Treatment of evaporative water from brewer’s yeast concentration by Fenton and Fenton-like processes

Abstract

problem is that organic contaminants removal in the system of treatment is not suf fi cient, which makes it dif fi cult to use the treated water as technological water for the needs of the manufacturing plant. This water contains organic contaminations that are by-products of the fermentation process. Part of them are volatile compounds, which migrate through the two-stage RO system. The aim of this work was to estimate the Fenton and Fenton-like reactions suitability to decrease the concentration of the organic compounds in the evaporative water from yeast slurry concentration. There were determined the conditions, which have a signi fi cant in fl uence on the achievement of the highest mineralization of the organic compounds. Abstract: Evaporative water from yeast slurry concentration is acidic, low mineralized and contains large amounts of dissolved organic contaminants. The treatment of evaporative water from yeast slurry concentration by Fenton (Fe(II)/H 2 O 2 ) and Fenton-like (Fe(III)/H 2 O 2 ) reactions has been studied. The processes in terms of system variables have been compared: catalyst and oxidant doses, initial pH, temperature of reaction, and the reaction kinetic. For determination of mineralization ef fi ciency the total organic carbon (TOC) in water before and after reactions was measured. The Fenton reaction was more ef fi cient for mineralization of organic compounds: the highest ef fi ciency of TOC removal was 45–50%, while for the Fenton-like it was 20–30%. The pH adjustment of evaporative water in the range of 2–5 did not change the ef fi ciency of treatment. Temperature of 30°C was the most favorable for both reactions. The Lumped Kinetic Model fi tted very well the experimental results. The reaction rate analysis indicated that the rate of direct mineralization of organic compounds is similar to the rate of its oxidation to organic intermediates, its selectivity factor was more favorable to the Fenton reaction. The strong correlation between chemical oxygen demand (COD) and TOC in evaporative water after the Fenton and Fenton-like reactions has been determined, providing a simple tool for calculating COD on the basis of values of TOC measurement.