Leachate Management

Prof. M.R.Ezhilkumar
Assistant Professor
Department of Civil Engineering
Sri Krishna College of Engineering and Technology
Coimbatore
ezhilkumar@skcet.ac.in
I only feel angry when I see waste.
When I see people throwing away
things we could use. – Mother
Teresa
1
17CE413
SOLID AND HAZARDOUS
WASTE MANAGEMENT
3.5 – Leachate Management

SHWM – Module 3 – SANITARY LANDFILL AND HAZARDOUS WASTE MANAGEMENT  Mr.M.R.Ezhilkumar 2
Learning Outcomes
☼ Leachate production
☼ Leachate Collection
☼ Leachate Treatment
☼ Leachate Management
3.5 – Leachate Management

Video Session

Leachate
 Infiltrative water percolates through waste materials, results in the leaching of
organic and inorganic compounds (McBean et al. 1995).
 A complex organic waste that changes with time
 Problematic components
– Degradable & nondegradable organics
– Hazardous organics and inorganics
– Ammonia, nitrate, and nitrite
– Suspended solids
– Color and odor
– Pathogens

Leachate
 Leachate is the liquid (or wastewater) that forms when water (rainfall,
groundwater) travels through solid waste
 Leachate can migrate into underlying groundwater, resulting in contamination
 Leachate can contain many different chemicals, depending on what is in the
solid waste

Leachate

Leachate
How is Leachate Produced?
 Waste Decomposition
• Phase I
– Aerobic
• Phase II
– Anaerobic
– Facultative
• Phase III
– Methanogenic

Leachate
Leaching Mechanisms
 Leaching of inherently soluble materials
 Leaching of soluble biodegradation products
 Leaching of soluble products of chemical reactions
 Washout of fines and colloids
 Leachate generation continues for typically 30-40 years following site closure

Leachate
Importance of Leachate Quality and Quantity Determination
 Design leachate collection systems
 Design leachate treatment facilities
 Determine acceptability of offsite treatment
 Estimate offsite migration potential

Leachate
Leachate Management Principles
 Chemical composition of leachate varies considerably depending on:-
– Waste composition – Site characteristics
– Climatic conditions – Age of landfill
 Leachate management strategies must be:-
– Practical – Cost effective
– Flexible – Developed for long term environmental
management

Leachate
Leachate Management Technologies
 There is a wide range of leachate management technologies adopted by
Landfill Managers. Technology selection often depends on a number of critical
factors including:
– Composition of leachate
– Type of collection method
– Volume of leachate generated
– Available space on site
– Access to sewer
– Availability of technologies

Leachate
Planning Treatment and Disposal
 Estimate leachate flow, Q
– WBM/HELP
– Variations with site age
 Estimate leachate contaminant conc., C
– Type
– Variations with age
 Identify treatment and disposal options with discharge standards and cost
 Select treatment and disposal system
– Introduce uncertainty
– Maintain flexibility

Leachate
Leachate Production Characteristics

Leachate
What Characterizes Leachate?
 Phase I
– Brief
– CO2
– H2
 Phase II
– Years
– High BOD
• >10,000mg/L
– High BOD:COD
• >0.7
– Low pH
• 5-6
 Phase II
– Smells
– High Ammonia
• 500-1000 mg/L
– High Levels
• Fe, Mg, Zn, Ca, Mn
 Phase III
Decades (never)
High fatty acids
No O2
CH4
CO2
Stabilized
Low BOD
Low BOD:COD
 Phase III
High
Ammonia/Nitrogen
High Levels
Fe, Na, K, Cl2, SO4

Leachate
Factors Affecting Leachate Quality and Quantity
 Particle size
 Compaction
 Waste composition
 Site Hydrology
 Cover Design
 Conditions within Landfill
• Chemical & Biological Activities
• MC %, Temperature, pH, Degree of Stabilization
 Waste Age
 Landfill design/operation
 Sampling procedures
 Interaction of leachate with environment

Leachate
What are Trends in Leachate Contamination?

Leachate
Landfill Leachate

Leachate
pH
 Influence chemical and biological processes of precipitation, redox, sorption,
methanogenesis
 Controlled by volatile acids during acid phase
 After methanogenesis begins, controlled by carbonates and ammonia
 Major factor in controlling metal solubility

Leachate
Heavy Metals
 May act as inhibitors of biological stabilization process
 Water quality concerns
 No discernable chronological pattern
 Leachate concentration controlled by sulfide, carbonate, chloride, and
phosphate

Leachate
Nitrogen/Phosphorus
 Indication of nutrient availability
 Phosphorus may be limiting nutrient
 Ammonia important buffer
 Nitrogen present for long periods of time

Leachate
How do you Remove Leachate from the Landfill?
 Drain as much as you can by gravity (liner system and pipes)
 Pump from low points
– Penetration through the liner
– Pumps inside landfill

Leachate
Leachate Collection System
 If leachate flow is intercepted or impeded by a liner, then it should be removed
from the landfill by use of a leachate collection system.
 A leachate collection system is a high-permeability layer designed to transmit
leachate from the liner.

