Reusing biomass in textile dyes removing from wastewater

When textile dyes are released into the water, they can have a range of negative effects on the environment, for example, azo dyes can break down into carcinogenic compounds when exposed to sunlight. Remazol Brilliant Blue R (RBBR) and Reactive Black 5 (RB5) are reactive dyes. Unfortunately, the discharge of untreated effluents from these industries into nature can result in the contamination of water, which can have harmful effects on the environment. Saccharomyces cerevisiae is widely used in different fields of biotechnology. In this work, the cell walls of used yeast were reused for the biosorption of textile dyes, and the possibility of their utilization in wastewater treatment was investigated. The response surface methodology approach was applied to determine the optimal levels of three input variables - pH, temperature, and time, and also to identify the relationship between the response functions and process variables. Five levels of three variables were used, pH range 2–13, temperature range 15–40°C and time 0.15–30 h. The decolorization processes were optimized using the Central Composite Design. A significant impact of pH and temperature was found, while satisfactory results in decolorization (≥ 90%) were shown in a short time (up to 1 h). The maximum adsorption capacity (MAC) of the used Saccharomyces cerevisiae cell wall for removing RBBR and RB5 from wastewater was tested according to results obtained by CCD considering the economy of the process (pH 4, 25°C and 1 hour). Experimentally obtained MAC was 400 mg/g and 200 mg/g for RBBR and RB5, respectively.