以RAS固体废弃物为碳源的改进型人工湿地对养殖尾水的脱氮效果

NITROGEN REMOVAL EFFECT OF AQUACULTURE WATER THROUGH IMPROVED CONSTRUCTED WETLAND USING RECIRCULATING AQUACULTURE SYSTEM SOLID WASTE AS CARBON SOURCE

循环水养殖系统(Recirculating Aquaculture System,RAS)具有排放高营养的养殖固体废弃物和高浓度硝酸盐的废水问题,为此研究构建一种改进型人工湿地处理装置,将养殖固体废弃物资源化为湿地系统的外加碳源,以期强化其对循环水养殖尾水脱氮效果,并通过高通量测序对湿地微生物群落进行分析。结果表明,养殖固体废弃物的投加量增加会提升湿地进水中N负荷,当进水TCOD/TN为8.78±0.41且厌氧区深度为30和50 cm时,模拟湿地系统对TN、NO~--N和NH~+-N的去除效果较好。在门水平上,各湿地系统优势菌门为变形菌门(Proteobacteria),其在各装置厌氧水解区(A)相对丰度为4.44%—62.87%,湿地填料区(B)相对丰度为61.93%—78.64%;模拟湿地系统中反硝化菌属丰度较高,主要为Silanimonas属(1.66%—23.42%)和Rivibacter属(4.74%—12.75%),且B区反硝化菌属相对丰度高于湿地填料区下部的A区;此外深度为30 cm和50 cm的A区还发现1种未培养的厌氧氨氧化菌属(uncultured_c_Anammox_3,0.22%—0.33%)。研究结果显示改进型人工湿地在以养殖固体废弃物为碳源时,主要通过反硝化作用脱氮,且存在一定的厌氧氨氧化过程,可为人工湿地处理循环水养殖系统废物的工程实践提供理论指导。

The recirculating aquaculture system has the inevitable feature of discharging high-nutrient aquaculture solid waste and high-concentration nitrate wastewater.To solve this problem,a set of improved configuration of constructed wetlands treatment device were built in this study.In order to strengthen their N removal on the wastewater from recirculating aquaculture system,the improved constructed wetlands used aquaculture solid waste as additional carbon source and investigated the microbial community composition of the constructed wetlands by high-throughput sequencing.The results showed that with the increased addition of the amount of aquaculture solid waste,the N load in the influent of the constructed wetlands improved.When TCOD/TN in the influent was 8.78±0.41 and the depths of the anaerobic hydrolysis zone(A)were 30 cm and 50 cm,the improved constructed wetlands system had better TN,NO-N and NH-N removal performance.At the phylum level,Proteobacteria was dominated in all constructed wetlands,with the relative abundance of 44.44%—62.87%in zone A and 61.93%—78.64%in constructed wetland packing zone B,respectively.Moreover,the improved constructed wetlands had a high relative abundance of denitrifying bacteria,which were mainly Silanimonas(1.66%—23.42%)and Rivibacter(4.74%—12.75%),while the relative abundance of denitrifying bacteria in the wetland packing zone B was higher than that in the lower anaerobic zone A.In addition,an uncultured Anammox bacteria genus(uncultured_c_Anammox_3,0.22%—0.33%)was also detected in the zone A.These results indicated that when the improved constructed wetlands was fed with aquaculture solid waste as the carbon source,nitrogen removal was mainly through denitrification process and a weak anammox effect was also involved.Thus,this study provided a preliminary theoretical guidance for the engineering practice of constructed wetland to deal with waste from recirculating aquaculture systems.