Characterization of unplanned water reuse for agricultural irrigation in the EU

Transcription

1 Characterization of unplanned water reuse for agricultural irrigation in the EU Jörg E. Drewes, Uwe Hübner, Sema Karakurt, Veronika Zhiteneva, Germany 3 rd Meeting of the CIS Ad-hoc Task Group on Water Reuse, Brussels, 23 June

2 Motivation Current effort to develop Minimum Quality Requirements for Water Reuse for Agricultural Irrigation is motivated to properly manage any non-acceptable risk to human and environmental health associated with the potential presence of microbiological and chemical contaminants Current practice is to use surface water for agricultural irrigation, which isn t free of risk In particular, in streams and rivers located in areas practicing agriculture irrigation water quality might be impacted by discharge from municipal wastewater effluents 2

3 Scenario 1 unplanned reuse dddddddddddddddd Agricultural irrigation Common water resource management still refers to surface or river water assuming an appropriate quality for various non-potable and potable uses Is there a higher risk associated with the practice of unplanned water reuse? 3

4 Scenario 2 Planned water reuse dddddddddddddddd llo llo Agricultural Irrigation with reclaimed water llo llo Is the risk of using reclaimed water higher than using conventional freshwater supplies including surface water? 4

5 Study Objectives Assess qualities of water sources presently used in agricultural irrigation in the EU, including direct and indirect reuse of treated wastewater Estimate extent of unplanned reuse in EU river basins, and Estimate the impact of the development of planned water reuse 5

6 Benchmarking current qualities of water sources used in agricultural irrigation Surface water and groundwater quality requirements used for agricultural irrigation were benchmarked against the quality of a.) treated urban effluents discharged to the environment, b.) treated urban effluents reused for irrigation purposes as currently regulated by individual member states, and c.) treated urban effluents (reclaimed water) reused for irrigation purposes as proposed in the JRC technical report (June 2017) 6

7 Assessment of unplanned Water Reuse in select EU River Basins For selected case studies of representative river basins in selected EU member states, irrigation practices were evaluated regarding the quantitative extent of unplanned reuse in select EU river basins. Case studies: #1: Ebro River Basin, Spain #2: Llobregat River Basin, Spain #3: Po River Basin, Italy #4: Garonne River Basin, France - #5: Havel River, Germany 7

8 Unplanned or De facto Water Reuse 71 (91) WWTP 26 Waterworks 100 Direct industrial discharges NRC (2012), Water Reuse 8

9 Water Sources used for Irrigation in 2010 Source: EuroStat

10 FAO Global Map of Irrigation Areas Source: FAO (2017) 10

11 Benchmarking Irrigation Water Qualities FAO Guidelines (Ayers & Westcot 1994) Salinity Specific ion toxicity Excessive nutrients Change of water infiltration rate ISO Guidelines for treated wastewater use for irrigation (2015) specifying chemical constituents including maximum levels of nutrients and salinity factors and also recommended regular monitoring of the concentration of microbial indicators WHO Guidelines for treated wastewater (2006) Proposing a risk-based approach and formulated health-based values for select pathogens 11

12 Benchmarking Irrigation Water Qualities European Commission Guidance document on addressing microbiological risks in fresh fruits and vegetables at primary production through good hygiene (2017) Suggests a risk assessment considering the source and the intended use of agricultural water defining the suitability for agricultural purposes, the recommended microbiological threshold values of a fecal indicator (i.e. Escherichia coli), and frequency of monitoring <100 E. coli/100 ml to <10,000 E. coli/100 ml (depending on crop type) 12

13 Comparison of Water Quality Standards Parameters Cyprus France Greece Italy Portugal Spain EU Com. (2017)* JRC Report (2017) E. coli (cfu/100 ml) E. coli (logs) Fecal coliforms (cfu/100 ml) Enterococci (logs) Anaerobic sulf. red. spores (logs) Clostridium perf. spores (logs) > >5 Bacteriophages (logs) F-spec. coliphages (logs) >6 TSS (mg/l) Turbidity (NTU) no limit BOD 5 (mg/l) COD (mg/l) Total nitrogen (mg/l)

