| Abstract: | Dimethyl Sulfoxide Reduction Method for the Characterization of Biomass Activity in Sludge of an Aerated Lagoon The microbial biomass activity was studied in sludge from a wastewater lagoon (Hatzbachtal) which consisted of 4 aerated ponds and one polishing pond. The lagoon was characterized by low BOD5 loading and high dilution because of water from the surroundings. Sludge samples were taken from 4 sampling sites of each aerated pond and from one site of the polishing pond. The biomass activity in the sludge samples was analysed with the help of dimethyl sulfoxide reductase (DRA) and dehydrogenase (DHA) activity. In addition, Corg-content was also determined. The effect of different reaction parameters on the DRA was studied in relation to incubation period, temperature and atmosphere as well as sludge weight and pH value. The results presented here show that a linear increase in the DRA occured for the sludge weight ranging from 0.1 to 0.5 g, incubation period from 0.5 to 11 h and incubation temperature from 20 to 50 °C. The pH spectrum from acidic to neutral did not effect the DMS formation in sludge. Although the values for DRA were always higher in anaerobic incubation of sludge than in aerobic incubation, the courses of the DRA in both conditions were parallel. Comparing the biomass activity in sludge from different sampling sites of the aerated ponds, the average Corg-content was found to be reflected by the DRA and DHA. Further, the variation in the DRA could represent also the influence of oxygen concentration. Therefore, a reduction in biomass activities indicated a decline in the availability of oxygen. |
