Anaerobic‐Aerobic Combined System for the Biological Treatment of Azo Dye Solution using Residual Yeast

Abstract

This study aimed to investigate the treatment efficiency of a synthetic dye solution in an anaerobic-aerobic combined reactor system, using pretreated residual yeast as a nutrient source and redox mediator. The applicability of the residual yeast as a nutrient source was firstly evaluated in anaerobic batch tests. Subsequently, two continuous bench-scale treatment settings were studied: (1) an Upflow Anaerobic Sludge Blanket (UASB) reactor followed by an activated sludge system and, (2) a UASB reactor followed by a shallow polishing pond. The two system configurations were fed with a synthetic azo dye solution of Yellow Gold Remazol (50 mg/L) and pretreated residual yeast (350 mg/L). According to the results, the UASB/shallow polishing pond-combined reactor attained the best values of chemical oxygen demand (COD) (85%) and dye removal (23%).

Evaluation of a Combined System Based on an Upflow Anaerobic Sludge Blanket Reactor (UASB) and Shallow Polishing Pond (SPP) for Textile Effluent Treatment

“…Previous studies also showed that the residual yeast could be used as the unique source of carbon and redox mediators in the anaerobic treatment of azo dyes. In those studies, the authors verified that the discoloration rates of dye solutions were practically the same (~72%) when using standard nutrient solution containing yeast extract and when using only residual yeast [11,12]. Moreover, color removal rates as high as 94% was observed for 10-fold diluted textile effluent supplied with commercial yeast extract in bench scale UASB [2].…”

“…Residual yeast biomass belonging to Saccharomyces cerevisiae species was obtained from a small brewery pretreated through osmotic lysis [11,12]. For this, yeasts were taken directly from fermentation vats and submitted to a clarification process, which consisted in a sequence of centrifugations and addition of ethanol solution 96% (10% M/M).…”

“…The solid fraction was then submitted to osmotic lysis by the addition of NaCl (45% per yeast dry weight) aiming the release of riboflavin and other nutrients to the solution. The resulting suspension was then dried and macerated as described in previous studies conducted in our research group [12]. A solution with 350 mg/L of pretreated yeast cells was prepared and used as feeding solution.…”

“…For instance, the application of immobilized redox mediators in microbial fuel cells was tested for electricity generation with simultaneous azo dye removal due to facilitated electrons transfer from bacteria to anodes and azo dyes [8]. In this context, the use of low cost redox mediators have been suggested, such as commercial yeast extract (source of riboflavin) [2,9,10] or residual yeast from the brewing industry [11,12]. Dyes are deficient in carbon and nitrogen sources, and the biodegradation of dyes without any supplement of these sources may be hampered.…”

Preparation and Adsorption Properties of Biochar/g-C3N4 Composites for Methylene Blue in Aqueous Solution

“…It accumulates in large amounts in the ecological environment, which will seriously affect photosynthesis in the aquatic environment and may cause cancer and mutagenesis [7]. At present, treatment methods mainly include oxidation method [8], biological method [9], and adsorption method, among which adsorption method is a fast, inexpensive, and universal treatment method [10].…”