Effect of particle size distribution and acid treated coal bottom ash on TSS and COD removal from textile effluent using fixed bed column

Abstract

Most wastewater treatment plant (WWTP) of textile industries in Bandung area have not operated optimally due to several reasons, such as high processing load and high operational cost. On the other hand, bottom ash which is a major pollutant generated from coal-fired boiler has good potential as adsorbent. In this paper bottom ash obtained from a textile industry in Bandung has been used to remove the organic contaminant from textile effluent in order to reduce the burden to WWTP. The ash was treated using acid solution prior to adsorption and filtration of waste, in order to avoid leaching of its metal content by wastewater and to enhance its adsorption capacity. The best contact time on COD removal and the adsorption capacity were obtained in batch processes. The effect of bed particle size to pressure drop, the influence of contact time, bed particle size on TSS filtration and COD removal were also studied using a fixed bed column. Acid treatment of ash was carried out using 0.25 M HCl solution. One gram of bottom ash was leached by 20 mL of acid solution to give 1.402 ppm of chromium effluent (below the threshold limit of 5 ppm). The highest adsorption of acid-treated bottom ash on Rhodamine B 233 was achieved on 2 h duration of adsorption, with adsorption capacity of 15.87 mg Rhodamine/g ash). Filtration of wastewater on fixed bed of finer grain (1.0625 mm) as well as coarser grain (1.200 mm) provided 55 % TSS reduction, 30% volumetric rate reduction, and 95% COD reduction in less than one hour.