Tratamento terciário do soro do leite por co-cultura microalga-levedura

Abstract

In Brazil, whey, a byproduct of cheese production, poses an environmental challenge due to its high organic load. To address this issue, bioremediation processes are employed, including aerobic methods (such as activated sludge) and anaerobic digestion during secondary treatment. To deal with remaining contaminants after these processes, tertiary treatment is used, where microalgae combined with microorganisms like yeast demonstrate effectiveness in removing nutrients, especially nitrogen and phosphorus, and reducing chemical oxygen demand (COD). This approach has the potential to mitigate environmental impacts associated with whey disposal. The study aimed to evaluate whey treatment using a co-culture of Tetradesmus obliquus and Saccharomyces cerevisiae in a batch aerated bubble column reactor at 1.5 vvm and 100 µmol m-2 s-1. Experiments were conducted with different concentrations of organic loads (300-400, 600-815, 1610, and 3240 mg L-1 for COD, 8-47 for NT, and 2.5-2.89, 5-6, 12, and 25 mg L-1 for TP) for 7 days. Results indicated that the consortium exhibited higher removal efficiency, achieving removal efficiencies of 94.07% for COD, 83.61% for total nitrogen (TN) and 95.18% for total phosphorus (TP). When yeast was used, maximum efficiencies were 78.22%, 77.56%, and 58.09% for COD, TN, and TP, respectively. Consortium biomass growth exceeded yeast monoculture, ranging between 72-380 mg L-1, proportional to the organic loads used. Furthermore, to assess the influence of the COD:N ratio on whey treatment, supplementation of the effluent with ammonium sulfate was conducted, obtaining ratios of 25:1 and 12.5:1 of COD:N. This supplementation improved the process, reducing the treatment time from 7 to 3 days, increasing microbial sludge growth, and maintaining more stable the process pH. These additional experiments provided valuable insights into optimizing the treatment process, highlighting the importance of nutritional balance to maximize bioremediation efficiency.