水培技术作为人工湿地预处理工艺可行性研究

Feasibility of using hydroponic cultivation as a pretreatment process for constructed wetland

以城市污水处理厂初沉池出水为原水,对以美人蕉为栽培植物的水培生态净化槽作为复合人工湿地预处理工艺的可行性进行了现场试验研究.结果表明,水培槽对COD、SS的最大平均去除率分别达到了64.8%和88.7%,有效地削减了人工湿地的COD负荷和降低了湿地介质孔隙堵塞的风险.在0.10,0.30,0.60m三种不同槽深条件下,槽深越浅,出水中的DO浓度越高,越有利于水中污染物的去除,运行水深是决定水培槽对污水净化效率的重要参数,另外,与水培槽相组合的复合潜流人工湿地对水中的污染物去除效率较高且效果稳定,出水COD和SS可达到国家《城镇污水处理厂污染物排放标准》中的一级B标准,氨氮和总磷可达到二级标准.

A pilot scale hybrid constructed wetland was employed to investigate the feasibility of using hydroponic cultivation as a pretreatment unit for the constructed wetland system treating the effluent of primary sedimentation tank in a municipal wastewater treatment plant in Xi＇an.Canna indica Linn was raised both in hydroponic ditch system and constructed wetland system.Organic loading rate and the clogging risk of the constructed wetland were reduced significantly,which was due to the fact that 64.8%of COD and 88.7%of SS were removed in the hydroponic ditch system.The water depth was an important parameter for DO in the aqueous phase and pollutant removal efficiency of the hydroponic ditch system.The DO was increased from 0.75 to 2.61 mg/L when the water level decreased from 0.60 to 0.10 m.As a result,the pollutant removal performance was increased.Additionally,it was found that the pollutant removal efficiency of the hybrid constructed wetland was improved using hydroponic ditch system as pretreatment process.The concentrations of COD and SS in the effluent of hybrid constructed wetland were lower than requirement for 1B level while the concentration of NH_4~＋-N and TP were reached the requirement for level 2 in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant.