design, operation and management of solid waste … short course...scharff, h., afvalzorg holding,...

Design, Operation and Management

of Solid Waste Landfills

Laboratory of Waste Management & Resource RecirculationSeoul National University, Koreahttp://waste.snu.ac.kr

Land Disposal

(1) the relatively low cost of land and disposal

procedures;

(2) stringent controls on releases to atmosphere and

waters in the ’70s and ’80s; and

(3) the beliefs that land disposal was safe and

proper ???

Why the discharging onto and beneath the

earth’s surface has been a popular method for

hazardous waste disposal?


Scharff, H., Afvalzorg Holding, NV (2007) “The role of sustainable landfill in future waste

management systems, ”Proceedings of ISWA/NVRD World Congress 2007, 9. 24-27 2007,

Amsterdam, Netherlands

Role of Landfill

(1) No matter how much prevention, reuse and recycling a society to

realize, there will be a role for landfill in waste management system;

(2) It is not economical to recycle or recover all waste under all

conditions; the capacity for recycling, recovery, or incineration cannot

be enough due to the fluctuation of waste generation; Some wastes

that cannot be recycled, recovered and incinerated landfill is the best

option; Any facility for recovery or incineration may be put of

operation because of maintenance, repair or accidents.

(3) The landfill sites are the “safety net” in a good waste management

system.


Figure 1. Management of municipal waste in the EU27 in 2004 (from Eurostat (2006)

Recovery and disposal of municipal waste, http://epp.eurostat.ec.europa.eu)


Classification

- Sanitary landfill: for MSW (Municipal Solid Waste)

= wastes from residential area + from commercial area

- Secure landfill: for hazardous waste

leachate collection, groundwater monitoring, double liners,

leakage detection, etc.

*** Engineered Facilities vs. Open Dumping Sites


Hierarchy of the Integrated Waste

Management in Korea

Final Disposal

(Landfill)

Energy Recovery

Reuse

Prevention and Reduction

(Avoidance)

Recycling

Incineration

Zero waste

(Cossu, 2007)


Balance of Processes

Goal direction

0 100%

Landfill (Cossu, 2007)


Evolution of Landfilling

- open dumping

- Unsanitary landfill

fence, daily cover, control of insect pests, control of scavenging,

etc.

- 1st generation of sanitary landfill

leachate liner, leachate treatment, compaction, LFG collection

and reuse, etc.

- 2nd generation of sanitary landfill

Multibarrier concept for leachate and gas, pretreatment, after

care, environmental monitoring, etc.


Final cover w/ vegetable zone

Rainwater control ditch

Leachate pumping

LFG Collection

Leachate collection

Slope stability

Control Hazardous gases emission

Leachatetreatment

Groundwater intrusion

Rainwater infiltration

Liner

Sanitary landfill


Disasters of Slope Failures


Philippines

Turkey

South Africa

Development and Types of Landfills

Siting- Haul distance

- Location restrictions: e.g., air ports, flood plains, unstable areas, etc.

- Available land area: e.g., buffer zone, storage, etc.

- Site access

- Soil conditions and topography

- Climatological conditions: temperature, wind, etc.

- Surface water hydrology

- Geologic and Hydrogeologic conditions

- Local environmental conditions: buffer zone due to noise, odor,

vectors, etc.

- Potential ultimate uses

- Public negotiation


Definition of Terms

- Cell: Volume of wastes during one operating period (e.g., one

day) + Daily cover material

- Lift: A complete layer of cells


Standards for Liner System in Korea

(1) Compacted Soil Liner System

100 cm (150 cm for Hazardous Waste Landfills) of compacted soil

layer

hydraulic conductivity of the soil layer < 10-7 cm/sec

* permeability vs. hydraulic conductivity

(2) Composite Liner System

50 cm (100 cm for Hazardous Waste Landfills) of compacted soil layer

+ HDPE > 2.0 mm (2.5 mm for Hazardous Waste Landfills)

(3) Leachate Collection System

Leachate collection layer > 30 cm w/ Kh > 10-2 cm/sec

Leachate collection pipers with holes

Rainwater and groundwater drainage system


Compaction Equipment


Tired roller

Sheepfoot roller

Smooth-wheel roller

Standards for Liner Systems

Hydraulic Conductivity


Special Equipment for Kh

- Large-scale fixed wall permeameter (right)

- Permeameters for VOC (volatile organic

compound) solution (above)


