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河道淤泥复合固化剂研发与环境特性研究

作者:优质期刊论文发表网  来源:www.yzqkw.com  发布时间:2019/10/26 14:02:29  

摘要:内陆城市湖泊河道众多,淤泥大量积聚于水底,且淤泥清挖和处理往往耗资巨大,工程量惊人。这些堆放的淤泥不光含水率高,强度低,还含有大量有毒化学物质、病原生物等有害成分。固化技术有利于淤泥的后续无害化处置并实现资源化利用,可期解决近年来日益严重的疏浚淤泥处置问题。

本文以常州市武进区大通河底泥为研究对象,从影响淤泥固化效果的主要因素出发,研究不同种类的单组份固化剂种类、掺量及固化时间对淤泥含水率的影响,从而得出最佳固化剂配比。以复合固化剂掺量、养护龄期及pH为影响因素,分析固化淤泥无侧限抗压强度变化规律,利用响应面法优化固化养护工艺条件。在配方及养护工艺基础上研究复合固化剂环境特性,分析固化淤泥无害化、资源化利用的可行性,并针对重金属污染淤泥进行复配稳定化研究。得出以下结论:

(1)粉煤灰、水泥、KPAM及磺化油等单组分固化剂对淤泥均有一定的减水固化效果;当固化时间为5 d时,KPAM及磺化油掺量为5‰,淤泥含水率可降低至49%下,前期减水效果优于高掺量下的无机固化剂;固化剂掺量及固化时间是影响淤泥含水率的主要因素。

(2)实验淤泥固化的最佳复合配方为水泥:粉煤灰:KPAM:磺化油=33.3:40:1.33:1,各组分对淤泥含水率的影响大小排序为:KPAM>磺化油>硅酸盐水泥>粉煤灰。

(3)淤泥强度随固化剂掺量增加而提高;在掺量为10%,养护龄期为45d时,复合固化剂的无侧限抗压强度为2.89 MPa;相同养护条件下,使用复合固化剂的淤泥强度高于单组分固化剂。

(4)在一定养护龄期内,固化淤泥强度随着固化剂掺量提高而变大,且在碱性条件下力学性能更强。利用响应面法得出使用复合固化剂的淤泥最佳养护条件为:固化剂掺量11%,养护pH值12.4,养护龄期65 d,在此条件下固化淤泥的无侧限抗压强度可以达到3.78 MPa。

(5)固化后淤泥具有良好的耐水性,但耐酸性差;复合固化剂在最优养护条件下,可有效稳定淤泥中的有机物;对重金属污染的淤泥进行稳定性研究,发现磷酸二氢钙作用时,浸出液中Pb浓度可降低97%;碳酸钙对Cu的稳定效果最佳,浸出液中Cu浓度可降低98%;硅酸钠对Pb及Cu均有较优稳定效果,浸出液中Pb浓度可降低93%。

There are many rivers and lakes in inlandcities, and there is a large amount of silt accumulation at the bottom of theriver. The excavation and treatment of silt is often expensive and costly.These stacked silt have high moisture content and low strength, and alsocontain harmful components such as toxic chemicals and pathogenic organisms.The solidification technology is beneficial to the subsequent disposal ofsludge and realizes resource utilization, and it is expected to solve theincreasingly serious problem of dredged sludge disposal in recent years.

In this paper, the bottom sediment ofDatong River in Wujin District of Changzhou City is taken as the researchobject. Based on the main factors affecting the solidification effect ofsludge, the dosage of different types of single-cured materials, curing timeand pH on the moisture content and mechanical strength of the sludge arestudied. The effect is to obtain the best curing agent ratio and optimize thecuring curing process conditions. On the basis of formulation and technology,the environmental characteristics of compound curing agent were studied, thefeasibility of harmless and resource utilization of solidified sludge wasanalyzed, and the compound stabilization of heavy metal contaminated sludge wasstudied. Draw the following conclusions:

(1)Fly ash, cement,KPAM and sulfonated oil and other single-component curing agents havesignificant water-reducing effect on the sludge; when the curing time is 5days, the KPAM and sulfonated oil content is 5‰, the sludge moisture contentCan be reduced to 49%, the previous water reduction effect is better than thehigh amount of inorganic curing agent; analysis shows that the curing agentdosage and curing time have a significant impact on the moisture content of thesludge.

(2)The compositecuring agent formula using orthogonal experiment to obtain the best waterreducing effect is cement: fly ash: KPAM: sulfonated oil is 33.3:40:1.33:1, theorder of influence of each solidified material on the moisture content of thesludge is: KPAM>sulfonated oil>silicate cement> fly ash.

(3)The strength ofthe sludge increases with the increase of the amount of curing agent. When thedosage is 10% and the curing age is 45 days, the unconfined compressivestrength of the composite curing agent is 2.89 MPa. Under the same conditions,the solidified agent solidified sludge strength performance Better thanone-component inorganic curing agent.

(4)Within 60 daysof curing age, the solidified sludge strength becomes larger as the amount ofcuring agent increases, and the solidified sludge has stronger mechanicalproperties under alkaline conditions. The response surface method was used tooptimize the curing process of the composite curing agent. The optimum curingconditions were as follows: the curing agent dosage was 11%, the curing pH was12.4, and the curing age was 65 days. Under this condition, the unconfinedcompressive strength of the solidified sludge was determined. The best result is3.78 MPa.

(5)Aftersolidification, the sludge has good water resistance, but the acid resistanceis poor; the composite curing agent can effectively stabilize the organicmatter in the sludge under the optimal curing conditions. The stability studyof heavy metal contaminated sludge shows that the concentration of Pb in theleachate can be reduced by 97% when calcium dihydrogen phosphate is applied;the stability of Cu is the best for Cu, and the concentration of Cu in theleachate can be reduced by 98%; Both Pb and Cu have better stability and the Pbconcentration in the leachate can be reduced by 93%.

关键词:河道底泥;固化处理;复合固化剂;无侧限抗压强度;环境特性;重金属浸出浓度

river sediment; solidification treatment;composite curing agent; unconfined compressive strength; environmentalcharacteristics;metal leaching concentration.

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