微小双胸蚓处理城市污泥的试验研究

Experimental study on vermicomposting of municipal sewage sludge using Bimastus parvus

为满足城市污泥的资源化利用,采用微小双胸蚓(Bimastusparvus)直接处理脱水污泥,研究处理后蚯蚓生物量及污泥理化性质(pH值、电导率、灰分、总有机碳TOC)、营养物质(氮TN、磷TP、钾TK)和重金属(Cu、Zn、Pb、Cr)质量比的变化。结果表明,蚯蚓能很好地适应直接投加污泥的生存环境,各组蚯蚓平均日增重0.48 g,日产卵3.30个。随着处理时间的增加,污泥的理化性质、营养物质及重金属质量比均有显著变化。蚯蚓处理30 d后,污泥的pH值由7.83降低至6.20,电导率由0.46 S/m增至2.19 S/m,灰分由43.89%增至58.80%,TOC由32.32%降至22.89%;营养物质TN、TP和TK分别提高了35.38%、15.32%和32.02%。;重金属显著减少,降幅由大到小依次为Zn、Cu、Pb、Cr。研究表明,微小双胸蚓可直接处理城市生活污泥,处理后污泥的性质稳定,呈颗粒状,无臭味,不生蛆。

The present paper is aimed at introducing a new approach to safe recycled use of sewage sludge （SS） with a kind of epigeic earthworm Bimastus parvus （ B. parvus ）. As a matter of fact, the above said worms can directly be used to treat the dewatered sludge with no need of any treatment. In order to proceed with our study, we tried to make a worm treating and a non-worm treating for comparison, and then tried to study the variations of the earthworm biomass, physical and chemical features （pH value, electrical conductivity, ash, and total organic carbon）, nutrients （nitrogen, phosphorus and potassium）, and heavy metals （copper, zinc, lead and chromium） in the sewage sludge in our work. The results of our investigation have shown that B. parvus can be made to adapt to the new environment properly. Their daily weight can be found increase about 0.48 g and daily egg production is about 3.30. With the increase of the treating time, the physical and chemical properties, nutrients, and amount of heavy metal content in the sewage sludge were found changing significantly. Its pH value has decreased from 7.83 to 6.20, electrical conductivity was found increased from 0.46 S/m to 2.19 S/m with ash increasing from 43.89% to 58.80%, TOC has decreased from 32.32% to 22.89%, and nutrient amount of TN, TP and TK has been raised by 35.38%, 15.32% and 32.02%, respectively. In addition, the presence and the activity of earthworms in the sewage sludge prove to help reduce the amount of heavy metals significantly in the order of Zn, Cu, Pb, Cr from the most tothe least. The treated sewage sludge after inoculating the earthworm remains stable in granular form, with no unpleasant smell or maggots detected.