Installation of Liner Systems


Seaming and Inspection of HDPE Liners


Covers

Daily & Intermediate Covers

- Scattering of wastes

- Odor

- Insect pests and animals

- Rainwater drainage

- Accessibility

- Esthetic

* Intermediate cover needs better accessibility of heavy equipment

Final Cover

- Rainwater drainage

- Gaseous contaminants

- Vegetation (erosion, esthetic)

- LFG control (fire)

- Insect pests and animals


Standards for Daily andIntermediate Covers in Korea

- Daily cover: soil > 15 cm after everyday practice

- Intemediate cover: soil > 30cm w/ 2% slope (when working area

is exposed more than 7 days)

- Final cover: at the closing of landfill

* Synthetic daily covers:

Performance and specification have to be approved by

government

foams, sprays, geosynthetic liners, recycled wastes (e.g., sludge,

ash, scrap tires, etc.)


Biodegradable Film Cover


Standards for Final Cover in Korea

- Gas drainage layer : > 30 cm

- Liner : (1) Clayey soil > 45 cm, Kh < 1x10-6 cm/sec

(2) Clayey soil > 30 cm + synthetic liner(e.g., LDPE, PVC,

etc.) > 1.5 mm

- Rainwater drainage layer : Sand > 30 cm

- Vegetation zone : > 60 cm

- Disinfection of insect pests

- Surface slope > 2%


Alternative Final Covers (1/2)

Phytocapping in dry regions (e.g., Australia)


Alternative Final Covers (2/2)

Capillary barrier


Facilities in Landfills (1/2)

- Fence to prevent people and animal accessibility

- Board including landfill’s information (e.g., name of the

landfill, information of wastes landfilled, manager’s

information, designer and constructor’s information,

etc.)

- Scale

- Cleaning vehicles


Facilities in Landfills (2/2)

- Rainwater drainage ditch: to reduce leachate

generation

- Groundwater monitoring wells: both of upstream and

downstream of groundwater system surrounding the

landfill

- Leachate storage tank with flow meters

- Leachate treatment facility (If the leachate generation

is not much, it can be delivered to wastewater

treatment plants)

- LFG treatment facility (simple burning, heat recover,

electricity generation, etc.)


Estimations of Gas Generation in Landfills (1/3)


(1) Stoichiometic (Eq. 11-2, p. 388)

(2) BMP tests

(3) Lysimeter tests



(2) BMP tests



(3) Lysimeter tests

Landfill Leachate and Gases – 5 phases


Landfill Gas (LFG) as a Fuel

- LFG primarily consists of CH4 and CO2 and is an energy alternative

- Pretreatment is necessary because it contains H2S, NH3, Siloxane,

etc.

- Siloxanes?

- Siloxanes are compounds that consist of Silicon, Oxygen, and

Methane (e.g., C8H24O4Si4, C10H30O5Si5, C12H36O6Si6, C6H18OSi2,

C8H24O2Si3, C10H30O3Si4, C12H36O4Si5)

- During combustion Siloxanes transform to SiO2 and cause damage,

efficiency drop, and failure of boilers and engines

- Soloxanes can be removed by adsorption

- Gas Fuels: LNG (Liquefied Natural Gas), LPG (Liquefied Petroleum

Gas) , CNG (Compressed Natural Gas), etc.


LandfillsEnteric fermentationsNatural gas systemsCoal miningManure managementRice cultivationStationary sourcesPetroleum systemsMobile sources

66.7

10 20 30 40 50 60 70 80

MMTCE

CH4 Discharge from Landfills


Gas GWP Lifetime(yr)

CO2 1 variable

CH4 21 12

N2O 310 120

PCFs 140 6,300

HCFs 6,500 9,200

SF6 23,900 3,200

- CH4 emits to atmosphere from

natural wet lands, rice paddy fields,

ruminants, gas and oil wells, landfills,

etc.

- Among the emission sources,

landfills are most dominant

anthropogenic source

LFG Extraction Wells


Radius of influence

Passive and Active Controls of LFG Migration


A Case Study for Active Control of LFG

190300 190400 190500 190600 190700 190800 190900 191000

451000

451100

451200

451300

451400

451500

451600

PB1

PB2

PB3

PB4

PB5

PB6

PB7

PB8

PB9PB10

WB1

WB2

WB3WB4

WB5WB6

WB7

WB8

WB9

WB10

WB11

WB12

WB13WB14

U

P

데크진

입

V2

V6

V7


Leachate Collection Systems (1/2)


Leachate Collection Systems (2/2)


Leachate Treatment

- Leachate storage tank: estimation of leachate generation rate

e.g,, HELP (Hydrologic Evaluation of Landfill Performance)

- Discharge standards

e.g., BOD 30, 50, 70 mg/l, CODcr 400, 600, 800 mg/l depending

on the discharge area

- Items: BOD, COD, SS, pH, oils, phenol, cyanide, Cr, Fe, Zn, Cu,

Cd, Hg, organic P, As, Pb, Mn, F, PCB, E coli, color, NH3-N,

inorganic N, total P, TCE, PCE, etc.


