Study of Leachate Characterization in Landfill by Municipal Solid Waste

 

Siripurapu Sriram¹, Venkata Ravibabu Mandla¹*, Chaithanya Sudha M¹, Saladi S.V. Subba Rao¹, Nagaveni Ch²., Vani V²., Gobinath P²., Raj Kumar KVG²., Jaydeep Lella¹, Sannidhi Krishna Praveen¹, Debjit Datta¹

¹OS-GST Lab, Department of Environmental and Water Resource Engineering, School of Civil and Chemical Engineering, VIT University, Vellore –TN.

²Center of Disaster Mitigation and Management (CDMM), VIT University, Vellore –TN.

 

ABSTRACT:

Background and Objectives: It is an expectation that Landfill continues to be the major disposal route for municipal solid waste in future also. It is evident from so many researchers that sanitary land filling is the one of the available cheap and best alternate for handling Municipal solid waste till this day.

·         Study on generation of leachate in landfills

·         Determination of composition, characteristics of leachate in landfills.

·         Determination of concentration and degree of landfill stabilization of leachate.

Methods: Leachate is produced during the landfill process. Leachate holding tank in landfill includes drainage, collection, removal with continuous monitoring. It includes treatment methods like: Biological, Physical and Chemical treatment processes. Results: Leachate generation, composition, characteristics, quantity with factors are discussed. Concentration and degree of landfill stabilization are measured. Variations with age in the typical concentrations of common factors for landfill leachate are measured. Typical constituents and characteristics are measured for leachate produced during landfill. Conclusions: Landfill technology is one of the popular methods for municipal solid waste and gaining popularity day by day. It has been implemented in so many countries. Modern landfills sites are well-engineered, operated and monitored. Through the landfills leachate is produced. In order to reduce environmental effects with the produced leachate-composition, quantity, concentration have to be minimize and new techniques are required to reduce green house gas emissions from landfills. Municipal solid waste increasing day by day not only population growth but also due to industrialization also.

 

 

1. INTRODUCTION:

In general Leachate contains mixture of large quantities of nitrogen (organic nitrogen and ammonium), heavy metals, and inert slowly degradable organic substances (fulvic and humic acids).  Leachate being the liquid that drains through a waste and posing problems of water  and soil contamination.

 

These consequences made treating of leachate are mandatory process irrespectto mode of disposal (i.e. Inland, Public sewer, and Land disposal).Improvements in landfill engineering are aimed at reducing leachate production, collection and treatment prior to discharge². Leachate collection was regularly done by using a graded under liners and drains, which finally leads to a collection pond or sump. Reductions in leachate generation may also have a favorable economics. As said above the main environmental problems at landfill sites are the infiltration of leachate and its subsequent contamination of the surrounding land and aquifers. Now a day’s researcher are still working in the areas of Improving in landfill engineering techniques, aimed at reducing leachate production, and treatment prior to discharge. M/s. Hyderabad Integrated MSW Ltd, Hyderabad has made some efforts in the treatment of leachate however there is still a need to make substantial improvements in the Leachate treatment for its disposal. Therefore, the objective of this research was to design the effective conceptual schemes for the treatment of landfill leachate.

 

2. Landfill Leachate Andits Treatment:

In most climates rain and snowfall will either infiltrate the soil cover or leave the site as surface runoff, depending on the type of covering provided ,the infiltrated water that is not subsequently lost by evapotranspiration or retained as soil moisture will percolate down through the waste deposit and generate the leachate, Landfill leachate is a highly potential polluting liquid, that is formed as infiltrating water migrates through the waste material extracting water-soluble compounds and particulate matter. The mass of leachate is directly related to precipitation ¹. Leachate generation changes from place to place and over time, the composition and characteristics of leachate depends on factors such as [3], (i) The type of the wastes deposited, (ii) Rainfall and other climatic factors (iii) The degree of surface and groundwater ingress (iv) The age of deposited waste (v) Degree of compaction and (vi) Cover, capping and restoration.  The quantity of leachate is dependent on the quantity of liquids entering the deposited wastes. Sources of liquid include: (a) Liquids within the wastes deposited (b) Rainfall (c) Surface water inflow and (d) Ground water intrusion. All these factors influence the production of leachate from the site. Reductions in leachate generation may also have a favorable economics, which unless managed and/or treated carefully, and eventually returned to the environment in such a way, may cause harmful effects on the surface water and also groundwater that surround a landfill site. Leachate collection was regularly done by using a graded under liners and drains ,which finally  leads to a collection pond or sump, Characteristics of leachate can be broadly divided into four categories: physical characteristics, inorganic chemicals, organic chemicals and toxicity⁴ following table 1  shows the landfill leachate concentration ranges as a function of the degree of landfill stabilization⁵. and while coming leachate concentration ranges according to landfill age were shown in table 2[6].

