A Study On Treatment Of Micro-Polluted In Source Waters Using Biological Filter

A study was conducted on the mechanism of purifying micro-polluted in raw waters using biological filter. This included raw water quality, biological biomass and activity, as well as the removal of seven kinds of pesticides. The main results were summarized as follows:1) It took 27 days for the formation of the stable biofilm on the medium of biological filter. Biofilm on the surface of haydite become almost matured and the removal rates of NH4+-N between 60% and 85%, the removal rates of TOC kept at 30%~57%.2) It has been shown that there were microorganisms on the biofilm attached on the ceramsite, including ball coli, bacillu, filament, algae, microorganism metabolites and so on. Eramsite pores were covered by biofilm, which had a large number of microorganisms, but less inside the ceramsite pores.3) The biomass were determined by the methods of phospholipid, protein and thepopulation of cell. The distribution of biomass and microbial activity were uneven and the biomass and microbial activity decreased along the filter bed.4) During the period of stable operation, TOC decreased along with the filter bed, about 53% of TOC was biodegraded at the depth of 22 cm of media, no further removal was seen as the deeper bed layers.5) During the period of dosing pesticide, NH4+-N?UV254 and TOC were removed effectively by biological filter. Up to 20% removal for some of the seven kinds of pesticides could be achieved depending on conditions and the individual species. Pesticides including triadinefon,prometryn,cyanazine,propazine,atrazine,fenobucarb can be biodegraded in the biofilter either via direct catabolism or cometabolism, except diuron that was recalcitrant to biodegration.6) Glucose showed a promoting effect to biodegradation of the pesticides, however, NH4+-N did not show such significant effect.7) The concentrations of the seven kinds of pesticides basically keep decreasing down along the biological filter and they are mainly removed within 0~50cm.8) The effect of backwashing on removing TOC?UV254 and NH4+-N was relatively small. Within 24 hours, the biological filter would restore the removal efficiencies for them. However, for the seven kinds of pesticides, it would take about 4 days for biological filter to restore the removal efficiencies.