深度脫水市政污泥的熱干化特性研究
發(fā)布時(shí)間：2018-10-20 11:26
【摘要】：市政污泥的產(chǎn)量逐年增加,污泥的減量化、穩(wěn)定化、無害化以及資源化處置方式得到了廣泛關(guān)注。脫水污泥含水率高是制約其處置的瓶頸問題,干化操作可以進(jìn)一步降低其含水率。在傳統(tǒng)脫水污泥的干化過程中,水分的釋放速率較慢且容易產(chǎn)生多種污染性氣體。本文對(duì)比傳統(tǒng)的聚丙烯酰胺(PAM)調(diào)理脫水、干化路線,采用Fe Cl3+助凝劑、芬頓試劑(Fenton’s reagent)+助凝劑對(duì)污泥進(jìn)行調(diào)理,以獲得深度脫水效果,隨后進(jìn)行干化,探究深度脫水調(diào)理劑對(duì)污泥干化過程水分釋放以及污染性氣體釋放的影響,同時(shí)關(guān)注不同干化氣氛以及溫度對(duì)這一過程的影響。實(shí)驗(yàn)結(jié)果表明復(fù)合調(diào)理劑可以破壞污泥結(jié)構(gòu),釋放內(nèi)部水,同時(shí)增大污泥孔隙結(jié)構(gòu),使得干化過程中具有相比PAM調(diào)理污泥更高的水分釋放速率,得到更短的干化時(shí)間。污泥干化過程所釋放的含硫污染性氣體主要有H2S、SO2、COS以及CS2,其中H2S、SO2占總硫釋放量的82.4%;含氮污染性氣體主要有NH3和HCN。Fe3+以及Fenton試劑將污泥中H2S等還原性分子以及不穩(wěn)定有機(jī)物氧化固定,Fe2+、Ca O與污泥中游離H2S、SO2等分子發(fā)生化合反應(yīng)生成鹽,從而實(shí)現(xiàn)對(duì)主要含硫污染性氣體的抑制。同時(shí),Ca O調(diào)理形成的堿性環(huán)境加強(qiáng)了污泥中游離NH3分子的釋放,促進(jìn)NH4+向NH3轉(zhuǎn)化,導(dǎo)致更高強(qiáng)度的NH3釋放。干化固相的XPS結(jié)果表明,相比于PAM調(diào)理污泥,干化后調(diào)理污泥的無機(jī)硫酸鹽含量升高,易釋放的有機(jī)硫含量、無機(jī)氨氮(N-H)含量下降,說明調(diào)理劑可以有效固硫,同時(shí)促進(jìn)NH3的提前釋放。調(diào)理污泥促進(jìn)NH3釋放而使得其干化冷凝液溶解了更多的NH3,導(dǎo)致較高的p H值。調(diào)理劑對(duì)污泥中易揮發(fā)有機(jī)物的破壞,使得調(diào)理污泥冷凝液COD低于PAM調(diào)理污泥。CO2因?yàn)榕cCa O發(fā)生反應(yīng)而減弱調(diào)理劑對(duì)H2S、SO2的固定作用,同時(shí)在水蒸氣存在條件與NH3反應(yīng)而抑制其釋放;O2因?yàn)閷?duì)H2S氧化而抑制其釋放,對(duì)SO2的影響不明顯。O2存在可能會(huì)加強(qiáng)污泥有機(jī)質(zhì)分解而產(chǎn)生更多的NH3。CO2與冷凝液中溶解NH3反應(yīng),降低冷凝液的p H,也減少含硫氣體的溶解,降低SO42-濃度。干化溫度從400℃提高到800℃,干化時(shí)間減少為20%左右。高溫條件可能由于調(diào)理劑與主要含硫氣體反應(yīng)的生成物受熱分解而導(dǎo)致其固硫效果降低。調(diào)理污泥在高溫條件下的NH3釋放量高于PAM調(diào)理污泥,主要來自有機(jī)氮的熱分解。提高干化溫度,冷凝液中有機(jī)物逐漸由脂肪族化合物轉(zhuǎn)變?yōu)榻褂?說明低溫過程主要是易揮發(fā)性有機(jī)物釋放,高溫則發(fā)生有機(jī)物熱分解產(chǎn)焦油過程。測(cè)定固相C、H、N元素含量,結(jié)果表明調(diào)理污泥熱穩(wěn)定性比PAM調(diào)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，
本文編號(hào)：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，
本文編號(hào)：2283023
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