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Landfill leachate can threaten the environment and human life. Therefore, this study aims to investigate the efficiency of ozone (O3 ), O3 with zirconium tetrachloride (O3 /ZrCl4 ) and O3 with tin tetrachloride (O3 /SnCl4 ) in remediating the stabilised anaerobic landfill leachate (SAL) from Alor Pongsu, Perak. Hydroxyl radical (OH•) is an important oxidising agent in the ozonation process. Its presence was tested using tert-Butyl alcohol. Results showed that using ZrCl4 and SnCl4 in ozonation boosted the generation of hydroxyl radical, thereby enhancing the oxidation process and pollutant removal inside the sample. The O3 /ZrCl4 mix at chemical oxygen demand (COD) to ZrCl4 ratio of 1:1.5, pH 8-9 and 90 min reaction time resulted in the highest reduction rates of COD and colour 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 oxidised 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 O3 /ZrCl4 , compared with using O3 alone and using O3 /SnCl4, which only recorded 0.23 and 0.28, respectively, after the treatment. The study demonstrated that O3 /ZrCl4 was the most efficient combination.

The current study investigated the performance of combined ozonation and zirconium tetrachloride (ZrCl4) for an anaerobic stabilized landfill leachate treatment. The effectiveness of ZrCl4 dosage [COD0/ZrCl4 ratio (g/g)], pH variation, and reaction time during ozonation were evaluated to obtain the optimal operational conditions of ozone (O3)/ZrCl4 oxidation process. The maximum removal efficiencies for chemical oxygen demand (COD) and color were 88 and 100 %, respectively, at 1/2 g zirconium tetrachloride dosage (COD0/ZrCl4), pH 6, and 90 min reaction time, whereas 79 % removal for ammonia (NH3–N) was obtained at pH 11. Biodegradability (BOD5/COD) was improved from 0.07 to 0.09 and 0.34 after treatment with O3 alone and O3/ZrCl4, respectively. Treatments using ozonation alone and zirconium alone were performed and compared with the results obtained from the treatment with the new catalytic ozone method (O3/ZrCl4). The new oxidation method (i.e., O3/ZrCl4) obtained better removal efficiencies for organic substances and ammonia and this method reported better biodegradability ratio compared with other related processes. The O3/ZrCl4 process is also more efficient than O3/Fenton and O3/persulfate for stabilizing leachate treatment.

Landfill leachate is a hazardous pollutant generated from a landfill site. Discharge of landfill leachate has caused a major contamination to the environment and detrimental to human health. This chapter introduces an alternative method to treat recalcitrant pollutant in leachate by using ozonation with catalyst. The production of hydroxyl radical in ozonation was not enough to oxidize complex molecular structure in the leachate. Theoretically, the addition of catalyst enhances the capacity of radical and accelerates the chemical reaction. The effectiveness of ozonation with Fenton (O3/Fenton), hydrogen peroxide (O3/H2O2), and zirconium tetrachloride (O3/ZrCl4) in removing pollutant such as chemical oxygen demand (COD), color, and improvement of biodegradability by using this process were also discussed in this chapter. Comparison in term of treatment cost and benefits of the application of chemical as catalyst are briefly elaborated at the end of this chapter.

Landfill leachate generation is one of the main problems from sanitary landfill. Chemical oxygen demand (COD), ammoniacal nitrogen (NH3-N), and color are among the most problematic parameters in stabilized leachate. In this regard, dedicated treatment facilities are required before leachate can be discharged into the environment. The performance of the combined ozonation (O3) and zirconium tetrachloride (ZrCl4) to treat two types of stabilized leachate was investigated during this study. Leachate samples were collected from an anaerobic stabilized leachate (Alor Pongsu Landfill Site, APLS) and semi-aerobic stabilized leachate (Pulau Burung Landfill Site, PBLS). Zirconium tetrachloride dosage was determined as 1 g/1 g (COD/ZrCl4 ratio) and then added to the leachate samples with 60 min ozonation at natural leachate pH (8). COD, color, and NH3-N were removed from the APLS sample at 33%, 70%, and 53% rates, respectively, whereas 48%, 75%, and 69%, respectively, from the PBLS samples. Ozone consumption was also calculated with the highest value (3.81 Kg O3/ Kg COD) reported in PBLS, whereas the lowest value (2.32 Kg O3/ Kg COD) was reported in APLS. Biodegradability of (BOD5/COD) was investigated and improved from 0.07 to 0.08 for the APLS samples and 0.05 to 0.11 for the PBLS samples after leachate oxidation. Results showed that the performance of O3/ZrCl4 oxidation is more efficient in treating semi-aerobic stabilized leachate than anaerobic stabilized leachate Moreover, the combined method proved to be more efficient in remediating leachate compared with ozone and zirconium treatment alone.

One of an anaerobic stabilized landfill leachate in Malaysia underwent ozonation process. The sample rich in chemical oxygen demand (COD) was collected from Alor Pongsu Landfill Site, Perak (APLS). This site has been operating since year 2000. The leachate also contains other pollutants that exceeded the standard discharge limit for wastewater effluents. The effectiveness of ozone (O3) dosage, pH variation, and reaction time during ozonation was evaluated to measure the performance of O3 and determine the maximum operational conditions for this treatment. The maximum removal efficiency for COD was 50% at an ozone dosage of 31 g/m3, natural of pH 8.5, and reaction time of 60 min. The biodegradability ratio (BOD5/COD) improved from 0.08 to 0.23 after treatment with O3. The ozonation method has enhanced the biodegradability ratio and resulted high percentage removal of COD. This improvement showed that oxidation has a great potential to remediate recalcitrant pollutant wastes, such as landfill leachate.

Leachate is a critical problem of sanitary landfills because it contains high organic matter and hazardous compounds that can generate negative environmental effects. The high chemical oxygen demand (COD) and color of the leachate necessitates its treatment before it can be released to the water body. Thus, an investigation into the performance of advanced oxidation processes (AOPs) was conducted using a combination of ozone (O3) with zirconium tetrachloride (ZrCl4) as catalyst in stabilized landfill leachate treatment. Such leachate was collected from the Alor Pongsu Landfill site (APLS), Perak, Malaysia. COD and color parameter were used as indicators to examine the effect of O3/ZrCl4 dosage, pH, and contact time. The experiment was run under gas flow rate of 1,000 mL/min±10% and temperature below 15 °C. The maximum removal obtained for COD and color were 88% and 100%, respectively. This outcome was achieved at 27 g/m3 ozone dosage, pH 6, 90 min reaction time, and dosage ratio of 1:2 (COD g: ZrCl4 g). T...

The current study aimed to assess the performance of utilise Zirconium reagent during ozonation of anaerobic stabilised leachate. In this study, quadratic models using response surface methodology software was utilised to design the experiments and evaluate the interaction between experimental factors, such as zirconium tetrachloride, pH, and reaction time, at constant ozone dosage (27 g/m3). The performance of the new ozonation method was evaluated in terms of the removal of the chemical oxygen demand (COD), NH3-N and colour. The obtained quadratic models for colour, NH3-N and COD removal was considered significant (P < 0.0001). The optimal removal for of 100%, 90%, and 66% for colour, COD and NH3-N, was obtained at 38 min reaction time, ZrCl4 dosage (1/2(COD/ZrCl4 g/g) and pH 4.5, using 27g/m3 ozone dosage, respectively. The results obtained in this study were compared with zirconium only and ozone only, to evaluate its effectiveness. The performance of the new oxidation method (O3/ZrCl4) better than other related methods for the removal of colour, COD and NH3-N.