Production of unicelular protein and reduction of contaminating amount of vinasse

Abstract

The vinasse from ethanol distillery, which is a highly contaminating industrial waste, is produced in large quantities. Through biotechnology, it can be used for the production of protein while reducing contamination. The Candida utilis strain was isolated and adapted under different concentrations of aqueous formulas of vinasse, from 10 to 50%. The experimental trials were carried out in a lab using a “batch” reactor with vinasse. The growth of the microorganism was monitored using a carbon dioxide sensor (CO2 ). The parameters measured were: total nitrogen, COD (chemical demand of oxygen), pH and conductivity, at the beginning and end of each trial. Every two hours, the DO (optics density in a liquid environment) was measured with the objective of knowing its cellular concentration. For each physic- chemical variable analyzed, an ANOVA was realized to evaluate the factors of repetition, treatment and reactor, and it was chosen a significance level of 1%. The parameters measured reported: in total nitrogen there was an enrichment of 136% in the environment composed of 50% of vinasse in aqueous formulas; the average removal of the chemical demand of oxygen was 43%; the variation of pH, which was compared at the end of the trials, was 4% less than at the beginning; and the conductivity lessened to 9%. The monitoring of yeast growth by measuring the carbon dioxide concentrations throughout the time and the environment’s OD, allowed for the creation of a growth curve of the microorganism, with a fermentation period of 21 hours. It was proved that the Candida utilis strain can develop in a batch reactor with vinasse, in aqueous solutions of 50%, and producing a proteic enrichment of it as well as the removal of COD. The proposed process reduces the contamination of the main industrial effluent of Tucumán.