混碱调控剩余污泥碱性发酵实现LDHs高效提取短链脂肪酸

氢氧化钙调控剩余污泥碱性发酵,可有效提高发酵液原位合成层状双金属氢氧化物(LDHs)提取短链脂肪酸(SCFAs)的效率.本文拟利用氢氧化钙和氢氧化钠混碱调控剩余污泥碱性发酵,提高发酵过程SCFAs产量,进一步提高SCFAs提取效率.通过配置不同氢氧化钠和氢氧化钙混合比例的碱液,用于调控剩余污泥碱性发酵实验,发现混碱比例为25∶75时,可避免钙离子对污泥水解产酸影响,发酵液中SCFAs浓度达到6581.4 mg·L~(-1)(以每COD计,下同),是空白对照组(4179.4 mg·L~(-1))的1.6倍.同时,碱液提供的钙离子可将污泥发酵过程释放的无机阴离子去除,CO■、PO■浓度分别低至3.7 mmol·L~(-1)和0.5 mg·L~(-1).利用氢氧化钠和氢氧化钙调控剩余污泥进行混碱厌氧发酵,可有效提高SCFAs的产量,消除主要无机阴离子对发酵液原位合成层状双金属氢氧化物(LDHs)提取SCFAs的干扰,合成的LDHs中SCFAs的含量为52.3 mg·g~(-1) LDHs,是空白组(18.9 mg·g~(-1)LDHs)的2.8倍.

Alkalinic fermentation of waste activated sludge with NaOH and Ca(OH)2 mixture to enhance short chain fatty acids extraction by layered double hydroxides

Alkalinic fermentation of waste activated sludge (WAS) with calcium hydroxide (Ca(OH)₂) has been proved to be effective to improve the extraction efficiency of short chain fatty acids (SCFAs) via in situ synthesis of layered double hydroxides (LDHs). In this study, mixture of sodium hydroxide (NaOH) and (Ca(OH)₂) was used to improve SCFAs production during alkaline fermentation and further improve SCFAs extraction efficiency. based on waste activated sludge of anaerobic fermentation with different ratios of NaOH and Ca(OH)₂ mixture adjustment, the optimal ratio was 25:75. In the optimal mixture system, the short chain fatty acids (SCFAs) concentration was enhanced to 6581.4 mg·L^-1, which was 1.6-fold of the control. Meanwhile, the carbonate and phosphate were reduced to 4.1 mmol·L^-1 and 0.5 mg·L^-1, respectively. With higher SCFAs concentration and interfering anions being removed, the SCFAs content in the synthesized SCFAs-LDHs-Mixture can be enhanced to 52.3 mg·g^-1 LDHs, which was 2.8 times higher than the control (18.9 mg·g^-1 LDHs), suggesting that utmost extraction of SCFAs from alkalinic fermentation of WAS by layered double hydroxides (LDHs) could be achieved.