Advanced Treatment Of Papermaking Wastewater By Sulfate Radical-based Advanced Oxidation Process

Pulp and paper industry is one of the major industries of national economy. The pulp andpapermaking wastewater has always been key source pollution in the field of industrialproduction. The pollutant from wastewater which has a higher concentration and complicatedcomposition, or even has carcionogenic, teratogenic and mutagenic agents in it, is a potentialsource that threatens human’s health. This type of wastewater constructed with benzene ring,which leds to the poor biochemical degradation and influences the wastewater treatment.Comprehensive treatment of pulp and papermaking wastewater is a research focus and urgentproblems to be solved at home or broad.Traditional methods used in papermaking enterprise can not meet the demand of furtherworseing environmental situations and stricter standards of wastewater discharge than everbefore. Pulp and papermaking wastewater from physical-chemical and biological secondarytreatment process is also with higher CODCrand chroma. Therefore advanced treatment is amust to ensure the discharged wastewater reaches standard and reused.Advanced oxidation process showed the great potential on the wastewater treatment,which contains toxic、hazardous or non-degradation organic compound. Study on advancedtreatment of non-degradation organic wastewater by sulfate radical-based advanced oxidationprocess has been developed recently. Per sulfate should be activated by light, heat ortransition metals etc, to produce sulfate radical. Papermaking wastewater by secondarytreatment was studied in this paper. And sulfate radical-based advanced oxidation was firstlyapplied into treatment of papermaking wastewater. The main studies were as follows:1) The zero-valent iron activated per sulfate （Na₂S₂O₈） for the oxidation of secondarytreatment papermaking wastewater was studied through a series of batch experiments. Theeffects of pH on the degradation efficiency of wastewater was investigated on the condition ofroom temperature, the ZVI dosage, Na₂S₂O₈dosage were examined at pH=3or initialpH=8.14. The results show that, the efficiencies of CODCrdegradation or color removal areabout57.5%and83%at condition of pH=3within3h, or about34.2%and89%at conditionof pH=8.14within3h when the ZVI=0.8g/L and S₂O₈^2-:12COD=2. The wastewater aftertreatment of SR-AOP was qualitative analyzed and quantitative determined by GC-MS analyzer. The results showed that some of organics were removed and others were partiallydegraded.2) Hydroxyl Radical-based and Sulfate Radical-based advanced oxidation process, withferrous ion catalyzed （activated）, was evaluated for the treatment of papermaking wastewaterby biological-chemical secondary treatment process. The results from the two processes werecompared, and the effects of pH on the degradation efficiency of wastewater was investigatedon the condition of room temperature, the Fe²⁺dosage, Na₂S₂O₈dosage were examined atpH=3or initial pH=8.14, with an emphasis on the CODCrand color of refractory organics. theefficiencies of CODCrdegradation or color removal at Sulfate radical-based oxidation processare equivalent to Hydroxyl radical-based oxidation process at pH=3, but higher than Fenton atpH＞3; Fenton oxidation process is even sensitive by the influence of Fe²⁺dosage oroxidation dosage. Sulfate radical-based oxidation with more gently reaction process showedby kinetic models, which indicates that the former is a promising alternative for the treatmentof papermaking wastewater.3) Simulation wastewater mixed with Phenol and Reactive Brilliant Blue KN-R wastreating by Sulfate radical-based advanced oxidation process. The effects of competition bytwo kinds of substrate were studied through a series of batch experiments. The experimentresults showed that, the degradation rate of Reactive Brilliant Blue KN-R was increased withthe increase of the ferrous ion and per sulfate concentration in the oxidation system. Theprocess of sulfate radical oxidation could be divided into two regions according to thesecondary kinetic characteristics. When the phenol was added into, the degradation rate ofReactive Brilliant Blue KN-R was decrease with increase of phenol concentration; the phenolconsumed sulfate radical competed with Reactive Brilliant Blue KN-R. The process ofoxidation also divided into two regions, and the two parts according to the secondary kineticcharacteristics respectively, with reaction rate constant was decrease as increase of phenolconcentration.