Landfill Leachate Treatment Using Sequencing Batch Reactor (SBR) Process: Limitation of Operational Parameters and Performance

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1 International Journal of Scientific Research in Knowledge (IJSRK), 1(3), pp , 2013 Available online at ISSN: ; 2013 IJSRPUB Review Paper Landfill Leachate Treatment Using Sequencing Batch Reactor (SBR) Process: Limitation of Operational Parameters and Performance Shuokr Qarani Aziz 1,*, Hamidi A. Aziz 2, Amin Mojiri 2, Mohammed J.K. Bashir 3, Salem S. Abu Amr 2 1 Department of Civil Engineering, College of Engineering., University of Salahaddin Erbil, Iraq 2 School of Civil Engineering, Engineering Campus, USM, Nibong Tebal, Penang, Malaysia 3 Faculty of Engineering and Green Tech. (FEGT), Universiti Tunku Abdul Rahman, Kampar, Perak, Malaysia *Corresponding Author: shoker71@yahoo.com Received 20 January 2013; Accepted 20 February 2013 Abstract. Sequencing batch reactor (SBR) process uses for treatment of different types of wastewaters such as municipal wastewater, landfill leachate, dairy wastewater, slaughterhouse wastewater etc. Operation parameters of SBR technique are cycle time, aeration rate, volume of reactor, hydraulic retention time (HRT) and other parameters. In this work, operational parameters and removal efficiencies of pollutants for SBR method were studied. In addition, boundaries for operational parameters in SBR process were explained as well. Key words: Landfill leachate, Treatment, Sequencing batch reactor, Operational parameters, Biological process, Aeration 1. INTRODUCTION In areas where sufficient land is available, sanitary landfill technique is widely used for the disposal of municipal solid wastes. Nevertheless of economic benefits, there are a number of environmental shortcomings related to the sanitary landfill method, one of which is the generation of landfill leachate. Leachate is a very complex liquid that may contain high concentrations of phenols, ammonia nitrogen (NH 3 -N), biodegradable and non-biodegradable organic matter, phosphate, heavy metals, sulfide, hardness, acidity, alkalinity etc. When untreated leachate is directly disposed to the natural environment, it severely contaminates the water sources. Thus, treatment of formed landfill leachate is essential prior disposal to the natural environment (Aziz et al., 2010). To prevent/reduce pollution of the natural environment, biological treatment, adsorption using various adsorbents, precipitation, ion exchange, coagulation-flocculation, chemical and electrochemical oxidation, and reverse osmosis are the common treatment processes for the landfill leachate (Renuo et al., 2008; Bashir et al., 2010; Aziz et al., 2011a,b,c; Mohajeri et al., 2011). Because landfill leachate has a high degree of variation in quality and quantity, the sequencing batch reactor (SBR), which has greater process flexibility among biological treatment methods, is therefore well fitted for leachate treatment. The high concentrations of organic matters, low biodegradability ratio, heavy metals, NH 3 -N, and other pollutants in leachate clearly 34 affect SBR performance. In the literature, adsorbents were added to activated sludge for the improvement of the biological treatment of landfill leachate (Aziz et al., 2011b,c, d). A gap of knowledge can be noticed in the literature, particularly in SBR operation parameters. Thus, the objectives of this study were to (1) reveal the operational parameters of SBR process and (2) show the applications and performance of the SBR technique. 