Estimation of Leachate Generation Rate (1/2)

LA = P + S – E – WA

where LA = Leachate generation rate [L3/T]

P = Precipitation [L3/T]

S = Moisture from wastes due to consolidation,

degradation, etc.) [L3/T]

E = Evaporation [L3/T]

WA = Absorption of moisture by wastes (i.e., field

capacity) [L3/T]

(1) During landfilling


Estimation of Leachate Generation Rate (2/2)

(2) After installation of final covers

- HELP (Hydrologic Evaluation of Landfill Performance)

(1) for landfills in plains, not good for valley areas

(2) does not consider reactions in landfills, e.g., compression,

biodegradation, etc. → may underestimate the leachate

generation rate

- Japan’s empirical equation

Q = (C/1000) x I x A

where C = Percolation coefficient

I = Intensity of precipitation

A = Landfill area

- Water balance method Example 11-12


Limitations of HELP Model

Lombardi, et al. “Water-

balance model for

predicting the leachate

production in landfills,”

proceedings of the ISWA

World Solid Waste

Congress 2012, Florence,

Italy, 2012. 9. 17-19


Leachate vs. Precipitation (1/3)


Fig. 3. Comparison of precipitation and generation of leachate in a closed landfill

(Young Su Lee and Jae Young Kim (2013)



1. It was known that in a closed landfill leachate is generated mainly

by the percolation of precipitation and leachate generation is

dependent on the precipitation. However, it was found that

leachate was generated regardless of precipitation.

2. It was possible to make an fairly accurate prediction of leachate

generation only using precipitation data collected in a closed

landfill. It is suggested that the amount of leachate generation is

4-8% of monthly precipitation and about 25,000 m3/month of base

generation regardless of precipitation.

3. However, the predicted values of leachate generation for the high

precipitation seasons were not close to those observed.



Fig. 4. Comparison of precipitation and prediction of leachate generation in a

closed landfill (Young Su Lee and Jae Young Kim, 2013)

Monitoring Wells for Groundwater

(1) Installation of monitoring wells

Monitoring should start before landfilling (e.g., at least 2 months

before in Korea)

Screen of groundwater monitoring well is located in the aquifer

that be directly affected by leachate leakage

(2) Frequency of monitoring

Before: > 1 / month

After: > 1 / 4 months

(3) Monitoring items


Indicator Compounds

(1) Less loss during travel in groundwater system

(2) High original concentration in leachate

(3) High mobility in groundwater

(4) Low detection limit and easy to measure at field

(Discussion) Which compounds have these properties?


General Standards for Landfills (1)

- Fences :

- Sign board:

- Weighing :

- Wheel and truck washing :


General Standards of Landfills (2)

- Groundwater monitoring wells:

- Rainwater drainage :

- Leachate storage tank :

- Leachate treatment facility :

- LFG disposal equipments:


Bad Cases in Korea


Emerging Technologies in Landfills


Classification of Landfilling Strategies (1)

Dry Moisture Wet

Air

Forced

aeration

Passive

aeration

Anaerobic

Dry

tomb

Uncontrolled

landfill

semi-aerobic

Bio

reacto

r la

ndfill

Passive change

Active control

Field capacity


Semi-aerobic Landfill


- to reduce leachate strength

- to enhance stabilization reactions

- to solve hazardous contaminant problems in leachate (e.g.,

Dioxins in ash)

Washing as a Mechanical Pretreatment

Figure 4. WOW system in Japan

Leachatetreatment

(simplified treatment)Biotope

Landfill site

Treatment water

Washing tankWater treatment

Washing water


Background

• Since the energy recovery from Incineration plants are in the range of 10%.

The world top is 30%. High temperature causes the corrosion problem due to

Cl and increase the maintenance cost dramatically. Due to the low energy

efficiency, i.e., 10-30%, incineration plants is less attractive now.

• Gasification is limited for application. Char produced from gasification has

market value only from specific species of waste such as tire. Char from

mixed waste gasification is useless.

• Due to the EU landfill directive, least organic materials are introduced into

landfills and consequently less biogas will be generated. Active gas extraction

system is not needed any more. Just passive system such as lateral pipes

and biofilter will become popular.

