Abstract: The present study is conducted on the existing landfill site of Daddu Majra in Chandigarh. The landfill is not provided with the collection system of leachate and its treatment as this landfill site is not designed as an engineered system of Municipal Solid Waste disposal. The study was conducted to analyse the characteristics of the leachate produced by the landfill and one particular treatment method using granular activated carbon (GAC), GAC treated with sodium hydroxide (NaOH) and advanced oxidation process (AOP) using hydrogen peroxide (H2O2). The leachate was initially analysed for pH, colour, electrical conductivity (EC), chlorides, total hardness, total solids (TS), suspended solids, dissolved solids, alkalinity, chemical oxygen demand (COD) and biochemical oxygen demand (BOD).The leachate had a very low biodegradability ratio (BOD3/COD) of 0.095, which suggested that direct biological treatment processes could not be applied to treat the leachate because it would be very toxic for the micro-organisms to work upon it. The GAC used was surface modified using NaOH to introduce additional basic oxygen-containing surface functional groups, responsible for its catalytic properties towards target compounds. The COD removal by the combined H2O2 and surface modified GAC treatment was evaluated, optimized and compared to that by H2O2 treatment alone and GAC treatment alone with respect to dose, contact time, pH, and biodegradability ratio(BOD3/COD) in batch mode. The results showed that at an initial COD concentration of 12000 mg/L and BOD3 of 1150 mg/L, the combined treatment has substantially achieved a higher removal (COD removal-85%) than the H2O2 oxidation alone (COD removal-38%),surface modified GAC adsorption alone (COD removal-60%) and as received GAC adsorption alone (COD removal-42%). Finally the optimized experimental conditions for the combined treatment obtained were 25 g/l of surface modified GAC dosage, 5 g/l of H2O2dosage, 60 minutes of contact time at 200 rpm of agitation speed and initial pH of the sample as 8.0. Although the combined H2O2 oxidation and surface modified GAC adsorption could treat leachate of varying strengths, treated effluents were unable to meet the local COD limit of less than 250 mg/l. However, the treatment significantly improved the biodegradability ratio of the treated leachate by 321% from 0.095 to 0.40, enabling the application of subsequent biological treatments such as Sequential Batch Reactor, UASB reactor etc. to further stabilize the target compounds in the leachate prior to their discharge as per the existing effluent discharge standards.

Keywords: Leachate, Granular Activated Carbon, Landfill, COD, BOD, Hydrogen Peroxide, NaOH.

| DOI: 10.17148/IARJSET.2020.71011