International Journal of Scientific Research in Environmental Sciences (IJSRES), 1(2), pp. 16-25, 2013 Available online at http://www.ijsrpub.com/ijsres

©2013 IJSRPUB

16

Trends in Physical-Chemical Methods for Landfill Leachate Treatment

Amin Mojiri1, Hamidi Abdul Aziz

1*, Shuokr Qarani Aziz

2

1School of Civil Engineering, Engineering Campus, University Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia

2Department of Civil Engineering, College of Engineering, University of Salahaddin–Erbil, Iraq

*Corresponding Author: cehamidi@eng.usm.my

Received 25 December 2012; Accepted 19 January 2013

Abstract. Leachate is created while water penetrates through the waste in a landfill, carrying some forms of pollutants. The

aims of this study were the review on physical-chemical methods for landfill leachate treatment. The physical-chemical ways

for landfill leachate treatment like Chemical precipitation, Chemical Oxidation, Coagulation–Flocculation, Membrane

filtration, Ion exchange, Adsorption and Electrochemical treatment are studied. Chemical precipitation is generally used as pre-

treatment in order to remove high strength of ammonium nitrogen; fenton oxidation is one of these advanced oxidation

processes with high efficiency and low capital costs; coagulation–flocculation has been used for the removal of non-

biodegradable organic compounds and heavy metals from landfill leachate; nanofiltration (NF) is one of membrane filter and it

has found a place in the removal of recalcitrant organic compounds and heavy metals from landfill leachate; adsorption is the

most widely used technique for the removal of recalcitrant organic compounds from landfill leachate; the ion-exchange method

offers a number of benefits containing the ability to handle shock loadings and operate over a wider range of temperatures. The

landfill leachate properties, technical applicability and constraints, effluent discharge alternatives, cost-effectiveness,

regulatory requirements and environmental impact are important factors to selection of the most suitable treatment technique

for landfill leachate treatment.

Key word: Adsorption method, Chemical Oxidation, Ion exchange, Leachate, Membrane filtration,

1. INTRODUCTION

Which passes through the solid waste fill and

facilitates transfer of pollutants from solid phase to

liquid phase, landfill leachate is generated by the

penetrating water. Because of the inhomogeneous

nature of the waste and due to the different

compaction densities that will be encountered, water

will be able to percolate through and appear as

leachate at the base of the site (Cotman and Gotvajn,

2010). Landfill leachate could be a main foundation of

water contamination, if not treated and disposed

safely, because it could enter through soil and subsoil.

Therefore, before release, the treatment of hazardous

leachate components has been made a legitimate

obligation to prevent pollution of water resources and

to elude both acute and chronic toxicities (Aziz et al.,

2011a).

Landfill leachate includes organic and inorganic

contaminants in high rates. Leachate is created while

water penetrates through the waste in a landfill,

carrying some forms of pollutants like ammonia-

nitrogen (NH3-N), chemical oxygen demand (COD),

biological oxygen demand (BOD5), colour, suspended

solids and heavy metals. It may become a potential

contamination source which threats soil, surface water

and groundwater, if they are not collected carefully

and not discharged safely. Therefore, landfill leachate

is recognized as a vital environmental problem by

modern societies (Deng, 2007).

Because of the increase in the world population

and changes in the consumption habits, solid waste

removal has become a serious environmental problem.

In the solid waste management, landfill is one of the

most prevalent methods used by many countries in the

world (Veli et al., 2008).

The any single way is no obtainable for

environmentally friendly and economically. There

will be many other studies concerning the top

available technology providing both maximum

treatment efficiency and optimum cost. The landfill

leachate treatment ways are physical, chemical and

biological ones which are used in combinations (Kılıç

et al., 2007).

Removals by direct biological treatment of urban

landfill leachates are generally low because of high

COD (6000–15,000 mg.l-1

) and ammonium ion (500–

3000 mg.l-1

) contents, high COD/BOD ratio and also

due to the presence of toxic compounds such as metal

ions and COD. The treatment strategy generally

depends on the characteristics of the leachate. Young

landfill leachates are generally treated more easily as

compared to the old ones. Ways advanced for

treatment of landfill leachates can be classified as

physical, chemical and biological which are usually

used in combinations in order to improve the

treatment efficiency. The sedimentation, air-stripping,

adsorption, membrane filtration are the physical

methods for leachate treatment. Among the chemical

ways used for leachate treatment coagulation–

flocculation, chemical precipitation, chemical–

electrochemical oxidations are the major ones (Karg

and Pamukoglu, 2004).

Mojiri et al.

Trends in Physical-Chemical Methods for Landfill Leachate Treatment

17

2. PHYSICAL AND CHEMICAL METHODS

The reduction of suspended solids, colloidal particles,

floating material, color, and toxic compounds by

flotation, coagulation/flocculation, adsorption,

chemical oxidation and air stripping are physical and

chemical processes. Physical/chemical treatments for

the landfill leachate are used in addition at the

treatment line (pre-treatment or last purification) or to

treat a specific pollutant (stripping for ammonia)

(Renou et al., 2008).

3. CHEMICAL PRECIPITATION

The chemical precipitation is generally used as pre-

treatment in order to remove high strength of

ammonium nitrogen (NH4+-N), in the case of leachate

treatment (Renou et al., 2008). Chemical precipitation

has been used for the removal of non-biodegradable

organic compounds, NH3–N and heavy metals from

landfill leachate because of its capability, the

simplicity of the process and inexpensive equipment

employed. During chemical precipitation, dissolved

ions in the solution are converted to the insoluble solid

phase via chemical reactions. The removal of

ammoniacal–nitrogen from anaerobically pre-treated

leachate was studied using struvite (magnesium

ammonium phosphate (MAP) precipitation in the

Odayeri landfill (Turkey). Using this method,

ammonia was converted into a nitrogen fertilizer such

as urea. About 50% COD and 90% NH3–N, with an

initial COD concentration of 4024 mg/L and NH3–N

concentration of 2240 mg/L, were removed

(Kurniawan et al., 2006).

Ozturk et al. (2003) used Struvite as precipitant for

the removal of NH3-N from anaerobically pre-treated

leachate. The removal efficiency of NH3-N and COD

were 90% and 50%, respectively. It is confirmed that

the ammonium concentration in leachate could be

considerably reduced by struvite precipitation.

However, this process requires relatively expensive

chemicals (Kochany and Lipczynska-Kochany, 2009).

4. CHEMICAL OXIDATION

Chemical oxidation processes were developed at

different sites in during the last years. A combination

of oxidation agents as ozone or hydrogen peroxide

and ultraviolet light (UV) is employed in opposite to

earlier experiments. This combination shows high

oxidation rates for leachate COD and AOX. The

process contains of a mixing chamber to mix influent

leachate and the oxidation agent and thereafter a

chamber with UV-lamps. Flows are recirculated to

increase elimination rates manifold of leachate. In

opposite to mixing hydrogen peroxide and water the

mixing of gaseous ozone and water is more difficult.

It has to be encountered that also anorganic

compounds may be oxidised during the chemical

oxidation step. To prevent the expensive oxidation of

easy biodegradable components a biological pre-

treatment including nitrification / denitrification

should be considered. During chemical oxidation not

all organics are oxidized to carbon dioxide and water.

Some organics are only partly oxidized often to

biological degradable inter medial products. These

“new” biodegradable organics shall be reduced by

biological treatment. A fixed film reactor may be an

option for the reduction of these relatively low

concentrations of organics. It can also be considered

to feed the effluent of the chemical oxidation plant

back to the influent of the biological reactor

(Stegmann et al., 2005).

Amokrane et al. (1997) used oxidants like chlorine,

potassium permanganate, ozone, and calcium

hydrochloride, for landfill leachate treatment and

found COD removal of 20–50%. Researchers reported

that the efficiency of COD reduction for mature and

biologically pretreated landfill leachates were 60 to 75

%, respectively by using Fenton reagent (Lopez et al.,

2004; Kang and Hwang, 2000).

