Thursday, 13 July 2006 - 4:00 PM

Agricultural Uses of Sewage Sludge and Water and their Impact on Soil Water and Environmental Health in Haryana, India.

S. K. Dubey1, R.K. Yadav2, P.K. Joshi3, R.K. Chaturvedi3, Barkha Goyel3, Rashmi Yadav3, and P.S. Minhas3. (1) Water Technology Centre, Indian Agricultural Research Institute, Pusa Campus, New Delhi, 110012, India, (2) National Buerou of Soil Survey and Land Use Planning, Regional Research Center, IARI Campus, New delhi, India, (3) Central Soil Salinity Research Institute, Karnal, Haryana, India

Large scale urbanization, a consiquence of economic development is leading to production of huge quantities of effluents in India and posing serious environmental problems for their disposal. Sewage sludge (bio solids ) generation in India is also increasing at a faster rate as more and more waste water treatment facilities with enhanced efficiencies are being developed. It is bound to increase further as a result of continuous by expanding collection systems and their treatment in already existing treatment plants. Sewage sludge and effluents are frequently disposed off on agricultural lands for irrigation/manures purposes that create both opportunities and problems. Opportunities exist as sewage sludge and effluents from municipal origin are rich in organic matter and also contain appreciable amounts of major and micronutrients. Therefore continuous use of sewage sludge and sewage irrigation reduces the nutrient requirement of the soil considerably. Problems exist because sewage sludge and effluents may contain high amount of heavy metals, which may limit their long term use in agriculture because of phyto-toxicity and environmental deterioration. A state level survey was conducted to evaluate the impact of sewage sludge and water on soil water and environmental health in Haryana. Sewage sludge and water samples were collected from all treatment plants and disposal sites available in the various districts. Sludge samples were analysed for pHs, ECe, available nutrients (NPK), total nutrients (NPK) and heavy metal contents such as Pb, Ni, Cr, Cd, Hg and As following standard procedures. The effluent samples were analysed for EC, pH, DO, BOD, COD, TDS, cations (Ca2+, Mg2+, Na+, K+), anions (Cl-, HCO3-, CO32-, NO3-), NH4-N and P, micronutrients (Zn, Fe and Cu), heavy metals (Cd, Cr, B, Ni and Pb,pathogens (Eschericha coli, Fecal coli, Straptococcus, Salmonella and Shigella), bacteria and fungi using standard media and procedures. Two case studies were also conducted to compare the spatial distribution of N, P, K and other micro nutrients and toxic elements in the top 0.6 m of alluvial soils along with their associated effects on composition of crops and ground waters. Results of sewage sludge analysis showed that the major nutrients were present in very high concentrations and ranges e.g., available N (0.46-0.63%), P (0.0044-0.0060%), K (0.029-0.041%) and total N ( 1.54-1.92%), P (0.61-0.92%), K (0.35-0.43%). Similarly, heavy metals Pb (26-154 ppm), Ni (12-596 ppm), Cr (66-1098 ppm), Cd ( 2-9 ppm), Hg (7-32 ppm) and As (8-23 ppm) were also present. The total volume of sewage water disposed (485 million litres/day) had a potential for supplemental irrigation to a land area of more then 16000 ha/annum in peri-urbun areas. It created a nutrient potential of 8100, 1200 and 11000 tonnes in terms of NPK. It also contained micronutrients like Zn, Fe and Cu in sufficient amounts. Most of the sewage waters were rated suitable for irrigation as they were having electrical conductivity 0.9-3.2 dS/m, sodium adsorption ratio 1.4-6.2 (mmol/litre)0.5 and residual sodium carbonate 0-8.6 meq/litre. Results of a case study in Kurukshetra district of Haryana showed that use of domestic sewage for irrigation in various proportions improved the organic matter to 1.24 1.78% and fertility status of soils especially up to a distance of 1 km along the disposal channel. Build up of total N was up to 2908 kg/ha, available P (58 kg/ha), total P (2115 ka/ha), available K (305 kg/ha) and total K (4712 kg/ha) in surface 0-15 cm soil layer. Vertical distribution of these parameters was also varied, with most accumulations occurring in surface 0-30 cm. Traces of NO3-N (up to 2.8 mg/l), Pb (up to 0.35 mg/l)and Mn (up to 0.23 mg/l) could also be observed in well waters near the disposal point, which indicated initiation of ground water contamination. Heavy metal contents in crops sampled from the area were below the permissible limits. Another case study was conducted at Panipat, an industrial town which disposes its treated effluents from sewage treatment plants of 10 mld capacity in a drain that also carries effluents from a number of dye houses situated along the drain. The analysis of effluents being discharged by dye houses showed their COD and TDS to average 310 and 3920 mg/l, respectively. The treated sewage had COD and TDS of 428 and 1470 mg/l that on mixing with effluent from dye houses acquired the values of 245 and 1780 mg/l respectively. Most of the heavy metals were within the permissible limits for irrigation purposes except for Pb (0.24 ug/l). The effluent is ultimately let in to the village pond, the water of which showed the COD and TDS values to be 428 and 1470 mg/l. Contamination of water samples collected from the existing hand pumps and tube wells along the village pond and ground water, became obvious from their analysis. COD and TDS of water samples from hand pumps were 264 and 1190 mg/l where as in tube well water, these values were 151 and 900 mg/l. Though the ground water contamination seemed to decrease with distance from the pond but COD, TDS and BOD values continued to be quite high in water samples drawn from hand pumps (~60m deep) down to a distance of 500m from disposal pond. NO3-N concentration in tube well waters also declined from 6.3 ppm at 10m to 1.75 ppm at 200m away from pond. However, the major cause of concern in these waters was Pb that varied between 0.11 to 0.45ppm. From the above studies, it was concluded that although the sewage sludge and sewage water samples had very high amount of major nutrients (N,P,K) and micro nutrients but presence of heavy metals such as Pb, Ni and Cd in plants and ground waters is a matter of concern and indicated the need for continuous monitoring.

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