2. COMMON SBRCHARACTERISTICS 2.1. General Activated sludge has become the most extensively employed secondary unit process for the treatment of wastewater. Arden and Lockett s original investigations in 1913 involved aerating sewage for several weeks before the treated liquor was permitted to settle and the supernatant water was decanted. Thus, the very original activated sludge process was operated as a batch reactor and became identified as the fill-and-draw method. A number of sequential treatment operations were repeated in order to treat the influent wastewater. A reactor was filled with settled sewage and aerated for adequate time to oxidize the majority of the BOD 5 (biodegradable matters). Following this aeration period, the aeration was turned off and reactor contents were then permitted to settle so the activated sludge separated from the supernatant (treated wastewater). The treated supernatant was consequently discharged from the

2 Aziz et al. Landfill Leachate Treatment Using Sequencing Batch Reactor (SBR) Process: Limitation of Operational Parameters and Performance batch reactor. A part of the settled sludge was wasted and the whole process was repeated for another cycle. The development of continuous process rapidly led to the neglect of fill-and-draw systems and their associated operating problems. On the other hand, with the advent of microprocessor control using programmable logic controllers, a modification of the original fill-and-draw technique, recognized as a SBR has emerged as a successful option to continuous flow activated sludge plants. SBRs treatment process is characterized by a repeated treatment cycle consisting of a series of sequential process phases; fill, react, settle, decant, and idle as shown in Figure 1 (Mahvi, 2008; Aziz, 2011). The phases are described below: Fig. 1: SBR operation for one cycle (Aziz et al., 2011a) 2.2. Basic Treatment Process a) Fill The fill process is where the reactor is filled with wastewater between a low water level and a high water level. The influent to the reactor could be either raw wastewater or primary effluent and it is distributed into the retained settled sludge. Fill could occur under mixed, unmixed, aerated or unaerated conditions. Practically, any aeration system (i.e. floating mechanical, diffused, or jet) could be used. The feed amount is determined based on a number of parameters including loading rate, F/M (food to microorganism ratio), HRT (hydraulic retention time), and settling characteristics of the organisms. The time of fill depends on the capacity of each reactor, the number of parallel reactors in operation, and the variations in the wastewater flow rate (Aziz, 2011). b) React The react phase begins once fill is complete. It includes mixing and aeration (dissolved oxygen (DO) > 2 mg /L). In this phase, no influent flow into SBR aeration and sludge could be wasted (Surampalli et al., ). Aeration process serves to nitrify ammonia, oxidize organic carbon, and promote uptake of phosphorus in the sludge, while unaerated conditions support denitrification of nitrite and nitrate. Time donated to this phase could be as high as 50% or more of the whole cycle time (Al-Rekabi et al., 2007). c) Settle When the react phase terminates, settle phase starts. In this phase, neither influent flow to SBR nor waste of sludge is permitted. It means that settle phase begins when all the mixing and aeration processes are turned off and the mixed liquor suspended solids (MLSS) settle. Clear supernatant appears in the upper part of the reactor. The duration of settle can be adjusted for sludge settleability. d) Decant Once settle process ends, the treated wastewater is withdrawn from the reactor and discharged during decant phase. In this phase, no influent flows to SBR as well no aeration is conducted. The decant process happens after an important depth of supernatant has

