The success of biological treatment plants depends almost entirely on the health and activity of the biomass in the process. EnviTreat has developed a reliable means for determining biomass activity in carbonaceous reactions, nitrification reactions, anoxic denitrification reactions, and anaerobic reactions. The method used for carbonaceous reactions involves measuring oxygen uptake in the presence of acetate as a sole carbon source. The oxygen uptake data are then analyzed using a model developed by EnviTreat that is based on well known kinetic and biological growth relationships. An example is shown in the figure below.
In this case, the figure to the left shows oxygen uptake measured in the presence of a nitrification inhibitor. The resulting analysis indicated the presence of a substantial amount of slowly biodegradable materials that were formed as biopolymers during treatment or by coflocculation of particulate matter into the mixed liquor solids (the blue shaded area). The figure to the right shows oxygen uptake in the absence of a nitrification inhibitor. The green shaded area shows the oxygen uptake rate attributable to nitrification. In this case, the analysis indicated that only 2.4% of the volatile solids in the mixed liquor was represented by active microorganisms. Activities for conventional activated sludge process usually range from 15 to 30%. Low activity can be caused by toxic impacts, discharge of inert organic solids into the aeration basin, or excessively high solids retention times. Identification of the causes of the low activity can help to improve the long-term stability and performance of the treatment process.