水熱處理對(duì)污泥水分分布的影響

毛華臻, 王 飛, 毛飛燕, 池 涌, 陸勝勇, 岑可法

(浙江大學(xué) 能源清潔利用國(guó)家重點(diǎn)實(shí)驗(yàn)室,浙江 杭州 310027)

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水熱處理對(duì)污泥水分分布的影響

毛華臻, 王 飛, 毛飛燕, 池 涌, 陸勝勇, 岑可法

(浙江大學(xué) 能源清潔利用國(guó)家重點(diǎn)實(shí)驗(yàn)室,浙江 杭州 310027)

采用低場(chǎng)核磁共振(LF-NMR)技術(shù)研究水熱處理對(duì)污泥水分分布的影響.通過研究水熱溫度、反應(yīng)時(shí)間、CaCl2與非離子型聚丙烯酰胺(PAM)添加量對(duì)污泥離心水的質(zhì)量分?jǐn)?shù)的影響,確定最佳處理工況.結(jié)合泥餅水的質(zhì)量分?jǐn)?shù)、氨氮(NH3-N)及溶解性化學(xué)需氧量(SCOD)分析,評(píng)價(jià)經(jīng)水熱處理后污泥樣品的脫水性能.研究水熱單一變量對(duì)污泥水分分布變化的影響.結(jié)果表明：反應(yīng)溫度的提高使得污泥中結(jié)合水和機(jī)械結(jié)合水均顯著降低；反應(yīng)時(shí)間的延長(zhǎng)降低了污泥中的結(jié)合水比例；投放氯化鈣主要降低機(jī)械結(jié)合水的比例；PAM的添加量對(duì)水分分布影響較小.水熱正交實(shí)驗(yàn)結(jié)果表明：在水熱溫度為230℃、處理時(shí)間為45 min時(shí),同時(shí)添加140 mg/g 干污泥(DS) CaCl2,在水熱處理后添加10-6g/g DS PAM試劑的工況下,泥餅經(jīng)離心脫水后水的質(zhì)量分?jǐn)?shù)由88.67%降至70.68%.與污泥原樣相比,懸浮液中的SCOD、NH3-N值大幅上升,說明污泥絮體中不溶的有機(jī)組分發(fā)生了水解,并改變了污泥的水分分布.

污泥；水熱；低場(chǎng)核磁共振(LF-NMR)；水分分布；預(yù)處理；脫水性能

污水處理廠二沉池污泥水的質(zhì)量分?jǐn)?shù)高達(dá)99 %,體積大、熱值低,難以被有效利用.污泥中含有重金屬、“三致”有機(jī)污染物等有毒化學(xué)物質(zhì)和病原微生物,隨意堆放污泥存在較高的二次污染風(fēng)險(xiǎn).對(duì)于污泥常規(guī)的處理處置方法,如填埋、土地利用、建材利用和焚燒[1-3]等,都要求污泥水的質(zhì)量分?jǐn)?shù)小于60 %.如何高效、節(jié)能、穩(wěn)定地降低污泥的水的質(zhì)量分?jǐn)?shù),已經(jīng)成為污泥處理處置過程中的關(guān)鍵問題.然而,由于污泥絮體中含有大量微生物及大分子有機(jī)物,污泥的脫水性能較低,需要采用預(yù)處理方法提高污泥的脫水性能,降低機(jī)械脫水后泥餅的水的質(zhì)量分?jǐn)?shù).水熱預(yù)處理技術(shù)通過破碎細(xì)胞,水解有機(jī)物,改變污泥絮體的微觀結(jié)構(gòu),釋放污泥內(nèi)部的結(jié)合水,可以改變污泥中的水分分布,具有提高污泥脫水和沉降性能的優(yōu)勢(shì)[4-5].通過測(cè)定水熱處理對(duì)污泥水分分布的影響,可以深入地探究水熱處理改善污泥脫水性能的效果及相關(guān)機(jī)理.

