Decomposition of solid waste in landfill site produces highly polluted leachate. In most of the landfill worldwide collection, handling, treatment and disposal are major issues associated with landfill operation. Open, untreated disposal of the landfill leachate poses serious threat to the receiving environment and public health. It also leaches and reaches groundwater polluting the aquifer. Since it is contains huge variety of pollutant or contaminant such as (organic matter, suspended and dissolved solids, heavy metals, persistent organic pollutants etc.), it required adequate treatment before disposal leachate treatment with municipal wastewater is neither required nor can produce efficient and economical results. Coagulation has be found to effectively reduce contaminant loading from leachate, alone and in combination with other method, as applied on leachate taken from different landfill in different studies. This study targeted characterizing the leachate from Lakhodair landfill site on the basis of the selected parameters (pH, EC, Turbidity, TDS, TSS, Hardness, BOD5, COD, Cl-1, Na, K, Ni, Cr, Pb, Mn, Zn, Cu and Fe). Leachate samples were collected from Lakhodair landfill site in plastic bottles, brought to laboratory, preserved and analyze for the above mentioned parameters. Lakhodair landfill site was inaugurated 18 April 2016. Since the leachate was young and the solid waste at Lakhodair landfill site had not undergone acidogenic phase of decomposition, the leachate was slightly alkaline (pH = 8.43) and quite high in organic loading (in term of COD and BOD5), Sodium, Potassium, and few heavy metals like Ni and Cr. High concentrations of some contaminants not studies in the literature (TDS, TSS, EC, Hardness, Turbidity, Chlorides). Other tested heavy metals (Pb, Mn, Cu, Zn, Fe) were found in low concentration due to low solubility at alkaline pH. Leachate samples were subjected to coagulation/flocculation with 0.8, 1.0, 1.2,
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1.4, 1.6 g/L of Alum, Ferric chloride and their mixer, and tested for same parameters after treatment. Treatment comprise 5 min rapid mixing, 30 min slow mixing and settling time of one hour. Heavymetals (Zn, Pb, Fe. Ni, Cr, Cu and Mn) have been detected in leachate through Hitachi Z-8230 atomic absorption spectrophotometer. Minerals (Na and K) have been detected by using flame photometer.pH, EC and Turbidity were measured by their respective meters. TSS and TDS were determined by gravimetric method. Titration was used for COD, Hardness and Chlorides. BOD readings were measured by BOD5 Incubator (SAYO MIR-153). Expect for TDS, Hardness, K and Cr the three coagulants responding different to all the tested pollutants, mixed coagulant perform the best giving as high as around 90-100 % removal for many of them. Post-treatment concentrations of all the parameters except TDS were significantly related to the coagulant dose. Since Ferric chloride and mixed coagulants had chlorides in them, they resulted in high post-treatment chloride concentration with increase in their doses while Alum its reduction. Alum and the mixed coagulant cause in increase in TDS while Ferric chloride cause an increase in TSS in the leachate at higher doses. Leachate TSS was maintaining constant at around 800 mg/L at all doses. The coagulant doses show positive correlation with Hardness and EC and negative correlation with pH, Turbidity, BOD5, COD, Na, K, Ni, Cr, Pb, and Mn. % removal from as low as 1.1 – 19.06 for BOD5 to as high as 32.59 – 92.7 % for Nickel was achieved as a result of coagulation. Comparison was made with standards for reuse of leachate in landscape irrigation (as prescribed by JS, 2002 in Annexure IV) and open disposal into inland water or sewage treatment plants (as prescribe in PEQS and given in (Annexure V). Stringent FEPA standard has also be included only for Pb. Comparison with standard shown that coagulation is good pre-treatment option as it has help lowering contaminant load from leachate and meeting PEQS standards for disposal into sewage treatment plant as set in PEQS, but it not sufficient to treat leachate to reuse for landfill irrigation.