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DR AZIL BAHARI ALIAS

SOLID WASTE MANAGEMENT (CPE655)SOLID WASTE MANAGEMENT (CPE655)

W aste G ene ratio n

W aste handling, separatio n,s to rage and pro ce ss ingat the so urce

Co llec tio n

Transfe r and Transpo rt

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Se paratio n and pro ce ss ingand transfo rm atio n o fso lid was te

Learning outcomes

To describe planning of a landfillTo describe the components of a landfill and

the processes which take place in a landfill To design effective and safe sanitary landfill

INTRODUCTION

Waste - Land

Disposal

Containment sites (landfill)Attenuate and disperse sites (dumping site):

Introduction

Attenuate and disperse sites (dumping site/ rubbish pit):

traditional form of landfilling. Attenuation mechanisms: dilution and dispersion through pores and micro fissures into underlying saturated zones. Impossible to monitor or track the leachate pollutants

Waste - Land

Disposal

Natural attenuation landfill – dumping site/ rubbish pit

Waste - Land

Disposal

Containment sites (sanitary / MSW landfill)

Wastes, leachate and gas are isolated from the surrounding environment.The containment is achieved either by natural clay bottom liners or synthetic liners or a combination of both - is expected to be ‘leak free’.Facilities for leachate and gas collection and removal are installed and regular monitoring is possible.

Modern sanitary landfill

Landfill classification, types & methodsLandfill classification, types & methods

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Types of landfillGenerally three types

1. Conventional LF for commingled MSW2. LF for milled solid wastes3. Monofills for designated or specialized wastes4. Other types of landfill

LF for Commingled waste Majority of LF in the world are designed for commingled MSW In class III LF, limited amounts of non-hazardous industrial

waste and sludge from water and wastewater treatment plants are also accepted

Normally native soil is used as intermediate and final cover material

If not available, compost, foam, old rugs and carpeting, dredging spoil, and demolition wastes can be used

To obtain additional LF capacity, abandoned or closed landfills can be reused to recover materials and using decomposed residue as daily cover


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Types of landfill

Landfill for shredded solid waste Shredded waste can be placed at up to 35% greater

density and some without daily cover since blowing waste, odors, flies and rates not signification problems

Less soil cover is used because shredded waste can be compacted tighter and more uniform surface

Disadvantage: needs of shredding facilities, special section for hard to shred wastes

Potential applications in areas where landfill capacity is very expensive, cover material not readily available and low precipitation

Shredded waste can also be used to produce compost which can be used as intermediate cover material


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Types of landfill

Landfill for Individual waste constituents (Monofills) E.g. Combustion ash and asbestos often identified as

designated waste Purpose is to isolate from materials placed in MSW LF Combustion ash monofill may have odor problem due to

reduction of sulfate – gas recovery system is recommended

Other types of LF1. LF designed to maximize gas production

Deep, individual lined cells, waste is placed without intermediate layers of cover material and leachate is recycled to enhance AD

2. LF as integrated treatment units Organic part will be separated and placed in separate landfill for

gas recovery and stabilized waste use for cover material

TERMS OF DEFINITIONS

Sanitary landfillDefinition:

“a method of disposing solid waste on land without creating nuisance or hazard to public health or safety. Utilising engineering principles to confine wastes to the smallest practical area and to reduce it to the smallest practical volume and cover it with a layer of earth at the conclusion of each day’s operation or at such more frequent intervals as may be necessary”.

The landfilling- terms of definitionsThe landfilling- terms of definitions

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Definition of terms (cont’d)

Cell – volume of material placed in a landfill during one operating period which includes solid waste deposited and daily cover material surrounding it

Daily cover – usually consists of 6 to 12 in of native soil or alternative materials (e.g. compost) applied to working faces of landfill at the end of operating period to minimize waste blowing, prevent rats, flies, etc. and control of water entering the landfill during operation

Lift – a complete layer of cells over the active area of the landfill

Bench (terrace) – a flat surface commonly used to maintain slope stability of landfill, placement of surface water drainage channel, location of landfill gas recovery piping (height LF > 50 to 75 ft)

Final lift – includes the cover layer

Final cover layer – multiple layers of soil and/or geomembrane material covering entire surface of landfill after completion of landfill operation to enhance surface drainage, intercept percolating water and support surface vegetation

The landfilling process The landfilling process

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Leachate – liquid from percolation of precipitation, uncontrolled runoff, irrigation water, infiltrating groundwater and water initially contained in wastes

Landfill gas – mixture of gas produced from anaerobic digestion of waste

Landfill liner – several layers of compacted clay and/or geomembrane material (natural or synthetic) use to line the bottom area and below-grade sides of a landfill designed to prevent migration of leachate and gas

Landfill control facilities – includes liners, landfill leachate and landfill gas collection and extraction systems, daily and final cover layers

Environmental monitoring – involves activities associated with collection and analysis of water and air samples to monitor the movement of LFG and leachate

Landfill closure – steps to be taken to close and secure and landfill after filling operation is completed

The landfilling process The landfilling process

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Postclosure – refers to activities associated with the long-term monitoring and maintenance of the completed landfill (30-50 years)

Figure 11-2 pg. 363

LANDFILL IN MALAYSIA

Landfill in MalaysiaThere are approximately 230 landfills in Malaysia

and all except a few are unsanitary in nature.

