添加劑對(duì)污泥堆肥過(guò)程中氣體排放和酶活性的影響

葛啟隆,王國(guó)英,侯 瑞,張 靜

添加劑對(duì)污泥堆肥過(guò)程中氣體排放和酶活性的影響

葛啟隆1*,王國(guó)英2,侯 瑞3,張 靜1

(1.太原學(xué)院建筑與環(huán)境工程系,山西 太原 030032；2.太原理工大學(xué)環(huán)境科學(xué)與工程學(xué)院,山西 太原 030024；3.中國(guó)科學(xué)院南海海洋研究所,廣東 廣州 510301)

針對(duì)市政污泥與秸稈混合在傳統(tǒng)堆肥過(guò)程中溫室氣體排放量與氮損失量較高的問(wèn)題,采用玉米秸稈生物炭(CSB)與煤矸石基沸石(ZL)聯(lián)合堆肥,為減少堆肥過(guò)程中CH4、NH3、N2O氣體排放.將10%的CSB與0%、10%、20%、30%的ZL混合(百分比為添加劑與污泥秸稈混合物質(zhì)量之比),同時(shí),無(wú)添加劑作為對(duì)照組,結(jié)果表明,與對(duì)照組相比,CSB與ZL聯(lián)合添加(記為10%CSB+ZL)顯著提高了堆肥過(guò)程中溫度和pH值,增加了堆肥有機(jī)質(zhì)降解,且降解速率高于對(duì)照組和10%CSB處理.兩種添加劑聯(lián)合添加降低了堆肥過(guò)程中氮損失,10%CSB+10%ZL、10%CSB+20%ZL、10%CSB+30%ZL處理中CH4、NH3、N2O累積排放量比對(duì)照組分別降低87.81%～90.87%、41.61%～57.45%、85.01%～94.92%,CO2累積排放量比對(duì)照組提高55.45%～86.55%;同時(shí),在堆肥過(guò)程中脫氫酶、蛋白酶、木聚糖酶、磷酸酶活性增強(qiáng).生物炭作為膨松劑,提高堆肥孔隙率促進(jìn)微生物生長(zhǎng)和相關(guān)酶活性提高,煤矸石基沸石通過(guò)吸附減少氣體排放,10%CSB+20%ZL處理通過(guò)減少堆肥過(guò)程中CH4、NH3、N2O排放速率實(shí)現(xiàn)降低氮損失的效果最佳,

脫水污泥；玉米秸稈；堆肥；生物炭；煤矸石基沸石；氮保留

污泥是廢水生物處理過(guò)程中產(chǎn)生的體積最大的副產(chǎn)物,中國(guó)年產(chǎn)生7×107～1×108t污泥(含水量約80%)[1],這些污泥若處理不當(dāng),則會(huì)造成嚴(yán)重的環(huán)境問(wèn)題.由于污泥富含蛋白質(zhì)、碳水化合物、氮磷等養(yǎng)分,許多學(xué)者研究用其進(jìn)行好氧堆肥[2-3],不但能夠殺滅污泥中的病原菌,而且將大量有機(jī)物與營(yíng)養(yǎng)元素轉(zhuǎn)化為肥料或易生物降解的碳源,施用適量腐熟度較高的污泥堆肥產(chǎn)品可大幅度提高土壤肥力[3-4].

通常污泥富含氮和高水分,其碳氮比較低,需添加輔料聯(lián)合堆肥,如秸稈、稻殼、木屑等有機(jī)膨脹廢物,這些輔料富含碳和低水分,與污泥混合堆肥,通過(guò)調(diào)整混合堆肥原料的水分含量(約55%)和碳氮比(約25:1),產(chǎn)生較穩(wěn)定的堆肥產(chǎn)品[5],其中污泥與玉米秸稈混合,是種較好的混合堆肥原料[6].

傳統(tǒng)堆肥過(guò)程中產(chǎn)生大量的CO2、N2O、CH4等溫室氣體,造成二次環(huán)境污染[7].其中N2O和CH4的100a溫室效應(yīng)分別是CO2的298倍、25倍[4].傳統(tǒng)堆肥還會(huì)有大量NH3揮發(fā),引起氮損失,使得堆肥產(chǎn)物農(nóng)用價(jià)值降低.因此,需深入研究來(lái)源廣泛且經(jīng)濟(jì)的添加劑,提高污泥堆肥產(chǎn)物品質(zhì),降低堆肥污染氣體排放.其中,生物炭是在無(wú)氧或缺氧條件下通過(guò)有機(jī)生物質(zhì)熱解產(chǎn)生的含碳固體產(chǎn)物.因具有豐富的微孔結(jié)構(gòu),生物炭廣泛用于市政污泥與農(nóng)業(yè)廢棄物堆肥[8],研究表明,添加生物炭有利于提高堆肥產(chǎn)物腐熟度,提高堆肥效率,該效率可用氮養(yǎng)分損失、種子發(fā)芽率、硝化指數(shù)(NH+ 4-N/NO- 3-N)等指標(biāo)來(lái)評(píng)價(jià)[5,9].生物炭也有助于增強(qiáng)堆肥微生物活性.通常微生物代謝過(guò)程中水解酶是控制特定污泥堆肥底物礦化速度的主要因素,這些水解酶隨堆肥時(shí)間延長(zhǎng),與底物相互作用產(chǎn)生酶活性差異[10-11].此外,添加生物炭能夠延長(zhǎng)堆肥高溫階段持續(xù)時(shí)間,加速有機(jī)物降解和腐殖化,同時(shí),減少臭氣和溫室氣體排放[12].

沸石是種多孔硅酸鹽材料,具有較強(qiáng)陽(yáng)離子交換和吸附能力,對(duì)堆肥進(jìn)程的有益影響也得到證實(shí).例如,沸石對(duì)堆肥體系中銨有較高的吸附性能,減少堆肥過(guò)程氨排放[13-14].通常天然沸石雜質(zhì)含量高,應(yīng)用于堆肥比較困難[15].近年來(lái),人工沸石應(yīng)用于堆肥和土壤修復(fù)得到關(guān)注.已報(bào)道的人工沸石一般是用純化學(xué)試劑合成,成本高且浪費(fèi)資源.煤矸石(煤礦開(kāi)采與洗選加工過(guò)程中產(chǎn)生的固體廢物)因其富含Al2O3和Si2O3,成為合成沸石的理想原料[16];同時(shí),這也實(shí)現(xiàn)了廢物利用.煤矸石基沸石由于對(duì)NH+ 4和N2O具有較高的吸附性能,降低堆肥氮養(yǎng)分損失,調(diào)節(jié)堆肥碳氮比.此外,煤矸石基沸石能夠提高堆肥基質(zhì)孔隙度,為微生物生長(zhǎng)提供棲息地,微生物活性提高,相關(guān)酶活性增強(qiáng),促進(jìn)堆肥有機(jī)質(zhì)分解[17].

