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木聚糖酶在纸浆顶漂白中的应用试验 总被引:4,自引:0,他引:4
采用自制的木聚糖酶LDA3对纸浆进行预漂白处理,可以显著降低纸浆的卡伯值。LDA3处理木浆的条件为30℃,15IU/g绝干浆,卡伯值最大差为3.0,处理麦草浆的条件为30℃,30IU/g绝干浆。卡伯值最大落差为7,经换算分别可以降低16%和15%的有效氯用量,具有降低漂白成本和减少环境污染的显著效果。 相似文献
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纸浆漂白废水中毒性有机氯化物的防治 总被引:4,自引:0,他引:4
纸浆漂白废水中的有机氯化物对水生生物和人类具有很大的毒害作用,对纸浆漂白废水中有机氯人物的形成机制以及各种预防和治理途径进行了综述。 相似文献
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蔗渣浆酶促漂白预处理对纤维形态性质和污染物发生的影响 总被引:1,自引:0,他引:1
采用Pulpzyme HC木聚糖酶对蔗渣纸浆进行酶促漂白处理。试验结果表明,酶处理的最佳纸浆浓度为5%,处理时间为60min.酶用量为1.0IU/g。酶处理后纸浆的得率下降不多.强度略有升高,但纸浆白度增加。试验结果还表明,酶处理对纸浆纤维不具有破坏性。对酶处理后纸浆的扫描电镜观察说明,随酶处理时间和酶用量的增加,蔗渣中木聚糖的溶出量加大。酶处理使木聚糖降解溶出,使木质素充分暴露出来,有利于后续漂白剂与之反应.同时可减少后续化学漂白剂的使用量,从而减少有毒氯化有机污染物的产生。随处理时间增长和酶用量增加,处理液中CODcr,和BOD5呈上升趋势。酶用量超过1.5IU/g后.BOD5增长较缓慢,表明酶的作用对纤维表面生物可降解成分的溶出较彻底。 相似文献
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《环境工程学报》2017,(8)
采用UV-Fenton联合的方法处理紫胶漂白废水,单因素实验研究了H_2O_2用量、FeSO_4用量、反应时间和初始pH值对紫胶漂白废水降解的影响,并通过数学回归模型和响应曲面法优化得到UV-Fenton深度处理紫胶漂白废水的最优条件:初始pH值5.0,H_2O_2用量49 g·L~(-1)、FeSO_4用量2.6 g·L~(-1)、反应时间为4 h。经最优工艺条件深度处理后的紫胶漂白废水COD、BOD_5、悬浮物、色度、总氮和总磷分别降低至48 mg·L~(-1)、32 mg·L~(-1)、27.3 mg·L~(-1)、24 NTU、0.027 mg·L~(-1)、0.021 mg·L~(-1),除BOD5稍高外,其余指标均达到污水综合排放一级标准。在最优条件下,以紫胶漂白废水COD值和COD去除率为指标的降解动力学模型可分别表示为:lny=0.034 98+0.001 85x+6.898×10~(-6)x2和z=95.36-92.78×0.9706t。由动力学方程可看出,废水COD值在反应开始的前2 h内,降低幅度接近90%,且以反应开始时最为剧烈,随着反应的进行,反应剧烈程度迅速减弱。 相似文献
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Lipophilic extractives in process waters during manufacturing of totally chlorine free kraft pulp from eucalypt wood 总被引:4,自引:0,他引:4
The chemical composition of lipophilic extractives from process waters throughout a totally chlorine free (TCF) bleaching sequence after kraft pulping of eucalypt wood has been studied. These compounds are among the most problematic wood constituents for both TCF and zero liquid effluent (ZLE) processes, since they tend to accumulate in circuits resulting in the formation of the so-called pitch deposits causing serious problems in the pulp and paper industry. Pitch deposits collected at different parts of the pulp mill were also characterized and their composition compared with that of lipophilic compounds in process waters and Eucalyptus globulus wood. The identification of these compounds from process waters, wood and pitch deposits was performed by gas chromatography and gas chromatography-mass spectrometry using short- and medium-length high temperature capillary columns. Sterols, sterol esters, steroid ketones and steroid hydrocarbons were the main compounds identified. These chemical species arise from eucalypt wood extractives that survive the pulping and are released from pulp into the process waters during the bleaching process. Finally, they can deposit in pulp and on different parts of the mill or remain suspended in process waters being discharged in effluents. 相似文献
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Levels of PCDDs and PCDFs in products and effluent from the Swedish pulp and paper industry and chloralkali process 总被引:1,自引:0,他引:1
Within the Swedish Dioxin Survey various samples from the pulp and paper industry and the chloralkali process have been analyzed by congener specific analytical methods. In addition to the generally discussed “bleaching pattern” of the tetrachlorinated congeners, these samples also contained higher chlorinated congeners like hexa-CDDs, hepta-CDFs, octa-CDD and octa-CDF. Consequently it is recommended that samples from the pulp industry should be analyzed for all PCDDs and PCDFs (tetra- through octa-). Counted as Nordic Toxic Equivalents (NTEQ), the recycled pulp samples had the highest contamination level followed by TMP, unbleached sulfite and bleached softwood and hardwood. In addition to the bleaching process, various chemicals used in the pulping, bleaching and wastewater treatment can contribute to the contamination. 相似文献
