Tomlin C, Forster C F
Department of Civil Engineering, University of Birmingham, Great Britain.
Microbios. 1988;56(226):7-17.
Mesophilic anaerobic digestion is a well established method for stabilising municipal sewage sludges. However, digestion in the thermophilic range is very restricted. The main reason for this has been the imbalance between the energy produced in the form of biogas and the energy required to maintain the temperature of a thermophilic system. It has been shown recently that an energy-positive process can be achieved using thickened sludges as the feedstock and, therefore, thermophilic digestion must be considered as a potentially attractive process for sludge stabilisation. However, before it can properly be offered as an alternative technology, the effect of toxic materials must be known. Currently, there is little information about the effect that known toxic agents can have on the microbial flora of a thermophilic sludge. This paper examines the toxicity (measured in terms of gas inhibition) of heavy metals, both individually and in combinations, on the sludge produced by a laboratory-scale digester (10 litres) operating at 55 degrees C with a solids retention time of 20 days. The metals used were zinc, lead, nickel, copper and cadmium and the gas inhibition studies were done in small (500 ml) flasks so that the gas production could be monitored precisely. Statistical analysis of the results showed that a model, developed previously to describe the toxicity of a range of compounds to mesophilic systems, was applicable to heavy metals and thermophilic sludges.
中温厌氧消化是一种成熟的城市污水污泥稳定化方法。然而，高温范围内的消化非常有限。主要原因是沼气形式产生的能量与维持高温系统温度所需的能量之间存在不平衡。最近有研究表明，使用浓缩污泥作为原料可以实现能量正向过程，因此，高温消化必须被视为污泥稳定化的一种潜在有吸引力的过程。然而，在它能够作为一种替代技术被恰当地提供之前，必须了解有毒物质的影响。目前，关于已知有毒物质对高温污泥微生物群落的影响的信息很少。本文研究了重金属单独及组合存在时，对一个在55摄氏度下运行、固体停留时间为20天的实验室规模消化器（10升）产生的污泥的毒性（以气体抑制来衡量）。所使用的金属为锌、铅、镍、铜和镉，气体抑制研究在小（500毫升）烧瓶中进行，以便能够精确监测气体产生情况。结果的统计分析表明，先前开发的用于描述一系列化合物对中温系统毒性的模型适用于重金属和高温污泥。
