<![CDATA[Laundry wastewater contains high organic matter and detergent residues that may degrade the receiving water quality if discharged without treatment. This study investigated the performance of coconut-shell activated carbon for reducing chemical oxygen demand (COD), biochemical oxygen demand (BOD), and detergent concentration in laundry wastewater, using batch and continuous fixed-bed adsorption systems. Four activation treatments were evaluated at the batch stage: no activation, NaOH 0.2 N, HCl 0.1 N, and sequential NaOH 0.2 N–HCl 0.1 N. The best activator was then applied in a continuous upflow column with adsorbent thicknesses of 15, 20, and 25 cm. HCl 0.1 N produced the highest batch removal efficiencies, reaching 73.30% for COD, 71.53% for BOD, and 75.73% for detergent. Adsorption equilibrium for all parameters was better described by the Freundlich model than by the Langmuir model, indicating adsorption on a heterogeneous carbon surface. In the continuous system, the 25 cm bed showed the highest concentration-based removal, reaching 97.12% for COD, 97.03% for BOD, and 99.66% for detergent, and provided the longest breakthrough delay. However, the 20 cm bed yielded the highest average pollutant-load reduction, indicating a more balanced operational performance. Hydraulic conductivity decreased from 0.000058 to 0.000036 m/s during operation, suggesting progressive pore blockage and adsorbent saturation. These results demonstrate that coconut-shell activated carbon has good potential as a simple and practical adsorbent for decentralized laundry wastewater treatment.]]>
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