A sanitary landfill is one that will deposit solid waste onto or into the land in such a manner that pollution to the environment is prevented as far as possible.

A sanitary landfill will have leachate management through internal basin drainage and treatment, external drainage and surface water management, landfill gas management, and closure and restoration provisions

1. Hazardous Waste Landfill disposal facility treatment storage must be appropriately permitted – specify all design & operating practices necessary to ensure compliance

2. Inert Waste Landfill - deploys environmental-friendly treatment

Acceptable Waste to be

disposedNon-Acceptable Waste

Construction Waste Domestic WasteSoil Toxic WasteTyres Fluid WasteGarden Waste Schedule WasteAny types of non-leaching

waste Condemned Food Waste

Type of Landfill

3. Open Dumping Landfill does not protect the environment susceptible to open burning exposed to the scavengers

4. Sanitary landfill new scientific technique purpose - treat wastes in an environment-friendly way guarantee protection risk of pollution minimized

Strictpermanent monitoring system

types of solid waste

Figure: Landfill Sites in Peninsular Malaysia (Yusof, 2008)

Level of Landfill

Reference: Agamuthu, P. and Fauziah S.H. (2008). Solid waste landfilling: Environmental factors and health. Proceedings of the EU-Asia Solid Waste Management Conference. Malaysia.

Table: Malaysia adopted a classification system that describes landfill state of technology (Idris, 2009)

Level Descriptions

1 Controlled tipping

2 Sanitary landfill with a bund and daily soil covering

3 Sanitary landfill with leachate re-circulation system

4 Sanitary landfill with leachate treatment system

Landfills in Malaysia

State

Number of Landfill Sites According to Types

Open Dumps

Level 1

Level 2 Level 3

Level 4

Total Number

Perlis 0 0 0 0 1 1Kedah 3 2 3 0 1 9Pulau Pinang 0 0 1 1 0 2Perak 9 5 2 2 0 18Selangor 0 7 1 1 2 11Negeri Sembilan 6 3 1 1 0 10Melaka 2 0 1 0 0 3Johor 13 8 4 1 0 26Pahang 5 3 2 3 1 14Terengganu 2 4 1 0 1 8Kelantan 10 1 1 0 0 12Kuala Lumpur 0 0 0 1 0 1Labuan 0 1 0 0 0 1Sarawak 15 11 2 0 0 28Sabah 12 4 0 1 0 17 161

Table: Number of landfill sites and levels in Malaysia (up to March 2002) by Idris, 2009

LANDFILL PLANNING

Principle elements that must be considered include

1. Landfill siting consideration

2. Landfill layout and design

3. Landfill operations and management

4. Reactions occurring in landfill

5. The management of LFG

6. The management of leachate

7. Environmental monitoring

8. Landfill closure and postclosure care

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SITING CONSIDERATION

Factors Remarks

1. Available land area Site should have useful life >1 yr (min value)

2. Haul distance Will have significant impact on operating costs

3. Soil conditions and topography

Cover material must be available at or near the site

4. Surface water hydrology

Impacts drainage requirements

5. Geologic and hydrogeology conditions

Probably most important factors establishment of landfill site – esp. with respect to site preparation

6. Climatologic conditions Provisions must be made for wet-weather operation

7. Local environmental conditions

Noise, odor, dust, vector and aesthetic factors control requirements

8. Ultimate use of site Affects long-term management for site.

Landfill site selection

The following site selection procedure is performed in four phases:

Phase 1: Site rating process (negative mapping) Phase 2: Identification of site areas (positive

areas) Phase 3: Site investigation Phase 4: Final decision

Phase 1: Site Rating Process (negative mapping)

Exclusion criteria are:Drinking water protection areas;High flood areas;Unstable ground;Extreme morphology;Unsuitable geological and hydrogeological

conditions;Residential areas including a protection distance;Nature protection areas;Important cultural sites.

Phase 2: Identification of Site Areas (positive area)

Criteria for elimination process by ranking are:

General data, e.g. volume, distance from main waste sources;

Hydro-geology and water management;Goetechnical and constructional aspects;Meteorological aspects;Nature protection and land use.

Site Construction Requirements

Location Easy access to transport by road Transfer stations if rail network is preferred Land value Cost of meeting government requirementsLocation of community servedStability

Underlying geology Nearby earthquake faults Water table Location of nearby rivers, streams, and flood plains

Costs Feasibility studies Site after care Site investigations (costs involved make small sites uneconomic).

OperationsConfined to as small an area as possible. Compacted to reduce their volume. Covered (usually daily) with layers of soil

Capacity of the wasteDensity of the wastes Amount of daily cover Amount of settlement (density of compacted waste)Construction of lining and drainage layers

Protection of soil and water

Installation of liner and collection systems. Storm water control Leachate management. Landfill gas management

LANDFILL LAYOUT, CONSTRUCTION

AND DESIGN

Methods of Landfilling

Figure: Ramp method Figure: Excavated/ trench method

Figure: Area Method

Definitions : refuse

Figure 4.14: Two methods of constructing a landfill; i) trench method and ii) area/ pit method.


