EFFECT OF CHEMICAL PRETREATMENT ON THE ANAEROBIC DIGESTION OF MUNICIPAL SLUDGE
The effective treatment and proper disposal of Excess Municipal Sludge (EMS) has been a matter of concern to both environmental and regulatory authorities.Even though the amount of primary and secondary sludge requiring disposal continues to grow,landfill and incinerator capacities are not increasing.Thus reduction in sludge volume is an appealing alternative for EMS handling.The research described herein is concerned with a comprehensive study on the disposal and treatment of EMS applying anaerobic digestion with a retention time of 30 days.The influence of employing a stress unit, involving the addition of Hydrogen peroxide(H 2 O 2 ), on the percentage removal of Volatile Suspended Solids (VSS) under three different configurations has been studied.The digesters are fed with the same mixture of primary and secondary sludge (1:1 mass ratio) with a combined VSS concentration of 30 gm/l throughout the study.Reactors were operated in three different configurations. They were mechanically mixed and maintained at 37°C.The stress units were magnetically stirred and maintained at 37°C.The stress unit involved the addition of 1g of H 2 O 2 /g VSS influent and 0.5 g of H 2 O 2 /g VSS influent, respectively at different time periods.The addition of H 2 O 2 was done over a period 6 hours.Sampling and analysis was done after three retention times that’s 90 days.The results showed that the performance of anaerobic digestion with chemical pretreatment was stable.Higher VSS removal efficiency was achieved with configurations that involved the addition of H 2 O 2 in the stress unit.The study involved biological analysis to measure fecal coliforms to study the effect of chemical agent on pathogen removal.
School:University of Cincinnati
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:anerobic digestion chemical pretreatment municipal sludge
Date of Publication:01/01/2004