Complete nitrogen removal was achieved through integrating anammox and autotrophic denitrification in an UASB reactor.The total nitrogen(TN)removal rate increased stepwise from 0.46 to 0.94 kg-N/(m3·d),with an effluent TN concentration of below 3.0 mg-N/L achieved.The process is relatively insensitive to the nitrite to ammonium ratio,achieving complete nitrogen removal when their ratio in the influent varied in the range of 1.35-1.55.The added S0 quantity in the system could be utilized to adjust the competition between autotrophic denitrifiers and anammox bacteria.High-throughput sequencing technology indicated that Candidatus_Kuenenia and Thiobacillus were the functional strains for anammox and autotrphic denitrification process,respectively,in the studied reactor.This result provides a theoretical and technical basis for the large-scale application of anaerobic ammonium oxidation process.
Rapid formation of autotrophic partial denitrification(APD)granules is of practical interest to start up an expanded granular sludge bed reactor for wastewater treatment.This study demonstrates that methanogenic granules can be easily acclimated into autotrophic partial denitrification granules in one day,with the ability to remove 82%of 2.7 kg-S/(m^3·d)sulfide into S^0 and to convert 97%of 0.9 kg-N/(m^3·d)nitrate into nitrite,which can provide a promising feedstock for anaerobic ammonia oxidation process.Arcobacter sp.is essential for S^0 accumulation.Under high loadings,the abundance of Arcobacter sp.decreased,while on the contrary the abundance of unclassified_p_Firmicutes increased,leading to the deterioration of autotrophic partial denitrification performance.The granules performance could be recovered by adopting the strategies of properly reducing the influent loadings.
Liu ChunshuangLi XuechenZhang XiaofeiBai XueGuo YadongWang YongxingZhao Chaocheng
In this study, the effects of temperature, acetate and nitrate on methane gas production from biodegradation of petroleum hydrocarbons were investigated. The results indicated that methane gas production at 35 ℃ was higher than that obtained at 55 ℃. The acetate addition significant enhanced the methane production at 35 ℃, however, at 55 ℃ the nitrate addition could largely promote the methane production. The microbial community structures were revealed by PCR-DGGE. The Actinobacteria, Clostridia, Clostridiales, Syntrophus, Pseudomonas, and Proteobacteria-like bacteria and Methanocellales, Methanosaeta, Methanomicrobiales, Methanolinea, Thermoprotei-like archaea had been enriched at 35 ℃ in the acetate addition test. The Thermoprotei, Proteobacterium, Thermodesulfovibrio-like bacteria and Methanocellales-like archaea had been enriched at 55 ℃ in the nitrate addition test. The results may shed light on the bio-utilization of marginal oil reservoirs for enhancing energy recovery.