14 Scenario 1 unplanned reuse dddddddddddddddd Urban Waste Water Treatment Directive (91/271/EEC) No disinfection required prior to discharge Agricultural irrigation Source: Costan-Longares et al.,

15 Risk Exemplar A hypothetical stream is impacted to different degrees by discharge of a secondary treated wastewater effluent, representing impacts of 5, 10, 20 and 50% discharge of wastewater It is assumed that the secondary effluent meets the requirements of the EU UWWT Directive. The residual concentrations of selected pathogens in nondisinfected secondary effluent are adopted from the peer-reviewed literature (as noted). The water quality of the stream upstream of the discharge is considered pristine, carrying no detectable levels of pathogens or any anthropogenicallyderived chemicals. It is further assumed that the pathogens being discharged to the river will survive for a few days, potentially a few weeks. 15

16 Concentration of microbial water quality parameters considering different dilution ratios Parameters Assumptions sec. effl. quality Scenario 5% Scenario 10% Scenario 20% Scenario 50% EU Com. (2017) JRC (2017) E. coli (cfu/100 ml) Enterococci (cfu/100 ml) Clostridium perf. spores (cfu/100 ml) 10 4 * 5* *10 3 5* * 5* *10 3 5* * 5* *10 2 5* Somatic coliphages (pfu/100 ml) 10 5 * 5* *10 4 5* Noro viruses (gc/l) 10 4 ** 5* *10 3 5* Levantesi et al. 2010; Costan-Longares et al., 2008;** NRC, > even high dilution ratios (10% and less) will result in a downstream water quality that will likely exceed the fecal indicator values of E. coli as specified in the EU Commission guidance document as well as the values proposed in the JRC report for irrigation of crops eaten raw (Class A and Class B). 16

17 Estimating the Degree of Impact from Unplanned Water Reuse Case Study 1: Ebro River Basin, Spain 17

18 Segre River Basin, Gaging Stations adopted from Automatic Hydrologic Information System of the Ebro river basin,

19 Location of Urban Wastewater Treatment Plants Source: European Environment Agency

20 Degree of Wastewater Impact in River Basins of the Ebro River, Spain Q_river Q_WWTPe Dilution ratio Gaging station [m 3 /day] [m 3 /day] % min max Average Average max min Average Segre-Balaquer 285,120 4,769, ,720 28, Segre-Lleida 319,680 9,936,000 1,149, , Segre -Serós 501,120 22,248,000 4,527, , Cinca Fraga 1,891,296 35,930,304 5,223,744 55, Gallego 282,528 18,036,864 1,759,968 25, Arba 141,696 7,826, ,856 16, Sources: Confederacíon Hidrográfica del Ebro, 2017; European Environment Agency, 2017; Departament d Explotacio de Sistemes de Sanejament, Barcelona,

21 Degree of Wastewater Impact in River Basins of the Segre River, Spain 21

22 Degree of Wastewater Impact in River Basins of the Llobregat River, Spain 22

23 Concluding Remarks Unintentional or de facto water reuse scenario occurs widespread. It is frequently not acknowledged but might adversely impact non-potable and potable use options and/or aquatic life A comprehensive documentation quantifying the degree of impact in European river basins is lacking Specific national guidelines or regulations for irrigation water quality requirements for surface or groundwater do not exist in any of the EU Member States due to the high monitoring effort to generate meaningful results and challenges to enforce their compliance Results of a risk exemplar suggest that even high dilution ratios (10% and less) will result in a downstream water quality that will likely exceed the fecal indicator values of E. coli as specified in the EU Commission guidance document for good produce hygiene as well as the values proposed in the JRC report for irrigation of crops eaten raw (Class A and Class B) For specific case studies, the degree of impact from wastewater discharge varied between 3 and more than 10% or 4 and 80% depending on flow conditions in the stream representing situations that pose a higher microbial risk than the use of Class A and Class B reclaimed water 23

24 Disclaimer The views set out and analysis presented are those of the authors and do not necessarily represent the views of the Commission in general or of DG Environment. Thank you! Prof. Dr.-Ing. Jörg E. Drewes 24