根據(jù)污泥中的水分和污泥絮體結(jié)合方式的不同,通常將污泥中的水分分為胞內(nèi)水、表面水、毛細(xì)水和自由水等4種類型[6].目前對(duì)于污泥的水分分布仍沒有標(biāo)準(zhǔn)的測(cè)定方法.通常采用的離心沉降法[7]、示差掃描量熱法(differential scanning calorimetry, DSC)[8-9]、測(cè)膨脹法[10]等方法僅能得到污泥中自由水和結(jié)合水2種形態(tài)的水分分布.低溫干燥法[11]存在測(cè)試時(shí)間長(zhǎng)、復(fù)現(xiàn)性較差的缺點(diǎn).熱重-差示掃描量熱儀法[12]要求測(cè)試樣品質(zhì)量在10 mg左右,對(duì)于內(nèi)部組成成分復(fù)雜的市政污泥,復(fù)現(xiàn)性較差.因此,本文采用了低場(chǎng)核磁共振研究污泥中的水分分布.張旭等[13]采用了核磁共振方法檢測(cè)煤中的結(jié)晶水質(zhì)量分?jǐn)?shù).姚武等[14]采用了核磁共振方法研究水泥中的可蒸發(fā)水演變過程.

本文以二沉池污泥為對(duì)象開展水熱處理實(shí)驗(yàn).選取水熱溫度、反應(yīng)時(shí)間、CaCl2添加量與非離子型聚丙烯酰胺(PAM)添加量4個(gè)因素進(jìn)行實(shí)驗(yàn).采用低場(chǎng)核磁共振(LF-NMR)技術(shù)研究泥餅水分分布,結(jié)合懸浮液中氨氮(NH3-N),溶解性化學(xué)需氧量(Soluted chemical oxygen demand,SCOD)值的變化,探討水熱處理參數(shù)對(duì)污泥水分分布及脫水性能的改善機(jī)理.

1 材料與方法

1.1 實(shí)驗(yàn)設(shè)計(jì)

污泥樣品取自杭州七格市政污水處理廠二沉池.污泥24 h重力沉降后泥餅水的質(zhì)量分?jǐn)?shù)為96.36%.將重力沉降后的泥餅放入離心機(jī)中,經(jīng)2 500 r/min離心脫水10 min后,離心懸浮液中NH3-N值ρ(NH3-N)為860 mg/L,離心懸浮液中溶解性化學(xué)需氧量ρ(SCOD)為1 500 mg/L,離心脫水后泥餅水的質(zhì)量分?jǐn)?shù)為88.67 %.

實(shí)驗(yàn)所用水熱裝置為美國(guó)Parr公司研制的4500系列高壓反應(yīng)釜,最高工作壓力可達(dá)40 MPa,最高工作溫度為550 ℃.實(shí)驗(yàn)裝置示意圖如圖1所示.將40 mL重力沉降后的污泥放入水熱反應(yīng)裝置中,添加一定量CaCl2并加熱至設(shè)定溫度,在一定時(shí)間下保溫進(jìn)行水熱反應(yīng).反應(yīng)結(jié)束后,待污泥冷卻至室溫取出,加入一定量PAM并充分?jǐn)嚢?將水熱處理后的樣品放入離心機(jī)中(ST-40,美國(guó)Thermo),以2 500 r/min的速度離心脫水10 min,傾倒出懸浮液后,采用數(shù)據(jù)型微電腦多參數(shù)水質(zhì)快速測(cè)定儀(ET99732,德國(guó)Lovibond)測(cè)量污泥懸浮液的SCOD與NH3-N值,并測(cè)量污泥泥餅水的質(zhì)量分?jǐn)?shù).同時(shí),將離心后污泥泥餅放入試樣管中,置入LF-NMR設(shè)備內(nèi),對(duì)其進(jìn)行核磁共振分析,通過測(cè)量污泥中H質(zhì)子的橫向弛豫時(shí)間,計(jì)算污泥泥餅的水分分布.

