劉 波,劉 筱,韓宇捷,杜 薇,高 巖,曾杰亮,關(guān) 雷,童 儀,范軍旗,楊 越,李文靜,何 斐,王文林※
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規(guī)?;B(yǎng)豬場典型沼氣工程各排放節(jié)點(diǎn)氨排放特征研究
劉 波1,劉 筱1,韓宇捷1,杜 薇2,高 巖1,曾杰亮1,關(guān) 雷1,童 儀1,范軍旗1,楊 越1,李文靜2,何 斐2,王文林2※
(1. 南通大學(xué)地理科學(xué)學(xué)院,南通 226007;2. 環(huán)境保護(hù)部南京環(huán)境科學(xué)研究所,南京 210042)
為了解典型規(guī)?;i場沼氣工程的氨排放特性,選取長三角地區(qū)某規(guī)?;B(yǎng)豬場的典型沼氣工程為研究對象,在沼氣工程設(shè)施的不同氨排放暴露節(jié)點(diǎn)(集糞池、調(diào)節(jié)池和沼液池)設(shè)置監(jiān)測點(diǎn)對氨排放進(jìn)行連續(xù)3 d的同步監(jiān)測,測定處理設(shè)施各排放節(jié)點(diǎn)氨濃度,核算各排放節(jié)點(diǎn)糞便氨排放速率,分析各排放節(jié)點(diǎn)氨排放特征。研究結(jié)果表明,集糞池、調(diào)節(jié)池和沼液池的氨日均排放速率分別為1.48、3.08和1.47 g/(d·m2);各節(jié)點(diǎn)氨排放具有明顯的日變化過程,大致表現(xiàn)為早晨氨排放呈波動增大趨勢,午后開始降低,至夜間保持低值排放;集糞池、調(diào)節(jié)池在糞污周轉(zhuǎn)時(shí)段出現(xiàn)日排放峰值;沼液池、集糞池和調(diào)節(jié)池靜置階段氨小時(shí)排放速率與溫度呈正相關(guān),與濕度呈負(fù)相關(guān);集糞池、調(diào)節(jié)池和沼液池日氨排放量分別為13.44、38.72和5 275.4 g/d。
氨;排放控制;沼氣工程;規(guī)?;B(yǎng)豬場;長三角
中國是畜禽養(yǎng)殖大國,2015年大牲畜年底養(yǎng)殖量數(shù)為12 195.74萬頭[1]。規(guī)?;陌l(fā)展帶來的環(huán)境污染問題也日漸突出,據(jù)預(yù)測2020年中國畜禽的糞便產(chǎn)生量將達(dá)到42.44 億t[2],畜禽糞便污染已居農(nóng)業(yè)源污染之首。畜禽糞便釋放的溫室氣體、惡臭氣味物質(zhì)是空氣污染物的重要來源。其中,氨是畜禽糞便釋放一種主要?dú)怏w[3-4]。氨不僅對畜禽及養(yǎng)殖場周邊人群的健康產(chǎn)生威脅,同時(shí)也是大氣酸沉降的重要組成部分,會導(dǎo)致土壤酸化和水體富營養(yǎng)化,嚴(yán)重威脅到生態(tài)環(huán)境的健康[5-8]。此外,大氣中氨(NH3)由于與二氧化硫、氮氧化物迅速形成細(xì)顆粒物(PM2.5)[3-4,9],已被證實(shí)是霧霾物質(zhì)的重要前體物[10]。研究表明,表明中國畜禽養(yǎng)殖氨排放量占總排放量54.06%[11]。中國作為養(yǎng)豬大國,其中生豬的養(yǎng)殖量已達(dá)全球生豬養(yǎng)殖量的55%,畜禽糞便量占全國畜禽糞便總量的50.6%,其氨排放為畜禽養(yǎng)殖業(yè)氨排放量之首[12-13]。因此,開展典型規(guī)模化豬場的氨排放特征研究,闡明典型農(nóng)業(yè)源氨排放現(xiàn)狀,進(jìn)而控制大氣顆粒物污染、改善區(qū)域環(huán)境空氣質(zhì)量都有著非常重要的意義。