 

Table-1: landfill leachate concentration ranges as a function of the degree of landfill stabilization

Source : (Reinhart and Townsend, 1997)

 

Table-2: Variation with age in the typical concentrations of common factors of landfill leachate

 

3. Characteristics of Leachate:

The important factors which influence leachate quality include waste composition, elapsed time, temperature, moisture and available oxygen. In general, leachate quality of the same waste type may be different in landfills located in different climatic regions. Landfill operational practices also influence leachate quality. Following table 5 indicates the typical data on characteristics of leachate reported by Bagchi (1994), Tchobanoglous et al. (1993) and Oweis and Khera (1990). Data on leachate quality has not been published in India. However, studies conducted by Indian Institute of Technology, Delhi, NEERI, Nagpur, and some State Pollution Control Boards have shown ground water contamination potential beneath sanitary landfills¹.The some of the important characteristics in detail are as fallows

 

3.1 Color and smell:

The color of leachate is orange brown or dark brown, associated with the leachate is a malodorous smell, mainly due to the presence of organic acids, which come from the high concentration of organic matter was decomposed⁷.  In general, leachate produced by an old landfill with low biodegradability is classified as stabilized leachate. Stabilized leachate contains high levels of organic substances such as humic and fluvic compounds, which can be indicated by leachate colour⁸. Humic substances are natural organic matter made up of complex structures of polymerized organic acids, carboxylic acids and carbohydrates ⁹. Such as dark color and alodor will disappear slowly or change to light, which is relate to the increase of precipitation.

 

3.2 pH:

The pH leachate varies depend up on the age of the landfills, as  reported in ¹the typical  pH values varies from 3.7 to 8.9, while coming to in brief according to age of land fill it was as fallows young leachate has pH value of 5.7-8.0 , and 6.4-8.0,6.6 -8.3 for medium and old leachat as reported by⁶Generally, the pH of a stabilized leachate is higher than that of a young leachate¹⁰. This above trend is matching with as values reported by ⁶.

 

3.3 BOD:

The activity of microorganism was increased by time was processed, such as the BOD was increased also in the leachate. The BOD will up to the maximum value when the normal land filling is processing from 6 months to 2.5 years. The BOD becomes very deliquescent, which is a main characteristic. Finally, the BOD index start to reduce until the landfill is steady should through 6~15 years¹¹. Typical BOD values varies in the range of 0 to 195000 as mentioned¹,Generally measure of BOD is one of the Important parameter, The BOD values reported in ⁶are as fallows 7.5-17.0 g/l , 0.37-1.1g/l ,and 0.07-0.26g/l for young ,medium and old leachate respectively.

 

3.4 COD:

Effluent COD values are in the range of 50-99000 (Manual of MSW) The CODcr is lower in the initial stages of landfills .The reduction of COD is slow and the decrease of BOD is fast by time was processed. The reduction of BOD₅ or CODcr leads to the biochemical treatability is reducing. ¹²For new landfills, BOD values were 2000-30000 mg/l; for mature landfills, BOD value varies from 100-200 mg/l¹³.The COD values reported in [6]are as fallows 10.0-48.0 g/l , 1.2-22.0g/l ,and 0.67-1.9g/l for young ,medium and old leachate respectively.

 

3.5  TDS (total dissolved solids):

The change of TDS relate to the age of landfills in leachate. In the initial stages of landfills contain the concentration of total soluble salt (TSS) is up to 10000mg/l, and also contain the sodium, calcium, chloride, sulphate and iron. TDS is one of the parameters taken into consideration for licensing discharge of landfill leachate in many countries such as in UK¹⁴. The discharge limits for DS In India were as 2100mg/l irrespective of mode of disposal i.e Inland, Land disposal, public sewer

 

 

3.6 Suspended solids:

The suspended solid means solid matter in the leachate, and they consist of organic matter, inorganic matter, clay and microorganism etc. Leachate from landfills normally contains only small amounts of suspended solids; Fortunately, the treatment method of suspended solid is easier than other components in leachate treatment. The disposal standards for suspended solids are as fallows 100,200 and 600mg/l for Inland, land, public sewers respectively.