1-氮?dú)馄浚?-熱電偶；3-電動(dòng)機(jī)；4-壓力傳感器；5-安全閥； 6-反應(yīng)釜；7-電加熱套；8-控制電腦；9-攪拌槳葉；10-冷凝管圖1 水熱反應(yīng)預(yù)處理設(shè)備示意圖Fig.1 Schematic diagram of thermal hydrolysisinstruments

1.2 低場(chǎng)核磁共振分析方法

污泥泥餅水分分布的測(cè)定采用低場(chǎng)核磁共振波譜儀(MicroMR20-025V,上海紐邁).低場(chǎng)核磁共振波譜儀主要由永磁體、射頻系統(tǒng)、溫控系統(tǒng)、數(shù)據(jù)采集分析系統(tǒng)和試樣管組成.MicroMR20-025V核磁共振分析儀磁場(chǎng)強(qiáng)度為0.5±0.08 T,磁體溫度維持在32.00±0.01 ℃,實(shí)驗(yàn)通過CPMG序列測(cè)量污泥中水分的橫向弛豫時(shí)間,其中采樣重復(fù)時(shí)間為3 000 ms,回波個(gè)數(shù)為5 000,半回波時(shí)間為175 μs.采用WIN-MRIXP軟件對(duì)樣品的FID信號(hào)進(jìn)行反演得到樣品的橫向弛豫時(shí)間(T2),并繪制橫向弛豫時(shí)間曲線.低場(chǎng)核磁共振技術(shù)通過測(cè)量聚合物中H質(zhì)子的橫向弛豫時(shí)間得到聚合物中水分的流動(dòng)性,在食品[15]、水泥[16]和石油[17]等行業(yè)已有應(yīng)用.

低場(chǎng)核磁共振分析儀采用CPMG序列測(cè)量水熱處理后樣品的橫向弛豫時(shí)間,通過下式得到橫向弛豫時(shí)間[14]：

(1)

式中：ρ2為污泥表面弛豫強(qiáng)度,S為污泥的表面積,V為污泥的總體積.

聚合物包括許多不同尺寸的孔,每個(gè)孔有不同的特性和橫向弛豫時(shí)間.因此,總的橫向弛豫時(shí)間M(t)可通過下式獲得：

(2)

式中：Ai為i組分孔徑的占比,T2i為i組分孔徑中水的橫向弛豫時(shí)間.

通過式(2)對(duì)污泥中水分橫向弛豫時(shí)間圖譜中的不同弛豫時(shí)間峰面積進(jìn)行積分,得到污泥中水分不同結(jié)合形式下的相對(duì)比例.根據(jù)之前的研究結(jié)果,通過測(cè)量污泥中H質(zhì)子低場(chǎng)核磁共振的橫向弛豫時(shí)間,可將污泥中不同結(jié)合能的水分按照T2時(shí)間從長(zhǎng)到短依次分為自由水、機(jī)械結(jié)合水和結(jié)合水[18].

2 結(jié)果與討論

2.1 水熱處理實(shí)驗(yàn)

二沉池污泥經(jīng)2 500 r/min離心脫水10 min后水的質(zhì)量分?jǐn)?shù)仍然高達(dá)88.67 %.高水的質(zhì)量分?jǐn)?shù)污泥因其體積大、熱值低等特性難以進(jìn)行有效的后續(xù)處理.對(duì)污泥樣品進(jìn)行水熱處理可提高其脫水性能.以水熱溫度、反應(yīng)時(shí)間、CaCl2與PAM添加量為因素進(jìn)行正交實(shí)驗(yàn),實(shí)驗(yàn)工況及實(shí)驗(yàn)結(jié)果如表1所示.

