Mohd Suffian Yusoff

Trends in the use of Fenton, electro-Fenton and photo-Fenton for the treatment of landfill leachate

Advanced oxidation processes (AOPs) such as Fenton, electro-Fenton and photo-Fenton have been applied effectively to remove refractory organics from landfill leachate. The Fenton reaction is based on the addition of hydrogen peroxide to the wastewater or leachate in the presence of ferrous salt as a catalyst. The use of this technique has proved to be one of the best compromises for landfill leachate treatment because of its environmental and economical advantages. Fenton process has been used successfully to mineralize wide range of organic constituents present in landfill leachate particularly those recalcitrant to biological degradation. The present study reviews the use of Fenton and related processes in terms of their increased application to landfill leachate. The effects of various operating parameters and their optimum ranges for maximum COD and color removal are reviewed with the conclusion that the Fenton and related processes are effective and competitive with other technologies for degradation of both raw and pre-treated landfill leachate.

Leachate characterization in semi-aerobic and anaerobic sanitary landfills: A comparative study

This study analyzes and compares the results of leachate composition at the semi-aerobic Pulau Burung Landfill Site (PBLS) (unaerated pond and intermittently aerated pond) and the anaerobic Kulim Sanitary Landfill in the northern region of Malaysia. The raw samples were collected and analyzed for twenty parameters. The average values of the parameters such as phenols (1.2, 6.7, and 2.6 mg/L), total nitrogen (448, 1200, and 300 mg/L N-TN), ammonia-N (542, 1568, and 538 mg/L NH(3)-N), nitrite (91, 49, and 52 mg/L NO(2)(-)-N), total phosphorus (21, 17, and 19 mg/L), BOD(5) (83, 243, and 326 mg/L), COD (935, 2345, and 1892 mg/L), BOD(5)/COD (0.096,0.1124,0.205%), pH (8.20, 8.28, and 7.76), turbidity (1546, 180, and 1936 Formazin attenuation units (FAU)), and color (3334, 3347, and 4041 Pt Co) for leachate at the semi-aerobic PBLS (unaerated and intermittently aerated) and the anaerobic Kulim Sanitary Landfill were recorded, respectively. The obtained results were compared with previously published data and data from the Malaysia Environmental Quality Act 1974. The results indicated that Pulau Burung leachate was more stabilized compared with Kulim leachate. Furthermore, the aeration process in PBLS has a considerable effect on reducing the concentration of several pollutants. The studied leachate requires treatment to minimize the pollutants to an acceptable level prior to discharge into water courses.

Landfill leachate treatment using powdered activated carbon augmented sequencing batch reactor (SBR) process: Optimization by response surface methodology

In this study, landfill leachate was treated by using the sequencing batch reactor (SBR) process. Two types of the SBR, namely non-powdered activated carbon and powdered activated carbon (PAC-SBR) were used. The influence of aeration rate and contact time on SBR and PAC-SBR performances was investigated. Removal efficiencies of chemical oxygen demand (COD), colour, ammoniacal nitrogen (NH(3)-N), total dissolved salts (TDS), and sludge volume index (SVI) were monitored throughout the experiments. Response surface methodology (RSM) was applied for experimental design, analysis and optimization. Based on the results, the PAC-SBR displayed superior performance in term of removal efficiencies when compared to SBR. At the optimum conditions of aeration rate of 1L/min and contact time of 5.5h the PAC-SBR achieved 64.1%, 71.2%, 81.4%, and 1.33% removal of COD, colour, NH(3)-N, and TDS, respectively. The SVI value of PAC-SBR was 122.2 mL/g at optimum conditions.

Variability of Parameters Involved in Leachate Pollution Index and Determination of LPI from Four Landfills in Malaysia

Landfill sites are potential sources of human and environmental hazards. Leachate produced form these waste dumping sites is heterogeneous and exhibits huge temporal and seasonal variations. Leachate pollution index (LPI) provides an overall pollution potential of a landfill site. The parameters required to calculate LPI from a landfill site are discussed in terms of their variations over time, and their significance has been highlighted in the context of LPI. The LPI values of two semiaerobic and two anaerobic landfill sites in Malaysia have been calculated in this study. Pulau Burung Landfill Site (PBLS) was found to have the highest LPI score while Ampang Jajar Landfill Site (AJLS) showed the lowest LPI as compared to other landfills. It is concluded that LPI value can be used as a tool to assess the leachate pollution potential from landfill sites particularly at places where there is a high risk of leachate migration and pollution of groundwater.

Stabilized sanitary landfill leachate treatment using anionic resin: treatment optimization by response surface methodology.

The treatability of stabilized sanitary landfill leachate via synthetic anion exchange resin (INDION FFIP MB) was investigated. An ideal experimental design was conducted based on central composite design using a response surface methodology to assess individual and interactive effects of critical operational variables (i.e., anionic dosage; contact time; shaking speed) and pH on treatment performance in terms of color, chemical oxygen demand (COD), suspended solid (SS), and turbidity removal efficiencies. Optimum operational conditions were established as 30.9 cm(3) anionic dosage, 90 min contact time, 150 rpm shaking speed, and pH 3.1. Under these conditions, the color, COD, SS, and turbidity removal efficiencies of 91.5, 70.3, 93.1, and 92.4% were experimentally attained and were found to fit well with the prediction model. According to these results, stabilized leachate treatment using INDION FFIP MB could be an effective alternative in the administration of color, COD, SS, and turbidity problems of landfill leachates.