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Landfilling methodsExcavated cell/trench method

Ideally suited to areas with adequate depth of cover material is available at site and deep water table

Waste placed in cells excavated in the soil which is used as daily & final cover

Cells usually lined with synthetic membrane liners or low permeability clay or combination of both (Fg 11.8)

Cells are typically square up to 1000 ft (l) x 1000 ft (w) with side slope of 1.5:1 to 2:1

Trenches vary from 200-1000 ft (l) x 15-50 ft (w) x 3-10 ft (h)


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Landfilling methodsCanyon/Depression method

Canyon, ravines, dry borrowpits and quarries can be used as landfills

Technique of waste placement and compaction vary with geometry of the site, characteristics of available cover material, hydrology and geology, type of leachate and gas control facilities and access to site

Critical factor – control of surface drainage Typically, filling for each lift starts at the head end of the

canyon and ends at mouth Key of success is availability of adequate material to

cover individual lifts and final cover

• Factors to be considered: Protection of components already

constructed; in particular, sealing layers and drainage blankets;

Minimum dimensions required for construction work;

Simple and non-sensitive design and construction;

Climate conditions; Availability of construction materials.

CONSTRUCTION

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Overview of Landfill Overview of Landfill constructionconstruction

Landfill – Construction Phase

During the phase one of landfill construction, land is excavated to within 3 feet of the top of the water table.

Confined to as small an area as possible:refuse cell confined portion -refuse is spread and compacted in thin layers several layers may be compacted on top of one another to a

maximum depth of about 10 feet (3 meters).

Confined Area


During phase two, a compacted clay or synthetic liner is added. This liner prevents contaminants from seeping into the groundwater. It has a permeability of 10-7 centimeters per second

Sanitary Landfill Liner System Installation

Natural clay

Soil cements

Asphaltic material

Polymeric membranes

Combination

Landfill Liners


During phase three, a leachate collection system is installed. This system is composed of pipes that overlay the compacted clay or synthetic liner.

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Landfill liner and leachate collection facilities Type of landfill liner used will depend on the local geology and

hydrology Generally, landfill sites should be located where there is little or

no possibility of contaminating potable water supplies Current trend is using composite liners including a geomembrane

and clay layer

Leachate treatment facilities Most common alternative to manage collected leachate

depending on local conditions:

1. Leachate recycling

2. Leachate evaporation

3. Treatment followed by disposal

4. Discharge to municiple wastewater collection system

Leachate Management FacilitiesLeachate Management Facilities


During phase four, a geosynthetic liner is installed. This layer will help to stabilize the waste.


During phase five, a sloped, sand drainage layer is installed. This layer will drain liquids away from the waste into the leachate collection system.

Composite Basal Lining SystemComposite Basal Lining System

waste

transitional layer – preventing fine-grained waste from blocking the drainage blanket

drainage blanket – collection and removal of leachate

protective layer – distribution of concentrated stresses

geomembrane – prevention of leakage

mineral sealing layers

subsoil

Landfill – Deposit Waste

During phase six, the landfill is opened and solid waste is deposited. New waste is spread and compacted every 6 feet. A soil or synthetic liner is added daily to prevent waste from blowing and to limit pests.

Compaction Process

Compaction process: To reduce waste volumeTo compact waste in order to reduce the volume it occupies and help stabilize the landfillCompactor vehicle – to spread the waste evenly in layers over the landfill and compact it.

Daily Cover

Layer of compressed soil or earth which is laid on top of a day's deposition of waste on an operational landfill site.

The cover helps prevent the interaction between the waste and the air, reducing odors and enabling a firm base upon which for vehicles to operate.

Landfill – Deposit Waste

Phase seven occurs throughout the active life of the landfill. During this phase, groundwater and gas monitoring wells are drilled into full waste cells

Landfill – Manage Landfill

Phase eight occurs after the landfill is filled to capacity. During this phase, a final stabilizing soil layer is placed over the compacted solid waste.


During phase nine, a clay cap is installed. This cap prevents water from filtering into the landfill. It is about 3 feet thick, with a permeability of 10-7 centimeters per second.


During phase 10, a geosynthetic cap is installed. This cap provides additional protection against water filtration.


During phase 11, a sand drainage layer is installed. The sand drains rainwater away from the waste.


During phase 12, a layer of topsoil is added to promote plant growth.

Soil cover (300mm) Landfill Gas Wells

Liner Clay Layer (1000mm)

Top Soil (200-400)mm Grass or Vegitative Cover

Site Closure““Capping””

Drainage System

Landfill – Final cover/ capping

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Usually composed of several layers, each with specific functions

Geomembrane liner as a barrier layer is favored by most LF designers to limit entry of surface water and control the release of LFG

Specific cover configuration depend on location of LF and climate conditions

E.g. to allow for regrading – use of deep layer of soil; for rapid removal of rainfall – sloped of about 3-5%

LF cover configurationLF cover configuration


During phase 13, grass and other short rooted plants are planted. These plants will prevent erosion of the landfill surface.


