Operational Characteristics And Microbial Community Structure Of Enhanced Nitrogen Removal ANDH Process

To solve the problems，including instability of nitrification in winter, carbonshortage for denitrification and difficulties in making the total nitrogen (TN) meet thedischarging stANDHrd, which exist commonly in most of the municipal wastewaterplants in south cities of China, we developed an enhanced nitrogen removal processcharacterized by carbon source regulation with biological adsorption and sludgehydrolysis (ANDH). A pilot-scale ANDH system was built in Chengbei municipalwastewater plant, Wu Xi city. Following the previous studies, the sludge hydrolysis anddenitrification units, long-term operation characteristics of the ANDH process werestudied in this thesis. The bacterial community structures in the ANDH system werealso examined by using clone library, terminal restriction fragment lengthpolymorphism (T-RFLP) and454sequencing tools.Operated continuously under hydraulic retention (HRT) of30, pH of11and watertemperature of60℃, the average SCOD in the effluent of the hydrolysis tank was1530mg/L, providing a large amount of carbon source for denitrification.The activated sludge could acclimated to the hydrolyzed carbon came from thesludge hydrolyzation which completely replaced the methanol step by step fordenitrification. The TN concentration in the effluent could keep below15.0mg/L whilethe average influent TN was37.3mg/L.During310days of long-term operation under the optimal operation parameters,the ANDH system showed good performance in pollutant removal. The averageconcentration of COD, TN and NH4+-N in the effluent were37.7mg/L,13.8mg/L and0.55mg/L respectively.The bacterial community structures in absorption tank, nitrification tank anddenitrificationg tank of the ANDH system was studied and compared by using clonelibrary, terminal restriction fragment length polymorphism (T-RFLP) and454sequencing tools. The results indicated that huge community information can beobtained by454sequencing. The bacterial community structures in the three tanks wereapparently different, such as the content of Proteobacteria in absorption tank,nitrification tank and denitrification tank were29.41%,14.16, and29.53%respectively.Each tank had a microbial structure which was different from the others.The bacterial community structures in the sludge of the denitrification tank at the initial stage and long term operation period, when the hydrolyzed carbon was used fordenitrification,were studied by using454sequencing and compared. The resultsindicated that the bacterial community structures were changed adapting to thehydrolyzed carbon. The content of Bacterioidtes increased from12.28%to29.52%while Chloroflexi decreased from14.12%to3.52%. The contents of the Rhizobiales andBurkholderiale in Proteobacteria were obviously changed too.