然而,由于尺寸較大的吸附質(zhì)離子或分子在煤矸石基沸石孔道中擴(kuò)散效果較差[18],使得煤矸石基沸石體積與表面積利用率下降.沸石性能受限,與生物炭聯(lián)合添加,生物炭的大孔和介孔能促進(jìn)吸附質(zhì)進(jìn)入沸石微孔的活性位點(diǎn).降低吸附質(zhì)在孔道中的擴(kuò)散阻力[19].同時(shí),雖然生物炭孔隙與表面官能團(tuán)豐富,但其穩(wěn)定性較差,而煤矸石基沸石孔徑結(jié)構(gòu)豐富程度雖然不如生物炭,但穩(wěn)定性好,兩種添加劑聯(lián)合添加很可能實(shí)現(xiàn)優(yōu)勢(shì)互補(bǔ).

鑒于此,為進(jìn)一步考察生物炭與煤矸石基沸石聯(lián)合添加對(duì)污泥秸稈混合堆肥的促進(jìn)作用,研究?jī)煞N添加劑聯(lián)合對(duì)堆肥溫室氣體排放、氮損失和堆肥產(chǎn)物品質(zhì)的影響.本研究擬將污泥與玉米秸稈混合后堆肥,將生物炭單獨(dú)添加及與煤矸石基沸石聯(lián)合添加,通過(guò)測(cè)定堆肥環(huán)境因子,氣體排放量,以及相關(guān)酶活性,建立酶活性與環(huán)境因子、氣體排放量的相關(guān)性,考察生物炭與不同添加量沸石混合對(duì)溫室氣體減排、堆肥產(chǎn)物品質(zhì)的影響,并與生物炭單獨(dú)處理和對(duì)照組(未添加生物炭與沸石)進(jìn)行比較,為利用固體廢棄物實(shí)現(xiàn)污泥堆肥工藝參數(shù)優(yōu)化提供科學(xué)依據(jù).

1 材料與方法

1.1 原料收集、處理及基本特性

污泥采集自山西省太原市郊區(qū)某污水處理廠(37°40'36''N,112°37'32''E)脫水污泥.玉米秸稈收集自太原市郊區(qū)某農(nóng)田(37°54'38''N,112°39'26''E),污泥和玉米秸稈的基本特性如表1所示.將其切碎(約2～3cm)作為膨化劑,與污泥按質(zhì)量比為1:1混合,使混合后含水率約為55%,C/N約為25:1[20].參照文獻(xiàn)[19]制備生物炭,以玉米秸稈為原料,將其加入管式爐中,充N(xiāo)2并密封,在常壓500℃條件下,熱解2h,制得的生物炭(CSB)中H、O、S含量分別為4.17%± 0.07%、14.79%±0.13%、0.16%±0.03%,其他基本特性見(jiàn)表1.將制備的生物炭研磨后篩分至2～3mm,作為添加劑.

煤矸石采集自太原市郊區(qū)某煤礦(38°10'31''N, 111°46'48''E)洗選矸石,參照文獻(xiàn)[21]制備沸石,將煤矸石樣品粉碎后再將其磨碎,過(guò)篩(150目),得矸石粉末,再將矸石粉末與固體NaOH按質(zhì)量比1:1.25混合,研磨,得均勻混合物,將其裝入坩堝后放入馬弗爐中,850℃焙燒2h,活化矸石粉末并除去其中未燃燒的碳,將熔融樣品冷卻至室溫,研磨成粉末,加入去離子水,攪拌30min,在烘箱中90℃,晶化12h,過(guò)濾,洗滌3次,放入烘箱中,105℃干燥6h.制備的沸石(ZL)含Al2O328.57%±0.52%, SiO248.73%±0.11%, Fe2O31.57%±0.02%, CaO 0.41%±0.01%, TiO20.73%± 0.01%, K2O 0.77%±0.01%, Na2O 18.97%±0.17%,其他基本特性如表1所示.

表1 實(shí)驗(yàn)所用堆肥材料理化性質(zhì)(以干重計(jì)算)

注:“ND”表示未檢測(cè)出.

1.2 實(shí)驗(yàn)裝置

圖1 堆肥裝置示意

堆肥實(shí)驗(yàn)在70L的反應(yīng)容器內(nèi)進(jìn)行,該反應(yīng)器內(nèi)填充25kg污泥與玉米秸稈(干重比為1:1),堆肥材料碳氮比約為25:1,參照文獻(xiàn)[13,22],實(shí)驗(yàn)組設(shè)10%CSB,10%CSB+10%ZL,10%CSB+20%ZL,10% CSB+30% ZL 4種不同處理,百分比為添加劑與污泥秸稈混合物質(zhì)量之比,對(duì)照組為無(wú)添加劑處理;同時(shí),將500g塑料小球(直徑1cm3,密度0.7g/cm3)與初始原料混合,調(diào)整堆肥原料密度約0.5kg/L,該塑料小球?yàn)榉尤?shù)脂材料,不可生物降解.實(shí)驗(yàn)裝置如圖1所示,圓柱形反應(yīng)器高為55cm,底部圓直徑40cm,空氣泵用于從裝置底部給堆肥原料供氣,供氣流量為0.03m3/(h·kg).在第0,1,3,5,7,10,15,20,27,34,41,48, 55d將堆肥材料人工翻堆,添加去離子水,調(diào)節(jié)含水率55%±1%.為獲得代表性樣品,采用多點(diǎn)混合法[23],在裝置約25cm深度處隨機(jī)采集5個(gè)堆肥樣品(每個(gè)樣品60g)混合均勻后分成3份,測(cè)定pH值、有機(jī)質(zhì)(TOM)含量及相關(guān)酶活性.

1.3 測(cè)試與分析方法

采用對(duì)硝基苯酚磷酸水解法測(cè)定磷酸酶活性[27];參照文獻(xiàn)[28]和[29]報(bào)道的標(biāo)準(zhǔn)方法分別測(cè)定脫氫酶活性和木聚糖酶活性;通過(guò)測(cè)定堆肥浸提液與酪蛋白在37℃培養(yǎng)1h后酪氨酸與Folin- Ciocalteu試劑反應(yīng),測(cè)定蛋白酶活性[30].

1.4 數(shù)據(jù)處理

采用Origin 8.0軟件作圖;采用SPSS 24.0軟件對(duì)實(shí)驗(yàn)數(shù)據(jù)進(jìn)行單因素方差分析和主成分分析(PCA),在<0.05水平比較顯著性差異(LSD);采用Canono 5.0軟件進(jìn)行環(huán)境因子、氣體排放及相關(guān)酶活性之間冗余分析(RDA).