 

3.7 Chlorides and Phosphorus:

The high concentration of salt in the leachate mostly is chlorides, those are most serious when the rainfall is less in that particular zone. For new and mature landfills, the chloride values are 500 and 100-400 mg/l, respectively¹³. Phosphorus is one of the key elements necessary for growth of plants and animals and is a backbone of the Krebs’s Cycle and Deoxyribonucleic acid (DNA). Phosphorus transported from agricultural lands to surface water can promote eutrophication, which is one of the leading water quality issues in lakes and reservoirs.

 

3.8 N (nitrogen):

The N is one of the major constituent in the inorganic pollutant from the leachate. The concentration of N is high when the landfill in the processing. Microbial decomposition of organic carbon influences on many processes of the nitrogen cycle. With time, nitrogen concentration decreased due to microbial utilization of nitrate compounds and denitrifying as ammonia gas, the nitrogen mostly exists in the form of ammonia nitrogen. The high concentration of ammonia nitrogen brings unbalance of scale for the nutrition elements of microorganism.

 

3.9 Heavy Metals:

The concentration of heavy was one of the burning issue, where ever may be the place in the world. There are so many places which the problem of removal of heavy metals in the leachate is a big headache .The normal heavy metals ionic consist of Cu, Zn, Pb, Cd, Hg etc. In Generall for removl of these heavy metals Reverse osmosis is the proven technology till this date. Concentration of heavy metals in a landfill is generally higher at earlier stages because of higher metal solubility as a result of low pH caused by production of organic acids ¹⁵As a result of decreased pH at later stages, a decrease in metal solubility occurs resulting in rapid decrease in concentration of heavy metals except lead because lead is known to produce very heavy complex with humic acids¹⁶, the disposal standards  in india of Arsenic as (As) ,Mercury as (Hg), Lead (as pb) Cadmium  (as cd) ,Copper, Zinc ae as 0.2, 0.01, 0.1, 2.0, 3.0, 5.0 mg/l for inland disposal (table 3, 4). While coming to the Public sewers and land disposal the disposal standards are varies.

 

Table-3:Typical constituents of leachate from landfills

Type`	Constituent	Range (mg/I)	Range (mg/I)
	Parameter	Minimum	Maximum
Physical	Ph	3.7	8.9
	Conductivity	480 mho/cm	72500 mho/cm
Inorganic	Total Suspended Solids	2	170900
	Total Dissolved Solids	725	55000
	Chloride	2`	11375
	Sulphate	0	1850
	Hardness	300	225000
	Alkalinity	0	20350
	Total Kjeldahi Nitrogen	2	3320
	Sodium	2	6010
	Potassium	0	3200
	Calcium	3	3000
	Magnesium	4	1500
	Lead	0	17.2
	Copper	0	9.0
	Arsenic	0	70.2
	Mercury	0	3.0
	Cyanide	0	6.0
Organic	COD	50	99000
	TOC	0	45000
	Acetone	170	11000
	Benzene	2	410
	Toluene	2	16000
	Chloroform	2	1300
	Delta	0	5
	1,2 dichloromethane	0	11000
	Methyl ethyl ketone	110	28000
	Naphthalene	4	19
	Phenol	10	28800
	Vinyl Chloride	0	100
Biological	BOD	0	195000
	Total Coli form bacteria	0	100
	Fecal Coli form bacteria	0	10

 

Table-4: Characteristics of leachate in Landfill site

 

 

4. Leachate Drainage, Collection and Removal:

While coming to the concept of leachate drainage, collection and removal, as reported in ¹ it was as fallows, a leachate collection system comprises of a drainage layer, a perforated pipe collector system, sump collection area, and a removal system. The leachate drainage layer is usually 30 cm thick, has a slope of 2% or higher and a permeability of greater than 0.01 cm/sec. A system of perforated pipes and sumps are provided within the drainage layer. The pipe spacing is governed by the requirement that the leachate head should not be greater than the drainage layer thickness. Pipe material selection is based on design requirements. HDPE pipes are most commonly used; other materials can also be examined for feasibility. Leachate is removed from the landfill  by (a) pumping in vertical wells or chimneys, (b) pumping in side slope risers, or (c) by gravity drains rough the base of a landfill in above -ground and sloped landfills. Side slope risers are preferred to vertical wells to avoid any down drag problems.

