pH ‐optimized electrocoagulation–Electroflotation augmented with Palygorskite or zeolite for high‐strength printing wastewater treatment

BACKGROUND Printing ink wastewater (PIW) contains high concentrations of organic matter, suspended solids, and colorants that challenge conventional treatment methods. Electrocoagulation–electroflotation (EC/EF) has emerged as a promising technique for such complex effluents. This study aimed to evaluate the efficiency of EC/EF using aluminum, iron, and stainless‐steel electrodes for PIW treatment and to assess performance improvements when coupled in a single step with adsorbents, such as palygorskite (EC/EF–P) and zeolite (EC/EF–Z). RESULTS Initial optimization focused on pH (5.0, 6.0, 7.5) and electrode type. Varying initial COD concentrations (~10 000–27 000 mg/L) had negligible impact on removal efficiencies, which remained high: COD (>90%), total suspended solids (>99%) and color (>90%). Notably, at lower initial COD levels (12 000 and 9970 mg/L), effluent COD concentrations were reduced below 1000 mg/L, meeting the discharge limits of the regional centralized wastewater treatment plant. The EC/EF–P and EC/EF–Z systems revealed that adsorbent addition significantly enhanced process performance. Palygorskite (6.0 g/L) accelerated COD removal, particularly under suboptimal electrochemical conditions, indicating its synergy with the EC/EF process. Zeolite (6.0 g/L) at pH 6.0 increased COD removal rate to 73.28 mg/(L·h) (20 min), compared to 48.38 mg/(L·h) (30 min) with palygorskite. CONCLUSION These findings highlight EC/EF, especially when augmented with adsorbents, as a highly effective strategy for rapid and compliant treatment of high‐strength industrial wastewater.