Advanced wastewater treatment process using algal photo-bioreactor associated with dissolved-air flotation system: A pilot-scale demonstration

Abstract

This research explores the feasibility of using an algal photo-bioreactor as an integrated algal-bacterial treatment system combined with a dissolved air flotation (DAF) system for the deduction of COD, BOD5, TSS, TN and TP from primary treated wastewater (PTW). Isolated algae species of Anomoeoneis, Scenedesmus, Anabaena and Spirulina at fixed hydraulic retention time (HRT) of 16 h were used to conduct batch experiments to determine optimum conditions of pH, temperature, light intensity and mixing rate on the removal rates of contaminants. The optimum removal rates were studied at neutral pH, 25 °C, light intensity of 90 μmol m−2S−1 and 100 rpm mixing rate. A scaled-up pilot plant treatment system was designed, constructed and operated to evaluate the system performance to treat (0.1 L/min) of primary treated wastewater disposed of ZENIN WWTP-Giza, Egypt. The design criteria of the algal photo-bioreactor were acquired from the batch investigations. The plant was operated for 10 continuous days and the analytical analysis was performed twice a day at a fixed time. The DAF system was used to isolate the infiltrated algae from the system for cultivation and reuse purposes. The achieved results revealed the superior COD, BOD5, TSS, TN and TP removal percent reached in average 56.4%, 61%, 59.2%, 48.3% and 51.7% at 12 pm and 49.7%, 54.9%, 52.4%, 39% and 40.57% at 12 am, respectively. All data gained from experimental studies demonstrated the efficiency of using algal photo-bioreactor combined with DAF system as an effective wastewater treatment technique.