Effect Of Biostimulant On Degradation Enhancement Of Papermaking Wastewater

For the papermaking industry, since the introduction of more stringent standard named The Pulp and Papermaking Industry Wastewater Pollution Discharge Standard "GB 3544-2008", the major of domestic papermaking enterprises and related industry were not only in face with increasingly difficult market to expand the space, but also had to handle with the problem of pollution root in process of production and operation. In order to meet emission requirements, many papermaking companies added tertiary depth treatment after the original the first stage of physical treatment and the second stage of biological treatment, which needed to invest more man work and financial resources. Therefore, it had become a focus and difficult issue to make the second stage of biochemical treatment more effect and reduce the pollution load of tertiary depth processing, and then to reduce the cost of wastewater treatment in the field of wastewater treatment research.The biostimulation technology was applied in oxygen section to enhance biochemical treatment effect of papermaking wastewater in the present work. Adding biostimulant in wastewater directly to act on microorganisms and pollutants aimed to explore the strengthened degradation effect for the organic pollutants in wastewater, and promoting effect and mechanism for microbial growth in activated sludge system. And then, the new kind of biostimulant for papermaking wastewater named BP was applied to verify the treatment effect in factory producing line.In order to study the properties of non-deinking middle-stage papermaking wastewater produced by waste paper, conventional analytical methods and modern instrumental analysis were used, such as GC-MS, ICP-AES, IR, UV, luminescent bacteria toxicity and other methods. The result showed that the pollution was in a higher degree:The CODcr was about 1500mg · L-1 and BOD5 was about 460mg · L-1, as for the chromaticity and turbidity, the data went to 240 times and 840NTU. Also, the total oil content was 157.08 mg · L-1 and the toxicity inhibition rate of luminescent bacteria is of 97.08%, and 8 kinds of metal ions were detected in the wastewater.The process of adding biostimulant for the treatment of non-deinking middle-stage papermaking wastewater was studied, the result showed that the optimum conditions for processing was:reaction time 22 hours, adding biostimulant amount 500 ?L·L-1, the reaction system pH 7.2, and temperature 25 ?. In this case, COD removal rate could be increased by 7.5% reaching 92.8% and for TOC was 14.2% compared to the blank group. But for total oil, the capacity of biostimulant was limited and the removal rate was only 30.8%. What's more, to add flotation+coagulation treatment after biochemical treatment could increase total oil removal rate reached 99.4%. As for biological toxicity, adding biostimulant in biochemical treatment did not inhibit the microbial growth but play a significant role which leading to promote the rate of 0.78%. After addition biostimulant, metal ion content showed reducing trend in water and increasing trend in sludge, indicating that the metal ions could be absorbed by sludge system. GC-MS analyses showed that ingredients could not degrade in biological treatment were mostly alkanes and the other small amount were lipids. IR analysis result showed that most of aldehydes, carboxylic acids could degradate, remaining contents were decreased after biochemical treatment by adding biostimulant. UV analysis showed that the concentration of the benzene-ring structure reduced in biological treatment, but the chroma of wastewater deepened. The results showed the growth of microbial proliferation was in good condition with biostimulant and the biological toxicity was eased. Totally, adding biostimulant could strengthen the degradation effect of papermaking wastewater.The influence of biostimulant on the activity of sludge was studied, it showed that biostimulant played a positive effect which could increase content of the protein, ATP, TTC-dehydrogenase such bioactivity indexes and increased the number of microbial and resistance to toxicity. Microbes preferentially absorbed the smaller particle size component of biostimulant, the priority order was:fulvic acid>laccase> gibberellic acid> trace elements> inorganic nitrogen and phosphate. Analysis of Raman spectra showed the content of benzene and its derivatives reduced with the function of biostimulant. In which the composition, such as gibberellic acid, trace elements, and inorganic nitrogen and phosphate could be absorbed by microorganisms respectively. The function of fulvic acid was synergistic effect transport. In the whole process, microorganisms were adapted to the papermaking wastewater under physicochemical environment gradually, which was from junior to senior, showing different stages with the corresponding indicative micro organisms. The abnormal phenomenon of sludge bulking was improved with biostimulant.Application of biostimulant to verify in factory showed that:adding BP instead of ordinary solid compound fertilizer during the biochemical aerobic section of the papermaking wastewater treatment could increase COD removal efficiency of the system about 6%, and increase the active sludge concentration MLSS 1500 to 2000 mg · L-1 stably. At the same time, the value of export ammonia could be reduced less than 0.8 mg · L-1. Reducing the normal nitrogen and phosphorus dosage of about 75% and the biochemical treatment system was stable and the resistance capacity was enhanced.