Advanced Treatment On Terminal Wastewater Of Papermaking By Immobilized Biotechnology

As a paper-making power, emission of papermaking wastewater from pulp andpaper enterprises is quite large every year. With the national environmental protection,the emission of terminal paper wastewater gets stricter. Wastewater, through thecoagulation and settlement, do not reach the national emission standard. It is necessaryto treat the wastewater. The conventional method of using of aerobic and anaerobicmicroorganism to deal with the terminal wastewater cannot last for a long time and thetreatment effect is not very good. With the development of the immobilized materialtechnology, we can use immobilized material to immobilize microorganisms, and thecarriers are wrapped in the natural gel membrane after adsorbing of microorganisms.Microorganisms can rapid proliferation through utilizing substances in the wastewater.Microorganisms can handle wastewater more complete and reduce time of handling. Sothe paper terminal wastewater can reach the national standard.The paper starts from the preparation of immobilized materials. Choosing goodbiocompatibility and inexpensive sodium alginate, which do not have toxicity, andcationic starch prepare immobilized materials. At the same time, the activated carbonfiber has larger surface area, so it is selected as carrier to absorb microorganisms.Preparing many components gel ball of calcium alginate and cationic starch-activatedcarbon fiber can not only overcomes the limitations of a two-component, but accelerateto deal with papermaking terminal wastewater in using physical adsorption andchemical entrapment.Through optimizing the experiment, we can optimize the hydro gels. Consideringthe concentration of cationic starch, the charge of cationic starch, the mass ratio incationic starch concentration and quantity of gel beads, the film of time and temperatureof cationic starch in calcium alginate gel ball, and the time of liquefaction in sodiumcitrate, we can further optimize the gel ball. After the selection of the optimalparameters, adding activated carbon fiber to gel ball. Studying the mechanical strength,swelling degree, particle size, and select the optimal gel ball. The results show that: atthe temperature of30℃,2.5%sodium alginate,4%calcium chloride,0.8%cationicstarch,0.15%activated carbon fiber, the membrane formation time, membrane overlaytime and liquefaction time are20min,10min and5min, gel ball can obtain the bestmechanical properties. Gel ball not only have good mechanical properties, but also have good masstransfer performance. Mass transfer performance is largely decided by the amount ofmicroorganisms dealing with wastewater. This paper discusses the small molecularsubstances, such as phenylalanine, glutamic acid, glucose, lactose in the diffusion timegel ball inside and outside and the final equilibrium concentrations. The results showthat the gel balls have good diffused ability and diffusion equilibrium reach themaximum in absorbing small molecular substances. For the MWCO of gel balls, thestudy of the molecular weight of polyethylene glycol800,1000,1500,2000, and4000show that small molecules can import and gel ball fast and large molecular substancescannot enter gel ball. These provide an ideal environment for gel ball embeddingmicroorganism.Utilization of waste material is reflected not only in the mass transfer performanceof gel beads, but also in microbial biomass. Because of the complexity of papermakingwastewater, single species cannot effectively treat it. Paper use different amount of mixmicroorganism to deal with terminal wastewater. Paper think about COD, pH, chroma,turbidity variation of wastewater. By comparing the selection condition, Optimizingresult show that w(free bacteria: alginate) is3:1, the immobilized gel ball is600, pH=9,and the temperature is30. From the result, we can see that microorganism can increaseto deal with the wastewater after prolonging the time. The COD decreased to182mg/land the chroma down to58.94in three days. The immobilized microorganisms can notonly speed up to use environmental harmful substances, but also maximize to deal withwastewater. The effect was stronger than the free microbial treatment.Microorganisms are wrapped in calcium alginate gel beads-cationic starch gel ballcan obviously handle wastewater. By biological methods and the combination ofphysical and chemical methods, gel ball not only overcome the disadvantage ofprocessed independently, but also obtain more good results. This provides a powerfulmethod for biological treatment of wastewater. Because gel ball have not goodmechanical strength, which need to find a biological non-toxic and better mass transferperformance of functional materials, we can use it in industry.