垂直流湿地接种蚯蚓对剩余污泥中有机物的去除效果

Removal of organic matter from excess sludge by inoculating earthworm into vertical-flow constructed wetland

在垂直流湿地中接种蚯蚓,构建蚯蚓垂直流湿地,以去除剩余污泥中有机物为研究目标,探讨蚯蚓垂直流湿地对剩余污泥的处理效果及机理。结果表明,蚯蚓垂直流湿地对剩余污泥中总固体(TS)、化学需氧量(COD)、氨氮及总磷(TP)的去除率分别为54.17%~84.13%、71.11%~98.47%、62.65%~86.57%和57.15%~85.63%。其中,高密度蚯蚓垂直流湿地对TS与COD的平均去除率较低密度蚯蚓垂直流湿地分别增加了6.02%和6.83%(P<0.05)。高、低密度蚯蚓垂直流湿地出水的特征紫外吸光度(SUVA)比进泥分别增加了79.75%和95.09%(P<0.05),而出水的溶解性有机碳(DOC)含量分别降低了79.91%和74.91%(P<0.05),同时,高密度蚯蚓垂直流湿地基床的有机质累积率较低密度蚯蚓垂直流湿地显著提高(P<0.05),对污泥中类腐殖酸表现出更高的转化效率。另外,蚯蚓垂直流湿地中细菌数量由上至下依次减少,而高密度蚯蚓垂直流湿地的细菌数量比低密度蚯蚓垂直流湿地在各层均显著降低(P<0.05)。研究结果证实,蚯蚓垂直流湿地可以有效去除剩余污泥中有机物,且高密度蚯蚓垂直流湿地有助于提升去除效果。

In order to remove the organic matter from excess sludge, the effects and mechanisms of excess sludge treatment were investigated with the inoculation of earthworms into vertical-flow constructed wetland to construct earthworm-constructed vertical flow(EVF). The results showed that the removal rates of TS,COD,ammonia nitrogen and TP reached 54.17%-84.13%,71.11%-98.47%,62.65%-86.57% and 57.15%-85.63%,respectively. Among them, the average removal rates of TS and COD in high-density EVF were significantly higher than those in low-density EVF(P<0.05),which increased by 6.02% and 6.83%,respectively. Compared with the sludge, the effluent SUVAof high-density and low-density EVF increased significantly by 79.75% and 95.09%(P<0.05),and the DOC content decreased dramatically by 79.91% and 74.91%(P<0.05),respectively. Further research revealed that the accumulation of organic matter intercepted by the foundation bed of high-density EVF significantly increased compared with low-density EVF(P<0.05),displaying higher conversion efficiency of humus-like substance. In addition, the number of bacteria in EVF decreased from top to bottom, and the number of bacteria in the high-density EVF was significantly lower than that in low-density EVF(P<0.05). The research results suggested that EVF could effectively and stably reduce organic matter in excess sludge, and the high-density EVF performed a better removal effect for organic matter.