铜和磺胺甲唑复合污染下人工湿地对禽畜养殖尾水的处理效果

PURIFICATION PERFORMANCE OF RURAL LIVESTOCK AND POULTRY BREEDING TAIL WATER BY CONSTRUCTED WETLAND UNDER CU AND SMZ COMBINED POLLUTION

  • 摘要: 为研究人工湿地同步去除养殖尾水中重金属和抗生素的效果, 文章以铜(Cu)和磺胺甲唑(Sulfamethoxazole, SMZ)为例, 设计了5组小试垂直流人工湿地模拟处理不同重金属-抗生素复合水平的养殖尾水(A: 空白; B: Cu 2 mg/L; C: Cu 2 mg/L, SMZ 5 mg/L; D: Cu 20 mg/L, SMZ 0.2 mg/L; E: Cu 20 mg/L, SMZ 5 mg/L), 探究复合污染下人工湿地处理效果的差异。结果显示, 复合污染下人工湿地对模拟禽畜养殖尾水中的N、P、化学需氧量(Chemical Oxygen Demands, COD)、Cu和SMZ仍具有较高的去除率和较为稳定的去除效果, 各组平均去除率均达到99%, 复合污染的影响主要体现在氨态氮(Ammonia Nitrogen, NH3-N)和总氮(Total Nitrogen, TN)的去除上。添加不同浓度Cu和SMZ后, 各组NH3-N平均去除率依次为81.75%、87.59%、79.50%、74.45%和65.41%, TN平均去除率依次为81.59%、87.63%、80.82%、74.15%和67.56%, C、D和E组植物地下部分干重分别较A组下降了 22.22%、30.58%和30.64%, 复合污染对植物产生毒害作用, 使微生物的群落结构产生变化, 一些在氮去除过程中具有重要作用的微生物比如PropionicicellaBacillus丰度降低, 从而影响NH3-N 和TN的去除。

     

    Abstract: Some heavy metals and antibiotics are widely used as feed additives in livestock breeding in rural areas. However, the bioavailability of the additives is quite low, while 40%—80% are discharged in the forms of prototypes or metabolites in feces, which causes a series of environmental pollution problems. Constructed wetlands (CWs) are sewage treatment technology with advantages of low costs, high efficiency and easy maintenance. Earlier studies have been reported that CWs have efficient removal effect on conventional pollutants such as N, P and COD, but there are few studies on the simultaneous removal of heavy metals and antibiotics in the tail water of livestock and poultry breeding in CWs. The influence and mechanism of combined pollution on the treatment effect of CWs is not clear yet. In this study, based on comprehensively considering the additives in aquaculture feed and their toxic effects, copper (Cu) and sulfamethoxazole (SMZ) were chosen as target pollutants. A group of five small-scale vertical flow constructed wetlands (VFCWs) were constructed, while different concentrations of Cu and SMZ wastewater were prepared to simulate different combined pollution levels (A: blank, B: 2 mg/L Cu, C: 2 mg/L Cu and 5 mg/L SMZ, D: 20 mg/L Cu and 0.2 mg/L SMZ, E: 20 mg/L Cu and 5 mg/L SMZ). The effects of combined pollution Cu and SMZ on the purification capacity of wetland system were then explored. Results showed that VFCWs had high removal rate and relatively stable removal effect of total phosphorus (TP), chemical oxygen demands (COD) and nitrate nitrogen (\rmNO_3^-\text-N ) under different combined pollution levels, while the average removal rate was higher than 99%. However, combined pollution showed inhibitory effect on the removal of NH3-N and TN. This effect became strong with the increased addition of the Cu and SMZ. The average NH3-N removal rate of 5 groups were 81.75%, 87.59%, 79.50%, 74.45% and 65.41%, and the average TP removal rate of 5 groups were 81.59%, 87.63%, 80.82%, 74.15% and 67.56%, respectively. When Cu and SMZ were added at the same time, the dry weight of plant foot end were 22.22%, 30.58% and 30.64%, which were lower than that of group A. Combined pollution of Cu and SMZ had a negative effect on canna as well as a selective effect on microorganisms. It implies that the combined pollution may affect the removal of NH3-N and TN by affecting plant functions and microbial community structure.

     

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