Development of a Wastewater Treatment System Based on a Fixed-Film, Anaerobic Bioreactor

摘要

An energy-conserving wastewater treatment system based on a fixed-film anaerobic bioreactor is being developed. The treatment process is based on passing wastewaters upward through the bioreactor for continuous treatment by gravitational settling, biophysical filtration, and biological decomposition. A 2-year pilot plant project using a bioreactor designed to treat 5000 gpd has beed conducted using raw wastewater on a municipal site in Oak Ridge, Tennessee. It is estimated that hydraulic loading rates of 0.2 gpm/ft exp 2 and hydraulic residence times of 10 h could be used in designing such bioreactors for the secondary treatment of municipal wastewaters. Conceptual designs for total treatment systems processing up to 1.0 million gallons of wastewater per day (mgd of wastewater) were developed based on the performance of the pilot-plant bioreactor. These systems were compared to activated sludge treatment systems also operating under secondary treatment requirements and were found to consume as little as 30% of the energy required by the activated sludge systems. The economic advantages of the process result from the elimination of operating energy requirements associated with the aeration of aerobic-based processes and with the significant decrease of sludge-handling costs required with conventional activated-sludge treatment systems. Methane produced by anaerobic fermentation processes occurring during the biological decomposition of carbonaceous wastes also represented a significant and recoverable energy production term as wastewater flow rates approached 1.0 mgd. (ERA citation 05:022610)