在污泥水熱處理過程中,污泥懸浮液中的ρ(NH3-N)和ρ(SCOD)值顯著上升,并隨著反應(yīng)溫度的提高、反應(yīng)時(shí)間的延長(zhǎng)而增加.說明污泥在水熱處理過程中,污泥中微生物細(xì)胞破碎,與水分子有強(qiáng)結(jié)合力的聚合物發(fā)生水解,導(dǎo)致污泥絮體內(nèi)的結(jié)合水被釋放出來.同時(shí),蛋白質(zhì)、碳水化合物、腐植酸等使污泥絮體呈負(fù)電性的聚合物在水熱作用下水解,降低了污泥絮體負(fù)電性,從而促進(jìn)污泥絮體的沉降,將泥餅間部分機(jī)械結(jié)合水釋放為自由水[19].如圖2所示為污泥水熱處理正交實(shí)驗(yàn)各因素對(duì)泥餅脫水的影響.結(jié)果表明,水熱溫度由140 ℃升高到230 ℃,泥餅水的質(zhì)量分?jǐn)?shù)從80.09 %降至72.10 %,ρ(NH3-N)值從1 355 mg/L增加至6 570 mg/L,ρ(SCOD)從7 450 mg/L增加至13 775 mg/L.并且,隨著反應(yīng)時(shí)間從15 min延長(zhǎng)至60 min,泥餅水的質(zhì)量分?jǐn)?shù)由76.52%逐漸下降至73.78%,ρ(NH3-N)值從2 770 mg/L增加至4 500 mg/L,ρ(SCOD)值從11 275 mg/L增加至11 850 mg/L.反應(yīng)溫度的升高與反應(yīng)時(shí)間的延長(zhǎng),將提高污泥中聚合物的水解程度與微生物細(xì)胞的破碎比例,提升污泥的脫水性能.同時(shí),泥餅的水的質(zhì)量分?jǐn)?shù)隨CaCl2添加量D(CaCl2)的增加從77.18 %降低至73.42 %.根據(jù)雙電層理論,Ca2+能中和污泥絮體表面的負(fù)電荷,降低污泥絮體間的斥力,促進(jìn)污泥絮體的絮凝與沉降[20],使污泥絮體結(jié)合地更緊密,脫除部分物理結(jié)合水,降低泥餅水的質(zhì)量分?jǐn)?shù).污泥水的質(zhì)量分?jǐn)?shù)與PAM的添加量D(PAM)關(guān)系較小,可能因?yàn)榛钚晕勰嘟?jīng)水熱處理后,Ca2+的添加降低了污泥絮體中雙電層間的斥力,增強(qiáng)了污泥絮體的絮凝與沉降,削弱了PAM的絮凝、架橋的效果.

表1 水熱處理污泥正交實(shí)驗(yàn)工況及水的質(zhì)量分?jǐn)?shù)、NH3-N值、溶解性化學(xué)需氧量值

Tab.1 Thermal hydrolysis orthogonal experiment conditions and water content, NH3-N, soluted chemical oxygen demand

序號(hào)θ/℃T/minD(CaCl2)/(mg/g-1DS)D(PAM)/(10-6g·g-1DS)ws/wt.%ρ(NH3-N)/(mg·L-1)ρ(SCOD)/(mg·L-1)11401520183.491090590021403060480.5711807000314045100779.45162082004140601401076.851530870051701560778.7917908900617030201077.68211011600717045140172.93231011500817060100471.682450110009200151001071.612040108001020030140771.73322014700112004520474.16420014700122006060173.236720148001323015140472.186160155001423030100172.155480140001523045601070.98734012700162306020773.38730012900

