<b>Excess Sludge Disintegration by Discharge Plasma Coupled with Thiosulfate</b>

Surplus sludge disposal and treatment are major issues in wastewater treatment plants. Discharge plasma oxidation is an effective approach for sludge dewatering and digestion. In this study, excess sludge disintegration by non-thermal discharge plasma coupled with thiosulfate (TSA) was investigated. After 20 min of the single discharge plasma treatment, the soluble chemical oxygen demand (SCOD) increased to 404.93 mg L−1, and it climbed even more to 549.08 mg L−1 after adding 15 mmol L−1 of TSA. The water content of the filter cake also reduced even more in the presence of TSA. There was an appropriate dosage of TSA available. In the discharge plasma coupled with TSA system, reactive oxygen species (·OH and ·O2-) were generated and had significant involvement in the disintegration of the sludge. The addition of TSA enhanced the production of ·OH. These reactive oxygen species decomposed the floc structures and facilitated the transformation of organic compounds, resulting in a decrease in the average size of the sludge aggregates. The ratio of soluble extracellular polymer substances (S-EPS) was enhanced, while the ratio of the tightly bound fraction was reduced after the treatment. Thus, discharge plasma coupled with TSA promoted microbial cell lysis and facilitated the release of intracellular organic matter and bound water, ultimately enhancing the sludge’s dewaterability.剩余污泥的处置与处理是污水处理厂面临的主要问题。放电等离子体氧化（discharge plasma oxidation）是实现污泥脱水与消解的有效手段。本研究探究了非热放电等离子体（non-thermal discharge plasma）耦合硫代硫酸盐（thiosulfate，TSA）对剩余污泥的破解效果。仅采用放电等离子体处理20分钟后，可溶性化学需氧量（soluble chemical oxygen demand，SCOD）升至404.93 mg·L⁻¹；当投加15 mmol·L⁻¹的TSA后，可溶性化学需氧量进一步攀升至549.08 mg·L⁻¹。体系中投加TSA可使滤饼（filter cake）含水率进一步降低，且存在适宜的TSA投加剂量。在该耦合体系中，会生成活性氧物种（reactive oxygen species，·OH与·O2-），其在污泥破解过程中发挥了显著作用；TSA的投加可强化·OH的生成。上述活性氧物种可破坏污泥絮体结构（floc structures），促进有机化合物转化，进而使污泥絮体的平均粒径减小。经处理后，可溶性胞外聚合物（soluble extracellular polymer substances，S-EPS）占比提升，而紧密结合组分（tightly bound fraction）占比则有所下降。综上，放电等离子体耦合TSA可促进微生物细胞裂解，加速胞内有机物与结合水的释放，最终有效改善污泥的脱水性能。