Phase 14 is the last phase of landfill construction. During this phase, a methane recovery building is constructed. This building uses landfill gas released during degradation to generate electricity for the facility.

Environmental Centre Infrastructure Facilities Environmental Centre Infrastructure Facilities Environmental Centre Leachate Treatment Plant Environmental Centre Leachate Treatment Plant

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Important to develop an overall drainage plan for the area that shows location of storm drains, culverts, ditches and subsurface drains as the filling operation proceeds

Depending on location and configuration of LF and capacity of natural drainage courses, it may be necessary to install storm water retention basin

Surface water drainage facilitiesSurface water drainage facilities

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Monitoring facilities are required for new landfills for Gases and liquids in the vadose zone Groundwater quality both upstream and downstream of landfill

sites Air quality at boundary of LF and from any processing facilities

(e.g. flares)

Specific number for monitoring stations will depend on the configuration and size of LF and the requirements of the local air and water pollution control agencies

Environmental monitoring facilitiesEnvironmental monitoring facilities

•Typical landfill progression showing internal, interim, and final slopes, and the facility bottom. •These types of slopes may also be present at other types of waste containment facilities.

Part Description

Facility bottom

•The base of a facility that is usually sloping 5% or less so that water, leachate, and other liquids can drain from a facility. •The term “facility bottom” excludes internal slopes or interim slopes.•Interfaces on facility bottoms that have grades of 5% or less may be assigned peak shear strength during stability analyses, if appropriate.

Final slopes

•Slopes that exist when the final grades for a facility have been achieved, including the cover system.•Interfaces on final slopes that will never be loaded with more than 1,440 pounds/ft2

may be assigned peak shear strength during stability analyses, if appropriate.

Schematic diagram of sanitary landfill

Landfill Designs

Landfill design

Foundationdesign

Liner design

Leachate collection and gas collection

Drainagedesign

Filling design

RunoffcollectionClosure

design

Figure: Schematic of double liner, leachate collection and landfill operations and process (Tchobanoglous et al., 1993).

Layout of landfill sitesLayout of landfill sites

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Layout of landfill sitesLayout of landfill sites

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New landfills are required to have gas collection and treatment facilities

Quantity of LFG must first be estimated before determining the size of gas collection and treatment facilities

Several rate should be analyzed as different operating procedures produce different rate of LFG

Horizontal or vertical gas recovery well depending on design and capacity of landfill and opportunity to sell power.

Selection of gas control facilitiesSelection of gas control facilities

LANDFILL DESIGN Important calculation

Determination of required areaLifespan of the landfill

Important criteriaWaste composition Waste generation rate Waste density Waste to soil ratio

Cont’

To estimate the volume required for a landfill, it is necessary to know the amount of refuse being produce and density of the in-place.

For estimating the annual volume required.

VLF = PEC

DC

Where;VLF = volume of landfill (m3/years)

P = populationE = ratio value of cover (soil) to compacted fill = (VSW + VC)/ VSW

VSW = volume of solid waste (m3)

VC = volume of cover (m3)

C = average mass of solid waste collected per capita per year (kg/ person.year)

DC = density of compacted fill (kg/ m3)

Example 1

Determine the area required for a new landfill

site with a projected life of 30 years for a populations of 250, 000 generating 2.02 kg/capita.day of solid waste. The density of compacted waste is 470 kg/m3. The height of

the landfill cannot exceed 15 m.

Solutions 1

KnownUnknown

projected life = 30 years area required =?

populations = 250, 000waste generated = 2.02 kg/capita.daydensity of compacted waste = 470 kg/m3

height of the landfill ≤15 m

Solutions 1 VLF = PEC

DC

Where;VLF = volume of landfill (m3 / years)






Volume of landfill for life span (years)VLF X ? yrs

Area needed; 15 m height restrictionArea, m2 = Volume, m3

Height, m

Solutions 1

Volume of waste (compacted at site) per day produced by community

Volume, m3/day = population, cap. X waste generated, kg/cap.ddensity of compacted waste, kg/m3

Volume of waste for 30 yearsVolume, m3 = Volume, m3 X life span, years X 365 day

day year


Height, m

Example 2

Estimate the area required (ha) in constructing a

landfill based on the following data:life span of the landfill = 25 yearsdensity of compacted waste = 530 kg/m3

waste generated = 2.5 kg/cap.day

average height = 10 mpopulation = 50, 000cover soil to waste ratio = 1:41 ha = 10000 m2

Solutions 2

Known Unknownlife span= 25 yrs area required

(ha)=? average height = 10 mpopulation = 50, 000cover soil to waste ratio = 1:4density of compacted waste = 530 kg/m3

waste generated = 2.5 kg/cap.day*1 ha = 10000 m2


DC









Height, m

Solutions 2 Volume of waste (compacted at site) per day produced by communityVolume, m3/day = population, cap. X waste generated, kg/cap.d

density of compacted waste, kg/m3

Volume of waste for 1 yearVolume, m3 /yr = Volume, m3 X 365 day

day year

Cover soil to waste ratio = 1:4Volume (cover), m3 /yr = 25% x volume of waste for 1 yrTotal volume (cover and waste), m3 /yr = Volume (cover), m3 /yr + Volume

(waste), m3 /yr


Height, m

Volume of waste for 25 yearsVolume, m3 = Volume, m3 X life span, years

year

Example 3

A community consist of 15, 000 population generate domestic waste about 2.3 kg/cap.day. Land area provided are 182, 000 m2. The

height of the landfill cannot exceed 6 m. The density of compacted waste are 347 kg/m3. Compute the

life span of the landfill and allow 25% of the volume for cover material.

