Wastewater Reuse for Irrigation, the Stabilization Reservoirs Concept

Transcription

1 Wastewater Reuse for Irrigation, the Stabilization Reservoirs Concept By Dr. Menahem Libhaber Lead Specialist, LAC Region Presented in the Water Week, March 4-6, 2003

2 Contents Context and Principles Public Health Risks, Standards and Protection Strategies The Stabilization Reservoirs Concept Examples and Case Studies

3 World Bank Publications on Wastewater Reuse for Irrigation World Bank Technical Paper No. 51, Wastewater Irrigation in Developing Countries, Health Effects and Technical Solutions, Shuval et al., 1986 Summary of World Bank Technical Paper No. 51, Shuval, 1990 Water and Sanitation Report No. 6, Reuse of Wastewater in Agriculture, A Guide for Planners, Khouri, Kalbermatten, Bartone, 1994

4 Commonly Mentioned Issues and Conditions for Successful Reuse Projects Public acceptance Legal and regulatory framework Institutional aspects Finance and economics Water Quality: reuse standards, public health risk assessment, monitoring Treatment technologies, efficiency and reliability

5 Conditions for Successful/Feasible Reuse Projects not Always Considered Existence of long term commitment for consumption of water for irrigation (agricultural infrastructure) Shortage of alternative water sources Efficient use of effluent (seasonal storage and efficient irrigation)

6 Word Population Growth Forecast Source: WDR 2003

7 Arid Lands of the World Source:WDR 2003

8 Projected Water Scarcity in 2025 Source:WDR 2003 Physical Water Scarcity Economic Water Scarcity

9 Implications of the Trends of Urbanization and Population Growth Increased urban water demand Increased generation of municipal wastewater Increased irrigated land and increased demand of water for agriculture to generate sufficient food for the growing population

10 Future Water Resources Management Strategy Efficient Irrigation Small scale Solutions Reuse of municipal effluents for irrigation Effluent recycling for industrial reuse Effluent recycling for non-potable municipal reuse Water conservation (Demand Management) Application of adequate tariff policy Application of adequate regulation Water etics Desalination

11 Potential Water Savings Utilizing currently avialable technologies enables reducing water consumption as follows: For irrigation by 50% For industry by 50-90% For urban use by 30%

12 The Attractiveness of Wastewater Reuse for Irrigation Wastewater contains 99.9% water Safe water source, independent of climatic conditions Irrigation is needed in areas were water is scarce and wastewater reuse is necessary to supplement available fresh water resources. It is a safe source, independent of climatic conditions Presents no danger of accumulation of contaminants Agriculture requires large amounts of water which are used only once since irrigation is a consumptive use. Thus there is no danger of gradual accumulation in the water of undesirable substances by continuous recycling

13 The Attractiveness of Wastewater Reuse for Irrigation (2) Wastewater contains nutrients and organic matter which are beneficial for plants Agriculture can use not only water but also additional water resources found in wastewater such as organic matter, major nutrients (N, P, K) and micronutrients which are thus converted from an environmental nuisance to an asset Irrigation is flexible in respect to water quality Irrigation is Relatively flexible with respect to water quality requirements. Some crops can be irrigated with low quality water and some water problems can be overcome by suitable agricultural practices Wastewater reuse prevents contamination of water resources Wastewater reuse prevents its discharge to receiving water bodies and pollution of water resources

14 Fertilizer Value of Sewage Effluents Fertilizer Commercial application rate Kg/ha mg/l Effluent Kg/ha % Ammonium Sulfate as N Superphosphate as P Potassium Chloride as K Calculations based on cotton irrigation using 5,000 m 3 /ha, 80% irrigation efficiency and assuming that 85% of the nutrients are available to the crops

15 Leading Countries in Wastewater Reuse Activities Australia High Morocco Middle Cyprus High South Africa High France Middle Saudi Arabia Intensive India High Spain High Israel Intensive Oman High Japan Intensive Tunisia Middle Kuwait Intensive U. Arab Emirates Intensive Namibia Middle USA Arizona, Florida High Mexico Middle USA, California Intensive

16 Impact of the Chemical Composition of Municipal Wastewater on Effluent Adequacy for Reuse in Irrigation The chemical composition of the wastewater and its impact on plants needs to be evaluated, but the same can be said for irrigation with any water water source For typical municipal wastewater, all potential negative effects can be controlled with existing knowledge and agronomic technology Pathogenic quality is the only parameter of importance which differentiates between effluents and other water sources