2 結(jié)果與討論

2.1 溫度、pH值及總有機(jī)質(zhì)變化

如圖2(a)所示,各處理在堆肥開(kāi)始時(shí),堆體溫度升高.1d后,10%CSB+ZL處理中堆體溫度均達(dá)到高溫水平(>50 ℃).10% CSB處理中堆體溫度在第3d達(dá)到高溫水平,而對(duì)照組在第10d達(dá)到高溫水平,在第15d對(duì)照組溫度達(dá)最高(55℃).可見(jiàn),實(shí)驗(yàn)組在堆肥開(kāi)始階段溫度快速升高,表明堆肥過(guò)程中有機(jī)質(zhì)分解較快,10%CSB, 10%CSB+10%ZL, 10%CSB+ 20%ZL, 10%CSB+30% ZL.處理中最高溫度分別為66℃,71℃,73℃,63℃.此后堆體溫度逐漸降低,直到堆肥結(jié)束.4種處理在第20d堆體溫度均降至45℃以下,表明該階段易獲得的有機(jī)質(zhì)組分含量下降.與對(duì)照組和10%CSB處理相比,10%CSB+ZL處理中觀察到較長(zhǎng)時(shí)間的高溫階段,這是由于生物炭能夠填充堆體中的孔隙,添加沸石還能保持堆肥最佳水分含量和孔隙率,減少由于堆體較大空間而產(chǎn)生的熱損失[5];同時(shí),聯(lián)合添加生物炭與沸石不僅能提高對(duì)氧氣的快速吸收,還可能改善堆體微生物種群的群落結(jié)構(gòu)與相對(duì)豐度[12],有利于有機(jī)質(zhì)快速降解,在堆肥高溫階段產(chǎn)生較多的熱量.

如圖2(b)所示,各處理在整個(gè)堆肥期間,pH值變化呈先上升再下降,最后趨于穩(wěn)定的趨勢(shì),這與堆體溫度先升高再降低最后趨于穩(wěn)定的變化趨勢(shì)基本一致.可能是因?yàn)樵诙逊书_(kāi)始階段,氨化細(xì)菌為堆肥體系中的優(yōu)勢(shì)菌屬,能將含氮有機(jī)物分解為銨態(tài)氮,pH升高,而后NH3揮發(fā),使得堆體pH值降低.在堆肥21～40d,由于大量有機(jī)酸積累導(dǎo)致pH降低[5].實(shí)驗(yàn)組處理中pH值高于對(duì)照組,均在堆肥第7d達(dá)到最大值,4種處理在堆肥第7d pH值分別為8.56 (10%CSB)、8.81(10%CSB+10%ZL)、8.91 (10%CSB+ 20%ZL)、9.02(10%CSB+30%ZL),堆肥結(jié)束時(shí)相應(yīng)處理pH值分別為7.81、7.95、8.17、8.29.

如圖2(c)所示,隨著堆肥時(shí)間的延長(zhǎng),各處理中TOM含量逐漸降低,10%CSB處理中有機(jī)質(zhì)降解速率比對(duì)照組快,表明添加生物炭提高了有機(jī)質(zhì)礦化程度和微生物酶活性.堆肥結(jié)束時(shí)10%CSB+ 10%ZL、10%CSB+20%ZL、10%CSB+30%ZL處理中TOM含量分別為62.70%、58.60%、68.43%,低于對(duì)照組(78.60%)和10%CSB處理(72.73%).表明添加煤矸石基沸石能進(jìn)一步促進(jìn)TOM降解.

2.2 CO2-C與CH4-C排放

CO2-C和CH4-C排放速率能反映堆肥效率高低和微生物呼吸速率快慢.如圖3所示,在堆肥初始階段,由于可降解有機(jī)質(zhì)快速降解,實(shí)驗(yàn)組CO2-C排放速率比對(duì)照組高(圖3(a)), 10%CSB+20%ZL處理中CO2-C排放速率在第5d達(dá)最大值(44.71g/d).這是兩種添加劑聯(lián)合添加促進(jìn)有機(jī)質(zhì)快速礦化,堆體溫度升高導(dǎo)致的.在高溫階段后期,各處理中CO2-C排放速率逐漸減少,表明堆體趨于穩(wěn)定.實(shí)驗(yàn)組在整個(gè)堆肥過(guò)程中CO2-C排放速率較高,添加兩種添加劑阻礙了堆體壓縮沉降,促進(jìn)了氧的傳質(zhì),提高了堆體孔隙率,供好氧微生物生長(zhǎng),使其活性增強(qiáng),促進(jìn)有機(jī)質(zhì)降解[31].10%CSB+ZL處理中堆體pH值較高(圖2(b))和有機(jī)質(zhì)降解較快(圖2(c))也說(shuō)明了這一點(diǎn).堆肥結(jié)束時(shí),10%CSB+10%ZL、10%CSB+20%ZL、10%CSB+30%ZL處理中CO2-C累積排放量比對(duì)照組分別提高55.45%、86.55%、74.67%.

對(duì)照組在整個(gè)堆肥過(guò)程中CH4-C排放量顯著高于實(shí)驗(yàn)組(圖3(b)),可能是因?yàn)閷?duì)照組無(wú)添加劑,堆體內(nèi)部形成了具有較高含水率的厭氧區(qū)域,產(chǎn)生CO2和乙酸等基質(zhì),產(chǎn)甲烷細(xì)菌利用這些基質(zhì)產(chǎn)生CH4.堆肥結(jié)束時(shí),10%CSB+10%ZL、10%CSB+ 20%ZL、10%CSB+30%ZL處理中CH4-C累積排放量比對(duì)照組分別降低87.81%、90.87%、89.29%.可見(jiàn),CSB與ZL聯(lián)合添加能顯著降低堆肥過(guò)程中CH4排放量.此外,生物炭與煤矸石基沸石對(duì)堆體也有較強(qiáng)的膨化效應(yīng),促進(jìn)堆體微生物氧化進(jìn)程,降低CH4產(chǎn)率[32].

2.3 NH3-N、N2O-N排放及NH+ 4-N、NO- 3-N含量

由圖4(a)可見(jiàn),實(shí)驗(yàn)組在高溫階段(3～20d), NH3排放速率較高,這是因?yàn)樵诖穗A段堆體溫度較高,同時(shí),CO2排放量提高,pH較高等因素也有助于NH3揮發(fā).研究表明,生物炭可以增強(qiáng)氣態(tài)NH3和水溶性氨吸附,提高微生物的生長(zhǎng)和堆肥效率[31].對(duì)照組由于較低溫度(圖2(a))和pH值(圖2(b))等不利條件阻礙了NH+ 4-N向NH3轉(zhuǎn)化.因此,對(duì)照組在堆肥升溫階段(0～7d)幾乎沒(méi)有觀察到NH3排放,7d后,對(duì)照處理觀察到大量NH3排放.由圖4(a)還可知,10%CSB+ZL處理中NH3排放速率低于10%CSB處理,這是因?yàn)槊喉肥惺簿哂形誑H3的能力,可見(jiàn),10%CSB+ ZL處理中NH3排放量較低.堆肥結(jié)束時(shí),10%CSB、10%CSB+10%ZL、10%CSB+20%ZL、10%CSB+ 30%ZL處理中以NH3-N累積排放量比對(duì)照組分別減少32.63%、41.61%、57.45%、53.03%..

