Zeng Huiping

Nitrogen removal efficiency and microbial community analysis of ANAMMOX biofilter at ambient temperature

An upflow anaerobic biofilter (AF) was developed to investigate anaerobic ammonium-oxidizing (ANAMMOX) efficiency in treating low-strength wastewater at ambient temperature (15.3-23.2 °C). Denaturing gradient gel electrophoresis (DGGE) and fluorescence in situ hybridization were used to investigate treatment effects on the microbial community. Stepwise decreases in influent ammonia concentration could help ANAMMOX bacteria selectively acclimate to low-ammonia conditions. With an influent ammonia concentration of 46.5 mg/L, the AF reactor obtained an average nitrogen removal rate of 2.26 kg/(m³ day), and a removal efficiency of 75.9%. polymerase chain reaction-DGGE results showed that microbial diversity in the low matrix was greater than in the high matrix. Microbial community structures changed when the influent ammonia concentration decreased. The genus of functional ANAMMOX bacteria was Candidatus Kuenenia stuttgartiensis, which remained stationary across study phases. Visual observation revealed that the relative proportions of ANAMMOX bacteria decreased from 41.6 to 36.3% across three study phases. The AF bioreactor successfully maintained high activity due to the ANAMMOX bacteria adaptation to low temperature and substrate conditions.

Bacterial composition and nutrient removal with a novel PIA-A2/O sewage treatment

A novel post intermittent aeration anaerobic-anoxic-oxic (PIA-A(2)/O) process was developed to integrate shortcut nitrification-denitrification with denitrifying phosphorus (P) removal for domestic sewage treatment. With the transformation in configuration and phased start-up strategy, the nitritation rate and the ratio of denitrifying phosphorus accumulating organisms to phosphorus accumulating organisms (DPAO/PAO) were enhanced greatly to 88.2% and 83.9-91.7% in the PIA-A(2)/O process, respectively. Improved total nitrogen and phosphorus removal were achieved at long sludge retention time and low aeration. High sludge activity was maintained through the periodic selection of the additional intermittent aeration zone. High-throughput sequencing revealed that Bacteroidetes (38.96%), Proteobacteria (33.59%), TM7 (4.53%), Chloroflexi (3.09%), and Firmicutes (2.49%) were the dominant phyla in the resultant bacterial community. Abundant anaerobic and facultative bacteria conducive to excess sludge reduction were generated by this process. Potential DPAOs involve the genera of Brevundimonas, Brachymonas, Steroidobacter, Haliscomenobacter, and Rhodocyclus.