两种生物电化学系统原位缓解人工湿地生物堵塞效果

EXPLORING THE IN-SITE MITIGATION OF BIO-CLOGGING OF CONSTRUCTED WETLANDS BY TWO BIO-ELECTROCHEMICAL SYSTEMS

生物电化学系统(Bio-electrochemical Systems,BES)利用附加电场或自产电场可以促进EPS分散、降解和利用,可在一定程度上控制和缓解人工湿地的生物堵塞。为此,研究采用CW-MEC和CW-MFC两种生物电化学系统对不同生物堵塞时期的人工湿地进行干预,通过比较系统直观堵塞指标(孔隙率、出水速率)、净化效果(COD和氮的去除)及垂直方向上分层EPS的含量等来评价不同干预时机,两种BES系统对生物堵塞的缓解能力。结果表明:两种BES系统均能体现较好的堵塞缓解效果。堵塞前干预,CW-MFC系统能很好地维持污染物COD、TN去除效果(91.4%—61.3%和65%—40%)并提高出水速率(变化率为CW组67.6%);堵塞后修复,CW-MEC系统能显著减少上层EPS含量,恢复系统孔隙率,具有更好的缓解堵塞效果。这两种BES系统原位缓解人工湿地生物堵塞方面皆有较好的应用潜力。

It is common and unavoidable that constructed wetland bio-clogging is caused by the massive secretion of Extracellular Polymeric Substances(EPS)of microorganisms.Bio-electrochemical Systems(BES)using additional electric fields or self-generated electric fields can promote the dispersion,degradation and utilization of EPS,and can control and alleviate the bio-clogging of constructed wetlands to a certain extent.Therefore,in this study,two bio-electrochemical systems,CW-MEC and CW-MFC,were used to intervene in constructed wetlands in different bio-clogging periods.Removals of COD and nitrogen and the content of stratified EPS in the vertical direction were used to evaluate the mitigation ability of the two BES systems to bio-clogging at different intervention timings.The results indicated that the two BES systems showed good clogging mitigation effect.Intervention before clogging,the CW-MFC system can well maintain the removal effect of pollutants COD and TN(91.4%—61.3%and 65%—40%)and increase the water output rate(the change rate is 67.6%in the CW group).The CW-MEC system can significantly reduce the EPS content of the upper layer,restore the porosity of the system,and have a better effect of relieving clogging.Both of these two BES have good in situ application potential in alleviating bio-clogging in constructed wetlands,which provides reference for the effective prevention and control of bio-clogging in constructed wetlands during different periods.