4.1. Fenton Treatment

The Fenton process has been widely studied in recent

years, and analyses indicate Fenton process to be one

of the most cost-effective alternatives among potential

physicochemical technologies for leachate treatment

(Deng, 2007). Fenton's oxidation is one of these

advanced oxidation processes (AOPs) with high

efficiency and low capital costs. It is a mixture of

H2O2 and ferrous salts, capable to generate aggressive

hydroxyl radicals at ambient temperature. The shaped

radicals are able to oxidise a wide range of chemicals

in aquatic medium, theoretically all organic

compounds containing hydrogen (RH). The Fenton's

procedure could be effective to achieve not only good

oxidation of organics, but also their removal due to

the coagulation run in the presence of ferrous salts

(Gotvajn et al., 2011).

Fenton process can achieve two alternative goals

exploiting the strong oxidation potential of hydroxyl

radicals (•OH) as one of advanced oxidation processes

(AOPs): first is the reduction of the chemical oxygen

demand (COD) content of wastewater up to the

chosen maximum allowable concentration value

through the mineralization of recalcitrant

contaminants; the second is the development of the

biodegradability of treated effluents with the aim of

making their subsequent biological treatment possible.

Commonly, Fenton process is composed of following

International Journal of Scientific Research in Environmental Sciences (IJSRES), 1(2), pp. 16-25, 2013

18

steps: pH adjustment, oxidation reaction,

neutralization, coagulation and solid–liquid

separation. Under acidic situation, the organic

substances are degraded by reactive free radicals •OH

produced in the H2O2/Fe2+

mixture, and removed by

means of coagulation with formation of ferric hydroxy

complexes after neutralization. Both oxidation and

coagulation play vital roles in the removal of organics.

It is vital to understand the mutual relationships

between reaction parameters in terms of hydroxyl

radical production and consumption, in order to

understand better and improve Fenton reaction (Wu et

al., 2010).

Fenton oxidation was used by Mohajeri et al.

(2010) for the removal of colour and COD from Pulau

Burung stabilized landfill leachate whereby colour

and COD removal were 78% and 58%, respectively

(Mohajeri et al., 2010). Additionally, Gotvajn et al.

(2009) mentioned that the removal efficiency of NH3-

N by Fenton oxidation was 40%.

Several authors have been reported, that Fenton's

process can achieve 60–90% of COD removal of

organics from landfill leachate (Gotvajn et al., 2011).

Kang and Hwang (2000) mentioned that COD

removal efficiency by oxidation was greatly affected

by the pH value and the most effective oxidation

reaction was observed below pH 4.0 (Wu et al., 2010).

5. COAGULATION-FLOCCULATION OR

FLOCCULATION-PRECIPITATION

As shown in Table 1, coagulation–flocculation has

been used for the removal of non-biodegradable

organic compounds and heavy metals from landfill

leachate. The coagulation process destabilizes

colloidal particles by the addition of a coagulant. To

increase the particle size, coagulation is typically

followed by flocculation of the unstable particles into

bulky floccules so that they can settle more easily.

This method facilitates the removal of suspended

solids and colloid particles from a solution. The

general approach for this method contains pH

adjustment and involves the addition of ferric/alum

salts as the coagulant to overcome the repulsive forces

between the particles. The coagulation with FeCl3 was

studied for removal of heavy metals from stabilized

leachate containing high concentrations of organic and

inorganic matter (Kurniawan et al., 2006).

Silva et al. (2004) was expressed the coagulation

and flocculation is a relatively simple method that

may be used successfully in treating old landfill

leachates. However, this treatment only leads to

moderate removals of COD and TOC, and it has its

drawbacks: sludge is produced, and in some cases,

when traditional chemical coagulants are employed,

an increase on the concentration of aluminium or iron,

in the liquid phase, may be observed.

After the biological treatment,

Flocculation/Precipitation e.g. with FeCl3, is mostly

practised to reduce the organic load of the leachate.

This method is not used frequently also due to the fact

of the increase of chloride and/or sulfate in the

leachate effluent. The flocculation / precipitation step

will be necessary for the removal of the loaded

activated carbon if powered activated carbon is used

(Stegmann et al., 2005). The coagulation–flocculation

processes are widely used in drinking and wastewater

treatment plants because of implementation and

operation simplicity (Rivas et al., 2004).

