Pollution Characteristics And Bio-Degradation Mechanism Of Poplar Wood Chemi-Mechanical Pulping Waste Liquor

The poplar pulping waste liquor contains a variety of compounds by preimpregnating and refining squeeze pulp, which will contaminate environment and waste resources if direct discharged. At present, it is rare that pollution characteristics and biodegradation mechanism on P-RC APMP pulping waste liquor of poplar. In this research, it can effectively degrade pollutants by combing treatment between white rot fungus and microbe in the environment, therefore, on the basis of analyzing pollution characteristics and organic pollutants of pulping waste liquor; we investigated the optimal conditions on bio-fermentation and degradation mechanism of organic pollutants. The microbe was acclimated by pulping waste liquor and aimed at effectively combination with the white rot fungi. This technology provide new ideas for dealing with the waste liquor effectively.In this paper, it is a starting point that the pollution component of pulping waste liquor, pollution feature of P-RC APMP pulping waste liquor were investigated through conventional analysis, ultrafiltration, infrared, gas chromatography and mass spectrometry. It was found that the concentration of dissolved organic compounds was high, with the dissolved chemical oxygen demand (COD) of 18108.1 mg/L. In addition, the value of BOD5/COD was 0.17, indicating bad biodegradability of the waste liquor. The composition of small-sized organic pollution in the pulping waste liquor were the main COD, however, the larger molecular weight of pollutants in the waste liquor were the main source of color. In the pulping process, larger organic molecular weight of compounds can be broken down into small-sized organic pollutants, which contain chromospheres and auxochrome, such as hydroxyl, carbonyl double bond, carboxyl and other groups. An analysis for the data from GC-MS showed that the pulping waste liquor contained a large number of organic compounds, up to 38, mainly including phenols, ketenes, alcohols, organic acids and so on.The white rot fungus was selected as the pulping waste liquor pretreatment technology by comparing the treatment of anaerobic. The optimum fermentation conditions on white rot fungus, the compounds of treated waste liquor, and the metabolites on benzene propionate were analyzed. The results showed that the optimal culture conditions on fungus were as follows:shaking speed 150 r/min, incubation time 4 d, culture temperature 30℃-35℃, initial pH of the medium 6.0-6.5. Glucose and ammonium tartrate were the best carbon source and nitrogen sources and the best C/N was 10. The removal rate of COD up to 62%, and the reducing sugar, total sugar and acid-soluble lignin were decreased by white rot fungus. Organic pollutants significantly reduced and the new composition generated after treatment. However, some residual compounds still exist in the pulping waste liquor.Benzene propionate acid was used single carbon source in the medium and its degradation metabolites were analyzed, in order to research for the biodegradation mechanism of organic components by white rot fungus. The pathway of benzene propionate acid degradation by white rot fungus was proposed as follow:benzene propionate acid transformed into benzoic acid through the side of chain broke; the benzoic acid was converted into methoxyphenol, then becoming para-or ortho-hydroxyl phenol and form 8,8-dimethoxy-2-octanol through the reaction of benzene ring-opening, finally, enter into the cycle of TCA.The microbe was domesticated and their degradation effect was investigated in the experiments. The microbe with isolated bacteria, it can be confirmed that microbe was an efficiency degradation bacterium as a whole. The removal rate of COD up to 35%, and the organic components significantly reduced after biological treatment. While the effluent still existing COD of 2800 mg/L or more, indicating that the effluent still contains non-biodegradable compounds, and these compounds did not detect by GC -MS.In this paper, the compounds of pulping waste liquor were analyzed by using a variety of analysis tools, and confirmed the technology of white rot fungus combined microbes to treat the P-RC APMP pulping waste liquor was feasible, which has good application prospects.