| With the increasing pressure of the environment, the closed degree of water system becomes higher and higher. The pollutants which are difficult to be removed will accumulate gradually in the system, and they will produce certain negative effects on papermaking process and paper quality. The gradual accumulation of the harmful pollutants are referred to Dissolved and Colloidal Substance (DCS), abbreviated as DCS as the dissolution of the papermaking industry. DCS substance is unique in papermaking wastewater which contains large amounts of dissolved and semi-dissolved. DCS substance contains both in organics and organics, and they are different in chemical and physical nature, which will interfere papermaking and sewage treatment.In this paper, Zhejiang Jingxing Paper Co. is as a research object. Based on high concentrations of Ca2+ and DCS in wastepaper circulating sewage, the adsorption effects of nano-4A zeolite on Ca2+ in papermaking wastewater were studied, and the influence of the factors including the different sources of raw materials, particle size distribution, reaction time, dosage, pH and modification on the adsorption of Ca2+, were investigated, respectively. The effect of using the blended CaCO3 and nano-4A zeolite of adsorbed Ca2+ as filler on the paper strength property was studied. Four strains of microorganisms which have a good removal effect on DCS have been separated by coating from the papermaking wastewater. Strengthen the SBR reactor.The results show that adsorption effects of 4A zeolite from different sources of raw materials on Ca2+ in papermaking wastewater were the same. The removal rate of nano-4A zeolite on Ca2+ increased by 44.44% than the conventional 4A zeolite. The reaction time, dosage and pH of wastewater had great influence on adsorption of nano-4A zeolite on Ca2+. The removal effect of Ca2+ in wastewater was better in the conditions of the reaction time 30 min, dosage 5 g/L and wastewater pH>7. Different modification methods of nano-4A zeolite had great influence on the adsorption effect of Ca2+ in wastewater. NaOH modify had the minimal impact. Subsequent experiments could explore optimized NaOH modification conditions and increase the adsorption of modified nano-4A zeolite on Ca2+. Nano-4A zeolite match with CaCO3 on the particle size distribution and morphology features. The tensile index of paper increased by 7.4% compared with the filler of CaCO3 when the replace quantity of nano-4A zeolite was 50%. Burst index increased by 4.8%, Ring crush index increased by 21.1% when the replace quantity was 25%. The nano-4A zeolite of adsorbed Ca2+ showed obviously intertexture with fiber. It improved the smoothness of the paper when the paper fiber has better combination degree. The introduction of nano-4A zeolite of adsorbed Ca2+ could reduce the concentration of Ca2+ in effluent of sheet. It was good for wastewater treatment and recycling.Identified by 16S rDNA sequence alignment and phylogenetic,1,3 and 4nd strains belong to the Bacillus and the 2nd strain belongs to pseudoxanthomonas. By continuous operation of SBR reactor, those composite strains are able to survive steadily in the reactor. The removal rate of CODcr, TOC, DCS and DS maintains at 60%,56%,42% and 40%. It shows good synergy. The results show that the four strains are good strains for the removing of DCS.In conclusion, firstly, through the research of adsorption of Ca2+ in DCS by nano-4A zeolite and nano-4A zeolite of adsorbed Ca2+ as filler with CaCO3, the results show that nano-4A zeolite could effectively control the high concentration of Ca2+ in DCS and nano-4A zeolite of adsorbed Ca2+ could be resource utilization. Secondly, through the research of composite strains screening of degradation for DCS and strengthen SBR process, the results show that the four strains had good degradation for DCS. It might provide a viable biological control technology for DCS in wastepaper papermaking sewage. |
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