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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. [ABSTRACT FROM AUTHOR]

Dyes are broadly utilized and therefore wastewaters discharged into rivers or public sewage treatment plants are extremely polluted. Thus, the current work aimed to study the kinetic for photocatalytic degradation of Basic Red 51 (BR51) dye in aqueous solution by green synthesized zinc oxide nanoparticles (ZnO NPs). The results revealed that the maximum degradation (98.40%) and chemical oxygen demand (COD) removal (98.08%) was recorded with 150 mg of ZnO NPs, pH 3 and 5 ppm of BR51. ZnO NPs showed high reusability of 95.73%. The photocatalytic degradation of BR51 follows pseudo first‐order kinetics, the apparent rate constants (Kapp) of solar photocatalytic degradation of BR51 were determined as 0.3798, 0.6066, 0.2747 and 0.1307 min−1 for 5, 10, 15 and 20 ppm of BR51 at optimum condition respectively. Phytotoxicity study confirms that the degraded products of BR51 are non‐toxic. This confers the possibility of applying green ZnO NPs for the treatment of industrial wastewaters containing dye pollutants to ensure the environmental sanitation for future generations. [ABSTRACT FROM AUTHOR]