堆肥過(guò)程中N2O產(chǎn)生不但會(huì)降低堆肥產(chǎn)物品質(zhì),而且會(huì)污染環(huán)境,N2O排放通常是硝化副產(chǎn)物或在反硝化過(guò)程中產(chǎn)生,若反硝化過(guò)程中產(chǎn)生N2O,表明體系有缺氧區(qū)或厭氧區(qū)存在或NO- 3/NO- 2積累.若硝化過(guò)程中產(chǎn)生N2O,表明有氧區(qū)域存在和微生物可利用的易降解有機(jī)質(zhì)含量較低[33].本研究N2O排放速率如圖4(b)所示,對(duì)照組堆肥初期N2O排放速率較高,而實(shí)驗(yàn)組N2O排放速率較低,這可能是由于實(shí)驗(yàn)組有機(jī)質(zhì)礦化較快,表明在堆肥初期N2O主要通過(guò)反硝化產(chǎn)生,此外,與對(duì)照組相比,實(shí)驗(yàn)組堆體壓縮沉降較小,這保持了堆肥基質(zhì)初期孔隙度,阻礙了N2O排放,堆肥結(jié)束時(shí),10%CSB、10%CSB+10%ZL、10%CSB+20%ZL、10%CSB+30%ZL處理中N2O-N累積排放量比對(duì)照組降低39.68%、85.01%、94.92%、87.66%.可見(jiàn),10%CSB+20%ZL處理中氮損失量最低.表明生物炭和煤矸石基沸石聯(lián)合添加是一種減少堆肥氮元素的有效方法.

NH+ 4-N含量是堆肥生物氧化階段有機(jī)質(zhì)快速礦化和氨化的重要指標(biāo)之一.如圖4(c)所示, 10%CSB+ZL處理NH+ 4-N在堆肥0～7d迅速增加,第7d NH+ 4-N含量達(dá)到最大值,分別為4.96g/kg (10%CSB+10%ZL)、4.98g/kg (10%CSB+20%ZL)、4.76g/kg (10%CSB+30%ZL).而對(duì)照組處理NH+ 4-N含量在第15d達(dá)到最大值(3.71g/kg),10%CSB處理NH+ 4-N含量在第10d達(dá)到最大值(4.36g/kg),這是由于微生物氨化作用,以及溫度和pH升高導(dǎo)致的.在高溫階段后期,NH+ 4-N含量逐漸減少,直到堆肥結(jié)束趨于穩(wěn)定,主要原因是NH+ 4-N轉(zhuǎn)化為NH3,并在高溫與較高pH條件下?lián)]發(fā)導(dǎo)致NH+ 4-N減少. 10%CSB+ZL處理中NH+ 4-N最高濃度大于10%CSB處理,原因是沸石會(huì)解吸出部分NH+ 4-N.對(duì)照組在堆肥結(jié)束時(shí)(第55d),NH+ 4-N含量高于允許限值(2383g/kg)[34],這主要是由于有機(jī)質(zhì)礦化緩慢導(dǎo)致的(圖2(c)).可見(jiàn),生物炭與煤矸石基沸石聯(lián)合添加能夠降低堆肥過(guò)程中NH+ 4-N揮發(fā),其主要原因有:(1)生物炭與煤矸石基沸石的多孔結(jié)構(gòu),較高比表面積,隨著有機(jī)物的快速礦化,兩種添加劑對(duì)NH+ 4-N吸附能力較強(qiáng),使得堆肥過(guò)程中可利用的NH+ 4-N減少;(2)生物炭與煤矸石基沸石為硝化細(xì)菌提供了碳源與生長(zhǎng)棲息地,將NH+ 4-N轉(zhuǎn)化為硝酸鹽氮提供了良好的環(huán)境條件,兩種添加劑聯(lián)合處理后的堆肥產(chǎn)物氮素含量較高[13].

圖4 堆肥過(guò)程中NH3-N排放速率(a),N2O-N排放速率(b),NH+ 4-N含量(c)及NO- 3-N含量變化(d)

表2 污泥堆肥過(guò)程中氣體累積排放減少量(與對(duì)照組相比)

注:”—”表示沒(méi)有數(shù)據(jù).

如圖4(d)所示,與對(duì)照組相比,實(shí)驗(yàn)組在堆肥0～3d硝酸鹽氮含量開(kāi)始緩慢增加,而后在3～21d逐漸減少,而對(duì)照組在0～28d硝酸鹽氮含量逐漸減少,這是因?yàn)樯锾烤哂休^高的硝酸鹽吸附能力,與對(duì)照組相比,實(shí)驗(yàn)組在堆肥結(jié)束時(shí)NH+ 4-N含量較低(圖4(c)),硝酸鹽氮含量較高(圖4(d)),可見(jiàn)10%CSB與10%CSB+ZL處理有利于硝化細(xì)菌增長(zhǎng).

兩種添加劑聯(lián)合處理與其他文獻(xiàn)報(bào)道的添加劑處理對(duì)污泥堆肥過(guò)程中氣體累積排放減少量的對(duì)比如表2所示,通過(guò)對(duì)比可以發(fā)現(xiàn),實(shí)驗(yàn)所用兩種添加劑聯(lián)合處理能有效減少CH4、NH3、N2O排放量.例如,陳是吏等[35]在污泥和玉米秸稈堆肥中添加0.1%雙氰胺和5%過(guò)磷酸鈣,降低了82.60%的CH4,30.59%的NH3,以及92.86%的N2O,該降低量均低于本研究10%CSB+20%ZL處理實(shí)驗(yàn)結(jié)果,值得注意的是,雖然本研究?jī)煞N添加劑添加量較高,但實(shí)現(xiàn)了污泥堆肥氮保留與固廢資源化利用的雙重功效.此外,有研究表明,較高的生物炭或沸石添加量能提高堆肥產(chǎn)物品質(zhì),并降低堆肥生態(tài)風(fēng)險(xiǎn)(如減少生物有效態(tài)重金屬含量)[10,13].而Awasthi等[5]在污泥和麥稈堆肥中添加18%麥稈生物炭,使得CH4、NH3、N2O顯著減少量分別為92.85%、58.03%、95.14%,略高于本研究.這可能是堆肥底物基質(zhì)不同,或是生物炭原料與添加量不同導(dǎo)致的.

