Slaughtering and piggery wastewater for cultivation and biomass generation of Chlorella vulgaris

Abstract

Several studies support the use of microalgae as source of products of biotechnological interest, but there are limitations for their implementation, such as the use of wastewater as a culture medium and the generation of biomass in presence of other microorganisms that compete for nutrients. In this study, 3 disinfection methods for slaughtering and piggery wastewater were compared, and their applicability for the cultivation of Chlorella vulgaris was evaluated. Three pretreatment methods were tested: UV irradiation, sodium hypochlorite (NaClO) and peracetic acid (CH3CO3H), and the results were compared with untreated water. The generation of biomass (g / L) and the consumption of nitrates, orthophosphates and chemical oxygen demand was determined, during 13 days of culture with pretreatment and in untreated water. UV disinfection for 30 minutes completely eliminated the bacteria, while chemical treatments with the concentrations used in this study managed to partially reduce the bacterial load. The residual water with UV pretreatment generated a C. vulgaris biomass of 0,2 g / L with high percentages of removal of nutrients from the medium (97 and 89% for nitrates and orthophosphates), removal values higher than those presented in the condition without pretreatments. These results suggest the need to disinfect wastewater for its implementation as a culture medium and support the feasibility of its use as a complex growth medium, to generate biomass.