厭氧發(fā)酵產(chǎn)沼氣是規(guī)?;笄蒺B(yǎng)殖場糞便污染治理的一種常用方式,該工藝既能產(chǎn)生清潔能源,減少糞便惡臭,同時(shí)以肥料形式循環(huán)使用營養(yǎng)物質(zhì),以規(guī)?;託夤こ虨楹诵牡奶幚砟J桨l(fā)展十分迅速[14]。國外針對養(yǎng)豬場畜禽糞便處理設(shè)施氨排放研究多集中于厭氧穩(wěn)定塘(anaerobic lagoon)[9],發(fā)現(xiàn)氨的釋放速率受到溫度[15]、風(fēng)速[16]、糞便pH值[17]、暴露面積[18]和糞便體積[19]等多個(gè)因素影響。國內(nèi)學(xué)者在室內(nèi)模擬條件下,對鮮糞污以及經(jīng)厭氧發(fā)酵后糞污的氨釋放進(jìn)行了探討[4,12]。目前針對這一典型糞便處理工藝各節(jié)點(diǎn)氨排放還缺少原位實(shí)地監(jiān)測研究,對于厭氧發(fā)酵產(chǎn)沼氣設(shè)施對豬糞便氨釋放的影響還缺少系統(tǒng)研究。
本研究選取典型規(guī)?;i場的厭氧發(fā)酵產(chǎn)沼氣設(shè)施,構(gòu)建實(shí)地監(jiān)測技術(shù)方法,測定處理設(shè)施各排放節(jié)點(diǎn)氨濃度,核算各排放節(jié)點(diǎn)糞便氨排放速率,分析各排放節(jié)點(diǎn)氨排放特征,辨析氨排放主要影響因素,評估處理設(shè)施對氨排放貢獻(xiàn),探討典型沼氣工程對畜禽糞便氨排放的影響,以期為區(qū)域畜禽養(yǎng)殖氨排放核算及制定氨減排措施提供依據(jù)。
選取的豬場位于江蘇如皋市搬經(jīng)鎮(zhèn),該豬場為江蘇省畜牧生態(tài)健康養(yǎng)殖示范基地,母豬存欄600頭,肥豬年出欄15 000頭左右?,F(xiàn)占地面積7.56 hm2,建筑面積12 000 m2。欄舍全自動喂料線及全自動化通風(fēng),水泥實(shí)心地板地面,人工水沖糞模式;糞污通過地下管道匯集到集糞池經(jīng)調(diào)節(jié)池后提升至厭氧發(fā)酵罐進(jìn)行沼氣發(fā)電,沼液與沼渣直接還田。厭氧發(fā)酵制沼工藝流程見圖1。
集糞池,有效容積約75 m3,4 m×6 m,磚混結(jié)構(gòu),暫時(shí)收集糞污。調(diào)節(jié)池,有效容積約45 m3,3.4 m× 5 m,磚混結(jié)構(gòu),去除部分水質(zhì)中的懸浮物(suspended substance,SS)物質(zhì)后將廢水提升至發(fā)酵罐。發(fā)酵罐工藝類型為升流式厭氧反應(yīng)器(up-flow solid reactor,USR),水力停留時(shí)間約10 d。沼液池長100 m,寬25 m,平均深度為2 m,容積為5 000 m3,池底及四周做防滲處理。每天上午和下午在清理欄舍后各進(jìn)料1次,每日發(fā)電時(shí)間為上午06:00至晚上19:00。
圖1 厭氧發(fā)酵工藝流程示意圖
