热活化过二硫酸盐改善污泥-餐厨垃圾厌氧消化物脱水性能

Improved dewaterability of anaerobic digestate of sewage sludge and food waste by thermally activated peroxydisulfate oxidation

为了解热活化过硫酸盐氧化对污泥-餐厨垃圾厌氧消化物脱水性能的影响,以毛细吸水时间(CST)、过二硫酸盐(PDS)分解速率、自由基产生种类、胞外聚合物(EPS)组分含量以及厌氧消化物的微观形貌等观察指标,比较了不同温度条件下(50~80℃)的热活化PDS氧化对脱水性能的影响,并探讨了其作用机理。结果表明,热活化PDS氧化可显著提高污泥-餐厨垃圾厌氧消化物的脱水性能,且升高温度可进一步促进脱水效果。在温度70℃、PDS投加量4 mmol·g^(-1) (以干物质计)、反应时间为240 min的最佳条件下,厌氧消化物的CST从初始1 064.9 s大幅降至39.4 s,脱水效果明显提升,沉淀后的上清液也较为清澈。处理体系中有大量SO4-·和·OH生成,TB-EPS中蛋白质的降解率高达76.6%,絮体结构变得较为松散,其表面和内部均有大量孔洞。热活化PDS处理污泥-餐厨垃圾厌氧消化物的过程中产生的自由基促使消化物絮体破解和物质释放并降解,可能是脱水性能改善的主要原因。该研究结果可为热活化过硫酸盐氧化技术在污泥-餐厨垃圾厌氧消化物脱水中的应用提供参考。

The influence of thermally activated peroxydisulfate(PDS) oxidation process with different temperature(50~80 ℃) on the dewaterability of the anaerobic digestate of sewage sludge and food waste was investigated in this study. The key parameters affecting the dewatering, such as capillary suction time(CST),PDS decomposition, radical species, the compositions and contents of extracellular polymer substances(EPS)and microstructure of anaerobic digestate, were determined to reveal the potential conditioning mechanism. The results indicated that thermally activated PDS oxidation significantly improved the dewaterability of the sludgefood waste anaerobic digestate, and that the extent of the improvement in the dewaterability increased with the increase in temperature. The optimal conditions for thermally activated PDS treatment were as follows:temperature of 70 ℃, sodium persulfate dosage of 4 mmol·g^(-1) PDS, and the reaction time of 240 min. After the PDS treatment, the CST of the anaerobic digestate decreased from 1 064.9 s to 39.4 s and the final supernatant is clear. It was also found that 76.6% of protein in TB-EPS was degraded and significant signals for SO4-· and ·OH were produced during the PDS treatment. Besides, surface morphology of the anaerobic digestate treated by PDS exhibited a porous structure, building a favorable condition for the release of internal water. These results suggest that during thermally activated PDS treatment, the production of radicals resulted in the destruction of the floc structure of anaerobic digestate and the degradation of microbial EPS, which may be responsible for the improvement in the dewaterability of the sludge-food waste anaerobic digestate. The results of this study can provide a fundamental guidance for the application of thermally activated persulfate oxidation technology to improve the dewatering of sewage sludge-food waste anaerobic digestate.