深度脱水市政污泥的热干化特性研究
发布时间：2018-10-20 11:26
【摘要】：市政污泥的产量逐年增加,污泥的减量化、稳定化、无害化以及资源化处置方式得到了广泛关注。脱水污泥含水率高是制约其处置的瓶颈问题,干化操作可以进一步降低其含水率。在传统脱水污泥的干化过程中,水分的释放速率较慢且容易产生多种污染性气体。本文对比传统的聚丙烯酰胺(PAM)调理脱水、干化路线,采用Fe Cl3+助凝剂、芬顿试剂(Fenton’s reagent)+助凝剂对污泥进行调理,以获得深度脱水效果,随后进行干化,探究深度脱水调理剂对污泥干化过程水分释放以及污染性气体释放的影响,同时关注不同干化气氛以及温度对这一过程的影响。实验结果表明复合调理剂可以破坏污泥结构,释放内部水,同时增大污泥孔隙结构,使得干化过程中具有相比PAM调理污泥更高的水分释放速率,得到更短的干化时间。污泥干化过程所释放的含硫污染性气体主要有H2S、SO2、COS以及CS2,其中H2S、SO2占总硫释放量的82.4%;含氮污染性气体主要有NH3和HCN。Fe3+以及Fenton试剂将污泥中H2S等还原性分子以及不稳定有机物氧化固定,Fe2+、Ca O与污泥中游离H2S、SO2等分子发生化合反应生成盐,从而实现对主要含硫污染性气体的抑制。同时,Ca O调理形成的碱性环境加强了污泥中游离NH3分子的释放,促进NH4+向NH3转化,导致更高强度的NH3释放。干化固相的XPS结果表明,相比于PAM调理污泥,干化后调理污泥的无机硫酸盐含量升高,易释放的有机硫含量、无机氨氮(N-H)含量下降,说明调理剂可以有效固硫,同时促进NH3的提前释放。调理污泥促进NH3释放而使得其干化冷凝液溶解了更多的NH3,导致较高的p H值。调理剂对污泥中易挥发有机物的破坏,使得调理污泥冷凝液COD低于PAM调理污泥。CO2因为与Ca O发生反应而减弱调理剂对H2S、SO2的固定作用,同时在水蒸气存在条件与NH3反应而抑制其释放;O2因为对H2S氧化而抑制其释放,对SO2的影响不明显。O2存在可能会加强污泥有机质分解而产生更多的NH3。CO2与冷凝液中溶解NH3反应,降低冷凝液的p H,也减少含硫气体的溶解,降低SO42-浓度。干化温度从400℃提高到800℃,干化时间减少为20%左右。高温条件可能由于调理剂与主要含硫气体反应的生成物受热分解而导致其固硫效果降低。调理污泥在高温条件下的NH3释放量高于PAM调理污泥,主要来自有机氮的热分解。提高干化温度,冷凝液中有机物逐渐由脂肪族化合物转变为焦油,说明低温过程主要是易挥发性有机物释放,高温则发生有机物热分解产焦油过程。测定固相C、H、N元素含量,结果表明调理污泥热稳定性比PAM调理污泥高。
[Abstract]:The production of municipal sludge is increasing year by year, and the ways of sludge reduction, stabilization, innocuity and recycling have been paid more and more attention. High moisture content of dewatered sludge is the bottleneck of its disposal, and drying operation can further reduce its moisture content. In the drying process of traditional dewatered sludge, the release rate of water is slow and it is easy to produce a variety of polluting gases. In this paper, the sludge was treated with Fe Cl3 coagulant and Fenton reagent (Fenton's reagent) coagulant in order to obtain deep dehydration effect, and then drying, compared with the traditional polyacrylamide (PAM) conditioning dehydration and drying route. The effects of deep dehydration conditioning agent on water release and pollutant gas release during sludge drying were investigated, and the effects of different drying atmosphere and temperature on the process were also discussed. The results showed that the compound conditioning agent could destroy the sludge structure, release the internal water and increase the pore structure of the sludge, which resulted in higher water release rate and shorter drying time in the drying process than that in the PAM conditioning sludge. The sulfur polluted gases released from sludge drying process are mainly H _ 2S _ 2SO _ 2COs and CS2, where H _ 2S _ 2O _ 2 accounts for 82.4% of total sulfur release, while nitrogen-containing polluting gases mainly include NH3 and HCN.Fe3 and Fenton reagents to reduce H _ 2S and unstable molecules in sludge. When the mechanism was oxidized and fixed, Fe2, Ca O reacted with free H _ 2S _ 2 _ 2 in sludge to form salt. In order to achieve the main sulfur pollution gas suppression. At the same time, the alkaline environment formed by, Ca O enhanced the release of free NH3 molecules in sludge, promoted the conversion of NH4 to NH3, and resulted in higher NH3 release. The XPS results of dry solid phase showed that compared with PAM, the content of inorganic sulfate increased, the content of organic sulfur and the content of inorganic ammonia nitrogen (N-H) decreased after drying, which indicated that the conditioning agent could effectively fix sulfur. At the same time, promote the early release of NH3. Sludge treatment promoted the release of NH3 and dissolved more NH3, in the dry condensate resulting in higher pH value. Because of the destruction of volatile organic matter in sludge by conditioning agent, the COD of conditioning sludge condensate is lower than that of PAM conditioning sludge. Because of the reaction with Ca O, CO2 weakens the fixing effect of conditioning agent on H _ 2S _ 2 so _ 2. At the same time, the release of NH3 was inhibited by the reaction of water vapor with NH3, and the effect of O2 on SO2 was not obvious because of the oxidation of H2S. The presence of O2 may enhance the decomposition of organic matter in sludge and produce more NH3.CO2 reaction with dissolved NH3 in condensate. It also reduces the solubility of sulfur-containing gases and the concentration of SO42-. When the drying temperature was raised from 400 鈩，