據(jù)工藝流程,分別在集糞池、調(diào)節(jié)池和沼液池3個(gè)氨排放暴露節(jié)點(diǎn)設(shè)置采樣點(diǎn)。采用改進(jìn)的靜態(tài)箱法對各排放節(jié)點(diǎn)進(jìn)行氨排放監(jiān)測。針對集糞池、調(diào)節(jié)池污水進(jìn)出頻繁、水位會頻繁變化特點(diǎn),采用適用于水位頻繁變化水體的液面揮發(fā)氣體檢測裝置(專利號:201621099783.4)進(jìn)行監(jiān)測(見圖2a)。該裝置包括支架結(jié)構(gòu)、控制裝置和液位感應(yīng)箱體組成。通過岸邊預(yù)設(shè)支架結(jié)構(gòu),安置氣體采集箱體,支架結(jié)構(gòu)上安置控制裝置,每次測定時(shí)自動收放檢測機(jī)構(gòu)(內(nèi)含便攜式氣體檢測儀探頭),可無人值守條件下對同一液面揮發(fā)氣體全天候連續(xù)、穩(wěn)定地(檢測時(shí)間相同、氣室恢復(fù)背景濃度時(shí)間相同)監(jiān)測。通過設(shè)置的液位高度感應(yīng)裝置,當(dāng)液位傳感器的感應(yīng)探針接觸水面時(shí),液位傳感器將信號回饋至控制器,控制器獲得液面高度信息,然后控制吊裝電機(jī)運(yùn)作預(yù)定時(shí)間后停止,保證氣體采集室的下端浸沒在水中。
在沼液池4條岸邊中心距池岸1 m處各設(shè)置1個(gè)監(jiān)測點(diǎn)。位于針對沼液池水位相對穩(wěn)定的特點(diǎn),采用改進(jìn)裝置進(jìn)行測定。該檢測器適用于只需在沼液池岸邊附近布設(shè)監(jiān)測點(diǎn)的沼液池。該檢測器除具備集糞池液面揮發(fā)氣體檢測裝置特點(diǎn)外,還針對液面無變化,對控制裝置設(shè)定了上下位移的時(shí)間指令,以嚴(yán)控位移距離,使得氣體采集室的下端剛好浸沒在水中;針對水面可能會有雜枝水草時(shí),密閉氣室結(jié)構(gòu)難以完全覆蓋水面,導(dǎo)致采樣失敗的情況,設(shè)置了清場板,清場板為空心柔性板,清場板的空腔內(nèi)設(shè)置有彈性塊,牽拉繩牽拉時(shí),能使彈性塊彎曲,彈性塊再迫使空心柔性板彎曲,從而使清場板形成鉤爪狀結(jié)構(gòu),方便將雜枝水草撥開(見圖2b)。靜態(tài)箱箱體為聚四氟乙烯材料,箱體壁厚5 mm,內(nèi)徑400 mm,所罩面積0.126 m2,高度500 mm。箱體頂部開孔2個(gè)(孔徑8 mm),分別安置通風(fēng)管和導(dǎo)氣管,導(dǎo)氣管(聚四氟乙烯,外徑8 mm、內(nèi)徑6 mm)與便攜式氨氣檢測儀相連(smart pro 10,監(jiān)測量程為0~100×10–6,分辨率為0.01×10–6,檢測精度為±2%FS)。箱體頂部內(nèi)側(cè),安置通風(fēng)扇和便攜氣象站(美國Kestrel 5000)同步測定氣象要素(溫度、氣壓、 濕度)。
圖2 監(jiān)測裝置示意圖
監(jiān)測期間,通過采樣自動控制裝置,設(shè)定箱體靜置液面時(shí)間為15 min,箱體懸于空中時(shí)間為45 min,以保證靜態(tài)箱與背景空氣充分混合,氨氣檢測儀和便攜氣象站工作參數(shù)均設(shè)定為每30 s記錄并存儲1次數(shù)據(jù),連續(xù)監(jiān)測3 d。背景監(jiān)測點(diǎn)氨氣檢測儀和便攜氣象站工作參數(shù)均設(shè)定為每30 s記錄并存儲1次數(shù)據(jù),連續(xù)監(jiān)測3 d,取平均值。