3 International Journal of Scientific Research in Knowledge (IJSRK), 1(3), pp , 2013 appeared. The supernatant is decanted from the upper part of the reactor via automatic valves. e) Idle The period between draw phase and the fill phase is termed as idle. The idle time could be employed effectively to waste settled sludge. It is optional phase and no influent is fed to the reactor in addition to the absence of aeration. It could be cancelled when an influent balance tank, holding tank, or some other technique of handling overload flow is obtainable. In addition, it could be eliminated where two or more tanks are used, and the SBRs are operated with fixed cycle times. Based on the design and operation of SBR, sludge wasting usually happens after settle phase, but could occur near the end of react, throughout settle phase, during decant process, or through idle, and could take place daily, weekly, or in every cycle. The advantages of SBR are: 1) Simple operation and low capital cost, 2) Very efficient in the removal of biodegradable organic matter, nitrify NH 3 -N as well removal of other pollutants, 3) Effectiveness in nitrification and denitrification processes, 4) The flexible nature of fill/react ratios and the time of aeration, 5) Needs fewer channels and pipe work, easily scalable and expandable, 6) Flexibility of operating parameters, and 7) Easy understanding of fundamental mechanisms of the process (Aziz, 2011; Mahvi, 2008; Al-Rekabi et al., 2007; Alkhaddar et al., 2005). 3. APPLICATION OF SBR PROCESS SBR is used for the treatment of domestic, municipal, industrial, diary, synthetic, textile effluent, tannery, meat product processing, toxic and slaughterhouse wastewaters, palm oil mill effluent, and landfill leachates because of high removal efficiency, simplicity in operation, and economical aspects. Table 1 shows the application of SBR in the treatment of various kinds of wastewaters. Due to low BOD 5 /COD ratio, high concentration of COD, NH 3 -N, heavy metals, and other compounds in landfill leachate, the capability of SBR in leachate treatment is weaker than that for municipal and industrial wastes (Mahvi, 2008; Al Rekabi et al., 2007; Uygur and Kargi, 2004). In literature, SBR was used for the treatment of leachate with low BOD 5 /COD ratio of 0.09 to 0.37 (Guo et al., 2010; Spagni et al., 2008; Klimiuk and Kulikowska, 2006). 4. ADVANTAGES AND DISADVANTAGES OF SBR Main advantages of SBR process are: 1) Simple construction, 2) Plant can fit into almost any shape, 3) Flow through plants requires regular shaped sites, 4) Fewer channels and pipe work, 5) Easily scaleable, and 6) Can be adapted to both nitrification and denitrification. While, the main disadvantages of SBR process are as following. A higher level of sophistication is required (compared to conventional systems), especially for larger systems, of timing units and controls, 2) Higher level of preservation (compared to conventional systems) associated with more sophisticated controls, automated switches, and automated valves, 3) Potential of discharging floating or settled sludge during the DRAW or decant phase with some SBR configurations, 4) Potential requirement for equalization after the SBR, depending on the downstream processes, and 5) Batch feeding from storage or bio-selectors required to control bulking (Aziz, 2011). 5. OPERATIONAL PARAMETERS FOR SBR PROCESS SBR performance depends on a number of parameters such as characteristics of wastewater (or leachate), sequential process phases for the repeated cycles, cycle time, ratio of treated wastewater to working volume of the reactor, aeration rate, contact time, DO concentration inside the reactor, MLSS concentration, mixed liquor volatile suspended solids (MLVSS), HRT, solids retention time (SRT), organic loading rate (OLR), nitrogen loading rate (NLR), adsorbent dosage, and F/M. Table 2 shows the operational parameters for the SBR process. Minimum and maximum figures for the operational parameters in the SBR process were obtained from literature (Table 3). 36

