劉艷芳,劉曉帥,尹思婕,高 瑋,張妙雨,韓嚴(yán)和,李再興*

包埋硫鐵生物填料的制備及自養(yǎng)反硝化性能

劉艷芳1,劉曉帥1,尹思婕1,高 瑋2,張妙雨1,韓嚴(yán)和3,李再興1*

(1.河北科技大學(xué)環(huán)境科學(xué)與工程學(xué)院,河北 石家莊 050018；2.河北科技大學(xué)建筑工程學(xué)院,河北 石家莊 050018；3.北京石油化工學(xué)院,環(huán)境工程系,北京 102617)

采用包埋固定化技術(shù)制備了包埋硫鐵生物填料(ESI Filler),基于升流式自養(yǎng)反硝化反應(yīng)器開展動(dòng)態(tài)實(shí)驗(yàn)研究,通過(guò)改變水力停留時(shí)間(HRT)、pH值、溶解氧(DO)等運(yùn)行條件,探究ESIFiller反應(yīng)器的脫氮效果及微生物群落結(jié)構(gòu)組成.結(jié)果表明,當(dāng)進(jìn)水硝酸鹽氮(NO3--N)濃度為30mg/L,HRT為10h時(shí),NO3--N去除率不斷上升至99.80%.當(dāng)HRT縮短為2.5h時(shí),NO3--N去除率降至61.35%.ESIFiller反應(yīng)器對(duì)pH值和DO的改變具有較高的穩(wěn)定性,NO3--N平去除率可維持在82.5%以上.但對(duì)低溫的耐受性較差,當(dāng)溫度從35℃降低至15℃時(shí),NO3--N平均去除率由90.12%降低至68.80%.運(yùn)行164d后,球體未出現(xiàn)破裂散落的現(xiàn)象,表現(xiàn)出較長(zhǎng)的使用壽命.通過(guò)掃描電鏡發(fā)現(xiàn),填料表面疏松多孔,附著大量桿狀細(xì)菌,已成為微生物的良好載體.高通量測(cè)序結(jié)果表明,包埋顆粒中優(yōu)勢(shì)菌屬為典型的自養(yǎng)反硝化功能菌,豐度為80.79%.

硫自養(yǎng)反硝化；鐵自養(yǎng)反硝化；包埋填料；脫氮穩(wěn)定性；微生物特性

單質(zhì)硫自養(yǎng)反硝化(SAD)工藝是利用硫自養(yǎng)反硝化菌以硫磺為電子供體,將硝酸鹽(NO3-)還原為氮?dú)?N2)過(guò)程.對(duì)于低C/N廢水而言, SAD工藝因具有無(wú)需額外投加有機(jī)碳源、污泥產(chǎn)量少、成本低等優(yōu)勢(shì)而備受關(guān)注[1-4].但SAD過(guò)程會(huì)引起反應(yīng)系統(tǒng)pH值降低,抑制反硝化進(jìn)行,通常向系統(tǒng)中添加堿性緩沖物質(zhì),如石灰石、雞蛋殼等來(lái)控制系統(tǒng)酸化,維持pH值的穩(wěn)定,不過(guò)存在Ca2+的溶出造成出水硬度增高問(wèn)題[5].此外, SAD過(guò)程中副產(chǎn)物SO42-也會(huì)對(duì)水質(zhì)安全構(gòu)成威脅.

單質(zhì)鐵(Fe0)被證明可以在缺氧條件作為唯一電子供體將NO3-還原為N2[6].有研究發(fā)現(xiàn),在SAD系統(tǒng)中添加Fe0,鐵自養(yǎng)反硝化可分擔(dān)SAD過(guò)程部分NO3--N負(fù)荷,出水SO42-濃度較硫自養(yǎng)反硝化理論值相比最高可以減少73%,同時(shí)鐵自養(yǎng)反硝化會(huì)產(chǎn)生堿度,可減緩SAD系統(tǒng)pH值的降低[3],與SAD系統(tǒng)相比,硫-鐵協(xié)同脫氮系統(tǒng)具有一定優(yōu)勢(shì).

