pH has an important effect on the physiological activity of eosinophilic microorganisms. Therefore, this study used excess sludge produced by the mixed treatment of leachate and municipal sewage to explore the impact of different sludge initial pH on microbial biochemical reactions associated with the performance of excess sludge dehydration. Shake-flask tests were performed using inoculated microorganisms and fresh excess sludge in 500 mL Erlenmeyer flasks at a ratio of 1:4, with the addition of 2 g/L S⁰ and 6 g/L FeS₂ as energy sources. Erlenmeyer flasks were shaken for 72 h at 180 rpm and 28 °C, in a reciprocating constant homeothermic oscillating water-bath. Results show that the specific resistance to filtration (SRF) of the bioleached excess sludge decreased from (1.45~6.68) × 10¹² m/kg to (1.21~14.30) × 10¹¹ m/kg and the sedimentation rate increased from 69.00~73.00% to 81.70~85.50%. The SRF decreased from 1.45 × 10¹² m/kg to 1.21 × 10¹¹ m/kg and the sedimentation rate increased from 69.00% to 85.00%, which both reached the highest level when the initial pH of the excess sludge was 5 and the bioleaching duration was 48 h. At this time, the rates of pH reduction and oxidative redox potential (ORP) reached the highest values (69.67% and 515 mV, respectively). Illumina HiSeq PE250 sequencing results show that the dominate microbial community members were Thiomonas (relative abundance 4.59~5.44%), which oxidize sulfur and ferrous iron, and Halothiobacillus (2.56~3.41%), which oxidizes sulfur. Thus, the acidic environment can promote microbial acidification and oxidation, which can help sludge dewatering. The presence of dominant sulfur oxidation bacteria is the essential reason for the deep dehydration of the bioleached sludge.

中文翻译：

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污泥初始pH值对过量污泥生物浸出的影响以提高脱水性能

pH对嗜酸性微生物的生理活性具有重要影响。因此，本研究使用渗滤液和城市污水的混合处理产生的过量污泥，以探索不同污泥初始pH对与过量污泥脱水性能相关的微生物生化反应的影响。使用接种的微生物和新鲜的多余污泥在500 mL锥形瓶中以1：4的比例进行摇瓶试验，并添加2 g / LS ⁰和6 g / L FeS ₂作为能源。在往复式恒定恒温振荡水浴中，将锥形瓶在180 rpm和28°C下摇动72 h。结果表明，生物浸出的剩余污泥的比过滤阻力（SRF）从（1.45〜6.68）×10 ¹² m / kg降至（1.21〜14.30）×10 ¹¹ m / kg，沉降速率从69.00〜73.00 ％至81.70〜85.50％。SRF从1.45×10 ¹² m / kg降至1.21×10 ¹¹m / kg，沉淀率从69.00％增加到85.00％，当过量污泥的初始pH为5且生物浸出时间为48 h时，两者均达到最高水平。此时，pH降低率和氧化还原电位（ORP）达到最高值（分别为69.67％和515 mV）。Illumina HiSeq PE250测序结果表明，主要的微生物群落成员为硫氧化菌（相对丰度为4.59〜5.44％），其氧化硫，亚铁和卤代硫杆菌（2.56〜3.41％），可氧化硫。因此，酸性环境可促进微生物酸化和氧化，从而有助于污泥脱水。优势硫氧化细菌的存在是生物浸出污泥深度脱水的根本原因。