Study On Biological Energizer Of Papermaking Wastewater

With the rapid development of China’s paper industry, wastewater and pollutants have been increasing year by year, and it is very important to improve the efficiency of wastewater treatment. Activated sludge process has become one of the main methods of two stage biological treatment of papermaking wastewater because of its advantages, and it has been more and more widely used. Study on strengthening biological wastewater treatment systems has become the hot spot of environmental research in the field. In this paper,pollution characteristics of papermaking wastewater was studied, a new type of biological energizer for paper-making wastewater was developed, and the treatment effect and mechanism of it were preliminary researched.Pollution feature of papermaking wastewater and its modification during biological treatment process were investigated through conventional analysis,infrared(IR) and ultraviolet(UV) spectra, gas chromatography(GC) and mass spectrometry. The results showed that the effluent concentration of dissolved organic compounds was high, with the dissolved chemical oxygen demand(CODCr) and dissolved biochemical oxygen demand(BOD5) of 944 mg/L and321 mg/L, respectively. In addition, the value of BOD5/CODCr was 0.34,indicating the biodegradability of the wastewater was common. And there was a large number of chromophore and auxochrome group resulting in the deep chroma of papermaking wastewater. An analysis for the data from GC-MS showed that the effluent contained a large number of organic compounds, mainly including organic acids, benzene, phenols, lipoid substances and alkanes, and the ralative content of aromatic compounds was up to 63.45%. CODCr and BOD5 of papermaking wastewater had significantly reduced after biological treatment,which were 275 mg/L and 44 mg/L, respectively, and their removal rates were71% and 86%, respectively, and BOD5/CODCr of the effluent decreased to 0.16.Furthermore, organic pollutant species of the effluent obviously reduced andchromatographic peak area and strength greatly decreased after biological treatment. But biological treatment process had deepened the chroma of wastewater, and the CODCr was still high, indicating that some recalcitrant organic compounds still existed in the wastewater.According to the pollution characteristics and growth characteristics of microorganisms, the main ingredients of biological energizer were determined to be enzyme(laccase, cellulase and xylanase), trace element nutrients(Fe3+, Zn2+),growth hormone(GA), organic acids(fulvic acid), nitrogen salts and phosphate salts. Using single-factor method analysis, the effects of these kinds of components under different usage were studied. The results showed that each component of the biological energizer had a improvement of removal effect on wastewater. The optimal usage of them was obtained as following: laccase dosage was 10 mg·L-1, cellulase dosage was 8 mg·L-1, xylanase dosage was 7mg·L-1, the amount of micronutrients was 2 mg·L-1, gibberellin dosage was 0.1mg·L-1, the amount of fulvic acid was 1 mg·L-1, the amount of nitrogen salts was1 mg·L-1, the amount of phosphate salts was 0.5 mg·L-1.Three kinds of biological energizer were made up according to the best ratio of biological energizer, respectively named as BE1, BE2 and BE3. CODCr removal rate, color removal rate and turbidity removal rate of BE1 group, BE2 group, BE3 group, BE1 + BE2 group, BE1 + BE3 group, BE2 + BE3 group and BE1 + BE2 + BE3 group were compared with the blank group.The results showed that BE1 experimental group had the best treatment efficiency, and compared to the control group, addition of BE1 made CODCr removal rate, color removal rate and turbidity removal rate be increased by 8.3%, 7.7% and 3.9%,respectively. Using biological energizer of BE1 to strengthening the biological treatment of papermaking wastewater, the best process parameters were as following: the best addition amount of BE1 was 0.8 mL/L, optimal aeration time was 20 h, the best temperature was 30℃, the best p H was 9.In this section, the experimental group was the one with biological energizer,and the control group was the one without biological energizer. The removal rate of CODCr and activated sludge properties were studied through contrast experiment.The experimental results showed that, compared to the control group,addition of biological energizer made CODCr of the experimental groupeventually be increased by 12.14% and reached to 86.77%. MLVSS/MLSS of the experimental group finally also was increased by about 7.58% and reached to0.724. And adding biological energizer improved the sludge settling property;the SVI of the experimental group reached to 68.1 mL/g, decreased by about11.03%. The addition of biological energizer made the activity of activated sludge be increased too and the SOUR increased by about 18.8% in the experimental group than the control group. Observed by microscope, it was found that the structure of activated sludge was tightly, zoogloea became large and closely connected and a rich species and quantity of microbial existed in activated sludge system by adding biological energizer.An analysis for the data from UV spectra, IR spectra and GC-MS showed that using biological energizer could effectively promote the growth of microorganisms, degrade and remove the organic pollutants in wastewater,destroy the chromophores of the organic in wastewater, greatly reduce the chroma and pollution of wastewater.