 

Fig:1. Leachate holding tank in landfill site

 

Submersible pumps have been used for pumping for several years; educator pumps are also being increasingly used. In some landfills, the leachate is stored in a holding tank (for a few days) before being sent for treatment. The possibility of fall in efficiency of the drainage system due to clogging associated with solid deposits and microbial growth is now well recognized. A number of options, including back flushing or breakthrough water after leachate head build-up need to be investigated at the design stage. The design steps for the leachate collection system are:(a) Finalization of layout pipe network and sumps in conjunction with drainage layer slopes of 2%;(b) Estimation of pipe diameter and spacing on the basis of estimated leach ate quantity and maximum permissible leach ate head(c) Estimating the size of sumps and pump;(d) Design of wells/side slopes risers for leach ate removal; and(e) Design of a holding tank (fig 1).

 

4.1  Need for Monitoring:

The following points deals with the Needs of the monitoring:

i.         To demonstrate that the landfill is performing as designed

ii.        To provide reassurance that leach ate controls are preventing pollution of the environment (by reference to a pre-established baseline)

iii.      To meet the control and monitoring requirements (iv) To demonstrate compliance with the Ground water Control and Trigger level requirements of Schedule

iv.      To indicate whether further investigation is required /Not

v.       (vi)To identify when a site no longer presents a significant risk of pollution or harm to human health

 

4.2  Lecahte Treatment methods:

In general leachate treatment was divided in to three main ways, that is physical, chemical and biological processes,while coming to in detail about these processes they are as fallows

 

4.2.1 Biological Treatment Processes:

Biological purification processes are classified as aerobic or anaerobic depending on whether or not the biological processing medium requires an O2 supply. In aerobic processing organic pollutants are mainly transformed into CO2 and solid biological products (sludge) by using the atmospheric O2 transferred to the wastewater. In anaerobic treatment organic matter is converted into biogas, a moisture comprising chiefly CO2 and CH4 and in a minor part into biological sludge. Biological processes have been shown to be very effective in removing organic and nitrogenous matter from immature leachates when the BOD/COD ratio has a high value (>0.5). With time, the major presence of refractory compounds (mainly humic and fulvic acids) tends to limit process's effectiveness¹⁷.Majority of leach ate treatment schemes that have been successfully installed in landfill sites, are anaerobic biological processes. The drawbacks generally experienced in biological treatment originate from operational problems such as foaming, metal toxicity, nutrient deficiency and sludge settling¹⁸. Among the various biological treatment processes, Sequencing Batch Reactors (SBRs) has been to be proved a reliable and robust method for leach ate treatment to meet specified effluent consent values. SBRs are often installed in combination with reed beds to provide consistently high effluent quality, which can be safely discharged into sensitive surface watercourses¹⁹.

 

4.2.2 Physical Treatment:

There are several physical processes used for leachate treatment, which include activated carbon adsorption, filtration, pressure-driven membrane filtration processes, reverse osmosis and evaporation. These processes -generally cannot be applied successfully to remove the organic material from raw leachate. Therefore, suggested that reverse osmosis, activated carbon (PAC and GAC) and ion exchange could be used more successfully as a post-treatment for leachate after biological treatment²⁰. Although each of the processes is coupled with a biological system, they have a limited application and therefore can be even more effective when physico-chemical treatment is used as pre- and post- treatment for biological systems.

 

4.2.3  Chemical Treatment:

A wide scope of chemical treatment is available for leachate. The advantages of chemical methods in general include immediate start-up, easy automation, insensitivity to temperature changes and simplicity of plant and material requirements.

 

Table: 5. Disposal standards of leachate

S. No.	Parameter	Standards
		Inland	Public sewers	Land disposal
1	SS	100	600	200
2	DS	2100	2100	2100
3	PH	5,5 to 9.0	5.5 to 9.0	5.5 to 9.0
4	Ammonical nitrogen	50	50	-
5	Total kjeldahl nitrogen	100	-	-
6	BOD	30	350	100
7	COD	250	-	-
8	Arsenic as (As)	0.2	0.2	0.2
9	Mercury as (Hg)	0.01	0.01	-
10	Lead (as pb)	0.1	1.0	-
11	Calcium (as Cd)	2.0	1.0	-
12	Total Chromium	2.0	2.0	-
13	Copper	3.0	3.0	-
14	Zinc	5.0	15	-

 

However, these advantages are out-weighed by the disadvantages of large quantities of sludge generated due to the addition of flocculants and chemicals with high running costs. Thus, chemical and physical treatments are merely used as pre- or post-treatment of leachate to complement biological processes. The various chemical processes used in leachate treatment are coagulation, precipitation, oxidation, reduction, stripping, ion exchange, etc ²¹. Disposal standards of leachate were as follows: The disposal standards of leachate depending on the mode of disposal (i.e. In Land, Sewage and soil) were as fallows table 5.

