Influence of C/N ratio on microalgae-bacteria joint culture: treatment performance and phytoplankton dynamics in mixed wastewaters

Abstract

Microalgae biotechnology may represent a potential solution for minimizing the impacts of food industry activities, acting in bioremediation of wastewaters, and producing value-added biomass. Therefore, this work aimed to evaluate the biomass production and treatment performance of 5 culture media obtained by mixing brewery and meat processing wastewaters and to test the effects of their different C/N ratios. Cultivation media under optimal conditions (C/N = 6), deficit (C/N < 6), and excess (C/N > 6) of carbon were evaluated. Microalgae biomass and total biomass have adapted to all conditions, revealing resilience and symbiosis balance. Although, treatment performance was statistically distinct (p > 0.1). Total carbon, nitrogen, and phosphorus removals were influenced by nutrient availability. Biomass growth removed total carbon, total nitrogen, and total phosphorus from the culture medium at a rate of 62 % (C/N ≥ 7.4), 59 % (C/N = 4.1), and 58 % (C/N = 4.1), respectively.