Use of enzyme tests to monitor the biomass activity of a trickling biofilter treating domestic wastewaters

Easy enzyme tests were used to monitor the biomass activity of a trickling biological aerated filter processing a domestic influent. Biofilter wash-wa ters were used as biomass source. Enzyme tests (hydrolases and dehydrogenas es) carried out on wash-waters showed relationships with the process active biomass (estimated by volatile suspended solids). Differences in dehydroge nase (DHA) specific activities were observed in two sampling campaigns and were Linked to process performance. The DHA activity evaluated using glucos e or acetate was also related to the substrate mass applied on the biologic al aerated filter (kg CODt m(-3) biolite). These results indicated that, un der normal operation, DHA activity is related to quantity of substrate appl ied to the biofilter. Similar relationships were obtained for hydrolases. H owever, beta -glucuronidase, Leu-aminopeptidase and protease, expressed spe cifically, were more significantly inversely related to process removal per formance. This reaction was probably caused by the biomass reacting with an influent that is difficult to biodegrade. Generally speaking, these tests can be easily applied to the regular monitoring of the active biomass from a process using biological filters or simply as an indicator of the active biomass content in the process. (C) 2000 Society of Chemical Industry.