Influence of Effective Microorganisms (EM) During Startup of Anaerobic Treatment of Pulp and Paper Mill Wastewater in HUASB Reactor

Anaerobic treatment of bagasse wash water from paper and pulp mill was studied using a lab scale HUASB reactor of 7.88 L effective volume with three phase system. The initial characteristics of bagasse wash water were: pH 5.2-6.5, TCOD 2000-6000 mg/L, BOD 900-2500 mg/L, TS 4000-4500 mg/L, VSS 1000-1500 mg/L. The reactor was loaded with pulp and paper mill wastewater, seed sludge and activated Effective Microorganisms (EM) operated on continuous mode for a period of 130 days with an HRT varying from 24 to 8 hrs and start up with successful granulation has been achieved. An optimum TCOD removal was attained at the OLR of 7.8 kg COD/m³/day with TCOD removal of 81% with a gas production of 2.66 L/L per day and 70% of methane gas content with a production rate of 0.29 m³/kg COD removal were observed. The introduction of effective microorganisms has aided the start up period in an efficient way for better acclimatization inside the reactor that facilitate the biomethanation. The SEM analysis also shows stabilized Methanothrix and other microorganisms present in the reactor at the end of the start up.