Chemical treatment technology Commonly used in industrial wastewater treatment, chemical reactions are used to remove toxic and harmful substances in wastewater and reduce wastewater concentration. Common chemical treatment technologies include: Coagulation and sedimentation: Use coagulants to condense colloids and fine suspended matter in wastewater into larger particles, and then remove them by precipitation, which can remove some organic matter. Redox reaction: using oxidants or reductants to oxidize or reduce organic matter in wastewater to harmless substances, such as using advanced oxidation treatment such as Fenton reaction to deeply degrade refractory organic matter2. The advantage of chemical treatment technology is that the treatment effect is better than physical treatment technology, and it can improve the biodegradability of wastewater, which is conducive to subsequent biochemical treatment; the disadvantage is that most processes require the addition of chemical agents, which increases the treatment cost. https://www.renkeer.com/what-is-cod-bod-toc-tod/