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湖南某造纸厂采用二相厌氧 混凝法处理制浆造纸综合废水取得了显著效果 ,CODCr排放总量削减率达 80 % ,水体水质明显改善。本文介绍了该工程的工艺设计及调试。 相似文献
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Daljeet Kaur Nishi K. Bhardwaj Rajesh Kumar Lohchab 《Environmental science and pollution research international》2017,24(30):23488-23497
Environmental degradation by industrial and other developmental activities is alarming for imperative environmental management by process advancements of production. Pulp and paper mills are now focusing on using nonwood-based raw materials to protect forest resources. In present study, rice straw was utilized for pulp production as it is easily and abundantly available as well as rich in carbohydrates (cellulose and hemicelluloses). Soda-anthraquinone method was used for pulp production as it is widely accepted for agro residues. Bleaching process during paper production is the chief source of wastewater generation. The chlorophenolic compounds generated during bleaching are highly toxic, mutagenic, and bioaccumulative in nature. The objectives of study were to use oxygen delignification (ODL) stage prior to elemental chlorine-free (ECF) bleaching to reduce wastewater load and to study its impact on bleached pulp characteristics. ODL stage prior to ECF bleaching improved the optical properties of pulp in comparison to only ECF bleaching. When ODL stage was incorporated prior to bleaching, the tensile index and folding endurance of the pulp were found to be 56.6 ± 1.5 Nm/g and 140, respectively, very high in comparison to ECF alone. A potential reduction of 51, 57, 43, and 53% in BOD3, COD, color, and AOX, respectively was observed on adding the ODL stage compared to ECF only. Generation of chlorophenolic compounds was reduced significantly. Incorporation of ODL stage prior to bleaching was found to be highly promising for reducing the toxicity of bleaching effluents and may lead to better management of nearby water resources. 相似文献
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按照水质情况,将多种来源于不同工业生产过程中的高浓度有机废水划分为高悬浮固体乳化液废水、难生化高浓度有机废水、高悬浮固体不含油有机废水、含铬有机废水和杂质含量较少的乳化液废水5类,分别采用酸化破乳/Fen-ton氧化/混凝/絮凝、Fenton氧化/混凝/絮凝、混凝/絮凝、还原/混凝/絮凝、震动膜过滤技术作为生化预处理技术,并通过小试和中试验证了各技术的效果。实验结果表明,按照上述分类结果,采用不同预处理技术可以得到良好的效果,废水水质明显改善,满足继续生化处理的基本条件。各预处理生产装置处理效果稳定,同时生化系统已经稳定运行120天以上,COD去除率超过90%,出水经过低剂量的Fenton试剂处理后可达到《污水排入城镇下水道水质标准》(CJ343-2012)。 相似文献
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The most abundant volatile organochlorine compounds (VOCCs), trichloroacetic and dichloroacetic acids and AOX, were determined in bleaching effluent and waste water from three kraft pulp mills during ClO2 bleaching. 0.6–7.7 g of VOCCs per ton bleached pulp were formed, the most abundant being chloroform and dichloroacetic acid methyl ester. Most of the VOCCs were removed during treatment, and it was estimated that 2–30 t of VOCCs would be removed annually from activated sludge treatment plants in Finnish kraft pulp mills using elemental chlorine free bleaching, most likely by volatilization. Dichloroacetic acid was formed in considerably higher amounts than trichloroacetic acid, and both compounds were removed effectively during treatment. The formation of all organochlorine compounds decreased considerably when non-chlorinated bleaching was employed. 相似文献
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采用直接接触式膜蒸馏(DCMD)工艺处理糖精钠生产废水。分析了经过活性炭吸附预处理前后,膜蒸馏连续循环运行的效果。实验结果表明,未经预处理的废水在膜蒸馏过程中,废水中所含有机物不仅导致膜材料的润湿,引起产水电导率升高及膜孔润湿,促进盐晶体在膜表面附着,使产水通量下降。经吸附预处理后,膜蒸馏过程中产水通量介于10.40~11.24 kg/(m2.h)。吸附预处理能有效减缓产水通量的衰减,提高产水水质。废水经过活性炭预处理后进行膜蒸馏浓缩处理,当浓缩倍数达到5倍时,通量保持在10.55 kg/(m2.h)左右;产水水质稳定,截留率在99.5%以上。研究结果表明,吸附-膜蒸馏工艺可以应用于糖精钠生产废水的回用处理,有明显的应用前景。 相似文献