Solutions 3

KnownUnknown

population = 15, 000 life span=?

waste generate =2.3 kg/cap.day. land area =182, 000 m2

height ≤ 6 m density of compacted waste = 347 kg/m3 cover material = 25% of the total volume


DC








Area; 6 m height restrictionArea, m2 = Volume, m3 /years X ? yrs

Height, m

LANDFILL OPERATIONS & MANAGEMENT

Waste collection

Waste weighbridge

Waste dumping process

Waste compaction process

Daily soil cover Capping/ covering process

Sanitary Landfill OperationsSanitary Landfill Operations

Track Loaders Hydraulic Excavators

Landfill Compactors Bulldozers

Tipper TrucksWheel Tractor-Scrapers

Motor Graders Backhoe Loaders

Standard Landfill Equipment

Covering OperationsCovering Operations

soil covering operation soil covering operation begins afterbegins after or or concurrently concurrently with tipping and with tipping and compaction operations.compaction operations.

cover materials helps to cover materials helps to protect the full range of protect the full range of environmental management environmental management objectivesobjectives

Covering operation at a landfill site

Types of covering operations in landfills Daily operations :

Carried out after the daily portion of tipping

Intermediate operation :Carried out as the landfill progresses helps in reducing leachate . No dump will be raised more than 10 meters.

Final covering operation : It is laid when the cell is full and depends on the future purpose of the site. A minimum cover thickness of 60 cm

Final Cover PlanTo provide permanent isolation of the cells from rainwater

by encapsulation

To integrate the site into the environment

To guarantee a long-term future compatible with the presence of waste

To allow easy management after operation

Finally be covered with a layer of topsoil (30 to 40 cm) Provides a barrier to the migration of water into the

waste, controls emissions to water and atmosphere, promotes sound land management and prevents hazards.

Covering operation at a landfill site

• Factors to be considered: Stability analyses of the waste body; Waste placement techniques, phasing and

supervision; Settlement and other types of deformation,

checked by monitoring programmes; Operating facility, buildings and roads; Gas management and monitoring

programmes; Surface water and drainage; Leachate management and groundwater

control; Environmental concerns, i.e. dust and noise

emissions, etc.

Landfill operationLandfill operation

REACTIONS OCCURING IN

LANDILL

Occurrence of Landfill Leachate and Gases

The following activities occur when solid wastes are placed in a sanitary landfill: Biological decay of organic materials (aerobical or anaerobic)

Chemical oxidation of waste materials

Escape of gases from the fill

Movement of liquids caused by differential heads

Dissolution and leaching of organic and inorganic materials by water and leachate moving through the fill;

Movement of dissolved material by concentration gradients and osmosis, and

Uneven settlement caused by consolidation of material into voids

LEACHATE MANAGEMENT

LANDFILL LEACHATELeachate may be defined as liquid that has

percolated through waste and has extracted dissolved or suspended materials from it.

Landfill leachate arises from the biochemical and physical breakdown of wastes

Leachate composed of liquid produced from the decomposition of the waste and liquid

LEACHATE FORMATION

PERC = P - RO - ET - ∆S + G

LEACHATE PRODUCTIONLEACHATE PRODUCTION

Typical composition of leachate (new and mature landfills)Value, mg/Lb

__________________________________________New landfill (less than 2 years) Mature

landfill_________________________

(greater thanConstituent Rangec Typicald 10 years)

BOD5 (5-day biochemical oxygen demand) 2,000-30,000 10,000 100-200TOC (total organic carbon) 1,500-20,000 6,000 80-160COD (chemical oxygen demand) 3,000-60,000 18,000 100-500Total suspended solids 200-2,000 500 100-400Organic nitrogen 10-800 200 80-120Ammonia nitrogen 10-800 200 20-40Nitrate 5-40 25 5-10Total phosphorus 5-100 30 5-10Ortho phosphorus 4-80 20 4-8Alkalinity as CaCO3 1,000-10,000 3,000 200-1,000pH 4.5-7.5 6 6.6-7.5Total hardness as CaCO3 300-10,000 3,500 200-500Calcium 200-3,000 1,000 100-400Magnesium 50-1,500 250 50-200Potassium 200-1,000 300 50-400Sodium 200-2,500 500 100-200Chloride 200-3,000 500 100-400Sulphate 50-1,000 300 20-50Total Iron 50-1,200 60 20-200

Leachate has entered the landfill from external sources, such as: Surface drainage Rainfall Groundwater Water from underground springs.

A. Ground WaterB. Compacted ClayC. GeomembraneD. Leachate Collection PipeE. Protection LayerF. GravelG. Drainage LayerH. Soil LayerI. Old CellsJ. New CellsF. Leachate Ponds

LEACHATE COLLECTION

Leachate Management Options?

