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1、好氧顆粒污泥溶解氧傳遞孫賀江(天津大學(xué)環(huán)境科學(xué)與工程學(xué)院,天津300072)摘要:假定顆粒污泥為球狀,通過實(shí)驗(yàn)確定動(dòng)力學(xué)參數(shù),建立氧傳質(zhì)模型并進(jìn)行了驗(yàn)證。結(jié)果表明,利用失活顆粒污泥DO變化,得出顆粒污泥氧擴(kuò)散系數(shù)為0·45×10-9m2·s-1;利用燒杯實(shí)驗(yàn),得出了氧比消耗速率0·10gO2·(gMLSS)-1·h-1,氧半飽和常數(shù)為0·65mg·L-1。模型求解發(fā)現(xiàn),表面DO越大,DO梯度越大,顆粒污泥表面徑向傳質(zhì)能力越強(qiáng),氧穿透顆粒污泥的距離越遠(yuǎn),但是粒徑很大時(shí)(如半徑1·5mm),雖然表面DO為4·0mg·L-1,但依然沒有穿透顆粒污泥,當(dāng)r/R為0·49~0·65之
2、間時(shí),DO梯度迅速為0;在顆粒污泥半徑很小(<0·5mm)時(shí),氧完全能穿透整個(gè)粒徑,同時(shí)梯爾模數(shù)足夠小,內(nèi)擴(kuò)散有效因子接近1不變,氧擴(kuò)散可忽略不計(jì);對于相同的梯爾模數(shù),表面DO高時(shí),內(nèi)擴(kuò)散有效因子越大,說明氧擴(kuò)散的動(dòng)力越強(qiáng)、受限制的程度越小。關(guān)鍵詞:好氧顆粒污泥;氧傳遞;梯爾模數(shù);內(nèi)擴(kuò)散有效因子OxygentransferinaerobicgranularsludgeSunHejiang(SchoolofEnvironmentalScienceandEngineering,TianjinUniversity,Tianjin300072,China)Abstract:Oxyg
3、entransferislimitedinaerobicgranulesbycompactmicrobialspatialstructure·Aerobicgranulesweresupposedtobespherical,andkineticparameterswerecalculatedthroughtests·Asimplifiedequationofmassbalanceforsteady-statediffusionofoxygenwassetupandverified·Effectivediffusivitywas0·45×10-9m2·s-1,throughd
4、issolvedoxygen(DO)changeofdeactivatedgranularsludge.Oxygenspecificconsumptionrateandoxygenhalfsaturationcoefficientwere0·10gO2·(gMLSS)-1·h-1and0·65mg·L-1throughbeakertestundertheconditionofCOD400mg·L-1andNH4-N100mg·L-1.Thehighertheoxygenconcentrationandconcentrationgradient,thestrongerandt
5、hefurtheroxygencouldpenetrate·Whentheradiusofgranularsludgewasmorethan1·5mm,oxygencouldnotpenetrate,despiteoxygenconcentrationwas4·0mg·L-1·Whenr/Rwasbetween0·49and0·65,theconcentrationgradientbecamezero·Whentheradiuswasverysmall(lessthan0·5mm),oxygencouldfullypenetrateintogranules·Atthesam
6、etime,Thielemoduluswasverysmallandeffectivenessfactorwasnearto1,oxygendiffusionlimitationcouldbeneglected·Effectivenessfactorwaslargerwiththeincreaseofoxygenconcentration,whichmadeoxygenlimitationless.Keywords:aerobicgranularsludge;oxygentransfer;Thielemodulus;effectivenessfactor 引 言好氧顆粒污泥
7、技術(shù)是一種新型的生物膜法工藝,沉降速度快、反應(yīng)活性高,其密實(shí)的微生物立體空間結(jié)構(gòu)對液固間氧傳遞的限制作用,形成同步硝化反硝化的微環(huán)境[1-6],但也可能會(huì)限制整個(gè)反應(yīng)器的處理能力。Martijn等[7]在上流式反應(yīng)器中對氣體含固率和質(zhì)量傳遞進(jìn)行了研究,確定了氧氣液傳質(zhì)系數(shù)。Paul等[8]和Su等[9]對顆粒污泥的氧傳質(zhì)進(jìn)行了研究,認(rèn)為顆粒污泥反應(yīng)器氣液間氧傳遞過程仍符合雙膜理論,而液固間氧傳遞過程則可忽略不計(jì);同時(shí)Su等[9]建立了好氧顆粒的氧傳質(zhì)模型,但沒有對模型進(jìn)行驗(yàn)證。本研究假定好氧顆粒污泥為球狀,僅考慮D