不同pH条件下剩余污泥厌氧发酵过程中溶出物的释放

对剩余污泥进行厌氧发酵处理可实现污泥中有机质和磷的释放并最终回收利用，而pH是影响厌氧发酵过程的重要因子。为研究pH对厌氧发酵中磷与有机物释放的影响，采用批次实验研究了pH分别为3、5、7、9、10、11时剩余污泥厌氧发酵过程中磷和有机物的释放与转化规律。结果表明，在不同pH下，剩余污泥厌氧发酵过程中发生着有机物与不同形态磷的迁移与转化，酸性和碱性环境下的厌氧发酵液成分的三维荧光结构不同。剩余污泥厌氧发酵过程中，泥相钙结合态磷(AP)在酸性条件下转化为液相磷，有机磷(OP)和大部分铁/铝结合态磷(NAIP)在碱性条件下转化为液相磷；其中, pH为11时，污泥发酵液中磷含量最高。污泥发酵类型为丁酸型发酵，发酵产物以异丁酸为主，其次是正戊酸和乙酸。pH为10时，发酵液中的蛋白质与多糖的总量、挥发性有机酸(VFAs)浓度最高，两者呈现正相关关系；类蛋白和类腐殖酸降解，利于VFAs的积累。

Dissolution substrate release during anaerobic fermentation of excess sludge at different pHs

Excess sludge is an important by-product of activated sludge process, which is rich in carbon, nitrogen, phosphorus and other resources. During its anaerobic fermentation treatment, the organic matters and phosphorus can be dissolved and released into the fermentation liquid for recycling, and pH is an important factor for this process. Static batch test was conducted to investigate the effect of pH (3, 5, 7, 9, 10 and 11) on the release and transformation of phosphorus and organic matters. The results showed that migration and transformation of organics and phosphorus speciation occurred at different pHs, the 3-D fluorescence structures of anaerobic fermentation compositions at acidic pHs were different from those at alkaline pHs. During the anaerobic fermentation process, apatite phosphorus (AP) in mud phase could be converted to liquid phosphorus under acidic conditions, while under alkaline conditions, organic phosphorus (OP) and most of none-apatite inorganic phosphorus (NAIP) could be converted to liquid phosphorus. At pH 11, the highest phosphorus concentration occurred in fermentation liquid, the sludge fermentation was a butyric acid-type one, and the main products were iso-butyric acid followed by n-valeric acid and acetic acid. At pH 10, fermentation liquid contained the highest total amount of protein and polysaccharides, and the highest concentration of volatile organic acids (VFAs), and a positive correlation was observed between them. The degradation of protein-like and humic acid-like matters was benefit for VFAs accumulation.