2.4 相關(guān)微生物酶活性

脫氫酶活性通常能反映堆肥過(guò)程整體微生物動(dòng)態(tài),因?yàn)樵撁钢饕獏⑴c原料生物礦化呼吸過(guò)程,通過(guò)測(cè)定該酶活性能間接反映堆肥最終產(chǎn)物的成熟度[38].與對(duì)照組相比,實(shí)驗(yàn)組隨堆肥時(shí)間延長(zhǎng)脫氫酶活性升高,且在高溫階段觀察到脫氫酶活性最大值,然后脫氫酶活性逐漸下降,直到堆肥結(jié)束(圖5(a)),這說(shuō)明添加生物炭和煤矸石基沸石有助于有機(jī)質(zhì)降解(圖2(c))和CO2釋放(圖3(a)).與10%CSB處理中脫氫酶活性最大值(17.51mg/(g·h))相比, 10%CSB+ ZL處理的脫氫酶活性最大值高,分別為24.77mg/(g·h)(10%CSB+10%ZL), 26.41mg/ (g·h)(10%CSB+20%ZL), 25.80mg/(g·h)(10%CSB+ 30%ZL).該酶活性在第7d達(dá)到最大值后下降(圖5(a)).對(duì)照組在堆肥過(guò)程中脫氫酶活性較低,可能是對(duì)照組pH值較低(圖2(b))不利于微生物生長(zhǎng)和有機(jī)質(zhì)降解.

磷酸酶活性如圖5(b)所示,實(shí)驗(yàn)組磷酸酶活性在整個(gè)堆肥過(guò)程中逐漸增大,其中,10%CSB+ZL處理在堆肥結(jié)束時(shí)磷酸酶活性較高,分別為4.22mg/ (g·h)(10%CSB+10%ZL), 4.47mg/(g·h) (10%CSB+ 20%ZL), 4,65mg/(g·h) (10%CSB+30% ZL),均高于10%CSB處理(3.67mg/(g·h))和對(duì)照組(2.78mg/(g·h)),可見(jiàn),對(duì)照組在堆肥結(jié)束時(shí)磷酸酶活性較低.這是由于生物炭與煤矸石基沸石均為多孔材料結(jié)構(gòu),能夠吸附水分子保持污泥中的水分,使得堆肥污泥中微生物磷酸酶活性較容易被激發(fā)[34],磷酸酶能夠促進(jìn)聚磷酸鹽和蛋白質(zhì)等大分子水解并釋放磷酸根,提高污泥中有效磷含量,促進(jìn)堆肥污泥中營(yíng)養(yǎng)物質(zhì)吸附負(fù)載和再利用[23].

木聚糖酶能將堆肥體系中纖維素水解為木糖,對(duì)溫室氣體排放有重要作用.堆肥過(guò)程中木聚糖酶變化如圖5(c)所示,其隨堆肥時(shí)間延長(zhǎng)的變化趨勢(shì)與脫氫酶活性類(lèi)似,10%CSB、10%CSB+10%ZL、 10%CSB+20%ZL處理在堆肥第7d木聚糖酶活性達(dá)到最大值,分別為6.97mg/(g·h)、7.27mg/(g·h)、7.61mg/(g·h),10%CSB+30%ZL處理在堆肥第15d達(dá)到最大值,為 8.07mg/(g·h),而對(duì)照組在堆肥第27d木聚糖酶活性達(dá)到最大值(2.53mg/(g·h)),表明實(shí)驗(yàn)組在高溫階段木聚糖酶活性最高,CH4和N2O排放量較低(圖3(b)和圖4(b)),CO2排放量較高(圖3(a))的原因可能是生物炭為微生物生長(zhǎng)提供碳源,兩種添加劑均具有多孔結(jié)構(gòu),有益于微生物生長(zhǎng),使得木聚糖酶活性提高,聯(lián)合添加有助于有機(jī)質(zhì)快速礦化或纖維素分解[39].

蛋白酶變化如圖5(d)所示,實(shí)驗(yàn)組蛋白酶活性在高溫階段達(dá)到較高值,分別為6.81mg/(g·h)(10%CSB)、8,57mg/(g·h) (10%CSB+10%ZL)、8.11mg/(g·h)(10%CSB+20%ZL)、7.42mg/(g·h)(10%CSB+30%ZL),而后蛋白酶活性逐漸下降,在腐熟期基本趨于穩(wěn)定.研究表明,蛋白酶與氮循環(huán)和復(fù)雜含氮化合物氨化降解密切相關(guān)[40].實(shí)驗(yàn)組氨排放量均較低(圖4(a)),這是由于含氮有機(jī)質(zhì)的快速降解.對(duì)照組在堆肥0～30d觀察到相對(duì)較低的蛋白酶,可見(jiàn),添加生物炭對(duì)堆體蛋白質(zhì)降解有一定促進(jìn)作用.此外,脫氫酶與木聚糖酶活性在降溫和腐熟階段活性呈下降趨勢(shì)(圖5(a))和圖5(c)),可能是酶復(fù)合物的形成導(dǎo)致的[41].

冗余分析(RDA)得到不同處理中氣體排放、環(huán)境因子和酶活性的關(guān)系如圖6所示,實(shí)驗(yàn)組兩個(gè)軸對(duì)堆肥過(guò)程中酶活性的貢獻(xiàn)百分比分別為86.95% (10%CSB)、84.44% (10%CSB+10%ZL)、86.24% (10%CSB+20%ZL)、85.80% (10%CSB+ 30%ZL)高于對(duì)照組(77.96%),這是因?yàn)閷?duì)照組中有機(jī)質(zhì)降解緩慢,添加生物炭與煤矸石基沸石既能提高堆體有機(jī)質(zhì)含量,又可加速有機(jī)質(zhì)礦化(圖2(c)).這些百分比不但反應(yīng)堆肥有機(jī)質(zhì)的礦化速率,也表明溫室氣體排放、酶活性與堆肥最終產(chǎn)物穩(wěn)定性具有較強(qiáng)的相關(guān)性.采用主成分分析法(PCA)研究結(jié)果如圖6(f)所示.從圖中可以看出,PC1的貢獻(xiàn)率為82.46%,PC2的貢獻(xiàn)率為8.72%,兩個(gè)主成分能夠解釋樣本總體變異的91.18%.因此,堆體溫度、pH值、TOM、CO2、CH4、N2O、脫氫酶、蛋白酶活性等主要指標(biāo)可用兩個(gè)主成分來(lái)表示.以PC1為橫軸,PC2為縱軸,建立坐標(biāo)系,圖中的彩色點(diǎn)表示不同的處理.由圖6(f)還可知,10%CSB+ZL處理與對(duì)照組比較差異較大,說(shuō)明該兩種添加劑聯(lián)合添加可顯著影響堆體溫室氣體排放和相關(guān)酶活性,其中, 10%CSB+10%ZL、10%CSB+20%ZL、10%CSB+ 30%ZL處理沿第一主成分與對(duì)照組分離,10%CSB處理沿第二主成分與對(duì)照組和10%CSB+ZL處理分離,表明添加生物炭和煤矸石基沸石對(duì)堆體溫度、pH等環(huán)境因子有顯著的影響,且煤矸石基沸石添加量的高低對(duì)溫室氣體排放量和相關(guān)酶活性也有一定影響,這是由于煤矸石基沸石雖然幾乎不含碳,但其獨(dú)特的孔道結(jié)構(gòu)能提高微生物酶活性,促進(jìn)氧在堆體中的傳質(zhì),降低氮元素在堆肥過(guò)程中的損失,提高堆肥產(chǎn)物品質(zhì)[28].