6. MEMBRANE FILTRATION

A membrane could be defined as a material that

creates a thin barrier capable of selectively resisting

the move of different constituents of a fluid and

therefore affecting separation of the constituents

(Visvanathan et al., 2000). Usually, a thin layer of

material with a high surface porosity and a narrow

domain of pore size affect the physical structure of the

membrane. Different membrane filtration techniques:

microfiltration, ultrafiltration, nanofiltration, and

reverse osmosis are used in landfill leachate treatment.

6.1. Microfiltration

Microfiltration with pore sizes of 0.05 to 10 microns

is employed to capture microbial cells, small particles,

and large colloidal. According to landfill leachate

treatment, this method is not suitable to be used alone.

It is recommended to be used as pretreatment process

with other membrane processes (i.e. ultrafiltration,

nanofiltration or reverse osmosis) or in combination

with chemical treatment 10 processes so as to remove

suspended matters and colloids. Piatkiewicz et al.

(2001) used this method as pre-filtration stage and

obtained COD removal of 25% to 35 %.

6.2. Ultrafiltration

Ultrafiltration is a selective process utilizing pressures

up to 10 bar. This technique is efficient to remove

suspended matters either by direct filtration or with

biological treatment to replace sedimentation unit. It is

strongly dependant on the kind of material

constituting the membrane. Syzdek and Ahlert (1984)

proposed that this process might prove to be useful as

a pre-treatment method for reverse osmosis. It could

be employed to eliminate the larger molecular weight

components of leachate that tend to foul reverse

osmosis membranes (Bohdziewicz et al., 2001;

Rautenbach et al., 1997). COD removal of 50% was

Mojiri et al.

Trends in Physical-Chemical Methods for Landfill Leachate Treatment

19

obtained by using ultrafiltration alone (Bohdziewicz et

al., 2001). Lastly, Tabet et al. (2002) reported that

ultrafiltration membranes have been successfully

employed in full scale membrane bioreactor plants by

combination of bioreactors and membrane technology.

High levels for landfill leachate treatment have been

obtained by using this method.

6.3. Nanofiltration (NF)

Nanofiltration (NF) has found a place in the removal

of recalcitrant organic compounds and heavy metals

from landfill leachate because of its unique properties

between ultrafiltration (UF) and reverse osmosis (RO)

membranes. It has the ability to remove particles with

a molecular weight of higher than 300 Da also to

inorganic substances through electrostatic interactions

between the ions and membranes. Which allow

charged solutes smaller than the membrane pores to

be rejected, along with bigger neutral solutes and salts

the significance of this membrane lies in its surface

charges. As shown in Table 2, NF is also effective for

the removal of heavy metals because of the negatively

charged groups on the membrane. The application of

NF allows material dissolved in water to be separated

into monovalent and divalent ions (Kurniawan et al.,

2006).

6.4. Reverse Osmosis (RO)

Reverse osmosis (RO) is one of the developments in

the last decade for leachate treatment is the. But in

contrast to the biological treatment it is a separation

process into two streams - one low contaminated

permeate stream and one highly contaminated

concentrate stream. If leachate from the acetic phase

has to be treated a biological pre-treatment may be

necessary for several reasons as increased

precipitation has to be expected, low molecules may

pass the membrane and fowling on the membrane

surface may be enhanced. The separation of

ammonium is often not sufficient during reverse

osmosis. The reduction of ammonia concentrations in

permeate may be increased by means of a two or

multiple step reverse osmosis. In some cases

ammonium is removed by means of a prestripping

process or a biological nitrification and denitrification

step. A disadvantage of RO is the production of the

liquid concentrate (about ± 20 % of the leachate). The

technique of back passing the concentrate into the

landfill is in the opinion of the authors not the best

option (Stegmann et al., 2005).

Unlike RO, NF has a looser membrane structure,

enabling higher fluxes and lower operating pressure

for the treatment of leachate (Kurniawan et al., 2006).

