劉昌庚,伍 斌,謝四才

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Fe(II)活化過一硫酸鹽氧化調(diào)理剩余活性污泥

劉昌庚*,伍 斌,謝四才

(攀枝花學(xué)院資源與環(huán)境工程學(xué)院,四川攀枝花 617000)

采用Fe(II)活化過一硫酸鹽(Fe(II)-PMS)氧化對(duì)剩余活性污泥進(jìn)行調(diào)理研究.結(jié)果表明,Fe(II)-PMS氧化能有效改善污泥的脫水性能;在優(yōu)化實(shí)驗(yàn)條件下(pH為6.7,Fe(II)和PMS投量分別為60和120mg/gTSS),標(biāo)準(zhǔn)化毛細(xì)吸附時(shí)間(SCST=CST0/CST)和毛細(xì)吸附時(shí)間(CST)減少率分別為11.28和91.13%.Fe(II)-PMS氧化有助于污泥穩(wěn)定性提高和組分溶出,處理后VSS減少率為15.74%、上清液中TN和TOC的含量較初始值分別增加6.21和9.13倍.此外,研究表明Fe(II)-PMS氧化能有效破解和降解胞外聚合物(EPS)(特別是蛋白質(zhì)),釋放出EPS結(jié)合水,進(jìn)而顯著改善污泥脫水性能.

過一硫酸鹽；脫水性能；剩余活性污泥；毛細(xì)吸附時(shí)間

1 材料與方法

1.1 實(shí)驗(yàn)材料

牛血清蛋白為生化試劑,其他試劑均為分析純?cè)噭?供試污泥取自攀枝花市某污水處理廠的污泥濃縮池,取回后自然沉淀12h,去掉上清液后將污泥存放于4℃的冰箱中,其基本性質(zhì)如表1.

表1 供試剩余活性污泥的基本性質(zhì)

注:a為污泥上清液中濃度.

1.2 實(shí)驗(yàn)方法

取200mL供試剩余活性污泥于500mL錐形瓶中,然后預(yù)熱至室溫(~20℃);隨后考察不同初始pH、Fe(II)及PMS投量對(duì)污泥脫水性能的影響.pH采用濃度為2mol/L的硫酸和氫氧化鈉調(diào)節(jié),待pH調(diào)至設(shè)置值后,同時(shí)加入Fe(II)及PMS進(jìn)行氧化調(diào)理,并以120r/min的速度攪拌至結(jié)束.在處理過程中,按預(yù)先設(shè)定時(shí)間取樣5mL用于測(cè)定毛細(xì)吸附時(shí)間(CST).為保證實(shí)驗(yàn)數(shù)據(jù)可靠性,每組實(shí)驗(yàn)重復(fù)操作3次.

1.3 分析方法

pH值和毛細(xì)吸附時(shí)間分別利用酸度計(jì)(雷磁,PHS-3C)和CST測(cè)定儀(304B,英國Triton公司)測(cè)定;總懸浮固體(TSS)和揮發(fā)性懸浮固體(VSS)采用重量法測(cè)定;EPS分層方法詳見文獻(xiàn)[13],多糖和蛋白質(zhì)濃度分別采用硫酸-蒽酮法和考馬斯亮藍(lán)G-250法測(cè)定[13,16];上清液中總氮(TN)和總有機(jī)碳(TOC)含量利用TOC/TN分析儀測(cè)定(TOC-L,日本Shimadzu公司).標(biāo)準(zhǔn)化毛細(xì)吸附時(shí)間(SCST)用于表征污泥的脫水性能,SCST值越大,污泥脫水性能越好,其計(jì)算式如下:

式中:CST0和CST分別表示污泥處理前后的毛細(xì)吸附時(shí)間.

2 結(jié)果與討論

2.1 pH對(duì)污泥脫水性能的影響

相比Fenton氧化,Fe(II)-PMS氧化調(diào)理污泥受初始pH值影響較小,可在污泥原始pH值條件下取得較好的脫水效率;而Fenton氧化則需在酸性條件才能獲得較好的污泥脫水效率,但是在極酸性條件下,其氧化效率會(huì)因[Fe(H2O2)]2+的形成而嚴(yán)重受到抑制[20].由圖1可知,在反應(yīng)20min后,pH值為3、5、6.7、9時(shí)的SCST值分別為6.32、8.95、11.18、3.24,對(duì)應(yīng)CST減少率分別為84.18%、88.83%、91.06%、69.14%.因此,可推斷出pH值并非Fe(II)-PMS氧化改善污泥脫水性能的主要影響因素.該研究結(jié)果與前期Zhen等[7]報(bào)道的結(jié)論相似,他們指出Fe(II)活化過硫酸鹽(Fe(II)-PDS)氧化能在較廣pH范圍內(nèi)(3.0~8.5)顯著改善污泥的脫水性能.由以上研究結(jié)果可知,Fe(II)-PMS氧化改善污泥脫水性能在成本控制和處理效率方面均具有優(yōu)勢(shì).

