Hauv kev ua haujlwm niaj hnub ntawm kev kho dej khib nyiab, ob lo lus feem ntau hnov: nitrification thiab denitrification. Ntau tus neeg uas tshiab rau kev kho cov dej khib nyiab yuav ua rau ob lub ntsiab lus tsis meej pem. Txawm hais tias lawv cov npe zoo sib xws, ob qho tib si hloov mus ib puag ncig tus cwj pwm "硝", lawv tau ua lub luag haujlwm sib txawv hauv kev kho dej khib nyiab.
Hauv cov ntsiab lus yooj yim, nitrification yog lub luag haujlwm rau kev hloov cov ammonia nitrogen rau hauv nitrate, thaum denitrification yog lub luag haujlwm rau hloov nitrate rau hauv cov roj nitrogen. Ib qho yog txheej txheem oxidation, thiab lwm qhov yog txheej txheem txo. Cov txheej txheem ob yog zoo li kev sib tw sib tw, thiab tsuas yog thaum lawv ua tiav hauv kev sib koom tes tuaj yeem tshem tawm nitrogen hauv cov dej phwj tuaj tiag tiag.
Thaum lub ntsiab lus no tau nkag siab, lub logic tom qab ntau yam txheej txheem tshem tawm nitrogen, xws li A / O, AAO, thiab oxidation ditch, ua kom pom tseeb.
I. Nitrification: hloov ammonia nitrogen rau hauv nitrate
Hauv cov dej phwj hauv tsev thiab ntau cov dej khib nyiab, nitrogen feem ntau muaj nyob rau hauv daim ntawv ntawm ammonia nitrogen. Yog tias ammonia nitrogen raug tso tawm ncaj qha mus rau hauv lub cev dej, nws tuaj yeem yooj yim ua rau eutrophication thiab tseem ua rau muaj kev phom sij rau cov kab mob hauv dej xws li ntses. Yog li ntawd, cov chaw kho dej khib nyiab yuav tsum tau hloov cov ammonia nitrogen ua ntej.
Txoj kev hloov pauv no hu ua nitrification.
Nitrification yog ib qho txheej txheem oxidation ua los ntawm cov kab mob, uas tuaj yeem muab faib ua ob theem:
Thawj kauj ruam yog oxidation ntawm ammonia nitrogen rau hauv nitrite
Kauj Ruam 2: Nitrate yog ntxiv oxidized rau nitrate
Tag nrho cov txheej txheem yuav tsum muaj cov pa oxygen txaus, yog li nitrification feem ntau tshwm sim nyob rau hauv ib puag ncig aerobic, xws li aeration tanks lossis MBR biochemical tanks.
Cov kab mob uas koom nrog hauv cov txheej txheem no yog hu ua nitrifying kab mob. Lawv txawv ntawm cov kab mob heterotrophic zoo tib yam nyob rau hauv uas lawv muaj nyob rau hauv qeb autotrophic, feem ntau muab lub zog los ntawm cov tshuaj inorganic. Lawv qhov kev loj hlob qeeb qeeb, thiab lawv kuj tseem ceeb rau kev hloov pauv ib puag ncig.
Qhov no kuj yog vim li cas ntau lub chaw kho dej khib nyiab yuav muaj kev poob qis hauv nitrification peev thaum lub caij ntuj no.
II. Denitrification: hloov nitrate mus rau nitrogen gas
Txawm hais tias nitrification tau daws qhov teeb meem ntawm ammonia nitrogen, nitrogen hauv dej tsis tau ploj mus tiag tiag ntawm qhov no; nws tsuas yog hloov los ntawm ib daim ntawv mus rau lwm qhov. Yuav kom "tshem" nitrogen los ntawm cov dej khib nyiab tiag tiag, cov kauj ruam thib ob - denitrification - yuav tsum ua kom tiav.
Denitrification yog ib qho kev txo qis. Hauv ib puag ncig anaerobic, cov kab mob me me siv cov pa oxygen hauv nitrate, maj mam txo nws mus rau cov roj nitrogen. Txoj kev tshuaj tiv thaiv yog kwv yees li hauv qab no:
Nitrate → Nitrite → Nitrous Oxide → Nitrous Oxide → Nitrogen
Thaum kawg generated nitrogen gas (N₂)* yuav tso tawm rau hauv cov huab cua nyob rau hauv gaseous daim ntawv, yog li cov nitrogen nyob rau hauv cov dej phwj yog tiag tiag tshem tawm. Cov kab mob uas ua tiav cov txheej txheem no hu ua denitrifying bacteria. Tsis zoo li cov kab mob nitrifying, lawv yog cov kab mob heterotrophic thiab xav tau cov pa roj carbon monoxide ua lub zog.
Qhov no kuj yog vim li cas ntau lub chaw kho dej khib nyiab yuav tsum tau ntxiv cov pa roj carbon monoxide thaum tshem tawm nitrogen.
III. Ntau qhov sib txawv tseem ceeb ntawm nitrification thiab denitrification
Yog tias peb saib ob txoj haujlwm no ua ke, peb yuav pom tias lawv tau tawm tsam diametrically hauv ntau yam.
1. Cov pa oxygen sib txawv
Nitrification yuav tsum tshwm sim nyob rau hauv ib qho chaw aerobic, feem ntau yuav tsum tau yaj cov pa oxygen kom tswj tau ntawm ib ncig ntawm 2 mg / L.
