CORRELATION OF AMMONIA REMOVAL RATES TO NITRIFYING BACTERIAL POPULATIONS IN A FULL-SCALE NITRIFYING TRICKLING FILTER USING FLUORESCENT IN SITU HYBRIDIZATION

摘要

Process control and optimization of nitrifying trickling filters are currently based onrnmacroscale chemical parameters and bulk measures of biomass (e.g. volatile solids).rnA relatively new microbiological technique that can provide ecological information fromrnan intact biofilm is Fluorescent In Situ Hybridization (FISH). The application of FISH torncharacterize nitrifying populations in full-scale wastewater treatment systems is limitedrnand recent (Wagner et al.1995, Mobarry et al.1996, Schramm et al.1996, Juretschkornet. al. 1998). FISH can yield important information about bacterial populations thatrncan then be correlated with system performance. Quantification of the active nitrifyingrnpopulations may also be used for process modeling and optimization.rnThe main research objective was to investigate the use of FISH in quantifying nitrifierrnpopulations within intact biofilm samples from various depths within a nitrifying tricklingrnfilter and to determine whether this information could be used to optimize the processrnand/or improve its modeling. The research hypothesis was that the vertical populationrndistribution of nitrifying bacteria as determined by FISH would correlate to measuredrnchanges in the concentrations of ammonia, nitrate, and nitrite. Both ammonia andrnnitrite oxidizing bacteria were found in NTF biofilm samples. A good correlation existsrnbetween ammonia-oxidizer populations quantified by FISH and observed ammoniarnremoval rates. The correlation significantly improved when the broader Nso190 probernwas utilized in place of the more specific probe NEU23a indicating that species otherrnthan Nitrosomonas are dominant in this system.