RECYCLING

TREATMENTEVAPORATION

DISCHARGE

LEACHATE RECYCLINGAn effective method for the treatment of leachate is

to collect and recirculate the leachate through landfill,

During early stages of landfill operation, the leachate will contain significant amounts of TDS, BOD, COD, nutrients and heavy metals.

When leachate recirculated, the constituents are attenuated by biological activity and other chemical and physical reactions occurring within the landfill.

Typically, the rate of gas production is greater in leachate recirculation

Leachate recirculation system

2. Recirculation Through Landfill• The biochemical activity of the waste has

not been exhausted, potentially offers advantages both in reducing the volume of liquid by evaporation and reducing its strength

• Recirculation will be most effective in summer months or in warm climates when ambient temperatures and the consequent losses by evaporation will be high and leachate production at a minimum.

LEACHATE RECYCLING CNTD…

ProsProsConsCons

Enhances landfill stabilisation Enhances landfill stabilisation because rate of landfill gas because rate of landfill gas production is increased due to production is increased due to increase waste moisture increase waste moisture content.content.

Increase rate of groundwater Increase rate of groundwater pollution if used in a landfill pollution if used in a landfill with single-composite-lining.with single-composite-lining.

Reduce volume of municipal Reduce volume of municipal solid waste leachates. solid waste leachates.

Increases toxicity of leachate Increases toxicity of leachate by concentrating it.by concentrating it.

LF LEACHATE TREAMENT

LECHATE TREATMENTLECHATE TREATMENTTreatment Option Removal Ob

jectiveComments

Biological BOD/COD Best used on "young" leachate

Activated Sludge Flexible, shock resistant, proven, min imum SRT increases with in creas ing organic strength, > 90% BOD re mov al possible

Aerated Lagoons Good application to small flows, > 90% BOD removal possible

Anaerobic Aerobic polishing nec es sary to achieve high quali ty effluent

Powdered Activated Carbon/Act. Sludge

> 95 % COD removal, > 99 % BOD re moval

Physical/Chemical Useful as polishing step or for tre at ment of "old" leachate

Coagula tion/Precipitation

Heavy Metals High removal of Fe, Zn; moder ate removal of Cr, Cu, Mn; little re mov al of Cd, Pb, Ni

Chemical Oxidation COD Raw leachate treatment requires high chemi cal dosages, better used as polish ing step

Ion Exchange COD 10-70% COD removal, slight metal removal

Adsorption BOD/COD 30-70% COD removal af ter bio logical or chem ical treatment

Reverse Osmosis TDS 90-96 % TDS removal

ON SITE TREATMENT• Minimize the contaminants in the leachate• Reduce high concentrations of COD & BOD• Removal of 90% COD and ammonia (10-50

days)• Methods: Aerobic treatment (aerated lagoon)Polishing treatment (reed bed) Wetland system Spray irrigation (evaporation)

AERATED LAGOON

AERATED LAGOON Shallow ponds (<1m deep)Light penetrates to bottomActive algal photosynthesisOrganic matter converted to CO₂, NO₃⁻,

HSO₄⁻

WETLAND SYSTEM

WETLAND SYSTEMUse wetland plants to treat leachate(e.g: cat

tail)Requires enough ground area for constructionLeachate is treated by filtration, adsorption,

and reactions with the soil, roots, and bacteria in the root system

EVAPORATION Used the energy from combustion of landfill

gases Contaminants in the raw leachate were

concentrated to a small volume. Exhaust air from the evaporator was used to

preheat the leachate and released to the atmosphere.

REED BED

a channel filled with gravel, sand or soilplanted with macrophytes i.e. reeds

POLISHING

Effluent present in a contaminated landfill site for waste disposal is known as leachate.

Landfill leachate have made a serious pollution threat to the water environment.

reed bed systems provide reliable treatment with lower energy requirement and operation cost.

Reed bed for leachate treatment

ADVANTAGESOn-site treatment is the best alternative:

Lowest costPrevents public disturbancesAccommodate the changes in leachate

quality and quantityPotential for fertilizer productionNew habitat for wildlife

LANDFILL GAS MANAGEMENT

LANDFILL GAS (LFG)LANDFILL GAS (LFG)

Definition:Definition:A product of the degradation of biodegradable waste (any organic matter that can be broken down by micro-organisms such as paper, wood or food stuffs).

