From waste to value: Screening brewery effluent and microalgae strains for resource recovery

Large-scale breweries produce nutrient-rich effluents that require effective treatment before discharge into the urban wastewater treatment plant. This study aimed to identify optimal combinations of brewery effluents and microalgae strains for enhanced nutrient removal and biomass generation. Effluents from five treatment stages of a brewery wastewater treatment plant were used as microalgae media: raw wastewater (E-1), pre-acidification (E-2), anaerobic treatment (E-3), aerobic treatment (E-4) and dissolved air flotation (E-5). The characterisation of these effluents showed high total organic carbon, with acetate present at higher concentrations in E-1 and E-2 (67.6 and 471.8 mg/L, respectively). Batch experiments demonstrated that Scenedesmus sp. cultivated in pre-acidification effluent (E-2) achieved the highest biomass production (0.93 g/L) and nutrient removal rates (100% phosphate, 81% total organic carbon, 68% total nitrogen). The nutrient load of E-1 and E-2 benefited the consortia of microalgae and indigenous bacteria present in the effluent, with Scenedesmus sp. predominating. Acetate was found to be a key nutrient favouring the consortia and biomass production. The consortia show potential to replace aerobic and anaerobic treatment in a brewery wastewater treatment plant, thereby reducing COD below discharge limits. Results highlight the potential of microalgae-bacteria consortia as sustainable and efficient alternatives to conventional brewery wastewater treatment, contributing to both environmental improvement and the production of biomass with potential applications as animal feed or agricultural biostimulants.