分時(shí)段同步現(xiàn)場測定集便池、調(diào)節(jié)池和沼液池溶解氧(DO)(美國YSI 550A)、水溫、pH 值(HANNA Hi8424),同步采集液體樣品迅速送回實(shí)驗(yàn)室,流動分析儀(Skalar san++)測定NH4+-N、NO3–-N、NO2–-N、TN,標(biāo)準(zhǔn)方法測定化學(xué)需氧量CODcr。
1.3.1 氨排放速率
氨排放速率按式(1)計(jì)算。
式中a為每小時(shí)糞污處理設(shè)施單位面積釋放速率,mg/(m2·h);為靜態(tài)箱內(nèi)氨氣濃度的變化率,mg/(m3·min);為靜態(tài)箱高,m。
1.3.2 氨排放通量
氨排放通量按式(2)計(jì)算。
式中為排放通量,g/d;為糞污處理設(shè)施暴露面積,m2。其中,采樣時(shí)間段糞污處理設(shè)施單位面積釋放速率a由式(1)計(jì)算。
各監(jiān)測點(diǎn)液體樣品理化性質(zhì)見表1。沿糞污流程pH值表現(xiàn)出先減小后增大的趨勢。集糞池的pH值均值為7.63,在經(jīng)管道輸送至調(diào)節(jié)池過程中由于微生物對高分子化合物進(jìn)行水解形成揮發(fā)性脂肪酸等中間產(chǎn)物,使pH值降低至7.47[13];當(dāng)糞污經(jīng)發(fā)酵罐厭氧發(fā)酵處理后,由于產(chǎn)甲烷菌群對簡短產(chǎn)酸物質(zhì)利用率提高,糞污中有機(jī)酸被消耗[20],加之氨化過程的共同作用導(dǎo)致經(jīng)發(fā)酵后的糞污進(jìn)入沼液池后pH值逐漸升高,最大值達(dá)到8.08。
調(diào)節(jié)池較集糞池的NH4+-N、TN和CODcr濃度增大,前者分別是后者1.21、1.39和1.20倍。分析原因主要有2個(gè)方面,一是由于前者容積小于后者,二是糞污在從集糞池輸送至調(diào)節(jié)池過程水分蒸發(fā)導(dǎo)致糞污進(jìn)一步被濃縮。除上述因素外,糞污輸送過程有機(jī)物礦化產(chǎn)NH4+-N也是一個(gè)重要的原因[21]。厭氧發(fā)酵前后,糞污中的CODcr濃度減少了52.7%;NH4+-N和TN濃度略有下降,沼液池NH4+-N和TN濃度分別是調(diào)節(jié)池的89.4%和90.6%。
表1 各監(jiān)測點(diǎn)糞污主要理化性質(zhì)
對各排放節(jié)點(diǎn)進(jìn)行連續(xù)3 d監(jiān)測,經(jīng)核算獲得各節(jié)點(diǎn)各時(shí)段的氨排放速率,結(jié)果見圖3。由圖3可知,集糞池和調(diào)節(jié)池氨排放日變化分為2個(gè)種模式,一是在每日急速進(jìn)出糞污時(shí)段出現(xiàn)擾動峰值;二是在每日無操作時(shí)段中,氨排放速率表現(xiàn)為清晨后排放開始緩慢增大,午后排放開始降低,至夜間保持低值排放的趨勢。