含生物質(zhì)炭城市污泥堆肥中溶解性有機(jī)質(zhì)的光譜特征

1、中國(guó)環(huán)境科學(xué) 2014,34(2:459465 China Environmental Science 含生物質(zhì)炭城市污泥堆肥中溶解性有機(jī)質(zhì)的光譜特征閆金龍1,江韜1,2,*,趙秀蘭1,2,魏世強(qiáng)1,2,王定勇1,2,李璐璐1,郭念1,孫文彬1 (1.西南大學(xué)資源環(huán)境學(xué)院,重慶 400716;2.重慶市農(nóng)業(yè)資源與環(huán)境研究重點(diǎn)實(shí)驗(yàn)室,重慶 400716摘要:以外源添加生物質(zhì)炭的城市污泥堆肥過(guò)程中溶解性有機(jī)質(zhì)(DOM為研究對(duì)象,討論了其紫外-可見(jiàn)和熒光光譜特征變化.結(jié)果表明:與對(duì)照組相比,外源添加生物質(zhì)炭的處理其堆肥DOM的芳香性和腐殖化程度更高,有利于提高堆肥的腐熟度,且外源添加花生殼炭的處理較

2、添加小麥秸稈炭的處理更有利于堆肥腐熟度的提高.外源添加花生殼炭的處理在堆肥21d后,其堆肥腐熟度可能達(dá)到峰值,而外源添加小麥秸稈炭的處理其堆肥腐熟度則隨著堆肥時(shí)間的進(jìn)行而增加.對(duì)照組和處理組堆肥DOM的FI0.7,BIX0.8,表明其來(lái)源為自生源,可能與微生物對(duì)有機(jī)物的降解有關(guān).因此,通過(guò)對(duì)城市污泥堆肥過(guò)程中DOM的光譜特征分析,能較好地評(píng)估城市污泥堆肥腐熟度的情況.關(guān)鍵詞:生物質(zhì)炭;堆肥;溶解性有機(jī)質(zhì)(DOM;紫外光譜;熒光光譜中圖分類號(hào):X705 文獻(xiàn)標(biāo)識(shí)碼:A 文章編號(hào):1000-6923(201402-0459-07Spectral characteristics of dissolv

3、ed organic matter in co-composting process of municipal sludge with biochar. YAN Jin-long1, JIANG Tao1,2*, ZHAO Xiu-lan1,2, WEI Shi-qiang1,2, WANG Ding-yong1,2, LI Lu-lu1, GUO Nian1, SUN Wen-bin1 (1.College of Resources and Environment, Southwest University, Chongqing 400716, China;2.Chongqing Key L

4、aboratory of Agricultural Resources and Environment, Chongqing 400716, China. China Environmental Science, 2014,34(2:459465Abstract:Changes in the UV-visible and fluorescence characteristics of DO M from the co-composting process of municipal sludge with two types of biochars were discussed. The res

5、ults showed the aromaticity and humification of DOM from the co-composting with biochars significantly increased compared with control, which indicated in favor of improving the maturity of compost. The treatment with biochar from peanut shell showed the highest maturity, followed by wheat straw bio

6、char. After 21days, compost treated with biochar from peanut shell reached its maximum maturity, while that treated with biochar from wheat straw continued to increase over the whole time. Meanwhile, the DOM from the compost with or without treatment was found to be autochthonous, FI0.7, BIX0.8, mai

7、nly attributed to the microbial decomposition of compost. Thus, the spectral characteristics of DOM are capable of assessing the degree of maturity of compost during the co-composting process with biochars from different source.Key words:biochar;compost;dissolved organic matter (DOM;UV-visible spect

8、rum;fluorescence spectrum隨著我國(guó)城市經(jīng)濟(jì)的高速發(fā)展,城市污水處理帶來(lái)的城市污泥產(chǎn)量急劇增加1.城市污泥是潛在的有機(jī)肥原料,同時(shí)污泥中還含有病原微生物、重金屬等污染物,極易造成二次污染,因此,對(duì)污泥的處置一直是研究的熱點(diǎn)2-3.其中,堆肥是污泥處置及實(shí)現(xiàn)無(wú)害化、資源化利用的重要方法之一4-5.近年來(lái),為提高堆肥效率,常采用外源添加生物質(zhì)炭的方式改善堆體條件(例如C/N比,含水率,孔隙度,堆肥養(yǎng)分等,提升堆體有機(jī)質(zhì)穩(wěn)定性和腐殖化程度6-7.堆肥中有機(jī)質(zhì)轉(zhuǎn)化是評(píng)估堆肥腐熟程度和環(huán)境安全性的重要基礎(chǔ).堆肥過(guò)程中溶解性有機(jī)質(zhì)(DOM的變化被認(rèn)為是能靈敏反映堆肥腐熟狀況的重要指標(biāo)

