Designing a typical activated sludge process plant for treatment of dye house effluent:

Abstract

This study provides the design of a typical activated sludge process plant meant to treat Rivatex Limited's dye house effluent, a Kenyan textile manufacturing plant. The textile industry, economically significant as it is, has a high risk to the environment due to the discharge of untreated wastewater with toxic pollutants in the form of synthetic dyes. This study fulfills the urgent need for effective solutions for the treatment of wastewater to prevent the environmental and health impacts of dye effluents. The study begins with a detailed characterization of the effluent, which is found to have extremely high Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), Total Suspended Solids (TSS), and excessive alkalinity. The study applies Response Surface Methodology (RSM) to identify optimal operational conditions for the activated sludge process, i.e., pH, temperature, and retention time, which significantly enhance the dye degradation and turbidity removal. The outcomes indicate that at optimal conditions (pH 10.69, temperature 36.33°C, and retention time 7.64 hours), the treatment system offers significant removals of BOD (from 250 to 45 mg/L), COD (from 850 to 297 mg/L), and turbidity (from 508 NTU to 140 NTU). The recycle ratio was found to be 25.5%, i.e., Return Activated Sludge (RAS) to influent flow rate, as crucial to develop a stable microbial community in the bioreactor. Furthermore, Sludge Volume Index (SVI) was found to be 66.67 mL/g, indicating good settleability of sludge. A low SVI is essential to ensure the successful separation of treated water from sludge so that the treatment plant can function optimally. This research not only provides a viable design for an activated sludge treatment plant but also emphasizes the importance of environmentally friendly wastewater management techniques in the textile sector to align with environmental norms to safeguard public health.