利用城市污水污泥制行道砖的工艺技术研究

发布时间：2018-04-16 13:26

  本文选题：湿污泥 + 烧结　； 参考：《西北农林科技大学》2015年硕士论文

【摘要】：城市污水处理厂的兴建对于水污染控制有积极的作用,但如何处理处置大量的污水污泥的问题也随之而来。以前由于受到技术、资金等因素的影响,我国长期以来只重视污水的处理,而忽视了污泥的处置。如今,国家加大了对污泥处理处置的投资力度,为我们研究新的污泥资源化利用方法提供了政策保障和资金支持。污泥建材利用尤其是污泥制砖是长期以来污泥资源化研究及应用的重点。但是总结发现,众多研究是利用干化污泥和污泥焚烧灰制砖,而污泥干化和焚烧需要消耗大量的能量。本研究的思路,就是利用湿污泥高含水率的特点,直接将湿污泥与粘土等材料混合陈化,使混合料达到一定的湿度,成型时不需要添加或只需少量的水,采用烧结工艺制砖,固化重金属,消灭病原微生物,同时达到减少能耗,节约水资源,无害化处置污泥的目的。我们通过对西安市四个污水处理厂脱水污泥理化性质的检测发现,个别污水处理厂污泥中Cd、Zn含量较高,超过了农用标准,可以通过制作园林绿化肥和烧结制砖来进行处置。我们以粘土和湿污泥为主体材料,结合试验结果,选取工程砂和煤粉为辅助掺料,其比例分别为8%和3%。在辅助掺料比例确定的情况下,我们以污泥掺量、烧成温度、保温时间、和成型压力为主要因素,每个因素三个水平,进行了正交试验。正交试验结果表明:污泥掺量对砖体抗压强度、吸水率的影响远大于其他三个因素,保温时间的影响最弱。污泥掺量20%时,砖还能保持一定的抗压强度和吸水性,可以作为行道砖用于人行道。通过单因素分析发现,同一试验条件下,随着污泥掺量增加,砖体抗压强度逐渐减小,烧成密度逐渐降低,吸水率逐渐升高。提高成型压力和烧成温度有利于改善砖的抗压性能。泛霜试验结果显示,在潮湿环境下,污泥烧结砖表面没有出现泛霜。冻融试验结果表明,污泥掺量小于24%时,污泥烧结砖具有一定的抗冻性,冻融质量损失率可以控制在2%以内。对污泥砖烧结前后浸出液中Pb、Cd、Cr等6种重金属浓度进行了检测,结果说明污泥烧结制砖具有显著的重金属固化作用,用作行道砖是是可行的。最终确定,当湿污泥掺量小于24%,烧成温度控制在1050℃左右,成型压力20MPa,可以使污泥行道砖强度达到10-20 MPa,满足国家标准《烧结普通砖》(GB5101——2003)MU10强度的要求。利用湿污泥制备烧结行道砖,可以消纳污泥,节能环保,节约水资源和土地资源,具有良好的社会经济效益。污泥处置需要多元化的资源化利用方式。
[Abstract]:The construction of municipal sewage treatment plant plays a positive role in water pollution control, but the problem of how to deal with a large amount of sewage sludge is followed.In the past, due to the influence of technology, capital and other factors, our country only attached importance to the treatment of sewage for a long time, but neglected the disposal of sludge.Nowadays, the government has increased the investment in sludge treatment and disposal, which provides policy guarantee and financial support for us to study new sludge resource utilization methods.The utilization of sludge building materials, especially sludge brick making, has long been the focus of sludge resource research and application.However, it is found that drying sludge and sludge incineration ash are used to make bricks, and sludge drying and incineration require a lot of energy consumption.The idea of this study is to make use of the characteristics of high moisture content of wet sludge, directly mix wet sludge with clay and other materials, so that the mixture can reach a certain humidity, and no or only a small amount of water is needed in the molding process, and the brick is made by sintering process.Solidify heavy metals, eliminate pathogenic microorganisms, reduce energy consumption, save water resources and dispose sludge innocuously.The physical and chemical properties of dewatered sludge from four sewage treatment plants in Xi'an were examined. It was found that the content of CD ~ (2 +) Zn in the sludge of several sewage treatment plants was higher than the agricultural standard, and could be disposed of by making garden fertilizer and sintered brick.With clay and wet sludge as main materials and combined with the test results, engineering sand and pulverized coal are selected as auxiliary admixtures, the proportions of which are 8% and 3% respectively.Under the condition that the proportion of auxiliary admixture is determined, the orthogonal experiments are carried out with the sludge content, sintering temperature, holding time and molding pressure as the main factors, three levels of each factor.The results of orthogonal test show that the influence of sludge content on the compressive strength and water absorption of brick is much greater than that of the other three factors, and the influence of holding time is the weakest.The brick can maintain a certain compressive strength and water absorption when the sludge content is 20 and can be used as the pavement brick.Through single factor analysis, it was found that under the same experimental conditions, with the increase of sludge content, the compressive strength of brick body gradually decreased, the firing density gradually decreased, and the water absorption rate gradually increased.Increasing the forming pressure and sintering temperature can improve the compressive performance of brick.The results of frosting test showed that there was no frosting on the surface of sintered brick in wet environment.The results of freeze-thaw test show that when the sludge content is less than 24%, the sludge sintered brick has a certain frost resistance, and the loss rate of freeze-thaw quality can be controlled within 2%.The concentration of six heavy metals, such as Pb, CD, Cr, etc. in leachate of sludge brick before and after sintering were detected. The results showed that the sludge sintered brick had remarkable solidification effect of heavy metal, and it was feasible to use it as a walking brick.Finally, when the wet sludge content is less than 24, the sintering temperature is controlled at about 1050 鈩，

本文编号：1759145