但在實(shí)際運(yùn)行過(guò)程中硫磺質(zhì)軟較輕,易隨出水流出而降低硫源的利用率[8].包埋法作為一種新興的固定化技術(shù),可將微生物、硫磺等材料束縛在一定的空間之內(nèi),具有易于固液分離、剩余污泥量少、資源損耗小等優(yōu)點(diǎn)[9-11].目前,研究多集中于異養(yǎng)型微生物包埋固定化.利用包埋異養(yǎng)反硝化菌進(jìn)行脫氮,可加快反應(yīng)器的啟動(dòng)時(shí)間,在15d TN去除率可達(dá)90%以上[12],同時(shí)包埋異養(yǎng)反硝化菌填料還可快速適應(yīng)污水廠二級(jí)出水,具有良好的抗沖擊性能[13].而目前有關(guān)自養(yǎng)反硝化微生物固定化技術(shù)研究卻鮮有報(bào)道.

本研究以硫磺粉、單質(zhì)鐵粉、污泥等為原料,以聚乙烯醇-海藻酸鈉為骨架材料,制備包埋硫鐵生物填料,探究不同運(yùn)行條件下反應(yīng)器的脫氮性能,并結(jié)合掃描電鏡(SEM)和微生物群落結(jié)構(gòu)組成對(duì)其進(jìn)行深入分析,旨在為自養(yǎng)微生物固定化技術(shù)在深度脫氮領(lǐng)域的應(yīng)用提供參考.

1 材料與方法

1.1 實(shí)驗(yàn)用水與接種污泥

研究用水為實(shí)驗(yàn)室模擬廢水,主要組分包含KNO3108.3～324.9mg/L、KH2PO4108.3～324.9mg/L和NaHCO3130.0～389.9mg/L.

污泥取自石家莊市某污水廠缺氧池,用自來(lái)水反復(fù)淘洗3次,測(cè)得MLSS為30g/L,MLVSS為10.2g/ L,用改良馴化培養(yǎng)基[14]進(jìn)行為期40d的富集. 培養(yǎng)基組分為(g/L):Na2S2O3·5H2O 4.96;NaHCO32.52; KNO32.02;KH2PO42.00;NH4Cl 1.00; MgSO4·7H2O 0.80;FeSO4·7H2O 0.06;CaCl2·2H2O 0.01.

1.2 包埋硫鐵生物填料(ESI Filler)的制備

將馴化污泥離心濃縮,與牡蠣殼粉以質(zhì)量比為1:4混合,吸附20min,得到包埋體;將包埋體,硫磺粉/鐵粉(=2:1)和質(zhì)量分?jǐn)?shù)為10%的聚乙烯醇、2%的海藻酸鈉按質(zhì)量比為1:1:1.2混合均勻制成粒徑在6～8mm的球型顆粒,置于飽和硼酸及2%的氯化鈣溶液下交聯(lián)固定16h.然后在4℃下冷藏保存6h,得到ESIFiller,如圖1放大部分所示,顏色偏黑,密度(1.17～1.62g/cm3)大于水,沉降性好.

1.3 實(shí)驗(yàn)裝置

實(shí)驗(yàn)裝置為有機(jī)玻璃制成的圓柱型升流式反應(yīng)器,如圖1所示.

圖1 ESI Filler反應(yīng)器裝置示意

反應(yīng)器柱體尺寸為:高100cm,內(nèi)徑9cm,底部添加1.5～2.5cm厚的鵝卵石作為承托層,ESIFiller填充高度為75cm.進(jìn)水由蠕動(dòng)泵泵入反應(yīng)器,在最高出水管流出.

1.4 實(shí)驗(yàn)方法

按表1參數(shù)運(yùn)行反應(yīng)器,探究ESIFiller反應(yīng)器在不同運(yùn)行條件下的脫氮性能.

表1 反應(yīng)器各階段運(yùn)行條件

1.5 微生物群落結(jié)構(gòu)變化

取馴化污泥(樣品A1)和運(yùn)行模擬廢水結(jié)束后的ESIFiller(樣品A2,取自反應(yīng)器中部位置)進(jìn)行高通量測(cè)序,對(duì)比運(yùn)行模擬廢水對(duì)微生物群落結(jié)構(gòu)的影響,使用正向引物338F(ACTCCTACGGG- AGGCAGCA)和反向引物806R(GGACTACHVGG- GTWTCTAAT)對(duì)細(xì)菌16S rRNA基因V3～V4區(qū)域進(jìn)行PCR擴(kuò)增,使用Quant-IT Pico Green雙鏈DNA分析試劑盒(美國(guó)加利福尼亞州卡爾斯巴德Invitrogen)定量.在個(gè)體量化步驟后,以等量匯集擴(kuò)增子,使用Illumina Nova Seq平臺(tái)和Nova Seq 6000SP試劑盒進(jìn)行雙端測(cè)序,該工作委托上海派森諾生物科技有限公司完成.

