Outdoor flat-panel membrane photobioreactor to treat the effluent of an anaerobic membrane bioreactor. Influence of operating, design, and environmental conditions

• Published in: Water science and technology 2018-08, Vol.78 (1-2), p.195-206
• Main Authors: González-Camejo, J, Barat, R, Ruano, M V, Seco, A, Ferrer, J
• Format: Article
• Language: English
• Subjects: Air flow; Air injection; Air sparging; Algae; Ammonium; Ammonium compounds; Anaerobic conditions; Anaerobic treatment; Bacteria; Biomass; Bioreactors; Chemical oxygen demand; Cyanobacteria; Effluents; Environmental conditions; Equipment Design; Experiments; Hydraulic retention time; Influents; Irradiance; Light; Microalgae; Microalgae - metabolism; Microorganisms; Mineral nutrients; Nitrogen - analysis; Nitrogen - isolation & purification; Nitrogen - metabolism; Nutrient concentrations; Nutrient removal; Nutrient retention; Nutrients; Phosphorus; Phosphorus - analysis; Phosphorus - isolation & purification; Phosphorus - metabolism; Phosphorus removal; Photobioreactors; Removal; Resource recovery; Retention; Retention time; Sewage; Sewage treatment; Sewage treatment plants; Solid suspensions; Sparging; Suspended particulate matter; Suspended solids; Waste Water - chemistry; Wastewater; Wastewater treatment; Water Purification - instrumentation; Water Purification - methods; Water treatment
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2018.259

As microalgae have the ability to simultaneously remove nutrients from wastewater streams while producing valuable biomass, microalgae-based wastewater treatment is a win-win strategy. Although recent advances have been made in this field in lab conditions, the transition to outdoor conditions on an industrial scale must be further investigated. In this work an outdoor pilot-scale membrane photobioreactor plant was operated for tertiary sewage treatment. The effects of different parameters on microalgae performance were studied including: temperature, light irradiance (solar and artificial irradiance), hydraulic retention time (HRT), biomass retention time (BRT), air sparging system and influent nutrient concentration. In addition the competition between microalgae and ammonium oxidising bacteria for ammonium was also evaluated. Maximum nitrogen and phosphorus removal rates of 12.5 ± 4.2 mgN·L ·d and 1.5 ± 0.4 mgP·L ·d , respectively, were achieved at a BRT of 4.5 days and HRT of 2.5 days, while a maximum biomass productivity of 78 ± 13 mgVSS·L ·d (VSS: volatile suspended solids) was reached. While the results obtained so far are promising, they need to be improved to make the transition to industrial scale operations feasible.