Bioaugmentation in LWA-filled horizontal subsurface flow filters for wastewater treatment: Impact of flow regime, temperature and donor system
Kuupäev
2010-11-16
Autorid
Ajakirja pealkiri
Ajakirja ISSN
Köite pealkiri
Kirjastaja
Abstrakt
Doktoritöös uuritakse lämmastikuärastuse efektiivsuse tõstmist hübriidses reoveepuhastus-tehismärgalas, kasutades tagasipumpamise erinevaid režiime ning spetsiifilise mikroobikoosluse lisamist ehk bioaugmentatsiooni. Tagasipumpamise mõju osutus selgelt lämmastikuärastust parandavaks meetmeks, mistõttu edaspidi keskenduti seni vähem uuritud küsimusele, kas vastrajatud hübriidse tehismärgala horisontaalvoolulise filtri denitrifikatsioonivõimet ja lämmastikuärastust saab kiirendada, kasutades selleks bioaugmentatsiooni. Erinevate katsete käigus uuriti olmereovett puhastava kergkruusa täidisega horisontaalse pinnasfiltri lämmastikuärastuse parandamist hästi toimiva hübriidse tehismärgala sarnase substraadiga horisontaalfiltrist võetud mikroobikoosluse lisamise teel. Esimeses katses viidi bioaugmentatsioon läbi talvel ja katseperioodi jooksul rakendati madalat hüdraulilist koormust. Selgus, et vastrajatud horisontaalvoolulistesse mesokosmidesse viidud mikroobikooslus jäi elama ja paljunes ning bioaugmentatsiooni tulemusel võis töödeldud mesokosmides katseperioodi jooksul täheldada denitrifikatsiooni intensiivistumist. Teises katses toimus bioaugmentatsioon soojal aastaajal ja suure hüdraulilise koormuse juures kahest sarnase substraadiga, aga erineva voolurežiimiga doonorsüsteemist võetud mikroobikooslusega. Katsete tulemusel leiti, et sarnase voolurežiimiga doonorsüsteemist pärineva mikroobikooslusega bioaugmenteeritud mesokosmide väljavoolude nitraadikontsentratsioon oli oluliselt madalam kontrollmesokosmide omast, samas aga erineva režiimiga süsteemist võetud kooslusega bioaugmentatsioonil olulist mõju ei olnud. Kokkuvõttes võib öelda, et hübriidsele tehismärgalale vajaliku denitrifikatsioonivõime kujunemist saame oluliselt kiirendada, lisades mikroobikooslust, mis on võetud sarnaste tingimustega hästi toimivast tehismärgalast.
The possibilities of enhancing nitrogen removal in hybrid compact constructed wetlands (CW) were examined in this PhD thesis. Different recirculation regimes and amendment with a specific microbial community (bioaugmentation) were used. Since the usage of recirculation gave visibly positive results, the study concentrated primarily on the question of whether bioaugmentation could help to enhance nitrogen removal in the horizontal subsurface flow (HSSF) filter of a newly established hybrid compact CW. During different trials, the use of bioaugmentation to enhance the denitrification of a light weight aggregates (LWA)-based horizontal subsurface flow filter receiving pre-treated municipal wastewater was studied. In the first trial, bioaugmentation was performed in the cold season, and low hydraulic loading was applied. This experiment offers evidence of the survival and reproduction of introduced microbes, and also resulted in a trend towards higher and more stable denitrification during the study period. In the second trial, bioaugmentation was performed in the warm season, and high hydraulic loading was applied. Two HSSF filters with the same LWA substrate but different wastewater flow regimes were used as donor systems for the bioaugmentation. We found that mesoocosms (MCs) bioaugmented with the sediment suspension from a similar HSSF had significantly lower NO3-N concentrations than the control MCs, whereas MCs bioaugmented with the sediment suspension from an HSSF with a different flow regime did not show significant differences compared to the control MCs. This finding shows that denitrification in newly-built hybrid CWs can be significantly enhanced by adding a microbial community taken from a well-functioning CW that has similar conditions to the new system.
The possibilities of enhancing nitrogen removal in hybrid compact constructed wetlands (CW) were examined in this PhD thesis. Different recirculation regimes and amendment with a specific microbial community (bioaugmentation) were used. Since the usage of recirculation gave visibly positive results, the study concentrated primarily on the question of whether bioaugmentation could help to enhance nitrogen removal in the horizontal subsurface flow (HSSF) filter of a newly established hybrid compact CW. During different trials, the use of bioaugmentation to enhance the denitrification of a light weight aggregates (LWA)-based horizontal subsurface flow filter receiving pre-treated municipal wastewater was studied. In the first trial, bioaugmentation was performed in the cold season, and low hydraulic loading was applied. This experiment offers evidence of the survival and reproduction of introduced microbes, and also resulted in a trend towards higher and more stable denitrification during the study period. In the second trial, bioaugmentation was performed in the warm season, and high hydraulic loading was applied. Two HSSF filters with the same LWA substrate but different wastewater flow regimes were used as donor systems for the bioaugmentation. We found that mesoocosms (MCs) bioaugmented with the sediment suspension from a similar HSSF had significantly lower NO3-N concentrations than the control MCs, whereas MCs bioaugmented with the sediment suspension from an HSSF with a different flow regime did not show significant differences compared to the control MCs. This finding shows that denitrification in newly-built hybrid CWs can be significantly enhanced by adding a microbial community taken from a well-functioning CW that has similar conditions to the new system.
Kirjeldus
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Märksõnad
dissertatsioonid, reoveepuhastus