Electrocoagulation: Removing colour and COD from simulated and actual batik wastewater
Julia Fadzli, Siti Wahidah Puasa, Nik Raikhan Nik Him, Ku Halim Ku Hamid, Nurulhuda Amri
Abstract
The study examined the properties of reactive black 5 (RB5) and reactive orange 16 (RO16) and how their molecular structures affected colour and COD removal in simulated batik wastewater. It also evaluated the impact of Al rod-type electrodes on energy and electrode consumption during electrocoagulation (EC). Parameters including current densities (10–30 mA/cm2), initial pH (3−11), reaction time (10–40 min), and NaCl dosage (0.5–2.0 g/L) were evaluated for maximum colour and COD removal. The study found that the highest colour removal rates for RB5, RO16, and their mixtures were 98.60 %, 58.40 %, and 70.69 %, respectively, while COD removal rates were 95.06 %, 91.83 %, and 96.69 %. FTIR analysis characterised the dyes, and a cost analysis showed energy and electrode consumption at 5.26 kWh/m3 and 0.234 kg/m3, resulting in an operating cost of RM 1.6/kWh. The best conditions for maximal removal were determined to be pH 3, an IED of 1 cm, 1.5 g/L NaCl, 120 rpm, 30 mA/cm2, and a reaction time of 40 min, as validated by regression analysis. The EC process applied to actual batik wastewater proved effective, achieving 96.69 % colour removal and 97.93 % COD removal. The challenges and potential avenues for future research within the EC process were also addressed.