Landfill gas formation

Typical constituents found in MSW landfill gasa

Component % (dry volume basis)b

Methane 45 – 60 Carbon dioxide 40 – 60 Nitrogen 2 – 5 Oxygen 0.1 – 1.0 Sulphides, disulphides, mercaptans, etc. 0 – 1.0 Ammonia 0.1 – 1.0 Hydrogen 0 – 0.2 Carbon monoxide 0 – 0.2 Trace constituents 0.01 – 0.6 Characteristic Value Temperature, 0F 100 – 120 Specific gravity 1.02 – 1.06 Moisture content Saturated High heating value, Btu/sft3 400 - 550

LANDFILL GAS (LFG)The evolution rate and quantity of landfill gas dependent on a number of factors:

Waste input rateAmbient pHAmbient temperatureWaste density (closely or loosely packed)The specific site management

strategy/strategies

LANDFILL GAS CONTROL MEASURES

The common landfill gas control technologies include:

i. Means to collect gasesii. Control and treat gasesiii. Use gases to benefits the community (eg.,

to generate electricity or heat building)

LANDFILL GAS collectionLFG collection is divided into two (2) systems:

1. Passive Gas Collection System2. Active Gas Collection System

Passive Gas Collection System

Active Gas Collection System

Passive Venting

Passive venting may be carrier out successfully gas wells of the type shown in figure 2

They are normally constructed from high density polyethylene or polypropylene pipe up to 225mm in diameter, surrounded by no-fines crushed aggregate Figure 2: Passive Venting SystemFigure 2: Passive Venting SystemFigure 2: Passive Venting SystemFigure 2: Passive Venting System

Active Venting

• This system should be considered for all deep landfill sites

• The pumped wells will need to spaced at maximum of 50 meter intervals around the site perimeter and closer in high risk areas

• An inner ring may be necessary in order to maintain a negative pressure gradient operating to the site boundary

• Over pumping this excess air is not drown into the system.

LANDFILL GAS CONTROLODOR CONTROL TECHNOLOGIES:~ Prevent odor-causing gases from leaving the

landfill1. Landfill Cover ~ prevent odors from newly

deposited waste or from gases produced during bacterial decomposition.

2. Flaring ~ eliminate landfill gas odors by thermally destroying the odor-causing gases.

3. Venting Landfill Gas through a Filter ~ reduce odors by using a filter of bacterial slime.

1. Gas Production• The rates at which gas will be produced

depend upon the physical, chemical and microbiological characteristics of the landfill

• For proposed and existing sites, the need for the installation of gas control system, with monitoring points, should be evaluated following a detailed assessment of the site and the surrounding area

• Completed sites should be monitored to establish the composition of the gas, its rate of production, migration routes and the extent of any potential hazard

2. Gas Movement and Migration• The extent of gas movement within and

beyond the site boundaries will be determined by the size of this force and the permeability of the waste and strata

• Movement of gas from the site will be influenced, to a certain extent, by:– changes in barometric pressure– changes in leachate level– changes in water table levels

3. Gas Monitoring• Surface monitoring

– Using portable instruments to assist in determining the presence of gas escape but using has chromatography to confirm the source of the gas.

– The use probes driven into waste or strata provides point source monitoring of the gas concentration source monitoring of the gas concentration in a local environment around the probe

4. Landfill Gas Control Measures• The flammable range for methane is

approximately 5 to 15% by volume in air and that for hydrogen approximately 4-74%.

• The presence of carbon dioxide (density 1.5) increases the density of landfill gas over and above that of methane and, consequently, it may be either lighter or heavier than air

• As a result, stratification may enable flammable volumes of gas to collect and remain in buildings, structures, pipe works or areas which were thought previously to be free from flammable gas concentrations.

5. Gas Utilization

• Exploitation of the energy available in landfill gas should always be considered because, with careful design, even small site can provide sufficient energy to warrant a survey of possible nearby users

• In order to justify gas exploitation schemes, an indication or forecast of the rate of gas generation must be obtained

• The landfill gas exploitation may classified as either:–Direct use of gas, or–Conversion to electricity

Direct use of gas

• Include brick-klin firing, boiler firing and cement-klin firing

• It is also technically feasible to clean-up the gas ( ie. remove the carbon dioxide and other gases) and compress the remaining methane which can be put into cylinders and sold, used as a vehicle fuel or put into natural gas systems.

LANDFILL GAS UTILIZATION

Conversion to electricity

• Spark ignition and diesel engineers can both be converted to operate on landfill gas

• Small sites, with less than 1 million tonnes waste in place are often considered to be below the threshold of exploitation viability but many in the UK are being investigated to assess these as well as larger sites in order to provide an estimate of national landfill gas resource.

WHERE THE ODOR COME FROM?

From landfill gas and leachate.Landfill gas (LFG)

produces from organic material that decomposed anaerobically. Made up primarily of methane and carbon dioxide LFG can also transport landfill odors offsite if vented to the

atmosphere.Other odors in landfill gas :

Hydrogen Sulfide largely formed if construction and demolition debris contain large quantities of wallboard ( drywall/ gypsum board).

Hydrogen sulfide has the foul smell of rotten eggs.Ammonia has a strong pungent odor.

Humans can detect hydrogen sulfide and ammonia odors at very low levels in air, generally below levels that would cause health effects.

HOW THE ODOR GENERATE FROM LANDFILL?

LANDFILL GAS

Gases released from municipal waste landfills have the potential to cause odors in neighborhoods surrounding the landfill. The household and commercial wastes brought to landfills decompose over time largely through the action of bacteria. Methane and carbon dioxide: 90 to 98% of landfill gas.The remaining 2 to 10% : nitrogen, oxygen, ammonia, sulfides, hydrogen and various other gases.