1.6 水質(zhì)分析方法

COD測(cè)定采用重鉻酸鉀法,NO3--N、NO2--N、NH4+-N和SO42-分別采用紫外分光光度法、N-(1-萘基)-乙二胺分光光度法、納氏試劑分光光度法和鉻酸鋇光度法測(cè)定(UV-5100);pH值測(cè)定采用玻璃電極法(pH值S-2F),DO測(cè)定采用便攜式溶氧儀法(JPB-607A).

1.7 SO42-理論生成量計(jì)算方法

式中:為摩爾質(zhì)量.

2 結(jié)果與討論

2.1 填料中有機(jī)物質(zhì)對(duì)反應(yīng)器運(yùn)行性能的影響

2.1.1 NO3--N的變化 由圖2(b)可知,進(jìn)水NO3-- N平均濃度為30.84mg/L,HRT為10h時(shí),隨著運(yùn)行時(shí)間的增加,NO3--N去除率整體呈不斷增高的趨勢(shì),去除率在第1d僅為34.63%,第12d增至99.80%,包埋微生物的活性得到較大提高,逐漸適應(yīng)了反應(yīng)器的運(yùn)行環(huán)境.

Cui等[15]研究表明,采用異養(yǎng)啟動(dòng)的MBBR反應(yīng)器比自養(yǎng)啟動(dòng)的MBBR反應(yīng)器在啟動(dòng)時(shí)間、硫化物去除性能、生物量和生物活性方面具有更多優(yōu)勢(shì),表明碳源對(duì)包埋填料中微生物的活性及生物量的提高具有促進(jìn)作用.由于骨架材料聚乙烯醇是一種具有緩釋性的有機(jī)物,部分可被微生物生長(zhǎng)代謝利用.反應(yīng)器在0～25d的釋碳期為自養(yǎng)-異養(yǎng)協(xié)同脫氮系統(tǒng).由圖2(a)可知,出水COD呈先增高后降低的趨勢(shì),在第9d達(dá)到峰值945.0mg/L,當(dāng)HRT縮短至5h時(shí),NO3--N去除率仍可以維持在89.69%以上,表明反應(yīng)器穩(wěn)定性高.第25d后,將HRT從5h縮短至2.5h,碳源釋放量逐漸趨于零,異養(yǎng)反硝化作用減弱直至消失,出水NO3--N濃度升高,NO3--N去除率降低至61.35%,達(dá)到了該系統(tǒng)的最大脫氮負(fù)荷.

2.1.2 NO2--N和NH4+-N的變化 如圖2(c)所示,出水NO2--N濃度最高為0.6mg/L,無(wú)明顯積累.HRT的縮短會(huì)導(dǎo)致污染物與微生物接觸不足引起出水NO2--N升高,Wang等[16]將HRT由1h降為0.5h時(shí), 出現(xiàn)NO2--N積累,為0.19mg/L.Fe0與NO3-的化學(xué)反應(yīng)會(huì)生成NH4+-N[17],在HRT=10h時(shí),出水中檢測(cè)到少量的NH4+-N,平均濃度為0.96mg/L.但在HRT為5h、2.5h時(shí),出水NH4+-N低于檢出限,這是由于進(jìn)水NO3--N濃度本身較低,隨著微生物活性提高,與Fe0間的化學(xué)作用減弱[18],同時(shí)生成的微量NH+-N可作為SAD過(guò)程的一種營(yíng)養(yǎng)物質(zhì),被微生物所消耗[19].