ASSESSING WATER HYACINTH (EICHHORNIA CRASSOPES) AND LETTUCE (PISTIA STRATIOTES) EFFECTIVENESS IN AQUACULTURE WASTEWATER TREATMENT

Water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes) were analyzed to determine their effectiveness in aquaculture wastewater treatment in Malaysia. Wastewater from fish farm in Semanggol Perak, Malaysia was sampled and the parameters determined included, the pH, turbidity, dissolved oxygen (DO), chemical oxygen demand (COD), biochemical oxygen demand (BOD), nitrite phosphate (PO43−), nitrate (NO3−), nitrite (NO2−), ammonia (NH3), and total kjedahl nitrogen (TKN). Also, hydroponics system was set up and was added with fresh plants weights of 150 ± 20 grams Eichhornia crassipes and 50 ± 10 grams Pistia stratiotes during the 30 days experiment. The phytoremediation treatment with Eichhornia crassipes had pH ranging from 5.52 to 5.59 and from 4.45 to 5.5 while Pistia stratiotes had its pH value from 5.76 to 6.49 and from 6.24 to 7.07. Considerable percentage reduction was observed in all the parameters treated with the phytoremediators. Percentage reduction of turbidity for Eichhornia crassipes were 85.26% and 87.05% while Pistia stratiotes were 92.70% and 93.69% respectively. Similar reductions were observed in COD, TKN, NO3−, NH3, and PO43−. The capability of these plants in removing nutrients was established from the study. Removal of aquatic macrophytes from water bodies is recommended for efficient water purification.

New sequential treatment for mature landfill leachate by cationic/anionic and anionic/cationic processes: optimization and comparative study.

Two new applications for sequence treatment of mature (stabilized) landfill leachate, that is, cationic resin followed by anionic resin (cationic/anionic) and anionic resin followed by cationic resin (anionic/cationic), are employed and documented for the first time in the literature. Response surface methodology (RSM) concerning central composite design (CCD) is used to optimize each treatment process, as well as evaluate the individual and interactive effects of operational cationic resin dosage and anionic resin dosage on the effectiveness of each application in terms of color, chemical oxygen demand (COD), and NH(3)-N removal efficiency. A statistically significant model for color, COD, and NH(3)-N removal was obtained with high coefficient of determination values (R(2)>0.8). Under optimum operational conditions, the removal efficiency levels for color, COD, and NH(3)-N are 96.8%, 87.9%, and 93.8% via cationic/anionic sequence, and 91.6%, 72.3%, and 92.5% via anionic/cationic sequence, respectively. The experimental results and the model predictions agree well with each other.

Landfill leachate treatment using sub-surface flow constructed wetland by Cyperus haspan.

Performance evaluation of pilot scale sub-surface constructed wetlands was carried out in treating leachate from Pulau Burung Sanitary Landfill (PBSL). The constructed wetland was planted with Cyperus haspan with sand and gravel used as substrate media. The experiment was operated for three weeks retention time and during the experimentation, the influent and effluent samples were tested for its pH, turbidity, color, total suspended solid (TSS), chemical oxygen demand (COD), biochemical oxygen demand (BOD(5)), ammonia nitrogen (NH(3)-N), Total phosphorus (TP), total nitrogen (TN) and also for heavy metals such as iron (Fe), magnesium (Mg), manganese (Mn) and zinc (Zn) concentrations. The results showed that the constructed wetlands with C. haspan were capable of removing 7.2-12.4% of pH, 39.3-86.6% of turbidity, 63.5-86.6% of color, 59.7-98.8% of TSS, 39.2-91.8% of COD, 60.8-78.7% of BOD(5), 29.8-53.8% of NH(3)-N, 59.8-99.7% of TP, 33.8-67.0% of TN, 34.9-59.0% of Fe, 29.0-75.0% of Mg, 51.2-70.5% of Mn, and 75.9-89.4% of Zn. The significance of removal was manifested in the quality of the effluent obtained at the end of the study. High removal efficiencies in the study proved that leachate could be treated effectively using subsurface constructed wetlands with C. haspan plant.

Application of psyllium husk as coagulant and coagulant aid in semi-aerobic landfill leachate treatment

Landfill leachate is a heavily polluted and a likely hazardous liquid that is produced as a result of water infiltration through solid wastes generated industrially and domestically. This study investigates the potential of using psyllium husk as coagulant and coagulant aid for the treatment of landfill leachate. Psyllium husk has been tested as primary coagulant and as coagulant aid with poly-aluminum chloride (PACl) and aluminum sulfate (alum). As primary coagulant, the optimum dosage and pH for PACl were 7.2 and 7.5 g/L, respectively, with removal efficiencies of 55, 80 and 95% for COD, color and TSS, respectively. For alum, the optimum conditions were 11 g/L alum dosage and pH 6.5 with removal efficiencies of 58, 79 and 78% for COD, color and TSS, respectively. The maximum removal efficiencies of COD, color and TSS were 64, 90 and 96%, respectively, when psyllium husk was used as coagulant aid with PACl. Based on the results, psyllium husk was found to be more effective as coagulant aid with PACl in the removal of COD, color and TSS as compared to alum. Zeta potential test was carried out for leachate, PACl, alum and psyllium husk before and after running the jar test to enhance the results of the jar test experiments.

Sustainable treatment of landfill leachate

Landfill leachate is a complex liquid that contains excessive concentrations of biodegradable and non-biodegradable products including organic matter, phenols, ammonia nitrogen, phosphate, heavy metals, and sulfide. If not properly treated and safely disposed, landfill leachate could be an impending source to surface and ground water contamination as it may percolate throughout soils and subsoils, causing adverse impacts to receiving waters. Lately, various types of treatment methods have been proposed to alleviate the risks of untreated leachate. However, some of the available techniques remain complicated, expensive and generally require definite adaptation during process. In this article, a review of literature reported from 2008 to 2012 on sustainable landfill leachate treatment technologies is discussed which includes biological and physical–chemical techniques, respectively.