requirements. UF satisfactory achieved the limit. SDI (%/min) 6 SDI and MFI values for direct UF are kept under the limits recommended for subsequent RO stages in all cases. 4 2 4,98 SDI max = 3%/min 1,98 MFI max = 1s/L 2 0,16 Silt density index (SDI) Modified Fouling Index (MFI) Figure 22 Average of SDI and MFI indexes obtained in conventional and direct UF pre-treated water. SDI (%/min), MFI (s/l 2 ) Conventional pre-treatment Direct UF Dissolved Organic Carbon (DOC) and Absorbance at 254nm (UV-254) 12 DOC (mg/l) Absorbance 10 8 6 9,48 7,00 8,36 Conventional pre-treatment reaches higher removal of DOC and Absorbance due to the dioxichlorination step used. DOC and Absorbance values are similar in both pre-treatment schemes. 4 2 4,33 3,40 DOC 3,83 UV254 Figure 23 Average of DOC and Absorbance obtained in raw and pre-treated water. DOC (mg/l), Abs-254 Raw water Conventional pre-treatment Direct UF Microbiological parameters Log of removal 5 4 3 2 3,2 4,6 3,6 3,5 3,0 3,1 2,7 2,0 Direct UF is useful for the disinfection of raw river water in the pre-treatment step, as it is not consuming disinfectants. Direct UF completely removes E.Coli, total coliforms, faecals coliforms and clostridium perfringens without the use of disinfectants. Aerobic bacteria was not totally removed due to biofilm formation in the UF prototype effluent pipes 1 0,0 0,6 E.Coli Total Coliforms Faecal Coliforms Clostridium perfringens Aerobic bacteria Figure 24 Average of microbiological parameters removal obtained in both conventional and direct UF pre-treated water Log of removal Conventional pre-treatment Direct UF 17
6.2 Impact of direct UF on RO membranes From the RO pilot plant operated within the project during a complete year, no fouling effect was observed in any of the membranes fed with UF permeates. Autopsies of the RO membranes have been conducted to asses the impact of the pre-treatments on subsequent stage. Figure 25 Pictures of the autopsy conducted on the RO membranes used in the project No detrimental effect on the membrane surface due to UF permeate quality was observed after one year of operation. 18
www.life-uftec.eu 6.3 Technical comparison of direct UF and conventional pre-treatment The data obtained during the two years of prototypes operation has been used to scale-up the direct UF technologies in the case of Sant Joan Despí DWTP (total production of 5.6 m 3 /s) and to finally compare the technical efficiency of both treatments in terms of energy and reagents consumptions as well as water losses. A conventional pre-treatment using dynamic settling was considered for the comparison. From the scale-up of the three prototypes, summarized in Table 5, it can be concluded that direct UF has similar water yields but lower reagents consumption than conventional pre-treatment. Direct UF can be operated without coagulants or with micro-coagulation (doses up to 1.5ppm) depending on the feed water quality conditions. Thus it minimizes the amount of sludge generated and reagents consumption in comparison to conventional pre-treatment. Direct UF allows avoiding the dioxichlorination step needed in the conventional pre-treatment, as the UF technology is able to remove part of the organic macromolecules without the use of disinfectants. In addition, direct UF increases water productivity as it can be operated at higher turbidity events in contrast to conventional pre-treatment, that needs to be stopped when inlet turbidity exceeds 500 NTU. However, energy consumption for direct UF is slightly higher than for conventional pre-treatment. PROJECTIONS Direct UF Conventional pre-treatment Produced Flow (m 3 /s) 5.6 Water yield (%) 89-95% ~90-97% % of operation time 100% 63-90% Coagulant dosing (ppm) 0-1.5 (FeCl 3 ) 20 (PAX) or 30-40 (FeCl 3 ) Total reagents needed (Tn/year) 700-1967 ~3776 Dioxichlorination reagents (Tn/year) 0 ~1311 Energy consumption (kwh/m 3 ) 0.10-0.27 ~0.08 Table 5 Results of the technical comparison of conventional pre-treatment and direct UF concept in Sant Joan Despí DWTP Technology scale-up data has been used for the assessment 19
7 Figure 26 Settlers of Sant Joan Despí DWTP Environmental and cost-effectiveness analysis of direct UF and conventional pre-treatment 20
www.life-uftec.eu 7.1 Environmental impact assessment: A life cycle assessment (LCA) focused on global warming impact was performed using the data obtained from the operation and optimization of the prototypes and from the different direct UF full scale-up projections performed. Only operation was considered for the LCA (e.g. commissioning and decommissioning of the plants were not taken into account). Conventional 0.0824* kg CO 2 eq./m 3 Results showed that both conventional pretreatment and direct UF present similar environmental impact, although impact of sludge produced has not been considered (Table 6). Direct UF main contribution to the impact generated is energy consumption whereas for conventional pre-treatment is chemical consumption (Figure 27). Direct UF (Range) 0.1296 (0.07-0.18) kg CO 2 eq./m 3 * sludge treatment not considered Table 6 Environmental impact of direct UF and conventional pre-treatment in global warming 100% 90% 11% 0,17% 8% 80% 24% 88% 70% % of CO 2 emissions 60% 50% 40% 30% 65% 20% 10% Conventional pre-treatment Direct UF Figure 28 Picture of the operation of the prototypes Transports Membrane Materials Chemicals Energy Figure 27 Contribution in the environmental impact assessed 21
7.2 Cost-effectiveness analysis An economic assessment of both pre-treatment schemes was conducted during the project taking into account the scale-up projections and the results obtained from the prototypes. From the results obtained, a cost-effective ratio (CER) was calculated using Equation 1. Effectiveness (E) was defined as the capacity of the different systems to improve pre-treated water quality, which is related to the removal efficiency experimentally measured in the prototypes. The most cost-effective UF is in comparison to conventional pre-treatment when CER tends to zero CER = C uf - C conv. Euf - E conv. Equation 1 0,45 0,40 0,35 0,30 0,37 0,28 C UF - Cost of direct UF C CONV. - Cost of conventional pre-treatment E UF - Effectiveness of direct UF in the parameter studied E CONV. - Effectiveness of conventional pre-treatment in the parameter studied CER Ratio 0,25 0,20 0,15 0,13 0,10 0,09 0,08 0,03 0,0 Clostridium perfringens Aerobic bacteria Total Coliforms Faecal Coliforms E. Coli SDI Figure 29 CER ratios where direct UF is more cost-effective. UF is more cost-effective when CER tends to zero The direct ultrafiltration system is more cost-effective for reducing fouling indexes (SDI) and some microbiological parameters whereas for turbidity, TSS, DOC and Absorbance parameters, conventional pre-treatment is more cost-effective. Nevertheless, conventional pre-treatment alone would not be suitable for subsequent RO stage, as SDI is above the recommended limit, and in consequence, further treatments increasing the final costs would be required. 22
