Investigation of Non-Chemical Methods for Wool Scouring Industrial Wastewater Treatment

Abstract

This study investigates non-chemical technologies for treating wastewater from Mongolia’s cashmere and wool scouring industry. The treatment process consisted of three stages: primary clarification using an Imhoff cone, electrocoagulation using different electrode materials, and filtration with natural zeolite. The Imhoff cone removed approximately 50% of total suspended solids (TSS), reducing concentrations from about 1500 mg/L to 370 mg/L, showing effective pre-treatment through simple sedimentation. Electrocoagulation was carried out using three electrode types: Al–Al, Cu–Al, and Fe–Al. Among them, the Cu–Al electrode achieved the highest organic matter removal, reducing COD from 1789.67 mg/L to 23.2 mg/L and BOD₅ from 614 mg/L to 5.0 mg/L, thus meeting the MNS 6561:2024 Mongolian wastewater discharge standard. The Al–Al electrodes were most efficient for solid removal, while Fe–Al electrodes offered a balanced performance in reducing both organics and solids. In the final stage, natural zeolite filtration was used with 2 mm and 10 mm particle sizes. The 2 mm zeolite provided better COD removal (24.99% after 24 hours), although overall filtration performance was limited and not sufficient as a standalone treatment. The findings indicate that the combined process, especially Cu–Al electrocoagulation followed by zeolite filtration, is a cost-effective, low-maintenance, and promising method for treating wool scouring wastewater. To confirm scalability and long-term effectiveness, pilot-scale testing in real factory conditions is recommended.