Recently, the production of short-chain fatty acids (SCFAs) from waste activated sludge (WAS) has received increasing attention. Although several pretreatment methods had been investigated, sludge hydrolysis through depletion of multivalent cations has rarely been reported. In this work, cation exchange resin (CER) was used for enhancing WAS hydrolysis and subsequent SCFAs production at various dosages of 0 to 3.5 g/g SS. With the addition of CER, the multivalent cations and trace metal elements (e.g. Ca²⁺, Mg²⁺, Fe³⁺, Zn²⁺, etc.) were removed from sludge through CER-mediated ion exchange, leading to disruption of extracellular polymeric substance (EPS), while triggering cell lysis which was evidenced by remarkable leakage of cellular DNA. This CER-mediated cyclic release-removal of multivalent cations resulted in substantial sludge hydrolysis with release of biodegradable organic matters. At the optimal CER dosage of 1.75 g/g SS, soluble COD (SCOD) was dramatically increased to 5944 mg/L (SCOD/TCOD=34.7%) against 1440 mg/L in the control after 2-day fermentation. Meanwhile, a considerable SCFAs of 334.5 mg COD/g VSS was produced within the first 4 days of anaerobic fermentation, which was 3.3 times higher than that in the control. It was found that the acetic and propionic acids accounted for 57.4-65.4% of SCFAs produced in CER-assisted anaerobic fermentation. Compared to pretreatment with potassium ferrate, surfactant and enzymes, a much higher SCFAs concentration was obtained in this study with CER. In fact, used CER could be recovered and reused, without harsh chemicals left in fermented sludge. This indeed created an environmentally and economically beneficial situation with considerably saved pretreatment agents.

近来，由废活性污泥（WAS）生产短链脂肪酸（SCFA）已受到越来越多的关注。尽管已经研究了几种预处理方法，但很少报道通过消耗多价阳离子来水解污泥的方法。在这项工作中，使用阳离子交换树脂（CER）增强WAS水解和后续SCFA的生产，其剂量为0至3.5 g / g SS。加入CER后，多价阳离子和微量金属元素（例如Ca 2 ⁺，Mg 2 ⁺，Fe ³⁺，Zn ²⁺等）通过CER介导的离子交换从污泥中去除，从而导致细胞外聚合物质（EPS）的破坏，同时引发细胞裂解，而细胞DNA的显着泄漏证明了这一点。这种CER介导的多价阳离子的循环释放去除导致大量污泥水解，同时释放出可生物降解的有机物。在1.75 g / g SS的最佳CER剂量下，发酵2天后，可溶性COD（SCOD）相对于对照组的1440 mg / L显着增加至5944 mg / L（SCOD / TCOD = 34.7％）。同时，在厌氧发酵的前4天内产生了相当多的SCFA，为334.5 mg COD / g VSS，比对照高3.3倍。已发现，乙酸和丙酸占CER辅助厌氧发酵中产生的SCFA的57.4-65.4％。与用高铁酸钾，表面活性剂和酶进行预处理相比，在本研究中使用CER获得了更高的SCFAs浓度。实际上，用过的CER可以回收再利用，而发酵污泥中不会残留刺激性化学物质。确实，这大大节省了预处理剂，从而在环境和经济上创造了有利条件。