Removal of dye particles in dye effluent using wood charcoal, a waste generated in dyeing process

Abstract

Maruthamunai is a hamlet located in the Eastern Province of Sri Lanka where the dyeing industry plays a significant role. The discharge of dyeing effluent is a serious problem in this area due to the pollution of the environment and the health of the inhabitants. Hence, the treatment of effluent is necessary. There are various technologies are available for the treatment process and most of them are costly. On account of this, Ganem & Nawas, (2020) have proposed a simple treatment method using a byproduct (charcoal) formed during the process itself. The objectives of the previous study were to improve its applicability and efficiency using one color. But in reality, there are different colors (different compounds) are released. Here five different colored samples, namely blue, pink, orange, green, and brown were collected and identified conditions, such as adsorbent (wood charcoal, 63 µm) dosage, agitation speed, retention time, and pH, were optimized for each case. The optimum conditions for each sample were as follows; for the blue color sample the adsorbent dosage was 6.0 g/100 ml, agitation speed was 210 rpm, retention time was 90 min, and pH was 7.00. For the pink color sample adsorbent dosage, agitation speed, retention time and pH were 6.0 g/100 ml, 140 rpm, 90 min and 9.60 respectively. For the orange color sample 7.5 g/100 ml, 140 rpm, 60 min, and 1.00 were adsorbent dosage, agitation speed, retention time, and pH respectively. For the green color sample adsorbent dosage, 7.0 g/100 ml, agitation speed, 178 rpm, retention time 90 min and pH, 2.00 and for the brown color sample 6.5 g/100 ml, 140 rpm, 120 min and 8.60 were the adsorbent dosage, agitation speed, retention time, and pH respectively.The percentage color reduction was 98.93%, 98.26%, 97.08%, 98.61%, and 98.49% for samples blue, pink, orange, green, and brown respectively. When the adsorbent particle size decreased the percentage of color reduction increased. As per the results, wood charcoal can be used as a simple, cheap, ecofriendly, and efficient adsorbent to remove any color (chemical compound) of the effluent, subject to the optimum conditions mentioned.