低繁殖量蚯蚓养殖法处理剩余污泥的可行性研究

Feasibility study on municipal excess sludge treatment by cultivating low-multiplication rate earthworms

针对城市剩余污泥饲养蚯蚓需要发酵预处理,以及繁殖的含重金属的蚯蚓利用难的问题,进行了不同种类污泥直接饲养蚯蚓实验,并考察了投料方式、投料厚度对蚯蚓的生长影响。结果显示,新鲜的城市剩余污泥直接饲养蚯蚓可行,与投料方式无关。发臭污泥块状投放适宜蚯蚓生长,密实投放不适宜蚯蚓生存。采用定时引出成蚓,改变泥中蚓卵的生存环境,控制卵发育的养殖方法,对污泥中重金属转移规律进行了研究。结果表明,饲养过程中蚯蚓体内的重金属质量比随饲养时间上升。饲养120 d左右,蚯蚓体内质量比达到极限,且处理后的污泥中重金属质量比明显下降。该养殖法处理剩余污泥是方法可行,且具有蚯蚓产量低,利于蚯蚓处理和处置的优点。

The present paper has its objective of searching for the feasibility of earthworm cultivation directly in the excess sludge and the influence of earthworms on the metal accumulation ureter their low multiplying rate. As is known, earthworms help to accumulate heavy metals in sewage sludge and therefore can be used for beavy metal treating from municipal excessive sludge. However, in order to successfully cultivate earthworms, it is required to pre-treat the municipal. excess sludge through fermentation and then make necessary disposal of the used earthworms with highly concentrated heavy metals. To achieve the purpose, the present author has repeatedly tested and observed ways for earthworm cultivation in different kinds of sludge and the influence of different culturing methods and culturing amounts on the earthworm growth. The author＇ s research results show that the earthworms can be cultivated directly without the need to pre-treat fresh excess sludge and disregard of the feeding methods. Our experience has shown that long term deposited block sludge is suitable for earthworms growing, while high density sludge is not suitable for their cultivation. In our experiments, we have taken the excess sludge from Ningbo municipal sewage plant as the sample for experiments. With the earthworm cultivating time increased, the concentrations of heavy metals in earthworms are getting higher and higher. And finally maximum level was reached about four months later. At the stone time, heavy metal concentration in the treated sludge proves to get remarkably reduced. Therefore, our experiments indicate that this earthworm cultivation method is feasible at the lower multiplication rate of earthworms and less amount of used earthworms is needed for final disposal.