Advanced Treatment Of Wastewater Effluent With The Immobilization Of Laccase

The pulp and paper companies discharge numerous industrial wastewater, and have caused serious pollution of water bodies in natural environment. The new national standard (GB3544-2008) made more rigorous requirements of various indicators of pulp and paper effluent. Therefore, in order to achieve the new wastewater discharge standards and better recycling, research and develop efficient papermaking wastewater advanced treatment technology has a very important significance. Chlorophenols are a class of highly toxic and resist degradation organic pollutants. Paper and other waste water contain a large number of 2,4-dichloro-phenol. General approach has many flaws, such as large energy consumption, high processing costs, secondary pollution, and so on. In recent years, with the rapid development of biotechnology in the field of environmental protection, the advantages of biological treatment of Chlorophenols pollutants become more apparent.Laccase can catalyze the degradation of phenolic that existed in papermaking wastewater. Immobilized laccase has more advantages:recyclable, strong stability. This paper use modified magnetic silica and modified microcrystalline cellulose as the carrier to immobilize laccase, respectively. And determine the best immobilization carner.Firstly, magnetic iron oxide particles (MNP) were prepared by co-precipitation method. Using XRD analysis to confirm the magnetic particles are magnetite iron oxide type. The optimum concentration of NaOH was 0.2mol/L, the optimum temperature is 40℃, and the optimum molar ratio of iron salt and the base is 3:10. First step, using a sol-gel method with magnetic iron oxide particles as the core, silicon source is TEOS, synthesized MS support. The second step, y-aminopropyl triethoxysilane as a coupling agent, and obtained AMS support. And by FTIR infrared spectra, we can find that, the content of amino of EDC- Melamine carrier determined by titration was about 0.15 mmol·g-1. SEM can be seen carrier, which facilitates to bind laccase.Secondly, deoxidized cellulose was obtained by the reaction between cellulose and epichlorohydrin. Further reduction via sodium borohydride to obtained relatively stable amino-modified cellulose (EDC-Melamine). Scanning electron micrograph suggested that the modified cellulose become porous, and the contact points was increased. The content of amino of EDC-Melamine carrier determined by titration was about 1.237 mmol·g-1.Finally, we discussed the immobilization efficiency for immobilization of the two carrier materia, which shown that the immobilized amount of EDC- Melamine can reach 8650 U·g-1, much higher than 4300U·g-1 of the AMS. We use EDC-Melamine as laccase immobilization to treat the 2,4-DCP. We can found that catalyzed oxidation of laccase play a major role in the degradation process of 2,4-dichlorophenol. With the increasing of dosage, the removal rate can reach about 71%. After immobilized laccase repeated use six times, which illustrated again that laccase have the better stabilition.By studying the influence of different dosage to different indicators of papermaking wastewater, we found that with the increasing of dosage, pH, color, lignin concentration and UV254 concentration of wastewater are reduced, but the value of COD and TOC are increases. Comprehensive analysis, each dealing with 60ml wastewater required dosage of 0.3g immobilized laccase. With this dosage, the removal rate of color reach to 75%, pH decreased to about 7.7, COD was reduced to about 140, TOC is reduced to about 55. The above proved that it is feasible to immobilization methods applied in proved in the papermaking wastewater treatment.