集糞池每日排放峰值出現(xiàn)在08:00-09:00和15:00- 16:00左右,氨最大排放速率為5.57 mg/(min·m2),最小排放速率為0.26 mg/(min·m2),僅為最大排放量的4.6%。調(diào)節(jié)池每日排放峰值出現(xiàn)在08:00-11:00和15:00-17:00左右,氨最大排放速率為6.18 mg/(min·m2),最小排放速率為1.18 mg/(min·m2),最小排放速率為最大排放量的19.1%。對比分析集糞池與調(diào)節(jié)池的氨排放速率發(fā)現(xiàn),二者存在極顯著性差異(<0.01,=72)。 集糞池與調(diào)節(jié)池氨日均排放速率分別為1.48和 3.08 g/(d·m2),后者是前者的2.09倍。集糞池與調(diào)節(jié)池氨日均排放量分別為13.44和38.72 g/d,調(diào)節(jié)池是集糞池的2.88倍
沼液池氨排放速率具有明顯的晝夜差異(見圖3c),大致表現(xiàn)為清晨后排放開始增大,午后排放開始降低,至夜間保持低值排放。日變化過程與相關(guān)厭氧穩(wěn)定塘研究結(jié)果相似[22]。每日排放峰值出現(xiàn)在12:00- 15:00左右,日最大排放速率平均為2.66 mg/(min·m2)。每日排放低值出現(xiàn)在凌晨04:00左右,最小排放速率平均為0.8 mg/(min·m2),沼液池氨日最大排放速率要小于集糞池和調(diào)節(jié)池,分別少2.91和3.52 mg/(min·m2)。沼液池平均釋放速率為1.47 mg/(min·m2),核算得到日均排放速率為2.11 g/(d·m2),大于集糞池而小于調(diào)節(jié)池,是調(diào)節(jié)池日均釋放速率的68.57%。由于面積大、體積大,沼液池氨日均排放量達(dá)到5 275.4 g/d,要遠(yuǎn)遠(yuǎn)大于集糞池與調(diào)節(jié)池,二者分別為沼液池的0.25% 和0.73%。
圖3 集糞池與調(diào)節(jié)池及沼液池氨排放速率日變化過程
集糞池與調(diào)節(jié)池是糞污處理的過程中對暫時(shí)存儲周轉(zhuǎn)設(shè)施,白天糞污周轉(zhuǎn)過程中人為擾動較大,糞污在操作機(jī)械的作用下處于流動或翻動狀態(tài),增大了糞污與空氣的接觸面積以及換氣頻率,促使氨排放速率有所增加[23],導(dǎo)致在糞污周轉(zhuǎn)過程中出現(xiàn)氨排放峰值,此時(shí)段二者的氨平均排放速率分比為3.25和 4.01 mg/(min·m2)(見圖4)。在無糞污周轉(zhuǎn)操作時(shí)段,集糞池與調(diào)節(jié)池內(nèi)所剩糞污較少,且無人為擾動,糞污處于相對靜止?fàn)顟B(tài),此時(shí)段二者的氨平均排放速率分別為0.44和1.50 mg/(min·m2)(見圖4)。糞污周轉(zhuǎn)時(shí)段內(nèi)集糞池和調(diào)節(jié)池的氨平均排放速率分別是非周轉(zhuǎn)時(shí)段的7.39倍和2.67倍,相比于周轉(zhuǎn)操作時(shí)段,靜置時(shí)段的氨排放速率顯著減小。研究表明,靜置狀態(tài)下的液面氨排放受到NH4+-N濃度、pH值、溫度、濕度等綜合作用的影響。其中,NH4+-N濃度是影響氨排放的一個(gè)重要因素。NH4+-N濃度越高氨排放潛力更高和更持久[24]。調(diào)節(jié)池的NH4+-N濃度要高于集糞池,這是導(dǎo)致調(diào)節(jié)池氨排速率高于集糞池的一個(gè)重要原因。pH值增大有利于氨揮發(fā)排放[25],沼液池氨排放大于集糞池,與沼液池pH值高有關(guān)。沼液池NH4+-N濃度要小于調(diào)節(jié)池,但沼液池氨排放速率與調(diào)節(jié)池非擾動時(shí)段氨排放速率相差不大,這可能與沼液池pH值相對較高有關(guān)。