圖2 有機(jī)物溶出對(duì)反應(yīng)器運(yùn)行效能的影響

(a)出水COD變化情況;(b)進(jìn)出水硝酸鹽氮變化情況;(c)出水亞硝酸鹽氮、氨氮變化情況;(d)出水硫酸鹽變化情況;(e)進(jìn)出水pH值變化情況

2.1.3 SO42-的變化 SAD過(guò)程中會(huì)產(chǎn)生SO42-, Moon等[20]和Sahinkaya等[21]根據(jù)反應(yīng)的化學(xué)計(jì)量得出的SO42-理論生成量與SAD過(guò)程實(shí)際生成量一致.由式(1)計(jì)算得出SAD過(guò)程理論SO42-產(chǎn)量為7.54mg/mg(以單位質(zhì)量NO3--N計(jì)).如圖2(d)所示,當(dāng)HRT為10和5h時(shí),SO42-實(shí)際生成量較理論生成量分別減少了28.32%～56.43%和19.57%～31.28%,而HRT為2.5h時(shí)主要由鐵自養(yǎng)分擔(dān)脫氮負(fù)荷,SO42-平均實(shí)際生成量較理論生成量減少了18.03%～ 37.42%,表明鐵自養(yǎng)反硝化可承擔(dān)一定量的NO3--N去除.經(jīng)SO42-與NO3--N計(jì)量轉(zhuǎn)換可得各階段脫氮貢獻(xiàn)占比.第1～24d(釋碳期)反應(yīng)系統(tǒng)內(nèi)主要存在硫、鐵自養(yǎng)和異養(yǎng)反硝化,其中硫自養(yǎng)脫氮負(fù)荷占比43.57%～80.43%,其余脫氮負(fù)荷由鐵自養(yǎng)和異養(yǎng)反硝化承擔(dān).在反應(yīng)第24～32d,反應(yīng)系統(tǒng)主要為自養(yǎng)反硝化過(guò)程,其中硫自養(yǎng)脫氮負(fù)荷占比68.72%～ 81.97%,其余脫氮負(fù)荷由鐵自養(yǎng)反硝化承擔(dān).

2.1.4 pH值的變化 反應(yīng)體系pH值的穩(wěn)定是維持脫氮效率的重要因素,其適宜pH值通常在6.8～8.2之間.任爭(zhēng)鳴等[22]構(gòu)建硫自養(yǎng)反硝化中試裝置,在進(jìn)水pH值為7.0時(shí),出水pH值降低至6.0左右,pH值過(guò)低會(huì)抑制反硝化過(guò)程.如圖2(e)可知,ESIFiller反應(yīng)器的平均進(jìn)水pH值為7.1,平均出水pH值為7.3,略有升高,無(wú)明顯變化.這歸因于鐵自養(yǎng)反硝化產(chǎn)生的OH-可中和SAD過(guò)程產(chǎn)生的H+[23].因此與SAD工藝相比,硫-鐵協(xié)同自養(yǎng)反硝化工藝可減少額外堿度的投加.

2.2 自養(yǎng)反硝化反應(yīng)器運(yùn)行效能探究

2.2.1 進(jìn)水NO3--N濃度對(duì)反應(yīng)器脫氮性能的影響 由圖3可知,反應(yīng)器進(jìn)水NO3--N為15mg/L左右時(shí),出水NO3--N濃度范圍為1.44～3.45mg/L,平均去除率為85.8%.當(dāng)進(jìn)水NO3--N負(fù)荷提升至30,45mg/L左右時(shí),平均去除率有所減小,但波動(dòng)不大,分別為79.7%和72.1%.中間產(chǎn)物NO2--N的生成量較小,出水濃度在0.07～0.24mg/L之間波動(dòng),自養(yǎng)反硝化過(guò)程中NO2--N轉(zhuǎn)換為N2的速率要快于NO3--N轉(zhuǎn)換為NO2--N的速率,反應(yīng)體系內(nèi)一般不會(huì)存在較高的NO2--N積累[24].以上分析表明進(jìn)水NO3--N負(fù)荷的提高對(duì)反應(yīng)體系脫氮性能未造成較大影響,反應(yīng)器穩(wěn)定性高.

2.2.2 進(jìn)水pH值對(duì)反應(yīng)器脫氮性能的影響 由圖4(a)可知,反應(yīng)器進(jìn)水pH值平均值為5.0、6.1、7.0、8.0和9.0的5個(gè)階段,對(duì)應(yīng)的出水pH值平均值分別為6.5、7.0、7.5、8.0和8.0.發(fā)現(xiàn)進(jìn)水偏酸性時(shí),反應(yīng)器對(duì)pH值有良好的緩沖效果.當(dāng)進(jìn)水pH值提升至9.0時(shí),出水pH值反而有所降低.這是由于進(jìn)水pH值較高阻礙了填料內(nèi)堿性緩沖材料的溶出,這也體現(xiàn)了SAD是一個(gè)產(chǎn)酸過(guò)程.

Liu等[25]通過(guò)批次實(shí)驗(yàn)發(fā)現(xiàn)pH值低于5.5時(shí)SAD過(guò)程受到嚴(yán)重抑制,而與其不同,ESIFiller反應(yīng)器進(jìn)水平均pH值由7.0降低至5.0左右時(shí), NO3--N平均去除率僅降低2.7%.進(jìn)水pH值的改變對(duì)ESIFiller反應(yīng)器NO3--N去除率影響不大,平均去除率可以穩(wěn)定在82.5%以上,如圖4(b)所示.由于包埋使大量微生物固定在填料內(nèi)部,可有效增加微生物與模擬廢水之間的緩沖距離,提高微生物對(duì)環(huán)境的適應(yīng)性.當(dāng)進(jìn)水pH值為8～9時(shí),NO2--N積累最高.pH值會(huì)改變底物以及微生物酶的帶點(diǎn)狀態(tài),從而對(duì)NO2--N的降解速率及NO2--N還原酶活性產(chǎn)生影響[26].

圖3 進(jìn)水NO3--N濃度對(duì)反應(yīng)器脫氮性能的影響

2.2.3 進(jìn)水DO濃度對(duì)反應(yīng)器脫氮性能的影響 當(dāng)進(jìn)水O2濃度較高時(shí),O2可以產(chǎn)生游離O2-,由于專性厭氧微生物不具備破壞O2-的超氧化物歧化酶(SOD)而被O2-殺死[27],導(dǎo)致反應(yīng)系統(tǒng)失穩(wěn).Qambrani等[28]的研究表明,反應(yīng)體系DO濃度從0.3mg/L升至7.19mg/L時(shí),會(huì)抑制NO3--N去除.由圖5(a)可知,當(dāng)ESIFiller反應(yīng)器將進(jìn)水DO調(diào)節(jié)至1～2mg/L和3～4mg/L后,出水DO均低于0.5mg/L,Fe0可以吸收進(jìn)水中的部分DO[29],降低DO對(duì)反硝化菌的毒害.另外,在進(jìn)水DO較高時(shí),O2較NO3--N或NO2--N更容易作為末端電子供體引起出水SO42-升高,因此提高反應(yīng)器對(duì)DO的適應(yīng)性是必要的.

(a)進(jìn)出水pH值變化情況;(b)進(jìn)出水硝酸鹽氮、亞硝酸鹽氮變化情況

如圖5(b)所示,進(jìn)水NO3--N為30mg/L左右時(shí),改變進(jìn)水DO對(duì)反應(yīng)器NO3--N去除效果影響不大,出水NO3--N平均去除率可保持在87.0%以上,出水NO2--N低于0.13mg/L.表明ESIFiller反應(yīng)器對(duì)進(jìn)水DO有較強(qiáng)的緩沖作用,穩(wěn)定性較高.

(a)進(jìn)出水溶解氧變化情況;(b)進(jìn)出水硝酸鹽氮、亞硝酸鹽氮變化情況

2.2.4 反應(yīng)溫度對(duì)反應(yīng)器脫氮性能的影響 自養(yǎng)反硝化作為生物驅(qū)動(dòng)的脫氮工藝,受溫度的影響變化較大.由圖6可知,在30和35℃時(shí)反應(yīng)器脫氮效果最好,NO3--N平均去除率為89.16%和90.12%,出水NO2--N低于檢出限,NO3--N可完全轉(zhuǎn)換為N2. Fajardo等[30]以小瓶為反應(yīng)裝置,通過(guò)批次實(shí)驗(yàn)探究了不同溫度下以S2-為電子供體的自養(yǎng)反硝化脫氮性能,溫度為35℃時(shí)NO3--N去除率可達(dá)95.0%,與本實(shí)驗(yàn)最佳溫度一致.溫度降低至15℃后,微生物受低溫的影響,脫氮效果較低,NO3--N平均去除率為68.80%,顯然需要延長(zhǎng)HRT才能達(dá)到相同的脫氮效果.低溫時(shí)出水中有少量NO2--N積累,有研究表明亞硝酸鹽還原菌較硝酸鹽還原菌對(duì)低溫的適應(yīng)性要更差[31].

