NaCl浓度对铁阳极强化污泥发酵液产氢及蓝铁矿生成的影响

Effect of NaCl concentration on hydrogen and vivianite recovery from sludge fermentation liquid enhanced by iron anode

基于剩余污泥的资源属性,构建了铁阳极介导的新型微生物电发酵体系,以氯化钠为电解质,探究了不同NaCl浓度(10mmol/L,30mmol/L和60mmol/L)对污泥发酵模拟液同步产氢及蓝铁矿生成效能的影响.结果表明,10mmol/L条件下,氢气产量达到峰值(387.8±14.2)mL,相比30mmol/L组(312.2±18.6)mL和60mmol/L组(100.3±10.4)mL分别提升23.5%和286.6%,短链挥发性脂肪酸(SCFAs)利用率达81.2%,均高于其他各组.各组溶解性磷酸盐在电发酵3d内实现完全去除,10mmol/L体系中Fe2+占比达77.6%,并随电解质浓度升高而降低.扫描电镜(SEM)、X射线能谱(EDS)和X射线衍射仪技术(XRD)表征发现,体系内沉淀以蓝铁矿结晶为主,且结晶度与电解质浓度呈负相关.低电解质浓度提升了体系生物膜的充放电性能,10mmol/L条件下,生物阴极微生物主要以电化学活性菌(EAB)和厌氧发酵菌为主,累积丰度达22.10%和42.37%,异化铁还原菌(如Bacteroides、Pseudomonas和Sphingomonas)占比达9.17%.

Based on the resource attribute of waste activated sludge(WAS),A novel electro-fermentation(EF)system mediated by iron anode was constructed to investigate the effect of NaCl concentration(10mmol/L,30mmol/L and 60mmol/L)on synchronous hydrogen and vivianite recovery from simulative sludge fermentation liquid.Results showed that hydrogen yield peaked at(387.8±14.2)mL under 10mmol/L,promoted by 23.5%and 286.6%compared with that of 30mmol/L(312.2±18.6)mL and 60mmol/L(100.3±10.4)mL.The corresponding utilizing efficiency of short-chain fatty acids(SCFAs)reached 81.2%,which was much higher than that obtained in other groups.Soluble phosphate was completely removed within 3d in each group,Fe2+content was reduced with NaCl concentration increase,accounted for 77.6%in 10mmol/L group.Scanning electron microscope(SEM),energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD)showed that the recovered precipitate was vivianite,and the crystallinity was negatively related with NaCl concentration.Meanwhile,the charge-discharge property of biofilm was promoted by the low electrolyte concentration,the dominating microbial consortia attached to the bio-cathode in 10mmol/L group,i.e.,electrochemically active bacteria(EAB),anaerobic fermentation bacteria(AFB)and dissimilatory iron reducing bacteria(DIRB,e.g,Bacteroides,Pseudomonas and Sphingomonas),accounting for 22.10%,42.37%and 9.17%,respectively.