Dissertation > Environmental science, safety science > Processing and comprehensive utilization of waste > General issues > Wastewater treatment and utilization

Research of Biological Reaction Character and Application of the Black-liquor-philic Fugus

Author QiaoWeiChuan
Tutor LiZhongZheng
School Nanjing Forestry University
Course Forest Chemical Process Engineering
Keywords Addicted to black liquor bacteria Biological response Anaerobic CABR Pulping
CLC X703
Type PhD thesis
Year 2007
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Pulping and paper industry is one of industry in which pollution is most serious. Blackliquor from alkaline pulping was so high concentration COD, strong basicity and very saltythat it has become the most difficult problem to solve of industry wastewater. Microbes whichcan degrade black liquor were separated from sludge in black liquor reserve pool. Theanaerobic degradation mechanism and biological reaction property were researched to solve theproblem. A novel anaerobic baffled reactor was designed to realize the anaerobic degradationprocess by the kinetics.The content and conclusion in this paper was that:The sludge was as microbe resource from the pool which reserved black liquor in strawpulping mill. The purify microbe was separated by strict technique for many times. Themorphological and physiological character of the microbe was identified. The results showedthat: The separated microbe not only can be fit for the extreme environment such as highpenetrability pressure, strong basicity and high concentration salty, but also can grow well.So, the microbe was considered as a kind of facultative actinomycetes which was namedblack-liquor-philic fugues. The biological character research showed that the microbe candegrade lignin and polysaccharide in black liquor.Anaerobic degraded by black-liquor-philic fungus, the mechanism was researched bydetermining lignin, polysacchide, pH, COD, and molecular weigh, group of methoxyl,carboxyl, carbonyl, quinonyl, ~1H-NMR and elemental analysis of lignin sample after anaerobicreaction were analyzed, too. Result showed: up to 50% of polysacchides in black liquor can bedegraded, and lignin can be degraded of which Removal rate was up to 30%. In the anaerobicdegradation process, the structure of lignin was changed, lignin was fragmented to solubleorganics whose molecular weigh was bigger than 4950, the coumarone, toupentine structureandβ-O-4,β-βbond would be disappear because of fragmentation. At the same time,demethoxylation and dehydroxylation reaction happened, and water-soluble lower molecularcompound produced.A noval anaerobic reactor was designed and named Center Anaerobic Baffled Reactor(CABR). The reactor was strenthened by several ways to be got the better results. That thesludge was accelerated to form granula by filling active carbon, and was cycled in reactor willincrease SRT by expanding the outer volume. These methods ensured the number of anaerobic microbes in the reactor. The reactor increased the mass transfer efficiency by which used sludgecircular and wastewater circular to mix the microbe and wastewater. The reactor was separatedto three room and the stream in the reactor was baffled, So the microbes in different roomlived lonely and were not disturbed each other. The experiment results and kinetics accountresults showed that the microbes in middle room degraded organics rapidly and the capabilityof degradation was strongly. The microbe in inner room grew most rapidly.The degradation kinetics of groundmass and grow kinetics of microbes were researched,and the kinetics parameter were calculated. The effect on the groundmass degradation andmicrobes grow was discussed. Results showed, increase of sludge concentration can help toenhance the adaptability of anaerobe to black liquor. So, activity of anaerobe is become better.Removal of COD and sugar, gas production rate was increased with sludge concentration.Increase of black liquor COD will increase the supply of the nutrition to anaerobe, and thetoxic substances will increase, too. Removal of COD and sugar, gas production rate wasincreased when COD<2000mg/L. However, the change trend is in contrast whenCOD>2000mg/L. If water residence time was increased, removal of COD was increased. Atthe same time, the sludge residence time will be increased, anaerobe can have plenty time todegrade organics in black liquor. Increase of reflux ratio can degrade organics more byincreasing sludge residence time to hold enough anaerobe. In conclusion, removal rate of blackliquor COD in CABR was about 60% in the experiment.

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