2.5 堆肥C/N變化與產(chǎn)物品質(zhì)分析

通常C/N比可作為衡量堆肥產(chǎn)物腐熟度的重要指標(biāo)之一,如圖7所示,實(shí)驗(yàn)組處理中堆肥C/N比在整個(gè)堆肥過(guò)程中逐漸降低,原因是總有機(jī)碳和氮分別主要以(CO2、CH4)和(NH3、N2O)形式散失.對(duì)照組中堆肥碳氮比變化趨勢(shì)為先逐漸升高后逐漸降低,由于無(wú)添加劑,對(duì)照組在堆肥升溫期和高溫期,氮養(yǎng)分快速流失導(dǎo)致碳氮比增加,在堆肥腐熟期,難降解有機(jī)物含量增多,且溫度較低,致使微生物酶活性降低,氮養(yǎng)分散失較慢,碳氮比降低.通常污泥堆肥C/N比小于20則認(rèn)為是腐熟度較高的水平[25], 10%CSB處理在堆肥34d達(dá)到該水平,10%CSB+ 10%ZL處理在27d達(dá)到該水平,10%CSB+20%ZL與10%CSB+30%ZL處理在20d即可達(dá)到該水平表明添加較高劑量的沸石能夠縮短污泥堆肥腐熟時(shí)間,對(duì)照組在堆肥55d腐熟程度仍較低(C/N為24.76),表明其需要更長(zhǎng)的時(shí)間來(lái)腐熟.

其他堆肥腐熟度指標(biāo)(如pH、HA/FA、NH+ 4-N/NO- 3-N、種子發(fā)芽率指數(shù))也可用來(lái)評(píng)估不同處理對(duì)污泥堆肥腐熟度的影響.堆肥結(jié)束時(shí)這些指標(biāo)如表3所示,對(duì)照組和10%CSB處理中均有部分指標(biāo)超出參考值范圍,兩種添加劑聯(lián)合處理中各項(xiàng)堆肥指標(biāo)在允許范圍內(nèi),其中,10%CSB+20%ZL處理在堆肥結(jié)束時(shí)顯示出較高的腐熟度,如較高的HA/FA比率和較低的NH+ 4-N/NO- 3-N比率,而這兩項(xiàng)指標(biāo)在對(duì)照處理中分別保持較低和較高的水平.Awasthi等[5]研究表明,堆肥的HA/FA值超過(guò)1%是符合要求的,硝化指數(shù)(NH+ 4-N/NO- 3-N)通常在0.5以下為完全成熟堆肥,在0.5～3.0之間為成熟堆肥,3.0以上為未成熟堆肥[39],本研究在堆肥結(jié)束時(shí),對(duì)照組、10%CSB、10%CSB+10%ZL、10%CSB+20%ZL、10%CSB+ 30%ZL處理中硝化指數(shù)分別為:3.57、0.53、0.42、0.21、0.31,表明生物炭與煤矸石基沸石聯(lián)合處理污泥堆肥硝化指數(shù)均低于堆肥應(yīng)用標(biāo)準(zhǔn)限值;同時(shí), 10%CSB+10%ZL、10%CSB+20%ZL、10%CSB+ 30%ZL處理中種子發(fā)芽率指數(shù)比對(duì)照組提高 74.98%、109.76%、70.61%.其他堆肥腐熟度指標(biāo)也表明,兩種添加劑聯(lián)合處理污泥堆肥具有較低的電導(dǎo)率、較高pH值和氮養(yǎng)分含量(表3).

表3 不同處理中堆肥的腐熟特性

注:“—”表示無(wú)參考值.

3 結(jié)論

3.1 研究表明,10%CSB+ZL處理對(duì)污泥堆肥有積極的影響,與對(duì)照組相比,該處理中CH4、NH3、N2O累積排放量分別顯著降低87.81%～90.87%、41.61%～57.45%、85.01%～94.92%.

3.2 10%CSB+ZL處理能有效提高堆肥過(guò)程中脫氫酶、蛋白酶、木聚糖酶及磷酸酶的酶活性,且使得CO2累積排放量比對(duì)照組提高55.45%～86.55%.

3.3 10%CSB+20%ZL處理對(duì)提高堆肥過(guò)程中溫度,促進(jìn)TOM降解的效果最佳,該處理能在有效減少CH4、NH3、N2O氣體排放的同時(shí)提高堆肥終產(chǎn)物品質(zhì).

[1] 辛文才,陳 蒙,陳屹林,等.高濕高黏固體廢棄物干化減量設(shè)備研究進(jìn)展 [J]. 環(huán)境工程, 2021,39(3):178-182. Xin W C, Chen M, Chen Q L, et al. Research progress of drying and reduction equipment for high-humidity and high-viscosity solid waste [J]. Environmental Engineering, 2021,39(3):178-182.

[2] 成慶利,張龍龍,王大偉.污泥－麥秸稈混合物料好氧堆肥中磷酸緩沖液強(qiáng)化保氮效果及機(jī)理 [J]. 環(huán)境污染與防治, 2021,43(10): 1225-1237. Chen Q L, Zhang L L, Wang D W. Effects and mechanisms of strengthening nitrogen preservation by phosphate buffer during the aerobic composting of sewage sludge and straw mixture [J]. Environmental pollution and control, 2021,43(10):1225-1237.

[3] 莫錦韜,李 軍,路一鳴,等.間歇通風(fēng)對(duì)污泥好氧堆肥過(guò)程中腐殖質(zhì)電子轉(zhuǎn)移能力的影響 [J]. 中國(guó)環(huán)境科學(xué), 2023,43(5):2393-2403. Mo J T, Li J, Lu Y M, et al. Effects of intermittent aeration on the electron transfer capacity of humic substances in aerobic composting of sewage sludge [J]. China Environmental Science, 2023,43(5):2493- 2403.

[4] 譚知涵,孫曉杰,席北斗,等.電場(chǎng)對(duì)污泥堆肥富里酸結(jié)構(gòu)特征的影響 [J]. 中國(guó)環(huán)境科學(xué), 2023,43(1):244-254. Tan Z H, Sun X J, Xi B D, et al. Effect of electric field on structure of fulvic acid during sludge composting [J]. China Environmental Science, 2023,43(1):244-254.

[5] Awasthi M K, Wang M, Chen H, et al. Heterogeneity of biochar amendment to improvethe carbon and nitrogen sequestration through reduce the greenhouse gasesemissions during sewage sludge composting [J]. Bioresource Technology, 2017,224:428-438.

[6] Li S, Li D, Li J, et al. Evaluation of humic substances during co- composting of sewage sludge and corn stalk under different aeration rates [J]. Bioresource Technology, 2017,245:1299-1302.

