Abstract
Effects of filter media on treatment characteristics and bacterial distribution were investigated by using an anaerobic filter system operated at 20°C. The low strength synthetic wastewater containing cellulose was used as the substrate. The degradation rate of cellulose was improved by the packing of the filter media. The methane gas recovery efficiency was increased from 23% to 56% by packing of the filter media. Because of the production of CH4 and CO2 as the result of substrate degradation, the hydraulic characteristics of the fixed bed reactor was similar to that of the completely mixed continuous flow reactor. The bacteria living in the filter zone at the upper part of the reactor were attached to the filter media or were trapped between the filter media, the density of the latter being two times as much as that of the former. Packig of the filter media improved significantly the retention of the methanogenic bacteria and the lipolytic bacteria, but did not improve that of the glucolytic and proteolytic bacteria. It is clear from these result that packing of the filter media improves treatment efficiency of the reactor remarkably when methane production is the rate determining step and when hydraulic retention time is shorter than the generation time of methanogenic bacteria.