本文编号：2283023
[Abstract]:The production of municipal sludge is increasing year by year, and the ways of sludge reduction, stabilization, innocuity and recycling have been paid more and more attention. High moisture content of dewatered sludge is the bottleneck of its disposal, and drying operation can further reduce its moisture content. In the drying process of traditional dewatered sludge, the release rate of water is slow and it is easy to produce a variety of polluting gases. In this paper, the sludge was treated with Fe Cl3 coagulant and Fenton reagent (Fenton's reagent) coagulant in order to obtain deep dehydration effect, and then drying, compared with the traditional polyacrylamide (PAM) conditioning dehydration and drying route. The effects of deep dehydration conditioning agent on water release and pollutant gas release during sludge drying were investigated, and the effects of different drying atmosphere and temperature on the process were also discussed. The results showed that the compound conditioning agent could destroy the sludge structure, release the internal water and increase the pore structure of the sludge, which resulted in higher water release rate and shorter drying time in the drying process than that in the PAM conditioning sludge. The sulfur polluted gases released from sludge drying process are mainly H _ 2S _ 2SO _ 2COs and CS2, where H _ 2S _ 2O _ 2 accounts for 82.4% of total sulfur release, while nitrogen-containing polluting gases mainly include NH3 and HCN.Fe3 and Fenton reagents to reduce H _ 2S and unstable molecules in sludge. When the mechanism was oxidized and fixed, Fe2, Ca O reacted with free H _ 2S _ 2 _ 2 in sludge to form salt. In order to achieve the main sulfur pollution gas suppression. At the same time, the alkaline environment formed by, Ca O enhanced the release of free NH3 molecules in sludge, promoted the conversion of NH4 to NH3, and resulted in higher NH3 release. The XPS results of dry solid phase showed that compared with PAM, the content of inorganic sulfate increased, the content of organic sulfur and the content of inorganic ammonia nitrogen (N-H) decreased after drying, which indicated that the conditioning agent could effectively fix sulfur. At the same time, promote the early release of NH3. Sludge treatment promoted the release of NH3 and dissolved more NH3, in the dry condensate resulting in higher pH value. Because of the destruction of volatile organic matter in sludge by conditioning agent, the COD of conditioning sludge condensate is lower than that of PAM conditioning sludge. Because of the reaction with Ca O, CO2 weakens the fixing effect of conditioning agent on H _ 2S _ 2 so _ 2. At the same time, the release of NH3 was inhibited by the reaction of water vapor with NH3, and the effect of O2 on SO2 was not obvious because of the oxidation of H2S. The presence of O2 may enhance the decomposition of organic matter in sludge and produce more NH3.CO2 reaction with dissolved NH3 in condensate. It also reduces the solubility of sulfur-containing gases and the concentration of SO42-. When the drying temperature was raised from 400 鈩，
本文编号：2283023
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