4 Aziz et al. Landfill Leachate Treatment Using Sequencing Batch Reactor (SBR) Process: Limitation of Operational Parameters and Performance Table 1: Treatment of different types of wastewaters by using SBR process No. Treatment of Removal of Removal (%) References 1 Municipal wastewater BOD 5 98 Umble and Ketchum (1997) TSS 90 NH 3 -N 89 2 Landfill leachate COD < 83 Timur and Ozturk (1999) 3 Dairy wastewater COD 80.2 Li and Zhang (2002) Total solids 63.4 Volatile solids 66.3 Total nitrogen Textile effluent Total organic 66 Shaw et al. (2002) carbon Colour 94 5 Landfill leachate COD 75 Uygur and Kargi NH 3 -N 44 (2004) Phosphate 44 6 Wool dyeng effluents COD Goncalves BOD et al. (2005) 7 Synthetic wastewater BOD Mahvi et al. COD 94.9 (2005) Total nitrogen 71.4 Total Tannery wastewater phosphorus COD Ganesh et al. (2006) NH 3 -N Slaughterhouse wastewater COD 96 Li et al. (2008) Total nitrogen 96 Total Landfill leachate phosphates Nitrification 98 Spagni and Nitrogen 95 Marsili-Labelli (2009) COD Landfill leachate diluted (1:10) COD 94.5 Bu et al. (2010) BOD Palm oil mill effluent COD Chan et al. (2010) BOD TSS Landfill leachate diluted (1:10) COD Lim et al with domestic wastewater 14 Industrial and domestic NH 3 -N > 90 Bassin et al. (2011) wastewater 15 Synthetic wastewater COD Guo et al. (2011) NH 4 -N Total nitrogen Phosphate Synthetic wastewater phenol up to about 100 Leong et al. (2011) 17 Meat products processing COD 99 Rodriguez et al. wastewater BOD 5 98 (2011a); (2011b) NH 4 -N 71 37

5 Fill time (h) React time (h) Settle time (h) Decant time (h) Idle time (h) Cycle time (h) Aeration Reactor vol. (L) Working vol. (L) Treated vol., L(%) Treated / Working (%) HRT (d) SRT (d) MLSS (mg/l) SVI (ml/g) OLR (kg COD/m 3.d) F/M International Journal of Scientific Research in Knowledge (IJSRK), 1(3), pp , 2013 Table 2: Operational parameters for SBR process No. Reference Treatment of Surampalli wastewater < > 2 b et al., a 2 a 8 a 4000 Azimi Synthetic et al. (2005) wastewater 11.9 c Timur and Leachate Ozturk (1999) Kennedy and Leachate Lentz (2000) Neczaj et al. (2005) Leachate Klimiuk and Leachate Kulikowsk (2006) 4 b Laetinen Leachate et al.( 2006) 40 Neczaj Leachatea and > 2 b et al. (2007) sewage 38

6 Fill time (h) React time (h) Settle time (h) Decant time (h) Idle time (h) Cycle time (h) Aeration Reactor vol. (L) Working vol. (L) Treated vol., L(%) Treated / Working (%) HRT (d) SRT (d) MLSS (mg/l) SVI (ml/g) OLR (kg COD/m 3.d) Aziz et al. Landfill Leachate Treatment Using Sequencing Batch Reactor (SBR) Process: Limitation of Operational Parameters and Performance Table 2: Operational parameters for SBR process (Cont.) No. Reference Treatment of Kurbus Synthetic c et al. (2008 ) wastewater Wang et al. (2009) Domestic wastewater b Li et al.(2008) Slaughterhouse wastewater 1.2 c Bu et al. (2010) Leachate Lim et al. (2010) Leachate and domestic w. (1:10) Chan et al. (2010) Bassin Gao et al. (2011) Leong et al.(2011) Palm oil mill Industrial and Synthetic Synthetic c c et al. (2011) effluent dom. wastewater wastewater wastewater Rodriguez et al. Meat products (2011a); (2011b) processing w a = typical, b = DO (mg/l), c = Aeration rate (L/min) 39

7 International Journal of Scientific Research in Knowledge (IJSRK), 1(3), pp , 2013 Table 3: Boundaries for operational parameters in SBR process (Based on Table 2.12) No. Parameter Values Minimum Maximum 1 Cycle time (h) Typical cycle time (h) Fill time (h) React time (h) Settle time (h) Decant time (h) Aeration rate (L/min) Treated volume/ working volume (%) DO concentration during react (mg/l) > 2 10 Nitrification process occur when DO (mg/l) > 1 11 Denitrification process occur when DO (mg/l) < 1 12 HRT (d) SRT (d) MLSS (mg/l) SVI (ml/g) OLR (kg COD/ m 3.d) LIMITATION OF OPERATIONAL PARAMETERS AND PERFORMANCE SBRs require oversize effluent outfalls because the entire daily wastewater volume must be discharged during the decant periods, which is typically 4 to 6 hours per day. Aeration systems must be sized to provide the total process air requirements during the aerated fill and react steps. The cost effectiveness of SBRs may limit their utility at design flow rates above 10 MGD. Earlier SBRs experienced maintenance problems with decant mechanisms but these have largely been resolved with present day designs (Aziz, 2011; Mahvi, 2008; Azimi et al., 2005). 