圖4 各排放節(jié)點(diǎn)各時(shí)段氨排放速率
通過沼液池氨排放速率與溫度、濕度的響應(yīng)關(guān)系綜合分析發(fā)現(xiàn),沼液池氨排放速率與溫度呈正相關(guān)關(guān)系,與濕度呈負(fù)相關(guān)關(guān)系。通過線性回歸分析發(fā)現(xiàn)氨排放日變化過程與排放口的溫度和濕度的日變化過程存在很好的擬合關(guān)系,即一定溫濕度范圍內(nèi),沼液池氨排放速率與溫、濕度響應(yīng)關(guān)系顯著,結(jié)果見表2。若將集糞池和調(diào)節(jié)池非糞污周轉(zhuǎn)時(shí)段的氨排放速率與溫度和濕度進(jìn)行線性擬合,也發(fā)現(xiàn)了同樣的結(jié)果,見表2。表明溫度、濕度是影響?zhàn)B殖場糞污處理設(shè)施氨排放的重要因素。在非人為擾動的情況下,溫度高、濕度低季節(jié)氨排放量會增大,反之則減小。這主要由于較高的溫度能提高脲酶活性,促進(jìn)糞便中含氮物質(zhì)分解釋放出氨[26],暴露開敞的糞污處理設(shè)施會向環(huán)境中排放更多的氨。由于氨的水溶性較大,濕度增大會降低空氣環(huán)境中氨濃度[26]。
研究發(fā)現(xiàn),新鮮糞污堆放過程中氨排放速率呈逐漸增大至峰值后逐漸減小的趨勢[18]。產(chǎn)生這一現(xiàn)象的主要原因是富含氮素的畜禽糞污在經(jīng)有機(jī)物礦化后會產(chǎn)生更多的NH4+-N,造成糞污在堆放一段時(shí)間后具有很大的氨排放潛力,即新鮮糞污隨著有機(jī)物礦化分解氨排放表現(xiàn)為逐漸增大至峰值后開始逐漸降低的過 程[27]。研究發(fā)現(xiàn),新鮮豬糞污在堆放12 d內(nèi)氨排放均在逐漸增大,直至第13 天才達(dá)到峰值[4],持續(xù)3 d后開始逐漸降低。本研究中新鮮糞污經(jīng)集糞池輸送到調(diào)節(jié)池后氨排放有所增大,表明糞污在堆放后隨著有機(jī)物礦化分解氨排放有增大的趨勢,見圖4。
表2 各排放節(jié)點(diǎn)氨排放速率與溫度、濕度響應(yīng)關(guān)系
注:為氨排放速率,m·min-1·m-2;1為溫度,℃;2為濕度,%;集糞池與調(diào)節(jié)池按非糞污周轉(zhuǎn)時(shí)段數(shù)據(jù)統(tǒng)計(jì)計(jì)算。
Note:indicates ammonia emission rate, mg·min–1·m–2;1indicates temperature, ℃;2indicates humidity, %; The data of the cesspool and regulating pool are calculated according to the period of non-dung turnover.
