Hendrickx T L G, Temmink H, Elissen H J H, Buisman C J N
Wetsus - Centre of Excellence for Sustainable Water Technology, P.O. Box 1113, 8900 CC Leeuwarden, The Netherlands.
Water Res. 2009 Mar;43(4):943-50. doi: 10.1016/j.watres.2008.11.034. Epub 2008 Dec 6.
Several techniques are available for dealing with the waste sludge produced in biological waste water treatment. A biological approach uses aquatic worms to consume and partially digest the waste sludge. In our concept for a worm reactor, the worms (Lumbriculus variegatus) are immobilised in a carrier material. For correct sizing and operation of such a worm reactor, the effect of changes in dissolved oxygen (DO) concentration, ammonia concentration, temperature and light exposure were studied in sequencing batch experiments. DO concentration had an effect on both sludge consumption rate and sludge reduction efficiency. Sludge consumption rate was four times higher at DO concentrations above 8.1 mg/L, when compared to DO concentrations below 2.5 mg/L. Sludge reduction was 36 and 77% at these respective DO concentrations. The effect is most likely the result of a difference in gut residence time. An increase in unionised ammonia concentration drastically decreased the consumption rate. Ammonia is released by the worms at a rate of 0.02 mg N/mg TSS digested; therefore, replacing the effluent in the worm reactor is required to maintain a low ammonia concentration. The highest sludge consumption rates were measured at a temperature around 15 degrees C, whilst the highest TSS reduction was achieved at 10 degrees C. Not exposing the worms to light did not affect consumption or digestion rates. High temperatures (above 25 degrees C) as well as low DO concentrations (below 1 mg/L) in the worm reactor should be avoided as these lead to significant decreases in the number of worms. The main challenges for applying the worm reactor at a larger scale are the supply of oxygen to the worms and maintaining a low ammonia concentration in the worm reactor. Applying a worm reactor at a waste water treatment plant was estimated to increase the oxygen consumption and the ammonia load by 15-20% and 5% respectively.
有几种技术可用于处理生物废水处理过程中产生的剩余污泥。一种生物方法是利用水生蠕虫来消耗并部分消化剩余污泥。在我们关于蠕虫反应器的概念中，蠕虫（颤蚓）被固定在载体材料中。为了正确确定这种蠕虫反应器的尺寸并使其正常运行，我们在序批式实验中研究了溶解氧（DO）浓度变化、氨浓度、温度和光照对其的影响。溶解氧浓度对污泥消耗速率和污泥减量效率均有影响。与溶解氧浓度低于2.5mg/L相比，溶解氧浓度高于8.1mg/L时，污泥消耗速率高出四倍。在这两种溶解氧浓度下，污泥减量分别为36%和77%。这种影响很可能是肠道停留时间差异的结果。游离氨浓度的增加会大幅降低消耗速率。蠕虫以每消化1mg总悬浮固体（TSS）释放0.02mg氮的速率释放氨；因此，需要更换蠕虫反应器中的流出物以保持低氨浓度。在约15摄氏度的温度下测得最高的污泥消耗速率，而在10摄氏度时实现了最高的总悬浮固体减少量。不将蠕虫暴露在光照下不会影响消耗或消化速率。应避免蠕虫反应器中出现高温（高于25摄氏度）以及低溶解氧浓度（低于1mg/L），因为这些会导致蠕虫数量显著减少。将蠕虫反应器大规模应用的主要挑战在于向蠕虫供应氧气以及在蠕虫反应器中保持低氨浓度。据估计，在污水处理厂应用蠕虫反应器会使氧气消耗量和氨负荷分别增加15 - 20%和5%。