9、,且較堆肥的固相組分更具代表性8-9.目前,針對(duì)DOM定性研究,應(yīng)用較多的是紫外-可見(jiàn)光譜和同步熒光技術(shù),因其靈敏度高和收稿日期:2013-05-10基金項(xiàng)目:中國(guó)博士后科學(xué)基金資助項(xiàng)目(2013M542238;中央高?；究蒲袠I(yè)務(wù)費(fèi)(XDJK2013C151;西南大學(xué)博士基金(SWU112098;重慶市科委科技攻關(guān)項(xiàng)目(CSTC-2008AC7013460 中國(guó)環(huán)境科學(xué) 34卷分析便捷,被廣泛應(yīng)用于自然有機(jī)質(zhì)(NOM研究中,尤其是水體DOM歸趨10.相比之下,針對(duì)堆肥DOM性質(zhì)的研究較少11-12.目前,已有報(bào)道表明添加外源生物質(zhì)炭有利于堆肥固炭,而高C/N比下堆肥腐熟度也相應(yīng)提高13-14

10、,而在該過(guò)程中對(duì)DOM的探討還相對(duì)不足,且以前研究的結(jié)論也并不一致15-16,尤其是對(duì)不同調(diào)理劑處理方式下堆肥DOM的性質(zhì)光譜表征缺少關(guān)注17-18.基于此,本研究采用紫外-可見(jiàn)光譜及三維熒光光譜對(duì)添加不同生物質(zhì)炭的城市污泥堆肥過(guò)程中DOM的光譜特征進(jìn)行表征,并通過(guò)特征參數(shù)的計(jì)算,進(jìn)一步了解不同處理堆肥在堆肥過(guò)程中的差異,為進(jìn)一步提高堆肥效率、正確評(píng)估堆肥腐熟程度和環(huán)境安全性提供一定的理論依據(jù).1 材料與方法1.1不同堆肥處理及樣品采集 圖1 堆肥試驗(yàn)示意Fig.1 The sketch map of compost表1不同處理堆肥的初始物料基本性質(zhì)Table 1 Basic characte

11、ristics of different compostingtreatments堆肥處理全碳(g/kg全氮(g/kg全磷(g/kg pH值CK 182.17 15.85 8.25 7.98 +麥 177.15 15.55 6.54 7.67 +花 210.16 13.92 6.68 7.981.2堆肥DOM提取采用去離子水提取堆肥DOM19.將所采集的堆肥樣品自然風(fēng)干后,磨細(xì),過(guò)2mm篩.按土:水=1:6(W/V,采用去離子水與堆肥固體混合后, 25下200r/min振蕩16h,然后400r/min下離心20min,上清液過(guò)0.45m濾膜后,濾液即為堆肥DOM樣品.DOM測(cè)定TOC和TON(

12、德國(guó),Yena Multi N/C 3000后,濃度以DOC(mg/L計(jì).所有樣品在進(jìn)行光譜測(cè)定前,均稀釋相同倍數(shù)(0.6mLDOM定容到100mL棕色容量瓶.1.3光譜測(cè)定紫外-可見(jiàn)光譜在Hitachi U-1800紫外-可見(jiàn)分光光度計(jì)上進(jìn)行測(cè)定.掃描波長(zhǎng)為200 800nm,程序自動(dòng)繪制掃描曲線.根據(jù)光譜數(shù)據(jù),計(jì)算特征紫外吸光系數(shù)SUV A254nmSUV A254nm= A254/(bc、SUV A280nmSUV A280nm=A280/(bc,單位:L/(mg Cm; A254為波長(zhǎng)254nm時(shí)吸光度;b為石英吸收池厚度(0.01m;c為DOM濃度(mg/L.同時(shí)計(jì)算E2/E3(25

13、0nm及365nm時(shí)吸光度比值和E4/E6(465nm和665nm時(shí)吸光度比值.采用Hitachi F-7000熒光光譜儀對(duì)DOM樣品進(jìn)行三維熒光掃描.激光光源150W氙弧燈, PMT電壓為700V,信噪比110;狹縫寬度E x=5nm, E m=2nm;響應(yīng)時(shí)間為自動(dòng).掃描范圍:E x=200 450nm,E m=200600nm,掃描速度1200nm/min.測(cè)定前,保持樣品溫度恒定,以去離子水做熒光測(cè)定2期 閆金龍等:含生物質(zhì)炭城市污泥堆肥中溶解性有機(jī)質(zhì)的光譜特征 461熒光強(qiáng)度比值20-21;BIX 為E x =310nm 時(shí),E m 波長(zhǎng)分別為380和430nm 時(shí)的熒光強(qiáng)度比值22