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18 WHO Recommended Microbial Quality Guidelines for Wastewater Use in Agriculture

19 Ranking of the Order of Risks Imposed by Pathogens and the Resulting Treatment Criteria Order of Risks High Risk: Intestinal Nematods-Helminths (Ascaris, Trichuris, Ancylostoma, Taenia) Lower Risk: Enteric Bacteria (Cholera, Typhoid, Shigalea and others); Protozoa (Amena, Giardia) Least Risk: Enteric Viruses (rotavirus, hepatitis) Treatment Criteria Maximum removal of helminths and protozoa Effective removal of pathogenic bacteria and viruses Effective reduction of BOD to prevent offensive smell and objectionable appearance of the effluent

20 Safe Reuse: Measures for Protection of Public Health Prescribing wastewater treatment processes and/or storage oriented towards effectively reducing priority pathogens to levels at which the index of excess infection by these pathogens is practically controlled Prescribing the methods and procedures of irrigation so as to minimize the direct contact between the crops and the effluent Restricting the type of crops allowed to be irrigated with effluent so as to eliminate the risk of direct consumption of vegetables eaten row

21 Principles of Wastewater Treatment Preliminary and Primary Treatment Secondary Biological Treatment Tertiary Treatment and/or Disinfection Preliminary and Primary Treatment Physical Biological Treatment Aerobic (Consumes Oxygen and produces sludge) Anaerobic (No Oxygen consumed No sludge produced, Methane produced) Tertiary Treatment Mostly Chemical, but can be biological (Nitrification/Denitrification and P removal) Disinfection Chemical Products (Chlorine, Chlor Dioxide) Radiation (Solar or Artificial UV)

22 Removal of Bacteria, Viruses and Helminth Eggs in Ponds

23 Application Methods: Drip Irrigation is the Recommended Method

24 Laying Drip irrigation Pipes

25 Drip Irrigation of Corn Using the Eial Reservoir Effluent

26 Drip Irrigation of Almonds and Fruit Trees

27 Sub-Surface Drip Irrigation

28 Water Use Efficiency In Irrigation Adoption of more efficient methods of irrigation can bring about important economic benefits Surface irrigation 50-60% Sprinkler irrigation 70-80% Drip irrigation 90-95%

29 Restriction of Crops According to Effluent Quality Crop Category A B C Crops for human consumption eaten cooked Cereals Crop Type Examples Crops not for human consumption (Industrial crops) Crops processed by heat before consumption Landscape irrigation in areas closed to public Fodder crops Pastures and trees Crops eaten uncooked Landscape irrigation in areas with free access to public Effluent Quality Low Medium High

30 Restriction of Crops According to Effluent Quality

31 Seasonal Storage of Effluent The Rationale Flow patterns: raw wastewater versus consumption for irrigation Wastewater is discharged at a year round constant flow Water for irrigation is consumed seasonally Increase of water use efficiency and consequently of economic feasibility Pollution control: without storage, other more expensive solutions would have been required during the non-irrigation season

32 Seasonal Storage of Effluent The Rationale (cont.) The incorporation of the combination of storage and drip irrigation in a project greatly enhances the economic feasibility of agricultural production since it enables irrigating with the annual amount of effluent areas 4 times larger than those irrigated in a project with no storage and which uses surface irrigation

33 The Need for Effluent Storage: Typical Annual Cycle of a Continuous-Flow Reservoir in Israel

34 Common Practice: No Relation Between Irrigation and Wastewater Disposal Water Collection System RESERVOIR SEWAGE TREATMENT SEWAGE COLLECTION SYSTEM IRRIGATED FIELDS EFFLUENT DISCHARGE

35 Proposed Approach in Water Scarce Zones SEWAGE TREATMENT RESERVOIR SEWAGE COLLECTION SYSTEM IRRIGATED FIELDS Unite Treatment and Storage

36 The Stabilization Reservoir Reuse Concept Water Depth 8-12 m Municipal Max. Level (Beginning of Irrigation Season) Effluent Wastewater Pretreatment Anaerobic Lagoons, Oxidation Ponds, Aerated Lagoons, Activated Sludge, Etc. Min. (End of Irrigation Season) Storage and Stabilization Deep Reservoir For Reuse (Usually by Drip Irrigation)