厭氧發(fā)酵是指在厭氧環(huán)境下微生物分解有機(jī)質(zhì)獲取物質(zhì)和能量維持自身的生長,最終將有機(jī)物分解為甲烷、二氧化碳和水的過程[28]。在厭氧發(fā)酵過程中,有機(jī)質(zhì)會礦化分解,經(jīng)厭氧發(fā)酵后COD濃度減少了52.7%,表明厭氧過程中有機(jī)質(zhì)礦化分解過程明顯,這與相關(guān)研究結(jié)果相似[29]。隨著有機(jī)物的礦化分解,富含氮素豬糞會產(chǎn)生新的NH4+-N。新鮮沼液中的NH4+-N是礦化過程和脫氮過程綜合的結(jié)果。經(jīng)厭氧發(fā)酵后TN和NH4+-N濃度分別減少了9.4%和11.6%,表明在有機(jī)質(zhì)礦化NH4+-N不斷產(chǎn)生的條件下,厭氧發(fā)酵過程中存在著明顯的脫氮過程。在厭氧發(fā)酵環(huán)境中,反硝化、厭氧氨氧化和氨揮發(fā)是脫氮的主要途徑[30]。本研究的養(yǎng)豬場采用水沖糞模式,糞尿在清洗水的作用下混合經(jīng)管道匯集與集糞池,后經(jīng)調(diào)節(jié)池進(jìn)入發(fā)酵罐進(jìn)行厭氧發(fā)酵。在混合、輸送過程中,通過硝化作用產(chǎn)生一定量的硝酸鹽,即糞污在進(jìn)入發(fā)酵罐前在硝化作用下會產(chǎn)生一定量的硝酸鹽。此外,在發(fā)酵罐內(nèi)也存在一定的硝化過程。有研究發(fā)現(xiàn)豬糞污厭氧發(fā)酵過程中產(chǎn)生的N2O是NH3的近5倍[31],表明反硝化、厭氧氨氧化作用是厭氧發(fā)酵過程中促使NH4+-N轉(zhuǎn)化為N2O排放到空氣環(huán)境中的重要途徑[21]。那么,厭氧發(fā)酵過程通過反硝化和厭氧氨氧化等作用直接減少了糞污的氨排放,與糞污直接儲存堆放相比一定程度上減少了氨排放潛力。
1)各節(jié)點(diǎn)氨排放速率存在顯著差異,集糞池、調(diào)節(jié)池和沼液池的氨日均排放速率分別為1.48、3.08和1.47 g/(d·m2)。
2)各節(jié)點(diǎn)氨排放具有日變化過程,早晨(06:00- 08:00)氨排放開始波動增大,午后(13:00-14:00)開始降低,至夜(20:00-06:00)間保持低值排放;集糞池和調(diào)節(jié)池在糞污周轉(zhuǎn)活動時(shí)段出現(xiàn)峰值,二者每日最大氨排放速率分別為5.57和6.18 mg/(min·m2);
3)糞污周轉(zhuǎn)的人為擾動增加了集糞池和調(diào)節(jié)池的氨排放;沼液池、集糞池和調(diào)節(jié)池靜置階段氨排放速率與溫度呈正相關(guān),與濕度呈負(fù)相關(guān)。
4)經(jīng)核算集糞池、調(diào)節(jié)池和沼液池日氨排放量分別為13.44、38.72和5 275.4 g/d;因此,沼液池是沼氣工程氨排放的主要貢獻(xiàn)者。
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Study on emission characteristics of ammonia from anaerobic digesters in industrial pig farm
Liu Bo1, Liu Xiao1, Han Yujie1, Du Wei2, Gao Yan1, Zeng Jieliang1, Guan Lei1, Tong Yi1, Fan Junqi1, Yang Yue1, Li Wenjing2, He Fei2, Wang Wenlin2※
(1.226007,2.210042,)
The problem of environmental pollution caused by large-scale development of livestock and poultry breeding is increasingly prominent in China, which has large amount of livestock and poultry. It is predicted that the fecal production of livestock and poultry in China will reach 42.44 billion ton in 2020, and the fecal pollution ranks first among the agricultural sources. Greenhouse gases and odorous odors released by livestock manure are important sources of air pollutants, and ammonia is one of the main gases released by livestock and poultry manure. Ammonia is not only a threat to the health of surrounding population of livestock and poultry farms, but also an important part of the atmospheric acid deposition which can lead to soil acidification and eutrophication, and further can become a serious threat to the ecological environment. Therefore, it is a great significance to carry out a study on the characteristics of ammonia emissions from typical large-scale pig farms, clarify the current situation of ammonia emissions from typical agricultural sources, which can provide the foundation for controlling the atmospheric particulate matter pollution and improving regional air quality. Biogas produced by anaerobic fermentation is a common method for treatment of fecal pollution in large-scale livestock and poultry farms. The process can not only generate clean energy and reduce fecal stench, but also recycle nutrients in the form of fertilizer. Therefore, the treatment model centering on large-scale biogas project has developed rapidly. At