Production of natural pigments from A. platensis grown on wastewater from local treatment facility.

Sammanfattning: Although microalgae have been considered for the biological treatment of wastewater since the 1950’s, their potential to efficiently remove pollutants from various streams remains largely untapped and is yet to be utilized at large scale. The production of algal biomass and extraction of high-value compounds has, however, become increasingly popular with large scale farms and biorefineries around the world producing many promising alternatives to petroleum-based products and processes. While microalgae systems rival traditional production in terms of environmental sustainability and health benefits, the economic viability remains a challenge. This study aimed to investigate the potential of a biorefinery concept using wastewater as growth medium for the production of natural pigments by cyanobacterium, Arthrospira platensis. Using effluent streams as a growth media drastically cuts costs of production and with this circular approach, we are able to address challenges facing the wastewater treatment industry while providing a sustainable alternative to petroleum-based products. During phase one, the growth of A. platensis was monitored on different amounts of wastewater supplemented with standard growth media. Biomass productivity and growth rate ranged from 233,12 – 2000 mg.L-1.d-1 and 0,19 – 0,37 d-1, with 50% FWW supplemented with 50% Zarrouk media resulting in the highest values and thus proving to be the preferred growth media. However, cultures grown on 75% FWW supplemented with 25% Zarrouk media resulted in the highest PC content and thus was chosen as the growth media for further investigation. Phase two investigated the effect of different photoperiods (14h:10h and 16h:8h) on the production of PC, while assessing the scale-up potential of the system and monitoring nutrient removal. Photoperiod had no significant effect on PC content, however, a decrease in total PC production was seen between phases, suggesting further optimization for scale-up to be viable. In all cases, NH4+, PO43-, and TN in the WW media were successfully reduced to levels below the lowest range of detection. While further optimization is necessary, the proposed process proved successful in reducing harmful nutrients from WW, maintaining A. platensis growth, and producing sufficient levels of PC.