This research was conducted essentially to treat fresh peat water using a series of adsorbents. Initially, the characterization of peat water was determined and five parameters, including pH, colour, COD, turbidity, and iron ion exhibited values that exceeded the water standard limit. There were two factors influencing the adsorption capacity such as pH, and adsorbent dosages that were observed in the batch study. The results obtained indicated that the majority of the adsorbents were very efficient in removing colour, COD, turbidity at pH range 2-4 and Fe at pH range 6-8. The optimum dosage of cationic surfactant modified zeolite (CSMZ) was found around 2 g while granular activated carbon (GAC) was exhibited at 2.5 g. In column study, serial sequence of CSMZ, GAC, and limestone showed that the optimal reduction on the 48 hours treatment were found pH = 7.78, colour = 12 TCU, turbidity = 0.23 NTU, COD = 0 mg/L, and Fe= 0.11 mg/L. Freundlich isotherm model was obtained for the best description on the adsorption mechanisms of all adsorbents.

The effectiveness of bentonite using chitosan as a coagulant for raw water treatment was assessed in this study. The possible link between Alzheimer's disease with conventional aluminium based coagulants, has become an issue in water treatment. A method for treating water, using a natural approach as an alternate to achieve enhanced coagulation, might help to reduce risk to health, and be more environmentally friendly. One method for removing turbidity from raw water is by the adding of a primary coagulant (e.g., a natural polymer of chitosan) and a coagulant aid (e.g., natural clay of bentonite) to the raw water. A series of batch coagulation tests were conducted by jar test to obtain the optimum dosage, pH, ratio of coagulant aid and primary coagulant, and the efficiency time for the jar test, by evaluating the standard parameters, such as turbidity, pH, colour, aluminium, and chlorine. In terms of these parameters, chitosan:bentonite showed the best result, with a ratio of 30:70 in an optimal concentration of 1,000 mg/l with 0.15 g chitosan plus 0.35 g bentonite. The coagulants performed with an optimal pH of 5, with 30 min of mixing time during flocculation. However, the optimal pH condition during the jar test showed an improvement in the water alkalinity results, from pH 5 to 6.8. Coagulation with bentonite-chitosan successfully removed the turbidity with a highest efficiency of 98%. After water treatment in the optimal condition, results showed a great water quality standard, with 1.38 NTU, 10 TCU, 0.01 mg/l amount of chlorine and aluminium, and a pH of 6.8. However, data only showed slight differences of efficiency, between natural and conventional coagulants. In terms of the sludge volume index (SVI), the ratio of alum to bentonite-chitosan was found to be 3:1 which indicated that less sludge was produced by the natural coagulant. In a cost comparison between these coagulants, based on a rough estimation, bentonite-chitosan is nearly 10 times more expensive than the alum coagulant. However, with mass production and commercial availability, in the long run the price of chitosan could be reduced tremendously.

Landfill leachate can threaten the environment and human life. Therefore, this study aims to investigate the efficiency of ozone (O 3 ), O 3 with zirconium tetrachloride (O 3 /ZrCl 4 ), and O 3 with tin tetrachloride (O 3 /SnCl 4 ) in remediating the stabilized anaerobic landfill leachate (SAL) from Alor Pongsu, Perak. Hydroxyl radical (OH•) is an important oxidizing agent in the ozonation process. Its presence was tested using tert-butyl alcohol. Results showed that using ZrCl 4 and SnCl 4 in ozonation boosted the generation of hydroxyl radical, thereby enhancing the oxidation process and pollutant removal inside the sample. The O 3 /ZrCl 4 mix at chemical oxygen demand (COD) to ZrCl 4 ratio of 1:1.5, pH 8-9, and 90-min reaction time resulted in the highest reduction rates of COD and color at 91.9% and 99.6%, respectively. All results demonstrated that the optimum performance occurred at alkaline conditions (pH > 8), proving that OH radicals primarily oxidized the pollutants through an indirect reaction pathway. The biodegradability (biochemical oxygen demand/COD) ratio was also considerably improved from 0.02 (raw) to 0.37 using O 3 /ZrCl 4 , compared with using O 3 alone and using O 3 / SnCl 4 , which only recorded 0.23 and 0.28, respectively, after the treatment. The study demonstrated that O 3 /ZrCl 4 was the most efficient combination. Practitioner Points• The O 3 /ZrCl 4 recorded the highest COD and color removals.• The O 3 /ZrCl 4 combination also recorded higher OH• concentrations.• The biodegradability of leachate (BOD 5 /COD ratio) improved from 0.02 to 0.37.

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