Performance of HUASB reactor for treating paper & Pulp wastewater using Effective Microorganism(EM)

摘要

Pulp and paper industry is one of the most polluting industries all over the world that uses significant amount of fresh water and produces substantial amount of solid and liquid waste. Wastewater from this industry is potentially polluting nature and before discharge into natural course, it is mandatory to adhere to the discharge norms. Anaerobic treatment of paper processing wastewater has a distinct advantage of recovery of inherent energy in the form of methane gas with less sludge production. A hybrid reactor (HUASB) that capitalizes on the positive features of anaerobic filter (AF) and up-flow anaerobic sludge blanket (UASB). The main objective of the thesis is to find out the performance efficiency of the hybrid up-flow anaerobic sludge blanket (HUASB) reactor for treatment of pulp & paper mill wastewater using Effective Microorganism(EM). In this study, a labscale HUASB reactor of 9.68 litres and an effective volume of 7.88 L had been used at ambient temperature with PVC packing materials in the top one third of the reactor. The reactor was initially filled with 2L of cow dung and 2L with seed sludge and remaining with pulp and paper mill wastewater. Start-up was successfully carried out for 130 days and a steady state condition has attained. The reactor was start with an initial influent COD of 750 mg/l, VFA of 65 mg/L with an Organic Loading rate (OLR) of 0.75 kg COD/m3.d and Hydraulic Retention Time( HRT) of 24 hours(hrs) and gradually OLR increased. In order to optimize HRT, various HRT were adapted from 24 hrs to 8 hrs and the maximum effluent COD removal of 83% was observed at a HRT of 12 hours with a gas production of 1.162 L/ L reactor volume/day and methane gas content observed as 71% with a rate of 0.28 m3/kg COD removed. After start up, treatment performance using Activated EM and higher OLR has been loaded for attaining steady state by increasing the influent COD concentration adopting HRT 12 hrs for a period of another 130 days. The maximum effluent COD removal efficiency of 92%, achieved with an OLR of 9.00 Kg COD/m3.day, with gas production of 3.2 L/L.day with 72% methane content and production rate of 0.29 m3/kg COD removed.