Declaration of Competing Interest the Authors Declare that They Have No Known Competing Financial Interests or Personal Relationships that Could Have Appeared to Influence the Work Reported in this Paper

Abstract

To use unicellular microalgae to remove waste nutrients from brewery wastewater while converting them into algal biomass has been explored but high-cost treatment and low-value biomass associated with current technologies have prevented this concept from further attempts. In this study, a filamentous microalga Tribonema aequale was introduced and the alga can grow vigorously in brewery wastewater and algal biomass concentration could be as high as 6.45g L-1 which can be harvested by a cost-effective filtration method. The alga together with autochthonous bacteria removed majority of waste nutrients from brewery wastewater. Specifically, 85.39% total organic carbon (TOC), 79.53% total dissolved nitrogen (TN), 93.38% ammonia (NH3-N) and 71.33% total dissolved phosphate (TP) in brewery wastewater were rapidly removed by co-cultivation of T. aequale and autochthonous bacteria. Treated wastewater met the national wastewater discharge quality, and resulting algal biomass contained large amounts of high-value products chrysolaminarin, palmitoleic acid (PLA) and eicosapentaenoic acid (EPA). It is anticipated that reduced cost of algal harvesting coupled with value-added biomass could make T. aequale as a promising candidate for brewery wastewater treatment and resource utilization.

Keywords: Organic wastewater, Algae-bacterial synergy, nutrient removal, Bacterial community, High-value products