Treat-ability of Manihot esculenta peel extract as coagulant aid for stabilised leachate

Agro-waste can be commercialised into another useful product such as natural coagulant for wastewater treatment. The purpose of this study was to quantify the ability of agro-waste (Manihot esculenta peel extract (MEP)) as an aid alongside the utilisation of chemical coagulant (polyaluminium chloride (PAC)) based on the removal percentages of selected parameters at the optimum coagulant dosage and pH of stabilised leachate. Series of jar tests were used to compare the leachate treatments using single and the dual coagulant of PAC and MEP with respective standard methods to analyse the removal parameters, i.e., Colorimetric (APHA Method:5220 C, HACH Method:8000) for chemical oxygen demand (COD), Conductimetric (APHA Method: 4500-N, HACH Method: 8038) for ammonia nitrogen (AN), Nephelometric (APHA Method:2130) for turbidity, Spectrophotometric (APHA Method: 2120 B, HACH Method: 8025) for colour, and Gravimetric (APHA Method:2540 D, HACH Method:630) for suspended solids (SS). Leachate treatment using the application of single PAC coagulant at the optimum conditions of 3,750 mg/L dosage and pH 6.0 of leachate managed to remove about 54.1%, 28%, 91.1%, 98%, and 98% for COD, AN, turbidity, colour, and SS, respectively. Meanwhile, by using dual coagulant at the optimum dosages of 3,500 mg/L (PAC) and 250 mg/L (MEP), and pH 7.0 of leachate, the treatment achieved higher removal except for the colour parameter. The final removal outcomes of this study were 58.3% of COD, 34% of AN, 96.9% of turbidity, 92.1% of colour, and 99% of SS. The application of MEP as coagulant aid also managed to reduce the aluminium (Al) content in PAC dosage from 577.5 mg/L to 539.0 mg/L without affecting much of its efficiency.