基于Fe^(3+)/EDTA-2Na的类芬顿对剩余污泥脱水性能的影响

Effect of Fenton-Like Sludge Conditioner on Waste Activated Sludge Dewatering Performance Based on Fe^(3+)/EDTA-2Na

剩余污泥的高含水率限制了对其后续处理以及资源化利用.为了改善污泥脱水性能,利用Fe^(3+)/EDTA-2Na类芬顿试剂作为调理剂强化污泥脱水,通过粒径分析、差示扫描量热仪(DSC)、傅里叶红外光谱(FTIR)和扫描电子显微镜(SEM)等方法对剩余污泥进行表征,探究其强化脱水机理.结果表明:经过氧化调理后的污泥泥饼含水率降至67.8%,并有62.32%的结合水得以释放.污泥胞外聚合物(EPS)结构被氧化破解,紧密结合的胞外聚合物(TB-EPS)中的多糖和蛋白质浓度显著减少;污泥絮体减小,但从SEM图可以看出絮体结构变得规整、平滑,且出现不规则孔洞,增加了污泥水分的输送通道,改善了污泥的脱水性能.FTIR分析表明,氧化处理后的污泥清液中水的吸收峰变小,多糖和蛋白质对应的吸收峰增强,而富里酸对应的峰消失.研究显示,基于Fe^(3+)/EDTA-2Na类芬顿的污泥调理可以高效氧化破解污泥,提高污泥脱水性能.

The disposal and resource utilization of waste activated sludge(WAS)has been challenging for decades due to its high moisture content.The WAS is traditionally conditioned by dosing organic/inorganic chemicals while the moisture content and inorganic solid mass remain high after the treatment.Considerable research has been conducted to improve sludge dewaterability and reveal its dewatering process.However,to date,there are two key unresolved issues:the difficulty of dewatering sludge,and why suitable chemical conditioning can improve sludge dewaterability.Herein,a Fenton-like process based on Fe^(3+)/EDTA-2Na was used as a conditioner to improve the dewatering performance of the WAS.The WAS was characterized by flocs size,differential scanning calorimeter(DSC),Fourier transform infrared spectroscopy(FTIR)and scanning electron microscope(SEM)to investigate the intensification mechanism.The results showed that the dewatering performance of the WAS conditioned by the Fenton-like process was significantly improved by reducing the bound water to 67.8%,and 62.32%of the bound water was removed.The Fenton-like peroxidation led to the dissolution of a large amount of extracellular polymeric substance(EPS)and the lysis of sludge cells,and the transformation of more bound water to free water.It brought a dramatic decrease in the contents of polysaccharides and proteins in tightly bound extracellular polymeric substance(TB-EPS)structure.The inactivation of microbial cells promoted the disintegration of flocs.Large flocs were converted into unstable small particles and biopolymers.Therefore,the degradation of plentiful EPS led to an increase in the hydrophobicity as well as a decrease in reflocculation energy barrier.In addition,the dewatering performance of the WAS was enhanced because new transportation channels of sludge water appeared from the SEM results.FTIR analysis showed that the absorption peaks of water decreased,the peaks of polysaccharides and proteins increased,and the peak of fulvic acid disappeared after the treatment.All of these results are responsible for the lowest moisture content in the sludge conditioned by the Fenton-like reaction.Fe^(3+)/EDTA-2Na based Fenton-like treatment shows excellent performance in enhancing sludge dewatering and is a promising pretreatment method for sludge disposal and resource utilization.