Algal Photo-Bioreactor for Sustainable Treatment of Potato-Chips Processing Wastewater and Production of Protein-Rich Biomass

Potato-Chips Processing (PCP) industry generates huge amount of wastewater heavily polluted with organic matter and nutrients. Current treatment technology of PCP wastewater uses dissolved air flotation (DAF) and activated sludge sequential batch reactor (SBR); both consumes large amount of chemicals and represents energy-intensive system. This study explores algal photobioreactor (APBR) as a sustainable system for PCP wastewater treatment, nutrients recovery and algal biomass production. Raw wastewater, anaerobically pre-treated effluent and DAF-SBR effluent were used in 1st, 2nd and 3rd APBR. Three feed volumes from each source (150, 200 and 500 ml for 1st and 2nd APBR and 200, 400 and 600 ml for 3rd APBR) to a fixed volume of algal seed (200 ml) were tested to select optimal feed volume and harvest time using 1-L APBR . System performance and impact of water characteristics on quantity and quality of algal biomass were explored at preselected feed volume and harvest time in 6-L APBRs. All experiments were carried out in growth chamber with continuous light (148.75 μmol.m-2.S-1). Results showed that 150 ml is the optimal feed volume for 1st and 2nd APBR at 10 days and 9 days growth cycle. 400 ml and 8 days were the optimal feed volume and growth cycle for 3rd APBR. Average dry biomass yields at preselected optimal conditions were 65.3±11.4, 69.9±12.0 and 100.6±11.7 mg/l.d in the 1st, 2nd and 3rd APBR. The 1st APBR achieved % removal of 99.2±0.4, 98.7±0.8, 89.1±4.3 and 97.5±1.4 for turbidity, COD, TKN and TP on average. Corresponding % removal in the 2nd APBR are 97.6±2.6, 91.6±7.5, 93.6±4.5 and 96.1±1.4 while the 3rd APBR achieved 98.5, 76.2 and 97.0. Additionally, the results of protein content and amino acids profile indicate significant impacts of feed water quality on the two parameters. The protein content was 30.64, 32.53 and 35.65% in the 1st, 2nd and 3rd APBR respectively. Similarly, the amino acids profile indicated significant higher % of the amino acids in the 3rd reactor compared with the 1st and 2nd one.