| Abstract | U ovom radu istražena je denitrifikacija sa aktivnim muljem podrijetlom iz uređaja za obradu komunalne otpadne vode sa tri različita izvora ugljika: natrijev acetat, metanol i otpadna voda. Određena je specifična brzina denitrifikacije, C/N omjer i učinkovitost denitrifikacije. Pokusi su provedeni pri anoksičnim uvjetima u šaržnim bioreaktorima volumena 600 mL, temperaturi 22-23°C, koncentraciji otopljenog kisika manjoj od 0,4 mg/L i koncentraciji biomase 3,2-5,9 gs.tv./L. Uporaba acetata i otpadne vode ima prednost pred uporabom metanola za denitrifikaciju. Uz natrijev acetat potreban omjer C/N za denitrifikaciju 33,5±2,5 mg/L je iznosio 3,38. Postignuto je smanjenje KPK i NO3-N 49% i 98,8%, uz specifičnu brzinu denitrifikacije NO3-N 3,7 mgNO3-N/g s.tv.h. Uz metanol kao izvor ugljika 98,5% smanjenje NO3-N i 70 % smanjenje KPK postignuto je uz omjer C/N 0,767 uz specifičnu brzinu denitrifikacije 0,2-0,27 mg NO3-N/gs.tv.h. Za otpadnu vodu potreban omjer KPK/N je bio 12 za smanjenje NO3-N za 96,7%. Denitrifikacija se provodi tako da se prvo utroše lako biorazgradivi sastojci uz maksimalnu specifičnu brzinu denitrifikacije 2,79 mgNO3-N/gs.tv.h, potom slijedi denitrifikacija uz uporabu teže biorazgradivog KPK uz brzinu od 0,9 mgNO3-N/gs.tv.h, te na kraju uz brzinu 0,26 mgNO3-N/gs.tv.h. Optimalni omjer C/N s acetatom bi trebao biti između 2,46 i 3,38 pri čemu bi se postigle zakonom dopuštene vrijednosti za KPK. Metanol zahtijeva prilagodbu aktivnog mulja. Pretpostavlja se da je u otpadnoj vodi prisutna teško biorazgradiva frakcija KPK koja se tijekom procesa denitrifikacije ne koristi i preostaje u suspenziji. |
| Abstract (english) | This paper investigated the denitrification with activated sludge originating from the municipal wastewater treatment plant with 3 different carbon sources: sodium acetate, methanol and wastewater. It was determined specific denitrification rate, C/N ratio and the efficiency of denitrification. Experiments were conducted under anoxic conditions in batch bioreactors volume of 600 mL, temperature 22-23 ° C, dissolved oxygen concentrations less than 0.4 mg/L and the biomass concentration from 3.2 to 5.9 g/L. The use of acetate and wastewater has the advantage over the use of methanol for denitrification. With sodium acetate required C/N ratio for denitrification of 33.5 ± 2.5 NO3-N mg/L was 3.38. COD and NO3-N reduction was of 49% and 98.8%, respectively, with a specific rate of denitrification of 3.7 mgNO3-N/gTSSh. With methanol as a carbon source 98.5% reduction of NO3-N and 70% COD reduction was achieved with a ratio C/N 0.767 and specific denitrification rate from 0.2 to 0.27 mgNO3-N/gTSSh. For the wastewater COD/N ratio required to reduce NO3-N for 96.7% was 12. Denitrification was carried out by first spending easily biodegradable ingredients with maximum specific denitrification rate of 2.79 mgNO3-N/gTSSh, followed by denitrification with hardly biodegradable COD and lower specific denitrification rate of 0.9 mgNO3-N/gTSSh, and finally with 0.26 mgNO3-N/gTSSh. The optimum ratio of C/N with acetate should be between 2.46 and 3.38 to achieve legally permissible values for COD. Methanol requires adaptation of activated sludge. It is assumed that in wastewater was present difficult biodegradable fraction of COD that was not used during denitrifcation and remained in the suspension. |
