Study On Papermaking Wastewater Advanced Treatment By Useing Advanced Oxidation Processes

Traditional physical-chemical and biological methods used by wastewater secondary treatment process does not meet the demand of further worsening environmental situations and stricter standards of wastewater discharge than ever before. Advanced oxidation processes (AOPs) are paid grater attentions by environmental scholar. AOPs have high efficiency; have no pollution after treatment, so they are prospective technology for treating toxic and low biodegraded contaminations in water. In this study, the second effluent of paper-making wastewater as the object mainly discussed how to treat, the wastewater quality and the characteristics of pollutants was detected, and was treated by using Titanium dioxide (TiO₂) Photocatalysis oxidation, Fenton and UV/Fenton reagent oxidation. The conclusions are as follows:The wastewater contains low-molecular-weight aromatic compounds which related on the structure of lignin. This part of compounds is the main reason of higher chromaticity, lower biological efficiency and toxicity of wastewater. The relation of COD and UV254 was studied and there are linear relationships between them at the certain range of COD.In this paper three advanced oxidation techniques incuding UV/TiO₂/O₂,Fenton and UV/Fenton was analyzed respectively, and got some conclusions: Orthogonal test shows in UV/TiO₂/O₂ system decolorization depended on the sequence of reaction time, the amount of TiO₂, reaction time, and then initial pH value, but in Fenton system the order was the amount of H₂O₂, pH value, the amount of Fe²⁺, and then reaction time. Chroma-removal efficiency was above 95%, COD removal efficiency was75% in both UV/TiO₂/O₂ and UV/Fenton system, but in Fenton system, Chroma-removal efficiency and COD removal efficiency was 86% and 66% respectively.Among these three systems, UV/Fenton system has the highest chroma and COD removal efficiency, and the shortest reaction time, however a bigger amount of chemicals is needed and a harder process control coparing with UV/TiO₂/O₂ system, in UV/Fenton system more energy was consumed comparing with Fenton system.