• Bioreactor landfill is antiquated. The service time of landfill confinement

system is not verified and even after the system fail the reaction may keep

going. It means the landfill is not a reactor anymore.

• Waste management is a combined problem solving plan. There cannot be one

solution.


Sustainable Landfill

Sustainable landfill = Acceptable risk

Acceptable risk based on concentration or flux

Multi barriers for sustainable landfill

1. Quality of the waste: pretreatment

2. Quality of the site: geological condition

3. Landfill design and operation


Closed landfill – Steel cover

Incinerated

residue

Shredded

dust

Home electrical

goods

Buttery

Sprinkling

water

Storage pond

Treated water

Water treatment

plant

Disposal facility using a steel plate


Closed landfills (1/3)


서울대학교 공과대학 건설환경공학부폐기물실험실 (http://waste.snu.ac.kr/)



Tent type closed landfill

Detachable roof


Offshore Disposal Sites

Figure 1. Pulau

Semakau (Singapore)

Figure 2. Amagasaki (Japan)


Circulated Landfill

Kinu Clean Park (Japan)


Figure 5. Equipments in a high rate MSW composting facility

- to reduce LFG generation

- to reduce settling

- aerobic composting : Windrow type or Reactor type

- Anaerobic digestion : to recover energy and nutrients

Composting as a Biological Pretreatment


Classification of Landfilling Strategies (2)

None Separation Separated

Pre

treatm

ent

Thermal

Mechanical

Biological

None

Mixed

waste

MBP

pretreatment

RDF

incineration

Landfill of

incombustibles

Incineration

of combustibles


- To recovery recyclable materials

and energy

- To produce recyclable materials

(e.g., compost)

- To reduce greenhouse gas

emission, i.e., CH4

Residual Waste

Size reduction

Screening

Anaerobicdigestion

Landfilling

Energy recovery

incineration

Aerobiccuring

End-productquality

Biologicaldrying

Figure 3. A Flow Diagram of MBP Process

Mechanical Biological Pretreatment (MBP)


서울대학교 공과대학 건설환경공학부폐기물실험실 (http://waste.snu.ac.kr/)

Figure 1. Main MBP options currently on the market (from Martel, J.-L., et al.

“Suez Environment’s Experience of MBT Technology,” Proceedings of

ISWA/NVRD World Congress 2007, 9. 24-27 2007, Amsterdam,

Netherlands)

Aftercare


Elapsed time

Envir

onm

enta

l Im

pac

tEnvironmental Impact

Open dumping

Dry tomb landfill

(Cossu, 2007)


Elapsed timeOperation Aftercare

Waste Management Contaminated Soil

(Fee) (Social Cost)

(e.g., 20 yrs)

Envir

onm

enta

l Im

pac

tHow long is the aftercare period?

(Cossu, 2007)


Sustainable landfill = low aftercare

+ low risk for short and long terms

Elapsed timeTime of Sustainability

(e.g., 20 yrs)

Envir

onm

enta

l Im

pac

t

Acceptable Impact

Alternatives

Pretreatment (e.g., MBP)

Bioreactor

Remediation (e.g., Aeration)


Standards for Aftercare

- Period: less than 20 years after closing

- Personnels

- Rainwater drainage, leachate management and treatment,

groundwater monitoring management are the same level as they

were

- Groundwater quality monitoring: 1 / month for the first 3 years

- Slope and structure stability, disinfection

- Monitoring of surface water and soil in the surrounding area

- Environmental impact report: every 5 years by certified institutes


Bad Cases of Closed Landfills in Korea (1/2)

Used car market Warehouse


- No trespassing control

- No LFG control (LFG emission)

- Failure of rainwater drainage

- Failure of vegetation (erosion)


Bad Cases of Closed Landfills in Korea (2/2)

Stabilization Standards

items Standards

Leachate - within discharge limits for 2 years

and and BOD/CODcr < 0.1

GW - no evidence of contamination by landfill leachate

LFG - LFG generation is not growing for recent 2 years

- CH4 of LFG < 5%

Solid - Combustibles < 5% or C/N < 10

Wastes - passed the leaching test

- No significant temperature difference

etc. - No significant impact (odor, stability of structure and

slope, surface water and soil quality, etc.)


Sampling for Evaluation and Stability


- Excavation and landfilling residuals in a new sanitary

landfill

- Landfill mining and treatments such as land farming,

thermal treatment, washing/flushing, etc.

- In-situ aerobic biological stabilization

- In-situ solidification

- Impermeable barrier (e.g., slurry wall, sheet pile,

geomembrane, et al.)

- Permeable reactive barrier (PRB)

Remediation/Management alternