Optimizing Domestic Wastewater Reuse Options in Agriculture: A Case Study N K Tyagi Former Member ASRB, ICAR Reduce fresh water use and recycle wastewater

Scheme of Presentation Research background & review Study area Optimization model and results Inferences and way forward Reduce freshwater use and recycle wastewater

CIRCULAR ECONOMY of Wastewater Management(www.wrap.org.uk) The linear economic model: “develop, , use and dispose”. It relies on large quantities of cheap easily accessible materials and energy. “A circular economy keeps resources in use for as long as possible…then recovers and regenerates products and materials at the end of each service life”. Waste water management can play an important role in the emerging circular economy - as huge amounts of “waste” water that is generated is full of material ( recycled water, energy, nitrogen, phosphorus, organic fertilizer) that can be recovered and regenerated. Reduce fresh water use and recycle wastewater

Resources embedded to municipal wastewater(per capita per yr Parameters Value Reusable water ,(m3) 80-120 Cellulose, (kg) 5-7 Biopolymers, (kg/capita year) 2-4 Phosphorus (for incorporation in P compound), (kg) 0.5-1.5 Nitrogen (for incorporation in N compound) ,(kg) 4-5 Methane, (m3) 12-13 Organic Fertilizer (P-rich compost), (kg) 9-10 Verstraete et al. (2009) Bioresource Technology 100, 5537–5545 Salehizadej and van Loosdrecht (2004) Biotechnology Advances 22, 261–279 Reduce freshwater use and recycle wastewater

A strong case for circular economy in wastewater in India 2030 WRG,2016) Water security parameter Value Water availability per capita, 1545 (m3/year) Groundwater situation 30 % over-exploited River pollution 91 % of 301 river stretches polluted Phosphate import 30 % of global import

Climate, Water balance and Sewage water Quality at Karnal

Agro-climatic water soil-water balance in Karnal Reduce freshwater use and recycle wastewater

Composition of domestic wastewater at CSSRI, Karnal (Pandey et al,2009) Parameter Value pH 7.93 P (mg/ l) 4.06 EC (dS/m ) 0.98 K (meq /l) 0.29 BODs (mg/ l) 198 Na (meq/ l) 2.38 COD(mg /l) 249 Ca (meq/ l) 2.19 NH4 -N (mg /l) 12.9 Mg (meq /l) 3.20 NO3 -N (mg/ l) 2.43 Zn (mg/ l) 0.24 HCO3 (meq/ l) 7.89 Fe (mg/ l) 0.94 E. coli (100 m/l) 1010 TSS (mg /l) 100 Reduce freshwater use and recycle wastewater

Sewage Water Quality in Haryana during Summer(CSSRI,2001) Constituents Concentration, (mg/l) Concentration, (ppm) Untreated Treated PH 7.5 8.1 DO 1.8 3.2 EC, dS/m 1.9 1.89 P 5.5 4.5 SAR 3.4 3.9 BOD 239 110 RSC 2.6 COD 240 185 Ca 2.9 NH3-N 30 24 Mg 4.9 3.8 NO3-N 5 K 0.7 0.6 Cd 0.1 Cl 9.1 Cr 0.49 Na 7 7.1 Ni 0.46 0.52

Long effect on soil and crop productivity Soil health Groundwater quality Crop productivity Quality of produce

Effect of Sewage Irrigation on Soil Salinity contents of Major Nutrients(Minhas and Samra,2004) Site & Years sewage use Treatm-ent pH (1:2) EC(1:2) dS/m O M C(%) Available N(kg/ha)   P(kg/ha) K(kg/ha) Kaithal (15 years) SI NSI 7.7 8.4 1.9 3.3 1.3 0.5 70 42 78 30 105 88 Narwana (12 years) 7.8 3.0 0.8 0.3 57 50 74 4 136 172 Rewari 8.6 8.2 0.7 77 14 16 - Hissar 8years) 7.5 7.9 0.6 56 49 43 34 81 SI-Sewage irrigation NSI Non-sewage irrigation Reduce freshwater use and recycle wastewater

Effect of long term sewage water use (10 years) on groundwater (Yadav et al,2002 Traces of NO3-N (up to 2.8 mg l(-1)), Pb (up to 0.35 mg l(-1)) and Mn (up to 0.23 mg l(-1)) could also be observed in well waters near the disposal point thus indicating initiation of ground water contamination.

Improvement in crop yield with sewage water over fresh water(CSSRI,2004)

L P OPTIMIZATION MODEL OBJECTIVE FUNCTION CONSTRAINTS   n Max Z= ∑ Pi Xi i=1 Pi= Profit from crop activity i ( i=1 ,2,3………..n) Activities include field crops like, rice, wheat, vegetable with subsurface drip, forest trees etc, disposal in river/drain Note: The model is run with and without sewage water; and with and without water treatment Reduce freshwater use and recycle wastewater CONSTRAINTS Crop area: ∑AiXi= TA(Total area) Crop irrigation water use: 12 n 12 ∑ ∑ IR ij= ∑ (FWj+SWj) , j=1 i=1 j=1 FW=Fresh water Sw=Sewage water, j=Months 1 ,2 ,3 ,…… 12 Sewage water use : 12 12 ∑SW . Xi ≤ ∑ TSWj j=1 j=1   TSW= Total sewage water

Options Employed in Sewage Water Use Optimization Irrigation of field crops Horticulture with drip system Forest trees Disposal in drain/river Reduce freshwater use and recycle wastewater

Utilization of Sewage Water during Different Months

Benefits (Rsx106) from Irrigated Cropping with and without Use of Sewage Water in Karnal Sewage Water Channel Command Alternative No treatment Primary treatment Without consideration of cost due to health hazard Without sewage water use 14.1 With sewage water use 35.2 30.09 Benefit accruing due to sewage water 21.2 15.99(114 % increase) With consideration of cost due to health hazard With consideration for cost on medical expenses and wages loss (Rs.1000/capita/year) 19.8 15.05 There were no reliable estimates of cost of medical expenses. So, primary treatment is advocated

Results Highlights Primary treated wastewater use increased farm profit by 114 % over no wastewater use On annual basis about 450 tons of nitrogen could harvested from wastewater irrigation, thereby reducing the need for equal amount of chemical fertilizers. The projected increase in nitrogen concentration after 50 years was only 4.0, and 2.5 mgl-1 for raw and primary treated wastewater, respectively. Forestry is a good option to dispose surplus wastewater in a controlled manner Reduce freshwater use and recycle wastewater

Inferences and Way Forward (I) Wastewaters from the municipalities and agro-industries provide nutrients and thus reduce cost of cultivation as well as of the treatment, as land application itself is a treatment method. The domestic wastewaters can be used for field crops with only primary treatment. Sub-surface drip system is the preferred option for vegetable crops as it avoids contact with edible components. Wastewater management promotes circular economy and saves freshwater /energy ,both of which are scarce Reduce freshwater use and recycle wastewater

Inferences and Way Forward(II) There are research gaps to be filled. Development of comprehensive guidelines, based on climatic conditions, soil type, water table, crops and irrigation technology be evolved. Facilitation mechanisms to implement circular economy in wastewater management A coherent national policy that would allow integration of wastewater with waters from other sources Coordination mechanism: Wastewater collection, treatment, disposal and use involve multiple agencies/departments. Reduce freshwater use and recycle wastewater

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