Ahn et al. (2002) stated that a landfill leachate

treatment plant in Korea was retrofitted to improve

treatment efficiency by employing integrated

membrane technique that was composed of membrane

bioreactor and reverse osmosis method. The removal

efficiencies of COD and NH3-N from young landfill

leachate were 96% and 97 %, respectively. Other

researchers stated that the removal of COD and NH3-

N from landfill leachate was 98% (Linde et al., 1995).

7. ION EXCHANGE

Ion exchange is a reversible interchange of ions

between the solid and liquid phases where there is no

permanent change in the structure of the solid. This

treatment is capable of effectively removing the traces

of metal impurities to meet the increasingly strict

discharge standards in developed countries. Prior to

ion exchange, the leachate should first be subjected to

a biological treatment (Kurniawan et al., 2006).

The solid ion exchange particles can be classified as

natural-inorganic particles (zeolites) and synthetic-

organic resins, which were developed from high-

molecular-weight polyelectrolytes (Bashir et al.,

2010). Development of ion exchange resins and

characterization of naturally occurring ion exchange

materials has demonstrated a wide range of possible

applications of the technology in water and

wastewater treatment (Wang and Peng, 2010).

The ion-exchange technique offers a number of

benefits containing the ability to handle shock

loadings and operate over a wider range of

temperatures. Ion-exchange/adsorption processes can

be advanced as post treatment to a membrane bio-

reactor (MBR) due to the very high degree of

clarification possible. Further, sorption processes by

selective ion-exchangers are ideal candidates for

reduction of dissolved ammonia and phosphate to

near-zero levels provided that the sorbent is ammonia

and/or phosphate selective, cost effective and

amenable to efficient regeneration and reuse. Some of

the most popular and widely available natural ion

exchangers are zeolites, which consist of an

aluminosilicate molecular structure with weak cationic

bonding sites. Natural zeolites have been avoided in

high purity processes or where consistency is vital

because of irregularities and impurities of the

material. Zeolites are hydrated alumino silicates

comprising silica and aluminium tetrahedra which are

mutually bound by chemical covalent bonds with

common oxygen atoms (Mojiri, 2011). 8. ADSORPTION

Adsorption is the most widely used technique for

the removal of recalcitrant organic compounds from

International Journal of Scientific Research in Environmental Sciences (IJSRES), 1(2), pp. 16-25, 2013

20

landfill leachate. Fundamentally, adsorption is a mass

transfer process by which a substance is transferred

from the liquid phase to the surface of a solid, and

becomes bound by physical and/or chemical

interactions (Kurniawan et al., 2006). The adsorption

of contaminants onto Activated Carbon in columns or

in powder form provides better reduction in COD

levels than the chemicals ways, whatever the initial

organic matter concentration (Table 3). The main

drawback is the need for frequent regeneration of

columns or an equivalently high consumption of

powdered activated carbon (PAC). Adsorption by

activated carbon has been used along with biological

treatment for effective treatment of landfill leachate.

Nonbiodegradable organics, inert COD and the color

may be reduced to acceptable levels for biologically

treated landfill leachate (Renou et al., 2008).

Adsorption technique is recognized as the efficient

and promising elementary approach in wastewater

treatment processes (Foo and Hameed, 2009). It is

used as a stage of integrated chemical-physical-

biological method for leachate treatment, or

simultaneously with a biological process. The most

commonly used adsorbent is granular activated carbon

or PAC (Mojiri, 2011).

The adsorption using granular activated carbon

(GAC) or powder activated carbon (PAC) has been

receiving a considerable attention newly for the

removal of organic and inorganic contaminants from

polluted wastewater because of its inherent physical

properties, large surface area, micro-porous structure,

high adsorption capacity and surface reactivity

(Kurniawan et al., 2006).

Rodriguez et al. (2004) studied PAC and different

resins efficiency in the reduction of non-

biodegradable organic matter from landfill leachate.

Activated carbon presented the highest adsorption

capacities with 85% COD decrease and a residual

COD of 200 mg L−1 (Renou et al., 2008).