[7] Wang Q, Awasthi M K, Ren X N, et al. Combining biochar, zeolite and wood vinegar for composting of pigmanure: The effect on greenhouse gas emission and nitrogenconservation [J]. Waste Management, 2018, 74:212-230.

[8] Silva E, Caixeta G, Borges T, et al. Combining biochar and sewage sludge for immobilization of heavy metals in mining soils [J]. Ecotoxicology and Environmental Safety, 2019,172:326-333.

[9] Villase?or J, Rodríguez L, Fernández F J, et al. Composting domestic sewagesludge with natural zeolites in a rotary drum reactor [J]. Bioresource Technology, 2011,102:1447-1454.

[10] Awasthi M K, Wang Q, Huang H, et al. Effect of biochar amendment on greenhousegas emission and bio-availability of heavy metals during sewage sludge co-composting [J]. Journal of Cleaner Production, 2016,135:829–835.

[11] Jiang T, Ma X, Tang Q, et al. Combined use of nitrification inhibitor and struvite crystallization to reduce the NH3and N2O emissions during composting [J]. Bioresource Technology, 2016,217:210-218.

[12] 黃 霞,何瑩瑩,張藝蝶,等.基于生物炭強(qiáng)化有機(jī)固廢好氧堆肥資源化的研究進(jìn)展 [J]. 化工進(jìn)展, 2022,41(8):4544-4554. Huang X, He Y Y, Zhang Y D, et al. Research progress on enhancing resource utilization of organic solid waste aerobic composting based on biochar [J]. Chemical Industry and Engineering Progress, 2022, 41(8):4544-4554.

[13] Awasthi M K, Wang Q, Huang H, et al. Influence of zeolite and lime as additives on greenhouse gas emissions and maturity evolution during sewage sludge composting [J]. Bioresource Technology, 2016, 216:172-181.

[14] 蔡琳琳,李素艷,康 躍,等.沸石、膨潤(rùn)土和過(guò)磷酸鈣對(duì)蚯蚓堆肥園林綠化廢棄物腐熟效果的影響 [J]. 應(yīng)用基礎(chǔ)與工程科學(xué)學(xué)報(bào), 2020,28(2):299-309. Cai L L, Li S Y, Kang Y, et al. Effects of zeolite, bentonite and calcium superphosphate on the vermicomposting of green wastes [J]. Journal of basic science and engineering, 2020,28(2):299-309.

[15] 夏 彬,王曉麗,張 艷.鄂爾多斯煤矸石合成A型沸石吸附劑試驗(yàn)研究[J]. 硅酸鹽通報(bào), 2018,37(4):1462-1466. Xia B, Wang X L, Zhang Y, et al. Synthesis of zeolite A adsorbents by coal gangue in Erdos [J]. Bulletin of the Chinese Ceramic Society, 2018,37(4):1462-1473.

[16] Bu N, Liu X, Song S, et al. Synthesis of NaY zeolite from coal gangue and its characterization for lead removal from aqueous solution [J]. Advanced Powder Technology, 2020,31:2699–2710.

[17] 葛啟隆,田 琦,豐開(kāi)慶,等.磷改性生物炭與沸石配施對(duì)土壤有效磷釋放的影響 [J]. 環(huán)境科學(xué)研究, 2022,35(1):219-229. Ge Q L, Tian Q, Feng K Q, et al. Effect of co-application of phosphorus-modified hydrochar and zeolite on release of soil available phosphorus [J]. Research of Environmental Sciences, 2022, 35(1):219-229.

[18] 鄧世茂,楚哲婷,梁佳欣,等.沸石材料在土壤修復(fù)工程中的應(yīng)用研究進(jìn)展 [J]. 科學(xué)通報(bào), 2021,66(9):1002-1013. Deng S M, Chu Z T, Liang J X, et al. Progress of using zeolite materials in soil remediation engineering [J]. Chinese Science Bulletin, 2021,66:1002-1013.

[19] Awasthi M K, Wang M, Pandey A, et al. Heterogeneity of zeolite combined with biochar properties as a function of sewage sludge composting and production of nutrient-rich compost [J]. Waste Management, 2017,68:760-773.

[20] Dias B O, Silva C A, Higashikawa F S, et al. Use of biochar as bulking agent for the composting of poultry manure: Effect on organic matter degradation and humification [J]. Bioresource Technology, 2010,101: 1239-1246.

[21] Ge Q L, Moeen M, Tian Q, et al. Highly effective removal of Pb2+in aqueous solution by Na-X zeolite derived from coal gangue [J]. Environental Science and Pollution Research, 2020,27:7398-7408.

[22] Jiang T, Ma X, Tang Q, et al. Combined use of nitrification inhibitor and struvite crystallization to reduce the NH3and N2O emissions during composting [J]. Bioresource Technology. 2016,217:210-218.

[23] 李 玉,方 文,祁光霞,等.污泥富磷堆肥前后重金屬賦存形態(tài)及釋放能力變化 [J]. 環(huán)境科學(xué), 2018,39(6):2786-2793.Li Y, Fang W, Qi G X, et al. Changes in heavy metal speciation and release behavior before and after sludge composting under a phosphate-rich atmosphere [J]. Environmental Science, 2018,39(6): 2786-2793.

[24] NY525-2021 有機(jī)肥料 [S].NY525-2021 Organic fertilizer [S].

[25] 沈玉君,李國(guó)學(xué),任麗梅,等.不同通風(fēng)速率對(duì)堆肥腐熟度和含氮?dú)怏w排放的影響 [J]. 農(nóng)業(yè)環(huán)境科學(xué)學(xué)報(bào), 2010,29(1):1814-1819. Shen Y J, Li G X, Ren L M, et al. The impact of composting with different aeration rates on maturity variation and emission of gas concluding N [J]. Journal of Agro-Environment Science, 2010,29(9): 1814-1819.

[26] 王 杰,閆鵬舉,楊春璐,等.污泥堆腐過(guò)程中腐殖酸組分及結(jié)構(gòu)變化特征 [J]. 生態(tài)環(huán)境學(xué)報(bào), 2017,26(1):154-158. Wang J, Yan P J, Yang C L. Variation characteristics of humic substances’ components and structure in sewage sludge during composting [J]. Ecology and Environmental Sciences, 2017,26(1): 154-158.

[27] Chu Q N, Lyu T, Xue L H, et al. Hydrothermal carbonization ofmicroalgae for phosphorus recycling from wastewater to crop- soilsystems as slow-release fertilizers [J]. Journal of Cleaner Production, 2021,283:124627.

[28] Barrena R, Vázquez F, Sanchez A. Dehydrogenase activity as a method formonitoring the composting process [J]. Bioresource Technology, 2008,99:905-908.

[29] Schinner F, Von-Mersi W. Xylanase, CM-cellulase and invertase activity in soil: An improved method [J]. Soil Biology &Biochemistry, 1990,22:511-515.