與改變pH值和DO不同,ESIFiller反應(yīng)器對(duì)低溫的抗沖擊負(fù)荷性能稍有欠佳,以包埋微生物來(lái)提高反應(yīng)系統(tǒng)對(duì)低溫的適應(yīng)性作用有限.ESIFiller反應(yīng)器最佳運(yùn)行溫度應(yīng)為30～35℃適宜自養(yǎng)反硝化微生物的生長(zhǎng)繁殖,脫氮效率最高.

圖6 溫度對(duì)反應(yīng)器脫氮性能的影響

2.3 微生物群落結(jié)構(gòu)分析

2.3.1 SEM觀察 在結(jié)束脫氮性能的探究試驗(yàn)后,取反應(yīng)器內(nèi)的填料進(jìn)行電鏡掃描.由圖7(a)(b)可知,填料表面疏松多孔,以保證固-液兩相之間的傳質(zhì)暢通,促進(jìn)微生物的生長(zhǎng)代謝,使其保持活性.并呈不規(guī)則的形狀分布,為微生物在填料上生長(zhǎng)繁殖提供附著點(diǎn),可以看出其中包含了大量的桿狀細(xì)菌,其大小為(0.1～0.3)μm×(0.6～1.0)μm.桿狀細(xì)菌的大小和形態(tài)與自養(yǎng)反硝化優(yōu)勢(shì)菌屬脫氮硫桿菌()的描述一致[32].圖7(d)為運(yùn)行164d后ESIFiller的照片,與初始的ESIFiller(圖7(c))對(duì)比可看出,部分硫磺鐵粉等物質(zhì)被微生物消耗利用,包埋顆粒表面稍有缺失,但整體骨架結(jié)構(gòu)未發(fā)生破碎、裂解等變化,表明ESIFiller具有較好的機(jī)械強(qiáng)度與穩(wěn)定性,應(yīng)用前景好.

圖7 SEM表征結(jié)果及ESI Filler實(shí)物圖

2.3.2 微生物群落結(jié)構(gòu)組成分析 在對(duì)樣品A1,樣品A2中的微生物結(jié)構(gòu)組成進(jìn)行門水平上的分析,由圖8(a)所示.在門水平上,Proteobacteria(變形菌門)占比最高,豐度分別為46.02%、94.72%.Zhang等[3]實(shí)驗(yàn)也證明了Proteobacteria是硫-鐵協(xié)同自養(yǎng)反硝化體系的優(yōu)勢(shì)菌門.Proteobacteria為細(xì)菌中最大的一門,包含了大量具有NO3--N、NO2--N還原作用的相關(guān)細(xì)菌,屬于革蘭氏陰性菌[33-34].

對(duì)A1、A2兩種反應(yīng)體系中的群落結(jié)構(gòu)組成進(jìn)一步進(jìn)行屬水平上的分析.由圖8(b)可知,(硫桿菌屬)在2個(gè)反應(yīng)體系中均占比最高,分別可達(dá)40.55%、80.79%.ESIFiller反應(yīng)器在運(yùn)行模擬廢水階段結(jié)束后,豐度增加40.24%,這也證實(shí)了SEM電鏡的觀察結(jié)果.是較早被發(fā)現(xiàn)的具有自養(yǎng)反硝化功能的優(yōu)勢(shì)菌屬,其中[35]屬于專性無(wú)機(jī)化能自養(yǎng)型細(xì)菌,可以以還原性硫(S2-、S0、S2O32-等)為電子供體,NO3--N和NO2--N為電子受體,將其還原為N2,在地球的N、S循環(huán)中起著重要的作用.

(鐵氧化菌屬)具有氧化Fe2+還原NO3--N的特性,是鐵自養(yǎng)反硝化中常見的一種菌屬,也是以上2個(gè)反應(yīng)體系中存在的主要鐵自養(yǎng)反硝化菌之一[8].屬中的反硝化硫單胞菌()也是一種典型的自養(yǎng)反硝化菌,除可以利用還原性硫外,還可利用H2還原NO3-[36].在馴化菌泥中含量較高,反應(yīng)器運(yùn)行階段含量較少.這說(shuō)明較更適合硫-鐵協(xié)同自養(yǎng)反硝化系統(tǒng).