9. ELECTROCHEMICAL TREATMENT

In recent years, electro-chemical ways were used for

treatment of organic materials having high toxicity

and low biological degradability. Electro-chemical

ways like electrocoagulation (EC), electro-oxidation

and electro-photo-oxidation were frequently applied

for treatment of wastewaters from textile, tannery and

oil industries. Treatment of landfill leachate via

electro-chemical ways is also another important

interest area. In most of the studies in this field,

especially the electro-oxidation method was examined

(Deng, 2007).

9.1. Electro oxidation

In recent years, the electrochemical oxidation

process has been shown to be promising for

wastewater treatment, mainly because of its

effectiveness and ease in operation, The process has a

great efficacy for the destruction of refractory

pollutants like cyanide, EDTA, aniline, and also for

color removal (Chiang et al., 1995). 10. CONLUSION

The landfill leachate treatment ways are physical,

chemical and biological ones which are used in

combinations. Physical/chemical treatments for the

landfill leachate are used in addition at the treatment

line (pre-treatment or last purification) or to treat a

specific pollutant. Physical/chemical treatments such

as Chemical precipitation, Chemical Oxidation,

Coagulation–Flocculation, Membrane filtration, Ion

exchange, Adsorption, and Electrochemical treatment

were studied in this manuscript. The landfill leachate

properties, technical applicability and constraints,

effluent discharge alternatives, cost-effectiveness,

regulatory requirements and environmental impact are

important factors to selection of the most suitable

treatment technique for landfill leachate treatment.

Mojiri et al.

Trends in Physical-Chemical Methods for Landfill Leachate Treatment

21

International Journal of Scientific Research in Environmental Sciences (IJSRES), 1(2), pp. 16-25, 2013

22

Table 2: Removal of organic and inorganic compounds using NF or RO (Kurniawan et al., 2006)

Location of Landfill Kind

of

Process

Type of

Membrane

Species Pressure

(bar)

Initial concentration (mg/L) BOD/COD pH Rejection rates (%)

COD NH3-N Metal BOD COD NH3-N Metal

NA (Not Available) NF NTR-7250 Cr(III)

Cu(II) Pb(II)

3

NA

NA

0.69

0.23 0.03

NA

NA

NA

NA

NA

100

99 93

Odayeri (Turkey)

Mustankorkea (Finland)

NF

NF

SW

Desal 5-DL

NA

NA

25

6-8

3000

920

950

220

NA

NA

NA

84

NA

0.40

NA

7.6

89

66

72

50

NA

NA Spillepeng (Sweden) NF AFC-30 Pb(II)

Zn(II)

Cd(II)

20

2000

NA

0.61

0.50

0.03

NA

NA

NA

NA

NA

97

88

94 Chung Nam (South

Korea) Yachiyo (Japan)

RO

RO

SW-4040

DT

NA

Mn(II)

NA

9-11

1500

97.4

1400

33.7

NA

4.77

450

5

0.30

0.05

NA

6

97

100

96

98

NA

100

Pietramelina (Italy) RO SW30-2521 Cd(II)

Zn(II)

Cu(II)

52

3840

NA

0.50

1200

0.31

6

98

NA

100

97

99

Hedeskoga (Sweden)

Spillepeng (Sweden) Wijster (Holland)

RO

RO

AFC99

NA NA

Cr(III)

NA NA

40

30 40

1254

925 335

541

280 140

0.02

NA NA

125

NA NA

0.10

NA NA

7

6.5 6.5

95

98 98

82

98 98

NA

NA NA

Ihlenberg (Germany) RO

NF

NA

NA

36-60

NA

1797

170000

336

3350

0.25

NA

54

510

0.03

0.03

7.7

6.4

99

96

100

58

98

NA Lipowka (Poland) RO SS NA 27.6 1780 743 NA 331 0.28 7-8 97 NA NA

Table 3: Treatment effectiveness of landfill leachate with the use of adsorption (Renou et al., 2008)

COD (mg.L-1) BOD/COD pH From Adsorbent Removal (%)

879-940 0.03 7.5 Landfill Granular activated carbon (columns) 91 COD

640 - - Landfill Granular activated carbon (columns) -

108 0.06 8 Landfill Powdered activated carbon -

800-2000 0.04-0.07 - Landfill Activated carbon (concentration range

2–10 g L−1)

