γ辐照预处理促进剩余污泥发酵产氢的研究

Effect of γ-irradiation on fermentative hydrogen production by excess sludge

为降低能耗，提高辐照技术的经济性，探讨了在0～9．5kGy范围内，γ辐照剂量对生活污水处理厂二沉池剩余污泥中耗氢菌的抑制效果和对发酵产氢的影响，建立了描述发酵产氢过程及辐照影响的动力学模型．结果表明，γ辐照剂量从0增加至9．5kGy时，污泥溶解率从0增加至4％，上清液中可检测出一定的蛋白质和多糖等物质，其中蛋白质中的氮素占溶出总氮素的90％，表明较低剂量辐照即对污泥菌体造成较明显的破解，这可在一定程度上抑制无法形成芽孢的耗氢菌活性；与之相对应的是污泥发酵产氢能力的明显提升，以葡萄糖为底物（1．0g/E），在35℃和初始pH值为7．0时，当辐射剂量仅为0．5kGy时，累积产氢量即比未辐照时有70％的提升，进一步增加辐照剂量至5kGy,累计产氢量和产氢得率均继续增长且达到最大值，分别为240mL／g葡萄糖和1．93mLH2／mol葡萄糖（发酵液的污泥量达2．0gVSS／L）；此后，污泥发酵产氢能力随辐射剂量的增加而降低．修正的Logistic模型能很好地描述本研究中累积产氢量随时间的变化规律，而修正的Han-Levenspiel模型能很好地描述辐照剂量对平均产氢速率的影响．

Effect of low gamma-ray doses ranging from 0 to 9.5kGy on sludge solubilization and hydrogen production was investigated to examine the potential utilization of irradiation technology in the fermentative hydrogen production by excess sludge. Experimental results showed that the solubilization efficiency of treated sludge from secondary sedimentation tank of a sewage treatment plant in Beijing was increased from 0 to 4% at irradiation doses from 0 to 9.5kGy. Certain soluble protein and polysaccharides were detected in the liquid supematant, indicating that low dose irradiation is efficient to inhibit non-spore forming hydrogen-consuming microorganisms and to promote hydrogen production efficiency by spore germination in genus Clostridium correspondingly, which is known as one of the key hydrogen producers. Consequently, the enhancement of hydrogen production was obvious, the hydrogen production potential and hydrogen yield increased with increasing irradiation doses from 0 to 5kGy, and then decreased with further increasing irradiation doses from 5 to 9.5kGy. The maximum cumulative hydrogen production of 240mL/g glucose and maximum hydrogen yield of 1.93mol H：/mol glucose were all obtained at irradiation dose of 5kGy under 35 ℃ and initial pH 7.0in batch tests using glucose as substrate （1.0g/L）. The modified Logistic model could describe the progress of cumulative hydrogen production in the batch tests of this study successfully, while modified Han-Levenspiel model could describe the effect of irradiation energies on average hydrogen production rate successfully.