Application of a full-scale electrocatalytic reactor as real batik printing wastewater treatment by indirect oxidation process

Batik printing wastewater is mainly characterized by toxic dyes; hence an effective treatment technology with simple operation is needed as a suitable solution. Electrochemical-based advanced oxidation process is a simple and easy method to degrade dyes without generating any harmful sludge as by-products. A full-scale electrocatalytic reactor was constructed as a sub-set of 6 tubes (1.2 m(3)) to treat actual batik printing wastewater; Ti/RuIrO2 electrode is designated as anode and stainless steel plate as cathode. The electrodes were positioned vertically with electrode gap of 30 mm and evenly installed inside the tubes. Surface-area-to-volume ratio (S/V) was 6.28 m(-1). Each tube was equipped with single motor mixer using a fan belt. Optimum operational parameters were investigated, i.e., hydraulic retention time (30, 60, 90, 120, 150 and 180 min), electrolyte (salt) concentration (2500, 3000, 3500, 4000 mg L-1) and initial pH (3, 5, 7, 9); color and COD was used as indicators of process efficiency. Reactor achieved a complete decolourization and COD reduction of 60.8% at potential of 5 V, HRT of 120 min, salt concentration of 4000 mg L-1 and pH 5. Three intermediate products were detected after electrodegradation with particular m/z values of 388, 300, and 256. The specific design and configuration of reactor employed in this research resulted in voltage and energy losses of 15.35% and 15.25%, respectively.