14、-23; HIX=I434480/(I300344+I434480,式中Ixy 表示在E x =255nm 時(shí),連續(xù)發(fā)射波長(zhǎng)范圍熒光強(qiáng)度的積分面積21,23-24.2 結(jié)果與討論2.1 不同處理堆肥過(guò)程中DOM 的紫外-可見(jiàn)光譜特征變化 200 400 6008000.00.10.2 0.3 吸光度CK0CK21CK42對(duì)照組200 400 600800 0.0 0.10.20.30.4 0.5 0.60.7 吸光度 +麥0+麥21+麥42添加小麥秸稈炭200 400 6008000.00.10.20.30.4 0.50.6吸光度 波長(zhǎng)(nm +花0+花21+花42添加花生殼炭圖2 不同堆肥處

15、理過(guò)程中DOM 的紫外-可見(jiàn)吸收光譜曲線Fig.2 UV -VIS spectrum of DOM extracted fromdifferent composting treatment progresses譜發(fā)生了明顯的紅移現(xiàn)象,且隨著堆肥時(shí)間的進(jìn)行其紅移現(xiàn)象越來(lái)越明顯.造成這種現(xiàn)象的原因可能是在堆肥過(guò)程中,處理組堆肥的腐熟度較對(duì)照組有大幅度的提高,DOM 共軛結(jié)構(gòu)和芳香結(jié)構(gòu)增多,腐殖化程度增強(qiáng).其次,表明添加小麥秸稈和花生殼外源生物有機(jī)質(zhì)炭后,有利于提高城市污泥堆肥的腐熟度.數(shù),其大小可間接表征有機(jī)質(zhì)的芳香性程度, SUV A 254nm 越高,有機(jī)質(zhì)芳香度越高26-27.從表2可知,對(duì)

16、照組和添加小麥秸稈炭的處理組隨堆肥時(shí)間進(jìn)行,其SUV A 254nm 值不斷增加,表明隨著堆肥的進(jìn)行,污泥堆肥的腐熟度不斷增加,芳香性結(jié)構(gòu)不斷增多.而添加花生殼炭的處理組在42d 后其值小于堆肥21d 后的SUV A 254nm 值,可能是由于添加花生殼炭的污泥在堆肥21d 達(dá)到了腐熟的峰值,之后有機(jī)質(zhì)在微生物的作用下開(kāi)始分解.另外,各堆肥過(guò)程中對(duì)照組的SUV A 254nm 值總體上小于處理組的值,進(jìn)一步說(shuō)明了添加小麥秸稈和花生殼的外源有機(jī)質(zhì)炭有利于提高城市污泥堆肥的腐熟度.此外,DOM 在280nm 摩爾吸光系數(shù)(SUV A 280nm 與相對(duì)分子質(zhì)量存在顯著正相關(guān)26,28.由表2可知,

17、處理組和對(duì)照組的SUV A 280和SUV A 254的變化趨勢(shì)基本一致,反映了不同處理堆肥過(guò)程中DOM 芳香性增強(qiáng)可能與大分子物質(zhì)的增加有關(guān). Dorado 等29研究表明E 2/E 3與E 4/E 6和有機(jī)質(zhì)的腐殖化程度、芳香性及相對(duì)分子質(zhì)量成負(fù)相關(guān),其值越高,腐殖化程度越低.本試驗(yàn)中,堆肥過(guò)462 中 國(guó) 環(huán) 境 科 學(xué) 34卷表2 不同處理堆肥過(guò)程中DOM 的紫外-可見(jiàn)光譜特征參數(shù)Table 2 Specific UV -Vis parameters of DOM extracted from different composting treatment processes 樣品 SU

18、V A 254nm L/(mg Cm SUV A 280nmL/(mg CmE 2/E 3 E 4/E 6CK0 1.03 0.87 2.9 1.83CK21 2.68 2.33 2.86 2.50CK42 3.79 3.25 2.68 2.20+麥0 1.49 1.29 2.14 1.42+麥21 3.18 2.69 3.15 2.20 +麥42 3.47 2.95 3.14 2.11+花0 0.60 0.48 3.70 4.00+花21 4.55 3.83 2.74 1.64+花42 3.07 2.49 2.73 1.83 2.2 不同處理堆肥過(guò)程中DOM 熒光光譜特征變化及堆肥中DOM

