Tanaka Yasuo
Waste Recycling Laboratory, National Institute of Livestock and Grassland Science, Kukuzaki Inashiki-gunn, Ibaraki, Japan.
Bioresour Technol. 2002 Aug;84(1):21-8. doi: 10.1016/s0960-8524(02)00031-7.
A wastewater treatment system employing a UASB reactor in temperate regions requires biogas as a heat source for the UASB reactor during low temperature seasons. In this case, removal of H2S in the biogas by means of a scrubber before burning is necessary in order to prevent the boilers from corroding. Heating of the UASB reactor is, however, unnecessary in a warm season, and the scrubber and biogas become useless. Methane-dependent water quality improvement using the scrubber and biogas would be one way to use them efficiently during the warm season. The possible dual-purpose use of a packed-bed reactor was examined, with one of its uses being the scrubbing of biogas during the cold season and the other being the methane-dependent improvement of effluent water quality during the warm season. A bench scale packed-bed filled with plastic latticed-ring media was installed in a livestock wastewater treatment plant consisting of a UASB reactor and a trickling filter for post-treatment. The packed-bed was operated with biogas flowing at a superficial velocity of 0.14-0.39 m h(-1) and the hydraulic loading of trickling filter effluent sprayed onto the media 9.4-26.1 m3 m2 day(-1). H2S in the biogas from the UASB reactor was reduced from 1,200-2,500 ppm to less than 2 ppm by the reactor. Methane-dependent water quality improvement was examined using a laboratory scale reactor to which methane and/or air was supplied from the bottom, while plant effluent was spread from the top of the reactor. When the mixture gas of methane and air (volume ratio 1:3) was added to the reactor, biofilm grew on the surface of the media. Accompanying this growth, ammonium and phosphate in the spread water decreased, probably due to assimilation by the methane-oxidizing bacteria. Though assimilation activity dropped after the accumulation of biomass, it could be reactivated by washing out the excess biomass. Periodical backwash at a rate of more than once a week seemed to efficiently maintain the removal activity. The dark brown color of the wastewater could be also reduced in concert with methane oxidation. It seemed that methane-oxidizing bacteria degraded color-causing compounds. These results suggest that the packed-bed reactor is useful for both H2S purification of biogas and methane-dependent effluent water quality improvement.
在温带地区，采用上流式厌氧污泥床（UASB）反应器的废水处理系统在低温季节需要沼气作为UASB反应器的热源。在这种情况下，为防止锅炉腐蚀，在燃烧前需通过洗涤器去除沼气中的硫化氢。然而，在温暖季节，UASB反应器无需加热，洗涤器和沼气也就无用了。利用洗涤器和沼气进行依赖甲烷的水质改善将是在温暖季节高效利用它们的一种方式。研究了填充床反应器的双重用途，其一是在寒冷季节洗涤沼气，其二是在温暖季节进行依赖甲烷的出水水质改善。在一个由UASB反应器和用于后处理的滴滤池组成的畜禽废水处理厂中，安装了一个填充有塑料格环填料的实验室规模填充床。填充床运行时，沼气以0.14 - 0.39 m h(-1)的表面流速流动，滴滤池出水以9.4 - 26.1 m3 m2 day(-1)的水力负荷喷洒在填料上。该反应器将UASB反应器产生的沼气中的硫化氢从1200 - 2500 ppm降至2 ppm以下。使用实验室规模的反应器研究了依赖甲烷的水质改善情况，从底部向反应器供应甲烷和/或空气，同时从反应器顶部喷洒工厂出水。当向反应器中添加甲烷和空气的混合气体（体积比1:3）时，填料表面生长出生物膜。随着生物膜的生长，喷洒水中的铵和磷减少，这可能是由于甲烷氧化细菌的同化作用。尽管在生物量积累后同化活性下降，但通过冲洗掉多余的生物量可以使其重新激活。每周一次以上的定期反冲洗似乎能有效维持去除活性。废水的深褐色也会随着甲烷氧化而减轻。似乎甲烷氧化细菌降解了导致颜色的化合物。这些结果表明，填充床反应器对于沼气中硫化氢的净化和依赖甲烷的出水水质改善都很有用。
