title: Granular activated algae for wastewater treatment.
abstract: The study used activated algae granules for low-strength wastewater treatment in sequential batch mode. Each treatment cycle was conducted within 24 h in a bioreactor exposed to 235 μmol/m²/s light intensity. Wastewater treatment was performed mostly in aerobic conditions, oxygen being provided by microalgae. High removal efficiency of chemical oxygen demand (COD) was achieved (86-98%) in the first hours of the reaction phase, during which the indicator's removal rate was 17.4 ± 3.9 mg O₂/g h; NH(4)(+) was removed during organic matter degradation processes with a rate of 1.8 ± 0.6 mg/g h. After almost complete COD removal, the (O⁺) remaining in the liquor was removed through nitrification processes promoted by the increase of the liquor's oxygen saturation (O₂%), the transformation rate of NH4(+) into NO(3)(-) increasing from 0.14 ± 0.05 to 1.5 ± 0.4 mg NH4(+)/g h, along with an O₂% increase. A wide removal efficiency was achieved in the case of PO(4)(3)(-) (11-85%), with the indicator's removal rate being 1.3 ± 0.7 mg/g h. In the provided optimum conditions, the occurrence of the denitrifying activity was also noticed. A large pH variation was registered (5-8.5) during treatment cycles. The granular activated algae system proved to be a promising alternative for wastewater treatment as it also sustains cost-efficient microalgae harvesting, with microalgae recovery efficiency ranging between 99.85 and 99.99% after granules settling with a velocity of 19 ± 3.6 m/h.
authors: National Research and Development Institute for Industrial Ecology - ECOIND, 71-73 Drumul Podu Dambovitei Street, 060652, Sector 6, Bucharest, Romania E-mail: costel.bumbac@incdecoind.ro; Department of Systems Ecology and Sustainability, Faculty of Biology, University of Bucharest, 91-95 Splaiul Independentei Street, 050095, Sector 5, Bucharest, Romania.
authors: O
authors: O
authors: Tiron
authors: National Research and Development Institute for Industrial Ecology - ECOIND, 71-73 Drumul Podu Dambovitei Street, 060652, Sector 6, Bucharest, Romania E-mail: costel.bumbac@incdecoind.ro.
authors: C
authors: C
authors: Bumbac
authors: National Research and Development Institute for Industrial Ecology - ECOIND, 71-73 Drumul Podu Dambovitei Street, 060652, Sector 6, Bucharest, Romania E-mail: costel.bumbac@incdecoind.ro.
authors: I V
authors: IV
authors: Patroescu
authors: National Research and Development Institute for Industrial Ecology - ECOIND, 71-73 Drumul Podu Dambovitei Street, 060652, Sector 6, Bucharest, Romania E-mail: costel.bumbac@incdecoind.ro.
authors: V R
authors: VR
authors: Badescu
authors: Department of Systems Ecology and Sustainability, Faculty of Biology, University of Bucharest, 91-95 Splaiul Independentei Street, 050095, Sector 5, Bucharest, Romania.
authors: C
authors: C
authors: Postolache
mesh_terms: D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D002708:Chlorella / Q000378:metabolism*; D058440:Denitrification; D058086:Microalgae / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D012722:Sewage / Q000032:analysis*; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D012722:Sewage; D010100:Oxygen