19、的熒光特征和自然水體的DOM 并沒(méi)有本質(zhì)區(qū)別,因此,可采用水體DOM 的熒光峰鑒別范圍對(duì)堆肥DOM 進(jìn)行劃分30-32,具體為紫外區(qū)類腐殖酸峰A(230250nm/426466nm;可見(jiàn)光區(qū)類腐殖酸峰C(300305nm/408456nm;類蛋白熒光峰B(270280/326348nm及類蛋白質(zhì)熒光峰D(225230/320360nm.數(shù) 熒光A 峰和熒光C 峰強(qiáng)度的比值r (A,C是一個(gè)與有機(jī)質(zhì)結(jié)構(gòu)和腐殖化程度相關(guān)的指標(biāo).由表3可知,堆肥21d 后,對(duì)照組和添加小麥秸稈炭的處理組均隨著堆肥過(guò)程的進(jìn)行,r (A,C值逐漸減小,而添加花生殼炭的處理組r (A,C值逐漸增大,說(shuō)明在堆肥21d 左右

20、添加花生殼炭的堆肥腐熟度可能達(dá)到了峰值,且處理組在堆肥過(guò)程中r (A,C值基本上小于對(duì)照組.而有研究報(bào)道,大分子量、相對(duì)穩(wěn)定的芳香性結(jié)構(gòu)是C 峰的主要貢獻(xiàn)者,而A 峰的主要來(lái)源是低分子量但熒光效率高的物質(zhì)33,本研究熒光圖譜也發(fā)現(xiàn)隨著堆肥時(shí)間的進(jìn)行,C 峰強(qiáng)度逐漸增大,r (A,C值減小.說(shuō)明隨著堆肥時(shí)間的進(jìn)行,堆肥腐殖化程度增加,添加外源有機(jī)質(zhì)炭有利于堆肥的腐殖化提高,進(jìn)一步形成穩(wěn)定的腐殖質(zhì).腐殖化指數(shù)(HIX是評(píng)價(jià)DOM 腐殖化程度的重要指標(biāo)34-35.由于有機(jī)質(zhì)芳香性越強(qiáng),熒光發(fā)射出現(xiàn)紅移(向長(zhǎng)波方向轉(zhuǎn)移,因此HIX 值范圍在01之間,HIX 越高意味著DOM 中碳?xì)浠衔锝M分越少,腐殖

21、化程度越高.間接水提取或直接抽濾的土壤間隙水DOM 的HIX 在0.60.921,36;而自然水體中DOM 的HIX 一般為:0.7(淡水.不同處理堆肥過(guò)程中DOM 的HIX 和海水DOM 的值更為接近,這可能和兩種來(lái)源的DOM 都有著明顯的自生源特征有關(guān).研究認(rèn)為BIX 在0.60.7之間時(shí),DOM主要為陸源輸入,外源輸入特征明顯22,而本研究中BIX 均0.8,進(jìn)一步證明了堆肥過(guò)程中DOM 主要來(lái)源為自生源23.2期閆金龍等:含生物質(zhì)炭城市污泥堆肥中溶解性有機(jī)質(zhì)的光譜特征 463 200 250 300 350400450500 550600E M (nmE X (n m 0 150 30

22、0 450 600 700CK0200250300350400450500550 600200250300350400450E M (nmE X(n m +麥21E M (nmE X (n m 0 150 300 450 600700CK21200250300350400450500550 600200250300350400450E M (nmE X(n m 0 150 300 450 600 700+麥42E M (nmE X (n m 0 150 300 450 600 700CK42200250300350400450500550 600200250300350400450E M (n

23、m E X(n m 0 150 300 450 600700+花0200 250 300 350400450500550 600E M (nmE X (n m 200250300350400450500550 600E M (nmE X(n m 150300 450 600 700+花21200250300 350 400450500550600E M (nmE X(n m +花42圖3 不同處理堆肥過(guò)程中DOM 的三維熒光圖譜Fig.3 3D -EEMs of DOM extracted from different composting treatment processes464 中 國(guó)

24、 環(huán) 境 科 學(xué) 34 卷 進(jìn)一步 ,FI 是評(píng)價(jià) DOM 來(lái)源的依據(jù) :FI= 1.72.0 時(shí)來(lái)自于微生物分解,芳香度不高;FI1.7,同時(shí) BIX 均0.8,表明其來(lái)源以自生源為 主,可能與微生物對(duì)有機(jī)物的降解有關(guān). 3.2 外源添加小麥秸稈炭的處理隨堆肥時(shí)間的 進(jìn)行,堆肥 DOM 的 SUVA254nm、SUVA280nm 以及 carbon/nitrogen ratios J. Waste Management and Research, 2013,31(2:203-211. 12 占新華 , 周立祥 ,黃煥忠 . 城市污泥堆肥中水溶性有機(jī)物的理化 特性變化 J. 中國(guó)環(huán)境科學(xué), 2

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