Culture of Microalgae in Mixed Wastewater Streams

MARÍA C. CUELLO; ESTER CHAMORRO; NAVID R. MOHEIMANI

Nantes

Congreso; 6th Congress of the International Society for Applied Phycology 2017; 2017

International Society of Applied Phycology y Nantes University

Microalgae cultivation in waste effluents can be feasible for efficient removal of nutrients. Additionally, there is potentially no ?sludge? generation and produced biomass can generate revenue. Nevertheless, to achieve optimal algal growth, in most cases these effluents must be diluted (using freshwater). Freshwater is a finite resource and its use should be avoided. In here, we studied the effect of culturing microalgae in mix of dairy farm effluent with 13mg.L-1 P-Phosphates, 70 mg.L-1 N-Nitrates and 120 mg.L-1 N-Ammonia concentrations and cheese whey effluent with 154 mg.L-1 P-Phosphates, 0.80 mg.L-1 N-Nitrates and 48.5 mg.L-1 N-Ammonia concentrations.For bioprospecting purpose, Scenedesmus dimorphus and Chlorella pyrenoidosa were cultured at laboratory scale as a) mono-species and b) Five mixed compositions of dairy farm and cheese whey effluents (Mix1: 0% Stream 1 - 100% Stream 2; Mix2: 25% Stream 1 - 75% Stream 2; Mix3: 50% Stream 1 - 50% Stream 2; Mix4: 75% Stream 1 - 25% Stream 2; Mix5: 100% Stream 1 - 0% Stream 2).Three out of the fifteen experiments showed highest algal productivity and therefore selected for outdoor cultivation. These were: Scenedesmus dimorphus in two mixes: a- 50/50 and b- 25/75 dairy farm/cheese whey wastewaters ratios and c- Chlorella pyrenoidosa cultured in 25/75 mixture of same wastewaters. These culture conditions were further cultured in batch mode under outdoor conditions in 5L airlift driven mesocosoms. Growth (µ, yield, productivity and biochemical composition) as well as nutrient removal rates were measured using internal standard methods. Scenedesmus dimorphus in the 50/50 blending under outdoor conditions showed the highest growth rate (0.38), biomass yield (2.07g.L-1) and nutrient removal rates (99% P-Phosphates, 96% N-Nitrates and 70% N-Ammonia reduction). However, the other two conditions resulted in higher lipid content (b- 22.6% and c- 21.5% respectively).Our results clearly indicated that mixing these waste effluents with different nutrient composition and color can enhance both nutrient ratio and light availability (foremost in dark wastewaters) for microalgae cultivation. Other parameters, such as pH, could be also corrected by mixing wastewaters.