如表2所示為泥餅水的質(zhì)量分?jǐn)?shù)方差分析結(jié)果表明,各因素對(duì)泥餅水的質(zhì)量分?jǐn)?shù)的影響程度依次為反應(yīng)溫度>CaCl2>反應(yīng)時(shí)間>PAM.其中,反應(yīng)溫度對(duì)泥餅水的質(zhì)量分?jǐn)?shù)有顯著影響.直觀分析表明，泥餅水的質(zhì)量分?jǐn)?shù)最低的工況為加熱時(shí)間230 ℃,反應(yīng)時(shí)間45 min,CaCl2添加量60 mg/g DS,PAM添加量10-5g/g DS).由圖2可以看出,反應(yīng)時(shí)間從45 min延長(zhǎng)至60 min,泥餅水的質(zhì)量分?jǐn)?shù)變化不大.CaCl2添加量的增加可顯著提高污泥脫水效果.從節(jié)約成本角度考慮,并綜合各因素對(duì)泥餅脫水效果影響,將最佳工況設(shè)定為：加熱時(shí)間230 ℃,反應(yīng)時(shí)間45 min,CaCl2添加量140 mg/g DS,PAM添加量10-6g/g DS.選取最佳工況進(jìn)行驗(yàn)證實(shí)驗(yàn),分別對(duì)3批污泥進(jìn)行水熱預(yù)處理,得到泥餅水的質(zhì)量分?jǐn)?shù)平均值為70.68%，低于正交試驗(yàn)組所測(cè)得的最低水的質(zhì)量分?jǐn)?shù),故選定的最佳工況可行.

表2 熱水解正交實(shí)驗(yàn)方差分析結(jié)果

Tab.2 Variance analysis results of thermal hydrolysisorthogonal experiments

因素離差平方和自由度F比F臨界值顯著性反應(yīng)溫度160.206316.2939.28顯著性反應(yīng)時(shí)間26.53432.6999.28-CaCl251.90235.2789.28-PAM6.40630.6519.28-誤差245.063---

圖2 污泥水熱處理正交實(shí)驗(yàn)各因素對(duì)泥餅水的質(zhì)量分?jǐn)?shù)的影響Fig.2 Influence of factors in sludge treatment orthogonal experiments on water content of sludge cake

2.2 水熱處理各參數(shù)對(duì)污泥水分分布的影響

為了研究水熱處理各項(xiàng)參數(shù)對(duì)污泥水分分布的影響.以最佳工況下污泥的水分分布作為對(duì)照,分別改變水熱反應(yīng)溫度、反應(yīng)時(shí)間、CaCl2添加量與PAM添加量進(jìn)行實(shí)驗(yàn),并測(cè)量泥餅水分分布.

圖3 不同水熱參數(shù)下的污泥橫向弛豫時(shí)間對(duì)比Fig.3 Comparison of spin-spin relaxation times with different thermal hydrolysis conditions

如圖3為不同水熱參數(shù)下污泥水分橫向弛豫時(shí)間對(duì)比圖.從圖中可以看到,污泥原樣有3個(gè)獨(dú)立的峰,峰值時(shí)間分別為1.32、11.50、123.29 ms.隨著橫向弛豫時(shí)間的增加,這3個(gè)峰依次被定義為結(jié)合水、機(jī)械結(jié)合水與自由水的信號(hào)峰[18].水熱處理后污泥樣品峰值時(shí)間與原樣相比,均發(fā)生了左移.同時(shí),污泥中機(jī)械結(jié)合水的峰面積顯著降低,因?yàn)樗疅崽幚砗蟮奈勰嘟?jīng)過離心脫水將部分結(jié)合水脫除后,泥餅的絮體結(jié)合更密實(shí),提高了被束縛水分的結(jié)合能力.

通過計(jì)算圖3中不同水分的峰面積,可以得到不同水熱工況下污泥中的結(jié)合水、機(jī)械結(jié)合水和自由水的含量.如圖4所示為展示水熱工況下污泥中的水分分布(moisture distribution, MD).如表3所示為采用污泥干基水的質(zhì)量分?jǐn)?shù)計(jì)算不同水熱參數(shù)下泥餅水分分布.采用下式計(jì)算污泥的干基水的質(zhì)量分?jǐn)?shù)：

w=ws×α/(1-ws).

(3)

式中：w為干基水的質(zhì)量分?jǐn)?shù),ws為污泥水的質(zhì)量分?jǐn)?shù),α為不同水分分布相對(duì)含量.