7. CONCLUSIONS SBR process is efficient in removal of pollutants from different types of wastewaters. Operational parameters such as cycle time, aeration rate, volume of reactor, HRT etc. have a great role on performance of SBR method. It is necessary to study and determine optimum operational parameters (via pilot plant) for SBR process prior application the full scale for treatment of wastewaters. REFERENCES Alkhaddar RM, Phipps DA, Cheng C (2005). Today and tomorrow! Research prospects for aerobic biological liquid waste treatment for reduction of carbon load. Official Publication of the European Water Association (EWA). Al-Rekabi WS, Qiang H, Qiang WW (2007). Review on sequencing batch reactors. Pakistan Journal of Nutrition, 6 (1): Azimi AA, Hashemi SH, Bidhendi GN, Mahmoodkhani R (2005). Aeration ratio effect on efficiency of organic materials removal in sequencing batch reactors. Pakistan Journal of Biological Sciences, 8 (1): Aziz SQ, Aziz HA, Yusoff MS (2011a). Powdered activated carbon augmented double react-settle sequencing batch reactor process for treatment of landfill leachate. Desalination, in press. 40

8 Aziz et al. Landfill Leachate Treatment Using Sequencing Batch Reactor (SBR) Process: Limitation of Operational Parameters and Performance Aziz SQ, Aziz HA, Yusoff MS, Bashir MJK (2011b). Landfill leachate treatment using powdered activated carbon augmented sequencing batch reactor (SBR) process: Optimization by response surface methodology. J. Hazard. Mater., 189: Aziz SQ (2011). Landfill Leachate Treatment Using Powdered Activated Carbon Augmented Sequencing Batch Reactor (SBR). Process Unpublished, PhD thesis, School of Civil Engineering, Universiti Sains Malaysia. Aziz SQ, Aziz HA, Yusoff MS, Mohajeri S (2011c). Removal of phenols and other pollutants from different landfill leachates using powdered activated carbon supplemented SBR technology. Environmental Monitoring and Assessment. DOI /s Aziz SQ, Aziz HA, Yusoff MS (2011d). Optimum process parameters for the treatment of landfill leachate using powdered activated carbon augmented sequencing batch reactor (SBR) technology. Separation Science and Technology, 46 (15): Aziz SQ, Aziz HA, Yusoff MS, Bashir MJK, Umar M (2010). Leachate characterization in semiaerobic and anaerobic sanitary landfills: A comparative study. Journal of Environmental Management, 91: Bashir MJK, Aziz HA, Yusoff MS, Aziz SQ, Mohajeri S (2010). Stabilized Sanitary Landfill Leachate Treatment Using Anionic Resin: Treatment optimization by Response Surface Methodology. J. Hazard. Mater., 182: Bassin JP, Dezotti M, Sant Anna Jr GL (2011). Nitrification of industrial and domestic saline wastewaters in moving bed biofilm reactor and sequencing batch reactor. Journal of Hazardous Materials, 185: Bu L, Wang K, Zhao QL, Wei LL, Zhang J, Yang JC (2010). Characterization of dissolved organic matter during landfill leachate treatment by sequencing batch reactor, aeration corrosive cell-fenton, and granular activated carbon in series. Journal of Hazardous Materials, 179: Chan YJ, Chong MF, Law CL (2010). Biological treatment of anaerobically digested palm oil mill effluent (POME) using a lab scale sequencing batch reactor(sbr). Journal of Environmental Management, 91: Ganesh R, Balaji G, Ramanujam RA (2006). Biodegradation of tannery wastewater using sequencing batch reactor Respirometric assessment. Bioresource Technology, 97(15): Gao D, Liu L, Liang H, Wu WM (2011). Comparison of four enhancement strategies for aerobic granulation in sequencing batch reactors. Journal of Hazardous Materials, 186: Goncalves I, Penha S, Matos M, Satos A, Franco F, Panheiro H (2005). Evaluation of an integrated anaerobic/aerobic SBR system for the treatment of wool dyeing effluents, purification of wool