www.life-uftec.eu 8 Figure 30 Attendants of the UFTEC Final Workshop Communication activities Numerous dissemination activities were carried out during the entire length of the project, aiming to disseminate the project s results and enhance the transferability of the know-how to other entities. 23
8.1 Final Workshop and site visits On June 20 th of 2013, the UFTEC final workshop was held in Cornellà de Llobregat. The event presented the main results and conclusions from the project through different presentations of the partners involved, and ended with a visit to the site in Sant Joan Despí. More than 70 water professionals attended the workshop. The visit to the UFTEC site was done several times throughout the project, with students, professionals and other people interested in the project. More than 150 experts visited the site during the 2 years of prototypes operation. 8.2 Technical events Figure 31 Attendants welcome and technical sessions of the UFTEC Final Workshop The project was presented in the following technical events (2 posters and 7 oral presentations): EDS Conference on Desalination for the Environment Clean Water and Energy (2012, Spain) International Conference on Membranes in Drinking and Industrial Water Production (2012, The Netherlands) Euromembrane (2012, UK) IX Congreso Internacional AEDyR (2012, Spain) Infoenviro: Aplicaciones Tecnológicas en el Tratamiento de Agua Potable (2012, Spain) 1 st International Conference on Desalination using membrane technologies (2013, Spain) 10 th IWA Leading Edge Conference on Water and Waste Water Technologies (2013, France) IDA World Congress (2013, China) 7 th IWA Specialised Membrane Technology Conference and Exhibition for Water and Wastewater Treatment and Reuse (2013, Canada) In addition, networking through the project was carried out through meetings with interested parties and attendance in exhibitions. 24
www.life-uftec.eu 8.3 Publications 2 PhDs thesis and 4 Master Thesis were conducted within the UFTEC project. In addition, 2 peerreviewed papers with the results of the operation of the prototypes were published in Desalination and Water Treatment Journal. More than 6 specialized press articles and 17 news on internet were published during the project to disseminate the results and conclusions obtained. 8.4 Website and video The project website (www.life-uftec.eu) was developed to open the door to the internet. The web contains general information about the project and its participants, receiving almost 8.000 visits in 3 years. A short 5-minutes documentary with a global overview of the entire UFTEC project is also available in the project website. Figure 32 UFTEC s website 25
9 Figure 33 Water sampling in the UFTEC prototypes Conclusions The UFTEC project has proven the feasibility of direct UF as a substitution of conventional pretreatment in challenging surface water sources. The three prototypes of direct UF were able successfully to deal with variable feed quality conditions, with turbidities ranging from 5 to >1000 NTU, in a continuous operation mode. The technical feasibility was proven and their performance was significantly optimized in order to become a competitive technical alternative to conventional pretreatment. 26
www.life-uftec.eu 9 Conclusions The innovative scheme proposed for DWTPs in the UFTEC project (direct UF followed by RO) offers technical advantages versus conventional pre-treatment: high and constant UF permeate quality independently of incoming water quality, soft need of coagulant for some feed water quality conditions (and hence, minimal sludge generation), reliability, modularity (and thus, easiness to scale-up), capacity to work even at extremely high turbidities (>1000 NTU) and operation easiness. Summary of technical advantages of direct UF vs. conventional pre-treatment: Complete elimination of dioxichlorination dosing Reduction of coagulants needs (up to 100% reduction) Similar water production yield (89-95%) Increase of water treatment availability (from 500 to > 1000 NTU) and increase in the operating time. Improvement of pre-treated water quality (especially in terms of fouling indexes and microbiological parameters) The environmental impact of the direct UF concept was assessed during the project, concluding that the global warming impact of this technology is similar to the produced by a conventional pre-treatment. The cost-effectiveness analysis demonstrates that direct UF is especially costly-effective for the reduction of microbiological parameters and SDI, which makes it an interesting alternative as a pretreatment for subsequent RO processes in challenging surface waters. Conventional pre-treatment alone would not be technically feasible for subsequent RO and in consequence, other combined pretreatment would be needed. That fact would increase the costs and the final environmental impact for the conventional pre-treatment scheme. Because the case study selected, the Llobregat River, is highly variable, multiple scenarios were assessed. Since direct UF has demonstrated to be feasible with this challenging water source, it may be applicable in further sites, being the results highly transferable among other sites. Therefore, the innovative scheme proposed could be applied either for the construction and the upgrade of DWTPs, paving the way for the implantation of more stringent pieces of legislation and upcoming challenges. 27
With the contribution of the Life financial instrument of the European Commission www.life-uftec.eu