Methanogenic biofilm: structure and microbial population activity in an anaerobic fluidized bed reactor treating synthetic wastewater (original) (raw)

Specific methanogenic activity measurements and scanning electron microscopy (SEM) were used as indirect tools to study the microbial population and structure of biofilms formed on sand grains. The biofilms were developed in an anaerobic fluidized bed reactor (diameter 0.08m; height 0.9m) fed with synthetic sewage wastewater. Biofilm thickness increased from 10 to 70 um after 510 days of reactor operation. Reactor bed stratification was observed http://www.bioline.org.br/request?bf98003 (1 of 14) [8/1/2002 10:25:52 AM] http://www.bioline.org.br/request?bf98003 after one year of operation, and agglomeration of various biofilms resulted in aggregates (2.0 to 5.0 mm). Microbial activities were determined through methane production from acetate, butyrate, propionate and sucrose. Samples were taken from two different points in the reactor, and the largest aggregates were found nearer the reactor base. These had 0.01 mmol CH4/gSSV.h of acetoclastic activity. Bacterial aggregates from the upper part of the reactor presented greater acetoclastic activity, 0.03 mmol CH4/gSSV.h. Microscopical observations of both samples revealed the predominant presence of methanogenic bacteria similar to Methanothrix, as well as hydrogenotrophic methanogen species and Desulfovibrio-like bacteria.