圖4 不同水熱參數(shù)下的污泥水分分布比較Fig.4 Comparison of moisture distributions with different thermal hydrolysis conditions

污泥原樣的結(jié)合水干基水的質(zhì)量分?jǐn)?shù)為0.341 8 g/g DS,機(jī)械結(jié)合水干基水的質(zhì)量分?jǐn)?shù)為7.427 g/g DS.水熱處理后的樣品與污泥原樣相比,結(jié)合水與機(jī)械結(jié)合水含量均大幅降低.其中,最佳工況下泥餅的結(jié)合水干基水的質(zhì)量分?jǐn)?shù)為0.121 1 g/g DS,機(jī)械結(jié)合水干基水的質(zhì)量分?jǐn)?shù)為2.21 2 g/g DS,與原樣相比,分別下降了64.58%和70.22%.泥餅中仍有自由水存在是因?yàn)樵陔x心脫水傾倒懸浮液的過程中,部分自由水由于表面張力的存在無法完全去除,殘存在泥餅表面,并進(jìn)入NMR設(shè)備測(cè)試.

對(duì)比不同水熱工況對(duì)泥餅水分分布的影響可知,當(dāng)反應(yīng)溫度從140 ℃上升至230 ℃時(shí),泥餅水的質(zhì)量分?jǐn)?shù)從79.45 %下降至70.68 %,泥餅中結(jié)合水與機(jī)械結(jié)合水分別下降36.66 %與39.51 %,說明反應(yīng)溫度的改變對(duì)結(jié)合水與機(jī)械結(jié)合水均有顯著影響；當(dāng)反應(yīng)時(shí)間從15 min增加至45 min時(shí),泥餅水的質(zhì)量分?jǐn)?shù)從74.28 %下降至70.68 %,結(jié)合水與機(jī)械結(jié)合水分別下降43.72%與14.45%,說明隨著反應(yīng)時(shí)間的延長(zhǎng),污泥中的結(jié)合水干基水的質(zhì)量分?jǐn)?shù)下降對(duì)污泥的水分分布變化作用更大,可能由于反應(yīng)時(shí)間的延長(zhǎng),微生物細(xì)胞破碎和聚合物發(fā)生水解程度增加引起；當(dāng)CaCl2添加量從20 mg/g DS增加至140 mg/gDS時(shí),結(jié)合水與機(jī)械結(jié)合水分別下降15.50 %與11.67 %,可能是因?yàn)镃a2+離子改變了絮體中蛋白質(zhì)和多糖的組成以及內(nèi)部結(jié)合方式[19],從而改變了污泥中結(jié)合水含量,同時(shí),又因?yàn)镃a2+的正電性中和負(fù)電性的污泥絮體,強(qiáng)化了絮體間的內(nèi)部結(jié)合,促進(jìn)污泥絮體的絮凝,降低了機(jī)械結(jié)合水含量；PAM的添加對(duì)于結(jié)合水和機(jī)械結(jié)合水的含量影響較小.

表3 水熱參數(shù)變化對(duì)泥餅水分分布的影響

Tab.3 Influence on moisture distributions with change of thermal hydrolysis conditions

θ/℃T/minD(CaCl2)/(mg·g-1DS)D(PAM)/(10-6g·g-1DS)ws/wt.%D/(g·g-1DS)結(jié)合水機(jī)械結(jié)合水自由水14045140179.450.19113.6570.0177523015140174.280.21512.5860.087102304520173.190.14332.5040.08233230451401070.980.12202.2180.0709723045140170.680.12112.2120.07748----88.670.34187.4270.05630

