海菜花-螺蛳经济湿地对农田低污染水的净化

Research on Purification of Low-Level Contaminated Water by Ottelia acuminataMargarya melanioides Constructed Wetland

为研究海菜花水培经济湿地对农田低污染水的净化效能及投放螺蛳对水体净化的影响,在进水ρ(TN)、ρ(NO3--N)、ρ(TP)分别为(5.08±0.14)、(4.71±0.15)、(0.10±0.03)mgL条件下,构建了无螺组(海菜花湿地)、有螺组(海菜花-螺蛳经济湿地)和空白组(无海菜花和螺蛳湿地)3种湿地,对比不同HRT(水力停留时间)对水质处理效果的影响,并考察了其经济效益.结果表明:1HRT为7 d时,无螺组对TN、NO3--N和TP的去除率分别为55.6%±5.8%、62.6%±5.8%和76.3%±4.8%,有螺组分别为50.8%±5.5%、61.2%±6.3%和75.5%±3.9%;HRT为42 d时的污染物去除率与HRT为28 d时相当,并且有螺组和无螺组也相当,对TN、NO3--N和TP的去除率分别在76.8%、92.4%和84.8%以上.2HRT为7和42 d时,投放螺蛳对N、P的去除均表现为抑制作用;HRT为7 d时有螺组浊度显著降低(P<0.05).3HRT为7 d时,有螺组和无螺组对TN、TP的处理量均在800和228 kg(hm2·a)以上,显著高于HRT为42 d〔141、46 kg(hm2·a)〕时.4HRT为7 d的有螺组经济效益最高,为20.3×104元(hm2·a),其中海菜花收益为15.4×104元(hm2·a),投加螺蛳增加经济效益为4.9×104元(hm2·a).综合考虑对农田低污染水的净化效能和经济效益,优选HRT为7 d的海菜花-螺蛳经济湿地处理农田低污染水.

Purification efficiency of farmland low-level contaminated water and the economic benefits of Ottelia acuminate hydroponics wetlands with added Margarya melanioides were studied though simulated experiments. With the influent p （TN） , p （ NO3^- -N） and p（TP） being （5.08 ± 0. 14） , （4.71 ± 0.15 ） and （ 0. 10 ± 0.03 ） mg/L respectively, three groups （ Ottelia acuminate group, Ottelia acuminate-Margarya melanioides group and the blank group） were simulated under different HRT situations. The results showed： 1） The removal ratios of TN, NO3^--N and TP in O. acuminate group reached 55.6% ± 5.8%, 62. 6% ±5.8% and 76.3% ± 4. 8% respectively, while in the O. acuminate-M, melanioides group they were 50.8% ±5.5%, 61.2% ± 6.3% and 75.5% ± 3.9% respectively under HRT 7 d situation. They reached above 76. 8% , 92.4% and 84.8% respectively in both the O. acuminate and O. acuminate-M. melanioides groups under HRT 42 d. 2） M. melanioides inhibited the removal of nitrogen and phosphorus under HRT 7 d and HRT 42 d conditions. M. melanioides significantly reduced turbidity in HRT 7 d wetlands （P 〈 0. 05）. 3） TN and TP removals reached above 800 and 228 kg/（ hm^2·a） in HRT 7 d wetlands, which were higher than HRT 42 d wetlands （ 141, 46 kg/（ hm^2 ·a） ）. 4）In total, 203 thousand yuan of benefits per hectare were yielded in the O. acuminate-M. melanioides group, which included 154 thousand yuan of income from the O. acuminate and 49 thousand yuan from the M. melanioides. There was a better purification capacity for farmland low-level contaminated water and a more considerable economic benefit in O. acuminate-M. melanioides wetlands under the HRT 7 d situation; therefore, it is more suitable for engineering projects.