Biomass characterization of slow sand filtration schmutzdecke and its effects on filter performance

A new approach of representing biomass by measuring the Total Kjeldahl Nitrogen (TKN) content of sand in the schmutzdecke of slow sand filtration (SSF) was established by correlating TKN, Volatile Solids (VS) and Total Plate Count, a better way for the representation of biomass against the usual method by measuring VS. Reasonably good correlations were found between TKN and Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD) of the extract from the schmutzdecke sand. The effects of the concentration of TKN on the efficiency of the SSF used as a tertiary unit of a wastewater treatment plant in removing BOD, COD, Ammonia Nitrogen (NH(3)-N) and Total Microorganisms have been evaluated and better performances of the filter have been observed at higher TKN concentration. The removal of NH(3)-N was almost proportional to TKN concentration further proving the importance of measuring the NH(3)-N in the effluent to identify the degree of ripening of the filter.