PILOT PLANT DEMONSTRATION OF AN ANAEROBIC FIXED-FILM BIOREACTOR FOR WASTEWATER TREATMENT

摘要

The design, operation, performance, and economics of alternatives to the anaerobic upflow (ANFLOW) bioreactor for treating waste waters and for providing some waste gasification and solids removal are described. Based on progress to date, it is obvious that significant treatment of dilute wastewaters at low temperatures can be obtained with an upflow, anaerobic, fixed-film bioreactor as demonstrated by the ORNL pilot plant. The bioreactor performance is stable after 16 months of operation and has been shown to be relatively insensitive to ambient temperature changes. Sludge removal requirements are still under evaluation, but preliminary indications suggest that the rate of biomass accumulation in the column is slow. The quality of the effluent produced by the pilot plant at the present stage of development indicates the need for a polishing step; a physical method such as sand filtration will probably be adequate. The overall performance of the bioreactor can probably be improved with better designs for mechanical flow distributors. Gas production rates have not been defined as yet due to mechanical difficulties in sealing the large-scale unit, but rates in excess of 100 liters/day have been observed with methane contents as high as 70%. These rates are still under investigation. A preliminary economic evaluation shows that the ORNL ANFLOW process is competitive at plant capacities of 1 mgd or less. The savings are primarily related to operating costs but occur in capital costs as well. (ERA citation 04:001230)