3 結(jié)論

3.1 在ESIFiller反應(yīng)器中,進(jìn)水NO3--N濃度30mg/L時(shí),HRT從10h縮短至2.5h后,出水NO3--N去除率由99.80%降低至61.35%.控制HRT為2.5h,進(jìn)水NO3--N濃度由15mg/L升至45mg/L時(shí),NO3--N去除率由85.8%變?yōu)?2.1%,反應(yīng)體系穩(wěn)定性較高.

3.2 ESIFiller反應(yīng)器SO42-的實(shí)際生成量整體上要低于硫自養(yǎng)反硝化理論值,表明鐵自養(yǎng)反硝化可分擔(dān)部分脫氮負(fù)荷.進(jìn)水pH值和DO變化對(duì)反應(yīng)器脫氮效果影響較小;溫度對(duì)系統(tǒng)影響較大,當(dāng)溫度從35℃降低至15℃,NO3--N平均去除率由90.12%降低至68.80%.

3.3 對(duì)微生物群落組成進(jìn)行分析,硫-鐵自養(yǎng)反硝化動(dòng)態(tài)實(shí)驗(yàn)結(jié)束后,主要功能菌的豐度較接種污泥相比增加了40.24%.

3.4 包埋填料經(jīng)歷164d的運(yùn)行,球體未出現(xiàn)破裂散落的現(xiàn)象,表現(xiàn)出較長(zhǎng)的使用壽命;結(jié)合掃描電鏡分析,其結(jié)構(gòu)有利于細(xì)菌在填料上正常生長(zhǎng)代謝.

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Preparation and autotrophic denitrification properties of embedded sulfur/iron biological filler.

LIU Yan-fang1, LIU Xiao-shuai1, YIN Si-jie1, GAO Wei2, ZHANG Miao-yu1, HAN Yan-he3, LI Zai-xing1*

(1.School of Environmental Science and Engineering, Hebei University of Science and Technology, Shijiazhuang 050018, China；2.School of Civil Engineering, Hebei University of Science and Technology, Shijiazhuang 050018,China；3.Department of Environmental Engineering, Beijing Institute of Petrochemical Technology, Beijing 102617, China)., 2022,42(11)：5136～5143

The embedded sulfur/iron biological filler (ESI Filler) was prepared by embedding and immobilization technology, and dynamic experimental research was carried out based on the upflow autotrophic denitrification reactor. By changing hydraulic retention time (HRT), pH, dissolved oxygen (DO) and other operating conditions, the denitrification performance and microbial community structure composition of ESI Filler reactor were explored. When the influent nitrate nitrogen (NO3--N) concentration was 30mg/L and the HRT was 10h, the NO3--N removal rate increased continuously to 99.80%. When the HRT was shortened to 2.5h, the removal rate of NO3--N decreased to about 61.35%. ESI Filler reactor had high stability to the changes of pH and DO, and the average removal rate of NO3--N could be maintained above 82.5%. However, the tolerance to low temperature was poor. When the temperature was reduced from 35℃ to 15℃, the average removal rate of NO3--N decreased from 90.12% to 68.80%. After running for 164days, the spheres did not break and scatter, showing a long service life. It was found by scanning electron microscopy that the surface of the filler was loose and porous, and a large number of rod-shaped bacteria were attached, which had become a good carrier of microorganisms. The results of high-throughput sequencing showed that the dominant bacterial genus in the embedded granules was the typical autotrophic denitrifying bacteria, with an abundance of 80.79%.

sulfur autotrophic denitrification；iron autotrophic denitrification；embedding filler；denitrification stability；microbial properties

X703.1

A

1000-6923(2022)11-5136-08

劉艷芳(1984-),女,河北石家莊人,副教授,博士,主要從事水污染控制技術(shù)研究.發(fā)表論文20余篇.

2022-04-06

河北省重點(diǎn)研發(fā)計(jì)劃項(xiàng)目(19273601D)

*責(zé)任作者, 教授, li_zaixing@163.com