不同耐盐植物人工湿地净化养殖外排水效果

Purification Efficiency of Mariculture Wastewater in Constructed Wetlands with Two Salt-Tolerant Plants

为了探究不同耐盐植物对海水养殖外排水的去污效果,选取了芦苇(Phragmites australis)与互花米草(Spartina alterniflora)为湿地植物,细沙、蛭石和珊瑚石为基质,构建了2套复合垂直流人工湿地系统。对比分析了2种挺水植物的耐盐性及对海水养殖外排水中氨氮(NH_4-N)、亚硝态氮(NO_2-N)、硝态氮(NO_3-N)、高锰酸钾指数(COD_(Mn))和磷的净化效果。结果显示,芦苇耐盐度最高为20,而互花米草在盐度35以下均能正常生长,芦苇和互花米草湿地系统对NH_4-N的平均去除率分别为(85.48±0.50)%和(95.01±1.18)%,对COD_(Mn)平均去除率分别为(57.74±4.40)%和(72.84±2.64)%。互花米草湿地系统对NH_4-N和COD_(Mn)的平均去除率高于芦苇湿地,分别高9.53%和15.01%,差异性显著(P<0.05)。互花米草和芦苇湿地系统对磷酸盐和总磷(TP)的去除率为40.00%~50.00%,差异性不显著(P>0.05)。研究表明,在高盐胁迫下,互花米草生长状况和对无机氮(DIN)和COD_(Mn)的去除效果均优于芦苇,2种植物对磷酸盐和TP的去除率差异不明显。

As an eco-friendly wastewater treatment method, constructed wetlands have been widely used in purifying aquaculture wastewater. However, due to the effects of salt stress of seawater, the feasibility of treating mariculture wastewater in constructed wetland with different plants needs further study. To investigate the water contaminant removal efficiency, two integrated vertical flow constructed wetlands（IVCW） were constructed. Phragmites australis and Spartina alterniflora were selected as the constructed wetland plants. The salinity tolerance of P. australis was significantly different from that of S. alterniflora. The content of ammonia nitrogen（NH_4-N）, nitrite nitrogen（NO_2-N）, nitrate nitrogen（NO_3-N）, phosphorus, total phosphorus（TP）, and potassium permanganate index（COD_（Mn）） were determined for 14 d. The two constructed wetland were filled with fine sand, vermiculite, and corallite. The results showed that the optimum salinity of P. australis was 20 and that of S. alterniflora was less than 35. The physical and chemical properties of the purified water were： temperature（28.60±0.71）℃, pH 7.60±0.04, and dissolved oxygen（DO）（5.32±0.45） mg/L. This demonstrated that the efficiency of P. australis wetland and S. alterniflora wetland in the removal of NH_4-N and COD_（Mn） was（85.48±0.50）% and（57.74±4.40）%; and（95.01±1.18）% and（72.84±2.64）%, respectively. The efficiency in the removal of phosphate and TP were 40.00%~50.00% by both the constructed wetlands. These results suggested that the salt tolerance of S. alterniflora was better than P. australis. There were significant differences in NH_4-N and COD_（Mn） between P. australis wetland and S. alterniflora wetland（P〈0.05）. However, the difference between the wetlands was not significant for phosphate and TP（P〉0.05）. In the short term, the efficiency of the removal of NH_4-N and COD_（Mn） from mariculture effluents by S. alterniflora wetland was better than by the P. australis wetland. Under high-salinity stress, S. alterniflora had strong salt tolerance and grew better in seawater, and had better purification efficiency than P. australis. However, the efficiency in the removal of phosphate and TP exhibited no significant difference between the two wetlands.