Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC, Delft, The Netherlands.
Water Res. 2011 Nov 15;45(18):5916-24. doi: 10.1016/j.watres.2011.08.046. Epub 2011 Sep 6.
Sludge predation can be an effective solution to reduce sludge production at a wastewater treatment plant. Oligochaete worms are the natural consumers of biomass in benthic layers in ecosystems. In this study the results of secondary sludge degradation by the aquatic Oligochaete worm Aulophorus furcatus in a 125 m(3) reactor and further sludge conversion in an anaerobic tank are presented. The system was operated over a period of 4 years at WWTP Wolvega, the Netherlands and was fed with secondary sludge from a low loaded activated sludge process. It was possible to maintain a stable and active population of the aquatic worm species A. furcatus during the full period. Under optimal conditions a sludge conversion of 150-200 kg TSS/d or 1.2-1.6 kg TSS/m(3)/d was established in the worm reactor. The worms grew as a biofilm on carrier material in the reactor. The surface specific conversion rate reached 140-180 g TSS/m(2)d and the worm biomass specific conversion rate was 0.5-1 g TSS sludge/g dry weight worms per day. The sludge reduction under optimal conditions in the worm reactor was 30-40%. The degradation by worms was an order of magnitude larger than the endogenous conversion rate of the secondary sludge. Effluent sludge from the worm reactor was stored in an anaerobic tank where methanogenic processes became apparent. It appeared that besides reducing the sludge amount, the worms' activity increased anaerobic digestibility, allowing for future optimisation of the total system by maximising sludge reduction and methane formation. In the whole system it was possible to reduce the amount of sludge by at least 65% on TSS basis. This is a much better total conversion than reported for anaerobic biodegradability of secondary sludge of 20-30% efficiency in terms of TSS reduction.
底泥捕食可以有效地减少污水处理厂的污泥产量。寡毛类蠕虫是生态系统中底泥层生物质的天然消费者。本研究介绍了在 125m3 反应器中利用水生寡毛类蠕虫 Aulophorus furcatus 降解二级污泥，以及在厌氧罐中进一步转化污泥的结果。该系统在荷兰 Wolvega 的 WWTP 运行了 4 年，以低负荷活性污泥工艺的二级污泥为食。在整个试验期间，稳定且活跃的水生蠕虫 A. furcatus 种群得以维持。在最佳条件下，蠕虫反应器中建立了 150-200kg TSS/d 或 1.2-1.6kg TSS/m3/d 的稳定污泥转化率。蠕虫在反应器中的载体材料上形成生物膜。比表面积转化速率达到 140-180g TSS/m2d，而蠕虫生物量比转化速率为 0.5-1g TSS 污泥/g 干重蠕虫/天。在最佳条件下，蠕虫反应器中的污泥减量率为 30-40%。蠕虫的降解速度比二级污泥的内源性转化速度高出一个数量级。从蠕虫反应器中排出的剩余污泥被储存在一个厌氧罐中，其中出现了产甲烷过程。似乎除了减少污泥量外，蠕虫的活动还增加了厌氧消化性，从而可以通过最大化污泥减少和甲烷形成来优化整个系统。在整个系统中，基于 TSS 减少量，污泥量至少可以减少 65%。这是一个比报道的二级污泥厌氧生物降解率 20-30%（以 TSS 减少为基准）更好的总转化率。