dyeing effluent in a SBR. Biodegradation, 16 (1): Guo JS, Abbas AA, Chen YP, Liu ZP, Chen P (2010). Treatment of landfill leachate using a combined stripping, Fenton, SBR, and coagulation process. Journal of Hazardous Materials, 178: Kennedy KJ, Lentz EM (2000). Treatment of landfill leachate using sequencing batch and continuous flow upflow anaerobic sludge blanket (UASB) reactors. Water Research, 34 (14): Klimiuk E, Kulikowska D (2006). The influence of hydraulic retention time and sludge age on the kinetics of nitrogen removal from leachate in SBR. Polish Journal of Environmental Studuies, 15 (2): Kurbus T, Vrtovsek J, Ros M (2008). An SBR system with a high flocculent biomass concentration. Acta Chim. Slov., 55: Laitinen N, Luonsi A, Vilen J (2006). Landfill leachate treatment with sequencing batch reactor and membrane bioreactor. Desalination, 191: Leong ML, Lee KM, Lai SO, Ooi BS (2011). Sludge characteristics and performances of the sequencing batch reactor at different influent phenol concentrations. Desalination, 270: Li JP, Healy MG, Zhan X, Norton D, Rodgers M (2008a). Effect of aeration rate on nutrient removal from slaughterhouse wastewater in intermittently aerated sequencing batch reactors. Water Air Soil Pollut. 192: Li X, Zhang R (2002). Aerobic treatment of dairy wastewater with sequencing batch reactor systems. Bioprocess Biosyst. Eng., 25 (2): Lim PE, Lim SP, Seng CE, Noor AM (2010). Treatment of landfill leachate in sequencing batch reactor supplemented with activated rice husk as adsorbent. Chemical Engineering Journal, 159, Mahvi AH, Brown P, Forough V, Farham K (2005). Feasibility of continuous flow sequencing batch reactor in synthetic wastewater treatment. Journal of Applied Science, 5(1): Mahvi AH, Brown P, Forough V, Farham K (2005). Feasibility of continuous flow sequencing batch

9 International Journal of Scientific Research in Knowledge (IJSRK), 1(3), pp , 2013 reactor in synthetic wastewater treatment. Journal of Applied Science, 5(1): Mohajeri S, Aziz HA, Isa MH, Zahed MA, Mohajeri L, Bashir MJK, Aziz SQ (2011). Multiple responses analysis and modeling of Fenton process for treatment of high strength landfill leachate. Water Sc. and Technol., in press. Neczaj E, Kacprzak M, Lach J, Okoniewska E (2007). Effect of sonication on combined treatment of landfill leachate and domestic sewage in SBR reactor. Desalination, 204: Neczaj E, Okoniewska E, Kacprzak M (2005). Treatment of landfill leachate by sequencing batch reactor. Desalination, 185: Renou S, Givaudan GJ, Poulain S, Dirassouyan F, Moulin P (2008). Landfill leachate treatment: Review and opportunity. J. Hazard. Mater., 150: Rodriguez DC, Pino N, Penuela G (2011a). Monitoring the removal of nitrogen by applying a nitrification denitrification process in a sequencing batch reactor (SBR). Bioresource Technology, 102: Rodriguez DC, Ramirez O, Mesa GP (2011b). Behavior of nitrifying and denitrifying bacteria in a sequencing batch reactor for the removal of ammoniacal nitrogen and organic matter. Desalination, 273 (2 3): Shaw CB, Carliellb CM, Whealtley AD (2002). Anaerobic/aerobic treatment of colored textile effluents using sequencing batch reactor. Water Research, 36 (8): Spagni A, Marsili-Libelli S (2009). Nitrogen removal via nitrite in a sequencing batch reactor treating sanitary landfill leachate. Bioresource Technology, 100: Spagni A, Marsili-Libelli S, Lavagnolo MC (2008). Optimisation of sanitary landfill leachate treatment in a sequencing batch reactor, Journal of Water Science and Technology 58(2), Surampalli RY, Tyagi RD, Scheible OK, Heidman JA (1997). Nitrification, denitrification and phosphorus removal in sequential batch reactors. Bioresource Technolnology, 61: Timur H, Ozturk I (1999) Anaerobic sequencing batch reactor treatment of landfill leachate. Water Research, 33 (15): Umble AK, Ketchum LH (1997). A strategy for coupling municipality wastewater treatment using the sequencing batch reactor with effluent nutrient recovery through aquaculture. Water Science and Technology, 35 (1), Uygur A, Kargi F (2004). Biological nutrient removal from pre-treated landfill leachate in a sequencing batch reactor. Journal of Environmental Management, 71: Wang Y, Peng Y, Stephenson T (2009). Effect of influent nutrient ratios and hydraulic retention time (HRT) on simultaneous phosphorus and nitrogen removal in a two-sludge sequencing batch reactor process. Bioresource Technology, 100:

10 Aziz et al. Landfill Leachate Treatment Using Sequencing Batch Reactor (SBR) Process: Limitation of Operational Parameters and Performance Dr. Shuokr Qarani Aziz is a lecturer in the Civil Engineering Department, College of Engineering, University of Salahaddin-Erbil, Iraq. He received B.Sc. degree in Civil Engineering and M.Sc. in Sanitary Engineering from University of Salahaddin-Erbil, Iraq; Ph.D. in Environmental Engineering from Universiti Sains Malaysia (USM), Malaysia. He is editor and reviewer of some international journals. His area of specialization is Water Supply Engineering, Wastewater Engineering, Solid Waste Management, and Noise Pollution. Dr Aziz is a Professor in environmental engineering at the School of Civil Engineering, Universiti Sains Malaysia. Dr. Aziz received his Ph.D in civil engineering (environmental engineering) from University of Strathclyde, Scotland in He has published over 200 refereed articles in professional journals/proceedings and currently sits as the Editorial Board Member for 8 International journals. Dr Aziz's research has focused on alleviating problems associated with water pollution issues from industrial wastewater discharge and solid waste management via landfilling, especially on leachate pollution. He also interests in biodegradation and bioremediation of oil spills. Amin Mojiri is a PhD candidate in environmental engineering, School of Civil Engineering, Universiti Sains Malaysia (USM), Pulau Pinang. He is fellowship holder and research assistant at the School of Civil Engineering (USM). He is a member of Young Researchers Club, Islamic Azad University, Iran. He is editor and reviewer of some international journals. His area of specialization is waste management, waste recycling, wastewater treatment, wastewater recycling, and soil pollutions. Dr Mohammed J.K. Bashir is an Assistant Professor in environmental engineering at the faculty of engineering and green technology, Universiti Tunku Abdul Rahman (UTAR), Malaysia. Dr. Bashir received his B.Sc. degree in Civil Engineering from Islamic University of Gaza, Palestine. He received M.Sc and Ph.D in Environ. Eng. from School of Civil Engineering, Universiti Sains Malaysia. He received several award and has published many refereed articles in professional journals/proceedings. Dr. Bashir's research has focused on wastewater treatment, solid and hazardous waste management, environmental sustainability. Salem S.S. Abu Amr has a bachelor, a master and a PhD in water and environmental engineering. He has worked several years for Governmental, local as well as international consultancy firms and gained a wide experience in the field of water and environmental control and monitoring. He has also worked as an academic researcher in several research centres, universities and institutes and gained a wide experience and high potential in both practical and academic research work. Moreover, He has worked as a graduate assistant in the filed environmental engineering and he gained a wide experience in practical and research supervision. He has an international award in the field of water and agriculture. He has over 21 publications. His research interests encompass subjects related to Water and Environmental engineering, and focus on Wastewater Treatment via ozone/fenton/persulfate oxidation Processes and Solid Waste Management. He is also a referee for a few international journals. 43