Leachate
Leachate Collection System with Graded Terraces

Leachate
How is Leachate Removed

Leachate
Leachate is then sent to Treatment and/or Storage Facility

Leachate
Leachate Storage
 Underground storage tanks
 Lagoons
 Above ground tanks
 Three day’s storage at peak annual flow

Leachate
How do you Predict Leachate Generation?
 You must estimate how much leachate is generated to design your landfill.
 HELP -- Hydrologic Evaluation of Landfill Performance
A Water Balance Model

Leachate
Notes about HELP Model
 Must assume an area and a depth (therefore not good for an open, operating
landfill)
 Many ways to manipulate
 Hydraulic conductivity of waste to high

Leachate
Porous cup suction Lysimeter for the collection of liquid samples
from the landfill

Leachate
Leachate Treatment Systems?
Options
 Full On-Site Treatment
 Partial On-Site Treatment
 Transport Off-Site
Considerations
o Recirculation
o Proximity of Sewer
o Haul Distance
o Pump System Costs
o WWTP Capacity
o Leachate Strength
Considerations
o Local Sewer Use
Laws
o Sewer Surcharges
o Surface Water
Discharge
Standards (On-Site)

Leachate
What are Common Leachate Treatment Types?
 Anaerobic or Aerobic Biological Treatment
 Physical & Chemical Treatment
 Leachate Recirculation & Land Application

Leachate
Anaerobic or Aerobic Biological Treatment
Biological Treatment
 Changes the form of Organic Constituents
 Removes BOD5, SS,NH3-N, Organic-N & Metals
 Generates large quantities of biomass (sludge)
Anaerobic Treatment
 Two-Stage Reactor
 Fixed Film Filters
Aerobic Treatment
 Lagoons
 Activated Sludge
 RBC’s
 Trickling Filters

Leachate
Anaerobic or Aerobic Biological Treatment
Biological Treatment
 Essential if BOD > 50 mg/L
 Expect
• BOD removal
• SS removal with sedimentation
• NH3-N and Org-N removal by biouptake and nitrification
• Metal removal by biosorption and precipitation at oxides and carbonates
• Priority organics removal

Leachate
Leachate Management Technologies

Leachate
Physical & Chemical Treatment
 More appropriate treatment as a landfill stabilizes
 Polishes biologically treated leachate
 Types of Treatment
Granular Filtration Carbon Adsorption
Chemical Precipitation Ultrafiltration
Reverse Osmosis Breakpoint Chlorination
Air Stripping Ion Exchange

Leachate
Reed Bed
 Removal of heavy metals, BOD, TSS, Nitrogen, & Phosphorus

Leachate
Constructed Wetland
Uses
 Polishing treatment
 Complete treatment
Advantages
 Relatively inexpensive to build/operate
 Associated with ‘green’ technologies
 Wetlands credits
Disadvantages
 Large land requirement
 Cold weather
 Mediocre results especially for
complete treatment systems

Leachate
Proposed Leachate Treatment

Leachate
Suitability Of Evaporation
Cost Of Operation
 Extremely Cost Effective
 Relatively High Initial Capital Costs
 Minimal Operating Costs
Effect Of Evaporation
 Leachate Volume Reduction
 Extremely Concentrated Solution
 Minimal Contamination Level Reduction
Risks
 Pond Overflow
 Leaks - Monitoring Bores
 Drowning - Perimeter Fencing

Leachate
Local Weather Conditions
 Evaporation Substantially Higher Than Precipitation
 Local Weather Data
 Theoretical Evaporation Greater Than Actual Evaporation
Leachate Composition
 Leachate Composition Affects Evaporation Rate
 Salinity and Concentration Reduce Evaporation Rate
 Dark Colour Increases Evaporation Rate

Leachate
Site Constraints
 Large Surface Area Required
 Possible Odour Issues Hence Buffer Zones Required
 Wind Direction And Intensity
Regulatory Approval
 Possible Regulatory Approval Required
 Location and Design Constraints
 Operational and Management Constraints

Leachate
Leachate treatment-issues
 High strength and magnitude of pollution potential
 Variation from landfill to landfill
 Seasonal and temporal variations in quantity and quality
 Processes designed to treat the leachates from an young landfill should be modified in the
future to treat old leachate/ to achieve changes in effluent standards

Leachate
Leachate Recirculation & Land Application
 Leachate is collected & returned to the top of landfill
 Accelerates the stabilization of organic materials present in the MSW
 Spray Irrigation or Well Injection
 Evapotranspiration

Leachate
Landfill as a Bioreactor Measure of Success
 Faster landfill stabilization
 Increased air space
 Reduced leachate management costs
 Reduced gases and odors
 Reduced long-term care costs
 Possibly, mining to regenerate cover material - a perpetual landfill?

Leachate
Leachate Recirculation
Demerits:-
 Ponding/localized accumulation of leachate
 Severe localized subsidence/side slope stability problems
 Other management requirement due to excess leachate production
 Selective attenuation of contaminants recirculation, thus further treatment required
 Mass/fluid transfer limitation

Leachate
Leachate Recirculation
Methods of Recirculation
 Spray irrigation
 Working face application
 Gravity well/trench
 Injection well/trench
 Infiltration ponds

Leachate
It is important to consider
 Leachate characteristics
 Its hazardous nature
 Discharge alternatives
 Regulatory limits
 Operational needs
 Costs
 Conduct of treatability studies

Assessment Time
Review
Question Recommend a suitable landfill method for Coimbatore region
based on the composition of waste generated in the city.

Leachate Management

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