Abstract
An upgraded integrated fixed-film activated sludge-oxic settling anoxic (IFAS-OSA) system is a new technology for reducing nutrients and excess sludge. The results showed that the average TN removal efficiency of the IFAS-OSA system was gradually increased up to 7.5%, while the PO4–3-P removal efficiency increased up-to 27%, compared with that of the IFAS system. The COD removal efficiency of the IFAS-OSA system was slightly increased up-to 5.4% and TSS removal efficiency increased up to 10.5% compared with the control system. Biomass yield coefficient (Yobs) in the IFAS and IFAS-OSA systems were 0.44 and 0.24 (gr MLSS/ gr COD). Hence, sludge production decreased by 45%. The average SVI was decreased by 48% in IFAS-OSA system compared with IFAS. This study demonstrated the better performance of the IFAS-OSA system compared to that of the IFAS system.
Highlights
Abbreviations anoxic sludge holding tank (ASHT) Anoxic sludge holding tank biological nitrogen removal (BNR) Biological nutrient removal BOD Biological oxygen demand CAS Conventional activated sludge CFU Colony forming unit chemical oxygen demand (COD) Chemical oxygen demand DO Dissolved oxygen ESR Excess sludge reduction HRT Hydraulic retention time integrated fixed-film activated sludge (IFAS) Integrated fixed-film activated sludge IFAS-OSA Integrated fixed film activated sludge-oxic settling anoxic internal spacer region (ITS) Internal spacer region modified Ludzack-Ettinger (MLE) Modified Ludzack-Ettinger mixed liquor suspended solids (MLSS) Mixed liquor suspended solids NH4+-N Ammonium nitrogen NO3–N Nitrate nitrogen oxidation–reduction potential (ORP) Oxidation–reduction potential OLR Organic loading rate OSA Oxic-settling-anoxic OUR Oxygen uptake rate PCR–RFLP Polymerase chain reaction-restriction fragment length polymorphism PAO Phosphorus accumulating organisms PO4-3-P Orthophosphate-phosphorus Q Excess Excess sludge flow rate return activated sludge (RAS) Return activated sludge Sludge Biotic Index (SBI) Sludge biotic index Sabouraud Dextrose Agar (SDA) Sabouraud dextrose agar gig.eu
After reaching steady state condition, the IFAS and IFAS-OSA systems were operated in parallel mode for 60 days and their results were compared
The results show that the average ammonia nitrogen (NH4+-N) were 98 ± 0.2%, 97 ± 0.3% for the IFAS and IFAS-OSA systems, respectively
Summary
Abbreviations ASHT Anoxic sludge holding tank BNR Biological nutrient removal BOD Biological oxygen demand CAS Conventional activated sludge CFU Colony forming unit COD Chemical oxygen demand DO Dissolved oxygen ESR Excess sludge reduction HRT Hydraulic retention time IFAS Integrated fixed-film activated sludge IFAS-OSA Integrated fixed film activated sludge-oxic settling anoxic ITS Internal spacer region MLE Modified Ludzack-Ettinger MLSS Mixed liquor suspended solids NH4+-N Ammonium nitrogen NO3–N Nitrate nitrogen ORP Oxidation–reduction potential OLR Organic loading rate OSA Oxic-settling-anoxic OUR Oxygen uptake rate PCR–RFLP Polymerase chain reaction-restriction fragment length polymorphism PAO Phosphorus accumulating organisms PO4-3-P Orthophosphate-phosphorus Q Excess Excess sludge flow rate RAS Return activated sludge SBI Sludge biotic index SDA Sabouraud dextrose agar gig.eu. Treated sewage are carrying plenty of nutrients and micropollutants that pose serious threats to receiving r ivers[34] Another issue is the excess sludge which is generated from the biological treatment of wastewaters and must be disposed of in a safe and cost-effective manner for example in agricultural p roducts[15,23]. OSA technique is a suitable solution for enhancement organic matter and nutrient (N & P) pollutants removal which significantly reduces biological excess sludge This technology usually includes an aeration tank, a settling tank, and an anoxic/anaerobic tank in the return activated sludge line of the aerobic s ystems[1,33,35,37]
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