This process produces odorous gases, the amount formed depends upon a variety of factors:

1. Nature and moisture content of the waste.

2. Amount of oxygen present.3. Temperature inside the landfill.4. Type of waste present in the landfill. 5. The age of the landfill.

For example, gas production will increase if the temperature or moisture content increases.

The amount of gases emitted will vary due to changing weather, changing landfill content.

Morning winds tend to be most gentle, providing the least dilution of the gas The worst odor release

Causes of odors at landfills

Landfill odors are caused by landfill gas, trash at the “working face” and leachate.

Landfill gas (LFG)- produces from organic material that decomposed anaerobically.

Made up primarily of methane and carbon dioxide that contain small amount of odorous compounds that human nose can perceive at low levels.

LFG can also transport landfill odors offsite if vented to the atmosphere.

Factors influencing odor strength

1) Type of waste

2) Volume of potentially odorous material

3) Time required to unload and cover

4) Meteorological and topographic conditions

5) Size of working face

6) Time of day

Health effects or symptoms from exposure to odors can usually be traced to three causes:The sensation of the odorThe odorant itself. The health effects or symptoms vary

depending upon the frequency, concentration, and duration of the odor.

EFFECT OF THE ODOR

Can the presence of odors trigger symptoms?

People in communities near landfills are often concerned about odors emitted from landfills.

They say that these odors are a source of undesirable health effects or symptoms, such as headaches and nausea.

At low-level concentrations—typically associated with landfill gas—it is unclear whetherit is the constituent itself or its odors that trigger a response.

ODOR CONTROL SYSTEM ELIMINATE THE GENERATION OF ODOR

o Stop accepting waste that cause odorso Example: Paper mill sludge, animal waste

COVER THE WASTE TO REDUCE ODORo Cover waste with more dirt

o Cover with compost waste can reduce odor capability

o Provide good cover materials (soil)- can filter odor, control gas and reduced water infiltration.

o Cover mainhole and leachate cleanout riser

COLLECT LANDFILL GASo Properly size your LFG collection system o Example: blower, headers, flares

o Install LFG collector in timely mannero Make sure that install enough collector in landfills

MASKING WASTE• Masking type

Neutralizing agentPleasant smelling agent

Other Controlling and Preventing odor at landfills

o Close attention to known problem areas, including the ends of leachate pipes, cleanouts and manholes.

o Making sure there are air- tight seals around all gas control equipment to keep air out and gas in, direct the gas to the control device and maintain a safe area.

o Ongoing operation, monitoring and maintenance by a trained gas technician.

o Improve stormwater management- water increase the production of landfill gas.

o Use odor-neutralizing chemicals- chemical that contains ore than 99% water and a trace of soap.

CLOSURE & POSTCLOSURE

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1. Development of long-term closure plani. Cover and landscape design

Cover must be design to divert surface runoff and snowmelt from LF site and to support the landscaping design selected for the LF

Landscaping design is based on local plant and grass species

ii. Control of LFG Major concern for long-term maintenance of LF Installation of gas control system in most modern LF, but older

completed LF are retrofitted with gas collection system along with remedial actions

iii. Collection and treatment of leachate Another major concern for long-term maintenance of LF Modern LF have some sort of leachate control system but older

ones are retrofitted

iv. Environmental monitoring systems Monitoring facilities must be installed for long-term

environmental monitoring Monitoring requirements: vandose zone for gas and liquids,

groundwater and air quality

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2. Post-closure carei. Routine inspection

Routine inspection program must be established to monitor continually the condition of completed LF

Criteria must be established when a corrective action(s) must be taken

E.g. How much settlement will be allowed before regrading must be undertaken?

ii. Infrastructure maintenance Typically involve continued maintenance of surface water

diversion facilities, landfill surface grades, condition of liners, revegetation and LFG and leachate collection equipment

Amount of equipment must be available at site will depend on the extent and capacity of the LF and the nature of facilities to be maintained

iii. Environmental monitoring systems To ensure no release of contaminants from LF that may affect

health or surrounding environments Number of samples and frequency will depend on regulations of

local air and water pollution control agencies (DOE)

POST-CLOSURE LANDFILL PLANGreen Areas At the Sanitary Landfill,

turning the area into a green area or a park is one of the best options selection of the trees will have to be done carefully so as not to perforate the watertight coverings

shows Glovers Landfill

Recreation

Landfills have also been converted into golf courses, play fields, playgrounds, flower gardens and parks. Small light structured buildings, such as car parks.

Butterworth landfill

Agriculturedepends largely on the

stabilization of the landfill and the proper coverage and capping of the landfill. Growing grass as feed for cattle and other pastoral animals with a very thick final cover to prevent roots perforate the lining of the landfill and absorbed Gardner Street Landfill

in the West Roxbury

Housing

Light structured buildings have been constructed in many of the landfills in the country. It possible soil movements and settlements, so takes a very long time as the landfill has to be stabilized first.

Head start school at MSW ash landfill in Florida

CONCLUSION Landfills have served for many decades as

ultimate disposal sites for all manner of wastes: residential, commercial, and industrial, both innocuous and hazardous.

However, it is essential to have a properly designed landfill to avoid unnecessary problem even though their preparation is a difficult and uncertain process

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