圖1 pH值對(duì)污泥脫水性能的影響

2.2 Fe(II)和PMS投量對(duì)污泥脫水性能的影響

2.3 Fe(II)-PMS氧化對(duì)污泥組分溶出的影響

本研究還探究了Fe(II)-PMS氧化對(duì)污泥穩(wěn)定性的改善效果.在優(yōu)化條件下,污泥經(jīng)Fe(II)- PMS氧化處理后,VSS減少率為15.74%.VSS減少率是污泥穩(wěn)定性的重要指標(biāo),VSS減少率越高,污泥穩(wěn)定性能越好[26].因此,Fe(II)-PMS氧化有利于提高污泥穩(wěn)定性.最近,Kim等[25]指出污泥經(jīng)熱活化PMS和PDS處理后,VSS減少率分別為4.9%~15.4%和4.1%~7.7%.此外,Chen等[14]同樣指出PMS較PDS氧化更能有效的降解有機(jī)物.因此,活化PMS氧化較活化PDS氧化可能更有助于提高污泥的穩(wěn)定性.

圖4 Fe(II)-PMS氧化處理后VSS減少率、上清液中TN和TOC的濃度

2.4 Fe(II)-PMS氧化對(duì)EPS的影響

EPS是污泥的重要組成部分,可分為黏液層EPS(S-EPS)、松散結(jié)合EPS(LB-EPS)和緊密結(jié)合EPS(TB-EPS)[13].EPS主要由蛋白質(zhì)和多糖組成,這兩者可占其總質(zhì)量的70%~80%,是影響污泥脫水性能的主要因素[7,27].本研究為考察Fe(II)-PMS氧化對(duì)污泥EPS破解的影響,在優(yōu)化條件下氧化處理前后EPS各層中蛋白質(zhì)和多糖的變化如圖5所示.由圖可知,原始污泥蛋白質(zhì)和多糖含量分別為413.34和60.47mg/L,且主要存在于S-EPS和TB-EPS層中.經(jīng)Fe(II)-PMS氧化后,蛋白質(zhì)含量迅速下降至91.46mg/L;而多糖含量則輕微增加至65.14mg/L.鑒于蛋白質(zhì)含量大量減少的同時(shí)污泥脫水性能得到顯著改善,因此可推測(cè)出EPS中蛋白質(zhì)含量對(duì)污泥的脫水性能的改善具有負(fù)面的影響.

圖5 Fe(II)-PMS氧化處理后蛋白質(zhì)和多糖在EPS各層中的濃度

3 結(jié)論

3.1 Fe(II)-PMS氧化能顯著改善污泥的脫水性能.優(yōu)化實(shí)驗(yàn)條件:pH為6.7,Fe(II)和PMS投量分別為60和120mg/gTSS.此時(shí),SCST值為11.28,CST減少率為91.13%.

3.2 Fe(II)-PMS氧化有助于污泥穩(wěn)定性提高和組分溶出.在優(yōu)化條件下,VSS減少率為15.74%、上清液中TN和TOC的含量較初始值分別增加6.21和9.13倍.

3.3 Fe(II)-PMS氧化處理污泥能有效破解和降解EPS(特別是蛋白質(zhì)),釋放出EPS結(jié)合水,進(jìn)而顯著改善污泥脫水性能.

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Conditioning of excess activate sludge by Fe(II)-activated peroxymonosulfate oxidation.

LIU Chang-geng*, WU Bin, XIE Si-cai

(School of Resources and Environmental Engineering, Panzhihua University, Panzhihua 617000, China)., 2017,37(10)：3794~3799

Fe(II)-activated peroxymonosulfate (Fe(II)-PMS) oxidation applied to condition excess activated sludge was investigated in this work. The results showed that Fe(II)-PMS oxidation could effectively improve sludge dewaterability. The optimal pH and dosages of Fe(II) and PMS were 6.7, 60mg/gTSS, and 120mg/gTSS, respectively, under which the standardized-capillary suction time (SCST=CST0/CST) and CST reduction were 11.28 and 91.13%, respectively.Fe(II)-PMS oxidation was also favor of sludge solubilization and enhanced stabilization. Under the optimum experimental conditions, VSS reduction was 15.74% and the concentrations of TN and TOC in the supernatant increased 6.21 and 9.13-fold compared to their initial values, respectively. In addition, Fe(II)-PMS oxidation was beneficial to destroy and degrade extracellular polymeric substances (EPS) (especially for proteins), which resulted in the release of EPS-bound water and subsequently improved sludge dewaterability significantly.

peroxymonosulfate；dewaterability；excess activated sludge；capillary suction time

X703.1

A

1000-6923(2017)10-3794-06

劉昌庚(1985-),男,四川宜賓人,副教授,博士,主要從事高級(jí)氧化技術(shù)及大氣環(huán)境化學(xué)研究.發(fā)表論文20余篇.

2017-03-17

國家自然科學(xué)基金資助項(xiàng)目(21607088);攀枝花學(xué)院博士基金資助項(xiàng)目(0210600022);攀枝花市科技計(jì)劃資助項(xiàng)目(2015TX-8);干熱河谷特色生物資源開發(fā)四川省高校重點(diǎn)實(shí)驗(yàn)室開放基金資助項(xiàng)目(GR-2017-E-04)

* 責(zé)任作者, 副教授, changwyx@163.com