present, there is still a lack of in-situ monitoring and research on ammonia discharge at the node of the typical fecal treatment process, and there is still a lack of systematic research on the impact of the anaerobic fermentation biogas production facility on the release of pig fecal ammonia. A typical methane project of large-scale pig farms in Yangtze river delta was used as the research object. Ammonia emission was synchronous monitored for 3 consecutive days in each emission node of the biogas engineering facilities (cesspool, regulating pond and biogas tank). The results showed that the average daily emission rate of ammonia in cesspool, regulating pond and biogas tank respectively was 1.48, 3.08 and 1.47 g/(d·m2). The ammonia emission of each node had an obvious daily change process, this process was generally manifested as the fluctuant increase of ammonia emission in the morning, decrease in the afternoon and keep the low-value emission at night. The cesspool and regulating pond in the turnover period of fecal pollution appeared daily emission peak; the ammonia emission rates of the cesspool, regulating pond and biogas tank were positively correlated with the temperature in stable stage, while was negatively correlated with the humidity. The daily ammonia emissions of cesspool, regulating pond and biogas tank were 13.44, 38.72 and 5 275.4 g/d, respectively. This study selected typical large-scale pig farms of anaerobic fermentation biogas production facilities and constructed the field monitoring technology method to measure each discharge ammonia concentration of treatment facilities node. By calculating the excreta ammonia emission rate of each emission node, the characteristics of ammonia emission of each emission node were analyzed, and the main influencing factors of ammonia emission were identified. The results provide a reference for the calculation of ammonia emissions from livestock and poultry breeding in the region and the formulation of ammonia emission reduction measures.
ammonia; emission control; biogas engineering; industrial pig farm; Yangtze River Delta
劉 波,劉 筱,韓宇捷,杜 薇,高 巖,曾杰亮,關(guān) 雷,童 儀,范軍旗,楊 越,李文靜,何 斐,王文林.規(guī)?;B(yǎng)豬場典型沼氣工程各排放節(jié)點(diǎn)氨排放特征研究[J]. 農(nóng)業(yè)工程學(xué)報(bào),2018,34(23):179-185. doi:10.11975/j.issn.1002-6819.2018.23.022 http://www.tcsae.org
Liu Bo, Liu Xiao, Han Yujie, Du Wei, Gao Yan, Zeng Jieliang, Guan Lei, Tong Yi, Fan Junqi, Yang Yue, Li Wenjing, He Fei, Wang Wenlin.Study on emission characteristics of ammonia from anaerobic digesters in industrial pig farm[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2018, 34(23): 179-185. (in Chinese with English abstract) doi:10.11975/j.issn.1002-6819.2018.23.022 http://www.tcsae.org
2018-05-16
2018-10-05
大氣重污染成因與治理攻關(guān)項(xiàng)目(DQGG0208);環(huán)保公益性行業(yè)科研專項(xiàng)(201509038);環(huán)境保護(hù)部部門預(yù)算項(xiàng)目“畜禽養(yǎng)殖大氣氨排放污染控制工作指南”;江蘇省大學(xué)生創(chuàng)新訓(xùn)練計(jì)劃項(xiàng)目(201810304035Z、201810304078Y)
劉 波,副教授,博士,主要從事農(nóng)業(yè)面源污染過程與防治研究。Email:lb@ntu.edu.cn
王文林,副研究員,博士,主要研究方向?yàn)榱饔蛎嬖次廴究刂?。Email:wangwenlin_jjl@126.con
10.11975/j.issn.1002-6819.2018.23.022
X552
A
1002-6819(2018)-23-0179-07