3 結(jié) 論

(1)采用低場(chǎng)核磁共振技術(shù)測(cè)定污泥水分分布,得到污泥中3種形態(tài)水分的含量.與污泥原樣相比,水熱處理后樣品的結(jié)合水與機(jī)械結(jié)合水干基水的質(zhì)量分?jǐn)?shù)均大幅降低.當(dāng)反應(yīng)溫度從140 ℃上升至230 ℃時(shí),結(jié)合水與機(jī)械結(jié)合水干基水的質(zhì)量分?jǐn)?shù)分別下降36.66%與39.51%;當(dāng)反應(yīng)時(shí)間從15 min增加至45 min,結(jié)合水與機(jī)械結(jié)合水干基水的質(zhì)量分?jǐn)?shù)分別下降43.72%與14.45%；當(dāng)CaCl2添加量從20 mg/g DS時(shí)增加至140 mg/g DS時(shí),結(jié)合水與機(jī)械結(jié)合水干基水的質(zhì)量分?jǐn)?shù)分別下降15.50%與11.67%；PAM的添加對(duì)于結(jié)合水和機(jī)械結(jié)合水的含量影響較小.

(2)確定杭州污泥水熱處理最佳工況：反應(yīng)溫度230 ℃,水熱處理45 min,同時(shí)添加140 mg/g DS CaCl2,并在水熱處理后添加10-6g/g的PAM試劑,此時(shí)的污泥經(jīng)2 500 r/min離心脫水10 min后,水的質(zhì)量分?jǐn)?shù)從88.67 %大幅降低至70.68 %.與污泥原樣相比,最佳工況的污泥懸浮液中的NH3-N與SCOD值大幅上升,說明污泥絮體中微生物細(xì)胞發(fā)生了破碎,不溶性的聚合物發(fā)生了水解.

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Effect of thermal hydrolysis on moisture distribution of sewage sludge

MAO Hua-zhen, WANG Fei, MAO Fei-yan, CHI Yong,LU Sheng-yong, CEN Ke-fa

(StateKeyLaboratoryofCleanEnergyUtilization,InstituteforThermalPowerEngineering,ZhejiangUniversity,Hangzhou310027,China)

The effect of thermal hydrolysis on moisture distribution of sewage sludge was investigated by using low-field NMR(LF-NMR). The optimal operating conditions were obtained by setting reaction temperature, reaction time, dosage of CaCl2and PAM as four impact factors. The water in sludge content of sludge cake, soluted chemical oxygen demand and NH3-N were employed to evaluate the dewaterability of sewage sludge after thermal hydrolysis. Various working conditions were tested to investigate the influence of different parameters on the moisture distribution of sludge. Results show that both mechanical bound water and bound water in sludge decrease significantly with the increase of working temperature. The increase of reaction time helps to decrease the bound water content. The changing dosage of CaCl2has major influence of mechanical bound water content; the addition of PAM causes small effect on moisture distribution. Results point out that the optimal operating conditions were 230 ℃,45 min with 140 mg/g dry sludge (DS) CaCl2and 10-6g/g DS PAM. After centrifugation, the water content of sludge cake dramatically decreases from 88.67 % to 70.68 %. Meanwhile, the SCOD and NH3-N in supernatant increase remarkably, indicating that the insoluble organic components from sludge flocs are hydrolyzed and the moisture distribution is changed.

sludge; thermal hydrolysis; low-field NMR(LF-NMR); moisture distribution; pre-treatment; dewater ablility

2015-12-18.

國(guó)家“973”重點(diǎn)基礎(chǔ)研究發(fā)展規(guī)劃資助項(xiàng)目(2011CB201506)；國(guó)家“863”高技術(shù)研究發(fā)展計(jì)劃資助項(xiàng)目(SS2012AA063305).

毛華臻(1989—),男,博士生,從事廢棄物資源化利用研究. ORCID: 0000-0002-0397-878X. E-mail: mhzhen@zju.edu.cn 通信聯(lián)系人：池涌，男，教授，博導(dǎo).ORCID: 0000-0001-6360-6198.E-mail: chiyong@zju.edu.cn

10.3785/j.issn.1008-973X.2016.12.006

X 705

A

1008-973X(2016)12-2283-06