Na^+和K^+共存对A^2/O工艺脱氮除磷效果及污泥性质的影响

Effect of coexistence of Na^+ and K^+ on sludge properties and microbial community structure in A^2/O process

为了揭示多种金属离子共存的含盐废水生物处理系统污染物的去除机制和污泥特性,考察Na^+、K^+共存对A^2/O工艺污染物去除率、污泥性质和微生物群落的影响,采用高通量测序技术分析了厌氧区、缺氧区和好氧区的微生物群落结构,结合脱氮除磷效果和污泥性质的变化,探讨不同Na^+/K^+摩尔比下A^2/O工艺优势种群的演替规律,以期从微生物角度明确Na^+、K^+共存对含盐废水污染物去除率的影响。结果表明:当进水Na^+/K^+摩尔比分别为2、1和0.5时,A^2/O工艺的COD去除率分别为80%、84%和86%,TN去除率分别为73%、77%和80%,K^+浓度的提高缓解了Na^+对COD和TN去除率的抑制作用;厌氧区释磷率分别为70%、73%和74%,缺氧区吸磷率分别为53%、55%和58%,好氧区吸磷率分别为70%、72%和75%。随着进水Na^+/K^+摩尔比的降低,厌氧区、缺氧区和好氧区微生物群落的丰富度和多样性降低,微生物群落差异显著,变形菌门的相对丰度均升高约30%,拟杆菌门和绿弯菌门相对丰度逐渐降低。陶氏菌属和固氮弧菌属作为优势菌属,其相对丰度逐渐增大,有利于氮磷污染物的去除。通过增加K^+的浓度有利于提高氮、磷去除率,增强污泥的生物絮凝性和反硝化聚磷菌的活性。

A large amount of salty wastewater is produced from industrial processes such as food processing,tanning,textiles,aquaculture and oil production.After the salty wastewater entered the activated sludge system and contacted with the activated sludge,the sedimentation,microbial activity and community structure of activated sludge were influenced,which could result in the change of pollutant removal efficiency.A^2/O process could achieve simultaneously nitrogen and phosphorus removal,but it was unclear how Na^+and K^+influenced the microbial communities and the removal efficiency of pollutants in the anaerobic,anoxic and oxic zones.In order to reveal the removal mechanism of the pollutants and the characteristics of activated sludge in the biological treatment system under the coexisting multiple metal ions,the effect of the coexisting Na^+and K^+on the removal efficiency of pollutants was investigated and the properties of sludge and microbial community in the anaerobic,anoxic and oxic zones were analyzed by high-throughput sequencing.Combined with the changes of removal efficiency of nitrogen and phosphorus and sludge properties,the succession regulation of dominant populations were explored based on the analysis of microbial community structure under different Na^+/K^+molar ratios to distinguish the effect of the coexistence of Na^+and K^+on the removal efficiency of the pollutants in the salty wastewater from the point of microorganisms.The results showed that when the influent Na^+/K^+molar ratio was 2,1 and 0.5,the removal efficiencies of COD were 80%,84%and 86%,respectively.The removal efficiencies of TN were 73%,77%and 80%,respectively.The increase of K^+concentration alleviated the inhibition of Na^+on the removal efficiency of COD and TN.The release rates of TP in anaerobic areas were 70%,73%and 74%,respectively.The phosphorus uptake rates in the anoxic zone were 53%,55%and 58%,respectively.The phosphorus uptake rates in the oxic zone were 70%,72%and 75%,respectively.The Zeta potential in anaerobic zone is-25.4,-23.2 and-14.7 mV,respectively.The Zeta potential in the anoxic zone is-33.0,-26.6 and-13.7 mV and the Zeta potential in oxic zone is-30.4,-18.6 and-11.0 mV,respectively.The positive charge adsorbed by sludge floc increased.Moreover,the biological flocculation of sludge increased gradually and the deflocculation ability of Na^+was inhibited.The richness and diversity of microbial communities in anaerobic,anoxic and oxic zones decreased and the differences of microbial communities were significant.The relative abundance of Proteus increased by about 30%and the relative abundance of Bacteroides phylum and Chloroflexi decreased gradually.As the dominant genera,the relative abundance of nitrogen-fixing Thauera and Azoarcus gradually increased and the proportion of unknown bacteria decreased,which were beneficial to the removal of pollutants.Therefore,the increase of K^+concentration contributed to increase the removal efficiency of nitrogen and phosphorus under the coexistence of Na^+and K^+.It was also beneficial to the improvement of dehydrogenase activity of sludge in anoxic zone and oxic zone and the enhancement of particle size and flocculation ability(FA)of sludge.