ASSESSMENT OF WASTEWATER FOR DISPOSAL IN ACCORDANCE WITH NEQS CRITERIA AND ITS REUSE FOR IRRIGATION WITH DILUTION

Abstract

According to Section 11 of Pakistan Environmental Protection Act (PEPA) 1997, “No person shall discharge or emit or allow the discharge of any effluent or waste in an amount, concentration or level which is more than the National Environmental Quality Standards(NEQS)”. Even in the presence of this act there are many housing societies and Industrial zones, which are continuously disposing off their untreated wastewater to the natural water bodies. In this study Laboratory investigations on 5 composite samples were carried out. Total of 19 parameters were analyzed including Total Dissolve Solid (TDS), Total Suspended Solids (TSS), Bio-Chemical Oxygen Demand (BOD), Chemical Oxygen demand (COD), Sulfide, Fluoride, Lead, Nickel, Boron, Copper, Iron, Zinc, Manganese, Chlorine Total and Chromium hexavalent with average value of 502.6, 665.6, 267.4, 453.8, 3.1,5.3 0.6, 0.4, 1.4, 0.5, 0.5, 2.15, 0.6 and 0.5 mg/L respectively. TSS, BOD, COD and Mn exceeded the limits of NEQS for all samples.The same wastewater can be used for irrigation purpose if it fulfills FAO irrigation water criteria. For this purpose, important properties like SAR, Sodium ratio, Salt Index, Residual Sodium Carbonate, Permeability Index, Magnesium Adsorption Ratio, Sulfate ion and Boron were analyzed having result of 9.36 √(meq/L), 5.64, 75 ppm, 4.66 meq/L, 110.46, 0.42, 6.07 meq/L, 1.386 mg/L mean concentrations respectively, violating the standards. A dilution factor of 1.09 litters is computed per liter of sewage to minimize, the concentrations of exceeded parameters by mixing with normal water, into a range that can be used safely for irrigation.