[30] Ladd J N, Butler J H A. Short-term assays of soil proteolytic enzymeactivities using proteins and dipeptide derivatives as substrates [J]. Soil Biology &Biochemistry, 1972,4:19-30.

[31] Zhu W J, Zhu F X, Wang W P, et al. Degradation characteristics of antibiotics during composting of four types of feces [J]. Environmental Science, 2020,41(2):1005-1012.

[32] Czekala W, Malinska K, Caceres R, et al. Co-composting of poultry manure mixtures amended with biochar–the effect of biochar on temperature and CO2emission [J]. Bioresource Technology. 2016,200: 921-927.

[33] 楊 燕,李國(guó)學(xué),羅一鳴,等.氫醌與含磷添加劑聯(lián)合使用對(duì)堆肥溫室氣體排放的影響 [J]. 中國(guó)環(huán)境科學(xué), 2022,42(2):936-944. Yang Y, Li G X, Luo Y M, et al. Effects of dicyandiamide, hydroquinone and phosphorus additives on greenhouse gas emissions during composting [J]. China Environmental Science, 2022,42(2):936- 944.

[34] Awasthi M K, Wang Q, Ren X, et al. Role of biochar amendment in mitigation of nitrogen loss and greenhouse gas emission during sewage sludge composting [J]. Bioresource Technology, 2016,219: 270-280.

[35] 陳是吏,袁 京,李國(guó)學(xué),等.過(guò)磷酸鈣和雙氰胺聯(lián)用減少污泥堆肥溫室氣體及NH3排放 [J]. 農(nóng)業(yè)工程學(xué)報(bào), 2017,33(6):199-206. Chen S L, Yuan J, Li G X, et al. Combination of superphosphate and dicyandiamide decreasing greenhouse gas and NH3emissions during sludge composting [J]. Transactions of the Chinese Society of Agricultural Engineering, 2017,33(6):199-206.

[36] Li Y B, Liu T T,Song J L, et al., Effects of chemical additives on emissions of ammonia and greenhouse gas during sewage sludge composting [J], ProcessSafety and Environmental Protection. 2020, 143:129-137.

[37] 陳桂華,曾環(huán)木,林芷君.脫水污泥堆肥過(guò)程中溫室氣體釋放與檢測(cè)及其減控措施 [J]. 科學(xué)技術(shù)與工程, 2020,20(6):2500-2507.Chen G H, Zeng H M, Liu Z J. Greenhouse gas emission and detection in dewatered sludge composting process and its reduction and control measures [J]. Science Technology and Engineering, 2020,20(6):2500- 2507.

[38] Liu D, Zhang R, Wu H, et al. Changes inbiochemical and microbiological parameters during the period of rapidcomposting of dairy manure with rice chaff [J]. Bioresource Technology, 2011,102: 9040-9049.

[39] Villar I, Alves D, Garrido J, et al. Evolution of microbial dynamics duringthe maturation phase of the composting of different types of waste [J]. Waste Management, 2016,54:83-92.

[40] Awasthi M K, Pandey A K, Bundela P S, et al. Co-composting of organicfraction of municipal solid waste mixed with different bulking waste:characterization of physicochemical parameters and microbial enzymaticdynamic [J]. Bioresource Technology, 2015,182:200-207.

[41] 齊 魯,張俊亞,鄭嘉熹,等.沸石粉和硝化抑制劑投加對(duì)污泥堆肥過(guò)程中氮素保存和溫室氣體排放的影響 [J]. 環(huán)境科學(xué)學(xué)報(bào), 2018, 38(6):2131–2139. Qi L, Zhang J Y, Zheng J J, et al. Effects of natural zeolite and nitrification inhibitors on the nitrogen loss and green house gas (GHG) emission during sludge composting [J]. Acta Scientiae Circumstantiae, 2018,38(6):2131-2139.

Effects of the additives on gas emission and enzyme activities during sludge composting.

GE Qi-long1*, WANG Guo-ying2, HOU Rui3, ZHANG Jing1

(1.Department of Architecture and Environmental Engineering, Taiyuan University, Taiyuan 030032, China；2.College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China；3.South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China)., 2023,43(11)：5873～5883

In response to the issue of elevated greenhouse gas emissions and nitrogen loss during the conventional co-composting of municipal sludge and straw blends, the combined addition of corn straw biochar (CSB) and coal gangue-based zeolite (ZL) was employed. To mitigate emissions of CH4, NH3and N2O during the composting process, 10% CSB was mixed with varying proportions of ZL (0%, 10%, 20% and 30%) based on the mass ratio of additives to the sludge and corn straw mixture. Meanwhile, an untreated control group was concurrently maintained. The findings revealed that the co-application of CSB and ZL (marked as 10%CSB+ZL) led to a significant augmentation in composting temperature and pH value in comparison to the control. This enhancement facilitated enhanced degradation of organic matter within the compost, with the degradation rates surpassing those observed in both the control group and 10%CSB treatment. The simultaneous application of these two addition agents yielded a reduction in the nitrogen loss during the composting process. Compared with the control, the cumulative emission of CH4, NH3and N2O in the 10%CSB+10%ZL, 10%CSB+20%ZL, 10%CSB+30%ZL treatments decreased by percentages ranging from 87.81% to 90.87%、41.61% to 57.45%、85.01% to 94.92%, respectively, The cumulative emission of CO2in these treatments exhibited a substantial increase, ranging from 55.45% to 86.55% relative to the control. Furthermore, enzymatic activities, including dehydrogenase, protease, xylanase and phosphatise, experienced augmentation during the composting process. Biochar functioned as a bulking agent, increasing compost porosity to stimulate microbial growth and bolster related enzymatic activities. Coal gangue-based zeolite contributed to gas emission reduction through an adsorption mechanism. The 10%CSB+20%ZL treatment emerged as the most effective strategy in decreasing nitrogen losses, primarily by curtailing the emission rates of CH4, NH3and N2O during the composting process.

dewatered sewage sludge；corn straw；compost；biochar；coal gangue based zeolite；nitrogen retention

X703.5

A

1000-6923(2023)11-5873-11

葛啟隆(1988-),男,山西運(yùn)城人,講師,博士,主要研究方向?yàn)樗屯寥牢廴局卫?發(fā)表論文10余篇.geqilongde@163.com.

葛啟隆,王國(guó)英,侯 瑞,等.添加劑對(duì)污泥堆肥過(guò)程中氣體排放和酶活性的影響 [J]. 中國(guó)環(huán)境科學(xué), 2023,43(11):5873-5883.

Ge Q L, Wang G Y, Hou R, et al. Effects of the additives on gas emission and enzyme activities during sludge composting [J]. China Environmental Science, 2023,43(11):5873-5883.

2023-03-13

山西省高等學(xué)?？萍紕?chuàng)新項(xiàng)目(2020L0721);山西省基礎(chǔ)研究計(jì)劃項(xiàng)目項(xiàng)目(202103021223009)

* 責(zé)任作者, 講師, geqilongde@163.com