 

5. CONCUSSION:

It is evident from so many researchers that sanitary land filling is the one of the available cheap and best   alternate for handling Municipal solid waste till this day, it was an accepted proof that, this landfill technology is gaining popularity day by day and has been tried in so many countries. It is an expectation that Landfill continues to be the major disposal route for municipal solid waste in future also. As mentioned already today, Modern landfills sites are well-engineered, operated, and monitored in order to reduce environmental effects and new techniques are required to reduce green house gas emissions from landfills and while coming to the Municipal solid waste utilization scenario it is increasing day by day along with population growth, population not only factor influencing the increase of MSW, other factors like industrialization and e.t.c contributes in their own way.

 

6. REFERENCE:

1.        S.R. Shukla Manual of “Municipal Solid Waste Management” by the Ministry of Urban Development, Government of India, 1998.

2.        Farquhar, G.J. Leachate production and characteristics. Canadian Journal of Civil Engineering, 16: 1989, 317-325.

3.        Land Fill operational practices, Environmental Protection Agency 1997

4.        Crawford, J.F., and Smith, P.G. Landfill technology, Butterworth’s, Anchor Brendon Ltd., Tip tree, Essex. 1985, ISBN 0-408-01407-5.

5.        Reinhart, D.R., and Townsend, T.G. Landfill bioreactor design and operation, Lewis publisher, USA. 1997, ISBN 1-56670-259-3.

6.        Alloway, B.j; ayres, D.C. Chemical principles of environmental pollution (Second edition). Waste and other multipollutant situation. P 357.Blackie A and P.1997. ISBN 0751403806

7.        H.A. Aziz, S. Alias, M. N. Adlan, F. A. H. Asaari and M. S. M. Zahari, Colour removal from landfill leachate by coagulation and flocculation process, Bioresource Technology, 98, 2007, 218-220.

8.        M. J. K. Bashir, H. A. Aziz, M. S. Yusoff, and M. N. Adlan, Application of response surface methodology for optimization of ammonical nitrogen removal from semi-aerobic landfill leachate using ion exchange resin. Desalination, 254, 2010, 154-161

9.        B. Langlais, D.A. Reckhow and D.R. Brink, Ozone in water treatment: application and engineering (Chelsea, MI: Lewis Publishers Inc., 1991. 

10.     T.G. Poznyak, L. Bautista, I.R. Chairez, I. Cordova and E. Rios, Decomposition of toxic pollutants in landfill leachate by ozone after coagulation treatment. Journal of Hazardous Materials, 152, 2008, 1108-1114.

11.     Ryding, Svenolof. Environmental management handbook The Holistic approach from problem to strategies. Published by IOS Press, 1992. ISBN 9051990626, 9789051990621

12.     W. Tyre, Bryan; C. Dennis, Michele. Site characterization and Design of Onsite Septic Systems – Onsit Sewage Disposal for a Subdivision in a high Groundwater Area. Editors: M. S. Bedinger; J. S. Fleming; A. I.Johnson. Now Orleans, Jan. 1617,1997. P278. ISBN 0803124201.

13.     G. Tchobanoglous, H. Theisen and S. A. Vigil, Integrated solid waste management engineering principles and management issues (1st ed.) (New York: McGraw-Hill, 1993.

14.     L. Koshy, T. Jones and K. BeruBe, Bioreactivity of municipal solid waste landfill leachates-Hormesis and DNA damage, Water Research, 42 (8-9), 2008, 2177-2183.

15.     D. Kulikowska and E. Klimiuk, The effect of landfill age on municipal leachate composition. Bioresource Technology, 99, 2008, 5981-5985.

16.     J. Harmsen, Identification of organic compounds in leachate from a waste tip, Journal of Water Research, 17(6), 1983, 699-705

17.     Lema, J.M., R. Mendez and R. Blazquez, Characteristics of landfill leachates and alternatives for their treatment: A review. Water Air Soil Pollution., 40: 1988, 223-250. DOI: 10.1007/BF00163730

18.     Qasim, S.R. and Chiang, W. Sanitary Landfill Leachate-Generation, Control and Treatment. Techonomic Publishing Co., Inc. Pennsylvania, USA: 1994, ISBN 1-56-676129-8

19.     Robinson, H. D. State-of-the-Art Landfill Leachate Treatment Systems inthe UK and Ireland, Paper presented to the IWM Annual Conference, 1999.

20.     Pohland, F.G. and Harper, S.R. Critical Reviews and Summary of Leachate and Gas Production from Landfills, EPA Report Number 1985, 600/2-86/073.

 

 

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