37 Arial View of a Typical Stabilization Reservoir Reuse System

38 Flow Diagram of an Activated Sludge Process

39 Arial View of an Activated Sludge Plant

40 Nirim Stabilization Reservoir

41 Empty Reservoir at the End of the Irrigation Season

42 Location of Stabilization Reservoirs in Israel Total No of Reservoirs: About 240 Volume Range: million m 3 The Majority is in the range: million m 3 Wastewater generated: 390 mcm/year Stored in surface reservoirs: 164 mcm/year Stored in aquifers: 90 mcm/year Total reclaimed for irrigation 254 mcm/year, i.e., 65% of the generated wastewater Surface storage volume (effluent plus marginal water) 140 mcm Reclaimed wastewater as percentage of fresh water resources is 15.4% Reclaimed wastewater as percentage of total water resources(fresh plus marginal) is 12.7%

43 Wind Induced Currents in a Reservoir

44 Naan Stabilization Reservoir Plan of Reservoir and Pre-Treatment Ponds

45 Naan Stabilization Reservoir Typical Cross Section 11 meters

46 Effluent Extraction Device Surface Water Level Float Screen Extracts effluent at a Constant Depth Beneath the Water surface Chain Point of Effluent Extraction Floating Tube Cable Bottom of Reservoir Effluent Extraction Pipe Reinforced Concrete Structure Rotating Axis

47 Permeabilization of the Bottom of a Reservoir

48 Variation of Effluent Coliforms and Organic Matter in the Getaot Reservoir During the Hydrological Year COD, mg/l The reservoir was operated as a continuous flow reactor, i.e., influent continues to enter the reservoir during the irrigation season Total Coliform, Log 10 MPN/100 cc

49 Raw Waste water Operational Regimes of Stabilization Reservoirs Anaerobic Lagoons Continuous filling all year Reservoir 1 Restricted irrigation A. One Stabilization Reservoir with Continuous inflow and Discontinuous discharge Raw Waste water Anaerobic Lagoons Filling Only During Aerated Lagoons Non-Irrigation Season Filling during Reservoir 1 irrigation season Unrestricted irrigation Raw Waste water B. Two Stabilization Reservoirs Operating as Quasi Sequential Batch Reactors in Parallel Anaerobic Lagoons Aerated Lagoons Continuous filling Reservoir 2 Filling During Next Non-Irrigation Season Restricted Irrigation Reservoir 1 Reservoir 2 Filling Only During Non -Irrigation Season Unrestricted irrigation C. Two Stabilization Reservoirs Operating as Sequential Batch Reactors in Series Restricted Irrigation

50 Migdal Haemek, Effluent Quality of a two Reservoirs System Operating in Series Continuous filling all year Filling Only During Non-Irrigation Season Fecal Coliforms 0-10 MPN/100 ml during the entire irrigation season BOD 20 mg/l during the irrigation season

51 Two Sequential Batch Reservoir Reactors in Series

52 The Four largest Wastewater Reuse Schemes in Israel Jerusalem Tel Aviv Haifa Jeezrael Valley

53 Satellite View of Central Israel Tel Aviv Ashdod Jerusalem

54 Satellite View of the Ashdod Region

55 The Ashdod Stabilization Reservoir

56 Satellite View of the Lod Ramla Region Lod Ramla Naan

57 The Naan Stabilization Reservoir

58 Eial Reservoir Layout

59 The Eial Stabilization Reservoir

60 Irrigation with Eial Reservoir Effluent

61 Satellite View of North Israel Haifa Nazareth Afula Cesarea Nathania

62 Haifa Wastewater Reuse Project

63 Satellite View of The Valley of Jeesrael Nazareth Afula

64 Maale Hakishon Reservoir Storing the City of Haifa Effluent

65 Maale Hakishon Reservoir

66 Nazareth Reservoir

67 Soreq Irrigation Scheme Utilizing the Jerusalem Effluent Total Irrigated Area 3500 ha Soreq River Network of 10 Reservoirs with Total Storage Capacity of 10 MCM Activated Sludge Treatment Plant

68 Kazaza Reservoirs Storing the Jerusalem Effluent

69 Location of Beer Sheva Beer Sheva

70 Satellite View of the Beer Sheva Region Beer Sheva

71 Eial Naan Effluent Samples of Three Reservoirs Maale Hakishon (Haifa)

72 Santiago Poniento Watewater Treatment Plant, Chile

73 Satellite View of Cochabamba Valley, Bolivia

74 Satellite View of the City of El Alto, La Paz, Bolivia

75 Discharge of Rio Seco, Containing the El Alto Effluent, to Lake Titikaka, Bolivia

76 Many Thanks for Your Attention