Denitrification yuav tsum muaj ib qho chaw anaerobic nrog cov pa oxygen uas nyob hauv qab 0.5 mg / L. Yog tias muaj cov pa ntau dhau, cov kab mob denitrifying yuav nyiam siv cov pa oxygen ntau dua li nitrate.
Hauv cov ntsiab lus yooj yim, nitrification thrives hauv oxygen, thaum denitrification yog inhibited los ntawm oxygen.
2. Cov kab mob sib txawv
Nitrification feem ntau ua tiav los ntawm cov kab mob nitrifying, uas suav nrog nitrosomonas thiab nitrobacter.
Cov kab mob no yog cov kab mob autotrophic, uas loj hlob qeeb thiab xav tau lub hnub nyoog sludge ntev dua.
Denitrification yog ua los ntawm cov kab mob denitrifying, uas yog nyob rau hauv pawg kab mob heterotrophic thiab nthuav tawm qhov kev loj hlob sai.
3. Cov pa roj carbon ntau qhov yuav tsum tau ua
Nitrifying kab mob feem ntau siv cov tshuaj inorganic rau lub zog thiab feem ntau tsis cia siab rau cov organic carbon.
Denitrifying kab mob yuav tsum tau cov organic carbon raws li ib tug electron pub. Yog li ntawd, thaum muaj cov organic teeb meem hauv cov dej khib nyiab tsis txaus, feem ntau yuav tsum tau ntxiv cov pa roj carbon monoxide xws li sodium acetate, methanol, thiab qabzib.
Hauv kev ua haujlwm ntawm ntau cov nroj tsuag dej khib nyiab, cov pa roj carbon tsis txaus feem ntau yog qhov tseem ceeb cuam tshuam rau kev tshem tawm nitrogen.
4. Qhov chaw ntawm qhov tshwm sim txawv
Hauv cov txheej txheem tshem tawm nitrogen ntau, ob feem ntau yog teem rau hauv cov tshuaj tiv thaiv sib txawv.
Piv txwv li, hauv A / O lossis AAO cov txheej txheem:
Anoxic tank - Denitrification Aerobic tank - Nitrification
Cov nitrate uas ua los ntawm nitrification rov qab mus rau thaj tsam anoxic ntawm sab hauv recirculation, qhov uas nws tau hloov dua tshiab los ntawm cov kab mob denitrifying.
5. Cov txiaj ntsig kawg sib txawv
Qhov tshwm sim ntawm nitrification yog txo qis hauv ammonia nitrogen thiab nce nitrate
Qhov tshwm sim ntawm denitrification yog: txo cov nitrate thiab tsim cov roj nitrogen
Hauv lwm lo lus, nitrogen tsuas tuaj yeem tawm hauv lub cev dej tom qab denitrification tiav.
IV. lawv yeej yog ib haiv neeg relay
Los ntawm txoj kev xav holistic, nitrification thiab denitrification tsis yog ob txoj kev ywj pheej, tab sis ob kauj ruam sib law liag hauv kev tshem tawm nitrogen lom.
Tag nrho cov txheej txheem hloov pauv nitrogen tuaj yeem nkag siab yooj yim xws li:
Ammonia nitrogen → Nitrite nitrogen → Nitrate nitrogen → Nitrite nitrogen → Nitrogen roj
Nitrification yog lub luag haujlwm rau kev hloov cov ammonia nitrogen rau hauv nitrate, thaum denitrification yog lub luag haujlwm txo nitrate rov qab rau cov roj nitrogen.
Ob qho tib si txuas zoo li kev sib tw sib tw.
Yog tias tsuas muaj nitrification thiab tsis muaj denitrification, nitrate hauv dej tseem yuav ua rau eutrophication.
Yog tias tsis muaj nitrification, yuav muaj qhov tsis muaj "cov ntaub ntawv raw" rau denitrification.
Qhov no kuj yog vim li cas feem ntau cov txheej txheem tshem tawm nitrogen suav nrog ob qho chaw aerobic thiab anoxic.
V. Xaus
Hauv kev kho dej khib nyiab, ntau lub tswv yim yuav tshwm sim zoo ib yam, tab sis lub hauv paus ntsiab lus yog txawv kiag li.
Nitrification thiab denitrification yog ib khub zoo.
Ib qho tshwm sim hauv ib puag ncig aerobic, thaum lwm qhov tshwm sim hauv ib puag ncig anaerobic;
Ib tug yog lub luag hauj lwm rau oxidizing ammonia nitrogen, thiab lwm yam yog lub luag hauj lwm rau txo nitrate;
Tsuas yog thaum ob qhov sib xyaw ua ke tuaj yeem tsim ua tiav cov txheej txheem tshem tawm nitrogen.
Tau nkag siab qhov no, thaum peb saib ntau yam txheej txheem tshem tawm nitrogen, xws li A / O, AAO, thiab oxidation ditch, peb tuaj yeem pom tias lawv tau ua kom zoo dua qub thiab ua ke ntawm ob kauj ruam no.
Ntau cov txheej txheem nyuaj hauv kev kho cov dej phwj tuaj, hauv kev txheeb xyuas zaum kawg, yog qhov tsim nyog tsim "kev ua haujlwm" rau cov kab mob no.