The efficiency of sludge dewatering is affected by the structure and composition of hydrated extracellular polymeric substances (EPS). Degrading EPS can improve the sludge dewatering performance. As an oxidizing agent, sodium periodate (NaIO4) has ability to oxidize organics, which is expected to decompose the protein and polysaccharide in EPS and improve the efficiency of sludge dewaterability. This study adopted NaIO4, for the first time, as an advanced oxidation agent to regulate EPS of waste activated sludge and was combined with anionic polyacrylamide (APAM) as a flocculant to subsequently enhance sludge dewatering. Response surface methodology (RSM) was used to determine the optimal conditions of pH, NaIO4, and APAM. The results showed that the composite conditioner's specific resistance of filtration (SRF) and the water content of the vacuum-filtered cake (Wc) were highly enhanced compared with those of the raw sludge (RS) under pH 6.5, a NaIO4 concentration of 50 mg/g dry solids (DS), and an APAM concentration of 5 mg/g DS. Owing to the pre-oxidation achieved by NaIO4 under a mildly acid environment, sludge flocs were broken. Subsequently, chemical coagulation (APAM) agglomerated the smaller particles into larger flocs of sludge by adsorption and bridging, thus improving sludge dewaterability. Practitioner points A novel conditioner, pH/NaIO4/APAM, was explored for sludge dewatering. IO3 center dot and HO center dot oxidized extracellular polymeric substances (EPS). Degradation of the protein content of EPS released bound water. Highly enhanced sludge dewaterability was achieved under optimal conditions.

采用热碱-EDTA耦合法进一步提升热碱法破解污泥的效果,以期减少碱量和热能的消耗.选用影响污泥破解效果的pH、温度和EDTA投加量等因素设计L16(45)的正交实验,在得出最佳污泥破解条件下,对比考察了热碱法和热碱-EDTA耦合法破解污泥的效果.结果 表明,热碱-EDTA耦合法相比热碱破解法,破解后SCOD、TN、TP、多糖和蛋白质溶出量分别提高了14.7％、5.6％、9.9％、3.6％和25.9％,污泥残渣中VS的含量(21.93％)也小于热碱破解法(29.68％),破解液中分子质量小于400 Da的小分子物质占比(40.68％)大于热碱破解的对应结果(32.34％).通过污泥粒径测定和SEM观察发现,热碱-EDTA耦合法破解的污泥粒径分布峰值响应小于热碱破解,污泥固体分散性优于热碱破解.通过分析可知,热碱-EDTA耦合法可以提高中低温条件下热碱破解的有机物溶出率和有机物水解性能,降低污泥残渣中VS的相对含量,热碱-EDTA耦合法相比热碱法强化了污泥的破解效果.

采用高碘酸钠与阴离子聚丙烯酰胺(APAM)联合调理改善污泥脱水性.以污泥比阻和污泥滤饼含水率作为衡量污泥脱水性的指标,分析胞外聚合物(EPS)中蛋白质和多糖含量,并测定污泥Zeta电位和粒径.结果表明:当污泥初始pH为8时,88 mg/g DS(干污泥)的高碘酸钠和2 mg/g DS的APAM可以有效改善污泥脱水,联合调理后污泥比阻降低至4.82×1012 m/kg,污泥滤饼含水率降低至69.67％.污泥经过高碘酸钠氧化后,Zeta负电性降低,可溶性胞外聚合物(S-EPS)中的蛋白质含量增加,荧光光谱显示腐植酸物质的荧光强度降低,污泥中值粒径经过高碘酸钠絮凝后减小.研究结果表明,组合调理剂可以有效改善污泥脱水性,并利于后续污泥处理与处置.