铁基污泥炭活化过硫酸盐调理剩余污泥脱水的效能和机理研究

Study on the waste activated sludge dewatering effect and mechanism conditioned by persulfate induced with iron-based sludge biochar

为了改善剩余污泥的脱水性能,采用铁基污泥炭(Iron-SBC)活化过硫酸盐(PDS)调理污泥。研究了PDS投加量、Iron-SBC投加量、反应时间、反应温度以及初始pH对剩余污泥脱水的影响,并分析了其机理。结果表明:65℃条件下,在单位质量TSS的PDS投加量150 mg/g、Iron-SBC投加量350 mg/g,初始pH=6.68时,经Iron-SBC/PDS调理20 min后,污泥毛细吸水时间、污泥比阻和泥饼含水率分别达到8.4 s、5.4×10^(12) m/kg、73.5%。机理分析表明,调理过程中发生了氧化反应,原本紧密平整的污泥絮体和胞外聚合物被破解,结合水被释放,污泥中高亲水性的紧密型胞外聚合物(TB-EPS)向松散型胞外聚合物(LB-EPS)和溶解性胞外聚合物(S-EPS)转化,对污泥脱水不利的蛋白质被氧化降解,TB-EPS的减少和铁离子的中和作用使Zeta电位上升;具有刚性结构的Iron-SBC降低了泥饼的压缩系数,同时在Fe3+絮凝作用下,污泥分形维数变大。最终在“氧化-骨架构建”耦合作用下,剩余污泥实现了深度脱水。

In order to improve the dewatering performance of waste activated sludge,iron-based sludge biochar(Iron-SBC)activating persulfate(PDS)was used to treat sludge.The effects of PDS dosage,Iron-SBC dosage,reaction time,reaction temperature and initial pH on waste activated sludge dewatering efficiency were studied,and the mechanism was also analyzed.The results showed that when the temperature was 65℃,the dosage of PDS per unit TSS was 150 mg/g,the dosage of Iron-SBC per unit TSS was 350 mg/g,the initial pH was 6.68,after being conditioned by Iron-SBC/PDS for 20 minutes,the sludge capillary water absorption time,sludge specific resistance and sludge cake moisture content decreased to 8.4 s,5.4×10^(12) m/kg and 73.5%,respectively.The mechanism analysis indicated that oxidation reaction occurred during the process.The originally tight and flat sludge flocs and extracellular polymers were cracked and the bound water was released.The highly hydrophilic tightly bound extracellular polymeric substances(TB-EPS)in sludge were transformed into loosely bound extracellular polymeric substances(LB-EPS)and soluble extracellular polymeric substances(S-EPS),and the proteins which were unfavorable to sludge dewatering were oxidized and degraded.The decrease of TB-EPS and neutralization of positive iron ions increased the Zeta potential value.Iron-SBC with rigid structure reduced the compressibility coefficient of sludge cake.At the same time,under the flocculation of Fe3+,the fractal dimension of sludge became larger.Under the coupling action of“oxidation-skeleton construction”,the waste activated sludge deep dewatering was realized.