96 TOC

- - - Landfill Powdered activated carbon (2 g L−1) 55-77 color

625 0.3 7.9 Landfill Peat 69 COD

9500 - 7 Landfill Powdered activated carbon (2 g L−1) 38 COD

1533-2580 0.03-0.04 7.5-9.4 Landfill CaCO3 (particle size range 2–4 mm) 90 COD

10,750-18,420 0.55 7.7-8.2 Landfill leachate +

Municipal sewage

Powdered activated carbon

(concentration range 0.1–3.5 g L−1)

-

7000 - 7 Synthetic wastewater Powdered activated carbon (0–2 g L−1) 90 COD

716-1765 - 7.58-7.60 Pilot plant Granular activated carbon and resins 85 non-biodegradable

COD (GAC)

59 non-biodegradable

COD (resin)

Acknowledgement

The authors would like to acknowledge the University

Sains Malaysia (USM) for provision of research grant

to conduct this work, and their supports.

REFERENCES

Ahn WY, Kang MS, Yim SK, Choi KH (2002).

Advanced landfill leachate treatment using an

integrated membrane process. Desalination,

149: 109–114.

Amokrane A, Comel C, Veron J (1997). Landfill

leachates pretreatment by coagulation-

flocculation. Water Resource, 31 (11): 2775-

2782.

Aziz SQ, Aziz HA, Yusoff MS (2011). Optimum

Process Parameters for the Treatment of Landfill

Leachate using Powdered Activated Carbon

Augmented Sequencing Batch Reactor (SBR)

Technology. Separation Science and Technology,

46: 1–12.

Bashir, MJK, Aziz HA, Yusoff MS, Adlan MN

(2010). Application of response surface

methodology (RSM) for optimization of

ammoniacal nitrogen removal from semi-

aerobic landfill leachate using ion exchange

resin. Desalination, 254: 154-161.

Bohdziewicz J, Bodzek M, Gorska J (2001).

Application of pressure-driven membrane

techniques to biological treatment of landfill

leachate. Process Biochemistry, 36: 641-646.

Chiang LC, Chang JE, Wen TC (1995). Indirect

Oxidation Effect in Electrochemical Oxidation

Treatment of Landfill Leachate. Wat. Res., 29

(2): 671-678.

Mojiri et al.

Trends in Physical-Chemical Methods for Landfill Leachate Treatment

23

Cotman M, Gotvajn AZ (2010). Comparison of

different physico-chemical methods for the

removal of toxicants from landfill leachate.

Journal of Hazardous Materials, 178: 298–305.

Deng Y (2007). Physical and oxidative removal of

organics during Fenton treatment of mature

municipal landfill leachate. Journal of

Hazardous Materials, 146: 334–340.

Foo KY, Hameed BH (2009). A Short Review of

Activated Carbon Assisted process: An

Overview, Current Stage And Future

Prospects. Journal of Hazardous Materials, 170:

552- 559.

Gotvajn AZ, Končan JZ, Cotman M (2011). Fenton's

oxidative treatment of municipal landfill

leachate as an alternative to biological process.

Desalination, 275: 269–275.

Gotvajn AZ, Tisler T, Zagorc-Koncan J

(2009). Comparison of different treatment

strategies for industrial landfill leachate. J.

Hazardous Mater., 162: 1446-1456.

Kang YW, Hwang KY (2000). Effects of reaction

conditions on the oxidation efficiencyin the

Fenton process. Water Res., 34: 2786–2790.

Karg F, Pamukoglu MY (2004). Adsorbent

supplemented biological treatment of pre-

treated landfill leachate by fed-batch operation.

Bioresource Technology, 94: 285–291.

Kılıç MY, Kestioglu K, Yonar T (2007). Landfill

leachate treatment by the combination of

physicochemical methods with adsorption

process. J. BIOL. ENVIRON. SCI., 1(1): 37-43.

Kochany J, Lipczynska-Kochany E (2009). Utilization

of land!ll leachate parameters for pretreatment

by Fenton reaction and struvite precipitation a

comparative study. J. Hazard. Mater., 166: 248-

254.

Kurniawan TA, Lo W, Chan GYS (2006). Physico-

chemical treatments for removal of recalcitrant

contaminants from landfill leachate. Journal of

Hazardous Materials. B129: 80–100.

Linde K, Jönsson A, Wimmerstedt R (1995).

Treatment of three types of landfill leachate

with reverse osmosis. Desalination, 101 (1): 21-

30

Lopez A, Pagano M, Volpe A, Di Pinto AC (2004).

Fenton’s pre-treatment of mature landfill

leachate. Chemosphere, 54(7): 1005–1010

Mojiri A (2011). Review on Membrane Bioreactor,

Ion Exchange and adsorption Methods for

Landfill Leachate Treatment. Australian Journal

of Basic and Applied Sciences, 5(12): 1365-

1370.

Mohajeri S, Aziz HA, Isa MH, Zahed MA, Adlan MN

(2010). Statistical optimization of process

parameters for landfill leachate treatment using

electro-Fenton technique. J. Hazard Mater.,

176: 749-758.

Ozturk I, Altinbas M, Koyuncu I, Arikan O, Gomec-

Yangin C (2003). Advanced physicochemical

treatment experiences on young municipal

landfill leachates. Waste Management, 23(5):

441- 446.

Renou S, Givaudan JG, Poulain S, Dirassouyan F,

Moulin P (2008). Landfill leachate treatment:

Review and opportunity. Journal of Hazardous

Materials, 150: 468–493.

Piatkiewicz W, Biemacka E, Suchecka T (2001). A

Polish Study: Treating Landfill leachate with

membranes. In: Filtration and Separation, vol

38, 6th edn, pp. 22-23.

Rautenbach R, Vossenkaul K, Linn T, Katz T (1997).

Waste water treatment by membrane processes-

New development in ultrafiltration,

nanofiltration and reverse osmosis.

Desalination, 108(1–3): 247–253

Rivas FJ, Beltran F, Carvalho F, Acedo B, Gimeno O

(2004). Stabilized leachates: sequential

coagulation–flocculation + chemical oxidation

process. Journal of Hazardous Materials, B116:

95–102.

Rodriguez J, Castrillon L, Maranon E, Sastre H,

Fernandez E (2004). Removal of non-

biodegradable organic matter from landfill

leachates by adsorption. Water Res., 38: 3297–

3303.

Silva AC, Dezotti M, Sant’Anna GL (2004).

Treatment and detoxification of a sanitary

landfill leachate. Chemosphere, 55: 207–214.

Stegmann R, Heyer KU, Cossu R (2005). Leachate

Treatment. Proceedings of Tenth International

Waste Management and Landfill Symposium,

Cagliari, Italy; 3 - 7 October.

Syzdek AC, Ahlert RC (1984). Separation of landfill

leachate with polymeric ultrafiltration

membranes. Journal of Hazardous Materials,

9(2): 209-220.

Tabet K, Moulin P, Vilomet JD, Amberto A, Charbit

F (2002). Purification of landfill leachate with

membrane processes: preliminary studies for an

industrial plant. Separation Science and

Technology, 37: 1041-1063.

Veli S, Ozturk T, Dimoglo A (2008). Treatment of

municipal solid wastes leachate by means of

chemical- and electro-coagulation. Separation

and Purification Technology, 61: 82–88.

Visvanathan C, Ben Aim R, Parameshwaran K

(2000). Membrane Separation Bioreactors for

Wastewater Treatment. Critical Reviews in

Environmental Science and Technology, 30(1):

1-48.

International Journal of Scientific Research in Environmental Sciences (IJSRES), 1(2), pp. 16-25, 2013

24

Wang S, Peng Y (2010). Natural zeolites as effective

adsorbents in water and wastewater treatment.

Chemical Engineering Journal, 156(1): 11-24.

Wu Y, Zhou S, Qin F, Ye X, Zheng K (2010).

Modeling physical and oxidative removal

properties of Fenton process for treatment of

landfill leachate using response surface

methodology (RSM). Journal of Hazardous

Materials, 180: 456–465.

Mojiri et al.

Trends in Physical-Chemical Methods for Landfill Leachate Treatment

25

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 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 1992. 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.

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.