Rapid degradation of pulping and papermaking wastewater in a pulp and paper mill is crucial for recycling purposes yet challenging to achieve. The purpose of this research is to provide a technical guide for the ozone degradation treatment process of pulp and paper mill wastewater and to explore the reaction mechanism of dissolved and colloidal substances (DCSs). This study is vital for effectively treating pulp and paper mill wastewater through ozonation. In the catalytic ozonation process to treat pulp and paper mill wastewater, a polyurethane sponge loaded with titanium dioxide was used as a catalyst. The optimal process conditions were determined to be 8 min of treatment time, a 16 mg/L ozone concentration, pH 9, and a 7.5% catalyst filling ratio. The COD reduction under these conditions is approximately 52%. The catalytic ozonation system, according to the FI-IR and GC-MS analyses, could degrade the large-molecule volatile organic compounds in the raw wastewater into small-molecule substances. Furthermore, the relative content of common DCSs in paper wastewater, such as palmitic acid and stilbene, could be reduced. The catalytic ozonation system is more effective for treating refractory organic compounds and has a higher COD reduction than the ozonation system.
Pyridine is a typical nitrogen-containing organic compound, which is encountered in wastewaters. Due to their hazardous effects on ecosystems and human health, their removal is imperative. In this study, photocatalysis and biodegradation were combined to degrade pyridine. TiO2
was used as the photocatalyst. To help the catalysts coating, hydroxypropyl methylcellulose was added to the catalyst dispersion system, and the performance of intimately coupled photocatalysis and biodegradation (ICPB) for pyridine degradation was evaluated under visible light conditions.
The effects of related parameters including carrier dosage, light intensity, initial concentration, and pH on the degradation of pyridine were investigated. The results showed that the degradation efficiency of pyridine was the highest under the optimal conditions of carrier dosage of 5%,
initial concentration of 50 mg/L, the light intensity of 1000 Lux, and pH of 6. Cyclic degradation is necessary, and the cycle performance of the system will provide a more sufficient reference for a system to degrade pyridine.
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