ALKALINE-EXTRACTED SUGARCANE BAGASSE AS A PLANT-BASED COAGULANT FOR CATTLE SLAUGHTERHOUSE WASTEWATER

Effluent from the Banda Aceh municipal slaughterhouse, Indonesia, receives only bar screening, and a single grab sample exceeded the national chemical oxygen demand (COD) limit. Plant-based coagulants are proposed alternatives to metal salts; sugarcane bagasse has been studied as an adsorbent and activated-carbon precursor but, to our knowledge, not as a coagulant for slaughterhouse effluent. We screened a crude alkaline bagasse extract (2% NaOH, hotplate set to 120 °C, 2 h, open beaker) as a coagulant for cattle slaughterhouse wastewater. Three stock concentrations (0.1–0.3% w/v) were each dosed at four volumes (5–20 mL; nominal doses 5–60 mg/L) in single-run jar tests, with a settling-only control. Raw COD was 1,422 mg/L, and settling alone reduced it by 53.3%. The lowest COD (155 mg/L; 0.2% stock, 20 mg/L nominal dose) was 76.7% lower than the control and below the 200 mg/L COD limit; pH stayed within 6.5–6.8, but other regulated parameters were not measured. Over-dosing increased COD, and in one treatment (0.3% stock, 60 mg/L) it exceeded the control. Three conditions met the COD limit (0.2% stock at 20 and 30 mg/L; 0.3% stock at 15 mg/L). Because equal nominal doses from different stock concentrations gave inconsistent results and each treatment was run once, these results identify conditions for further testing rather than an optimum. Replicated jar tests with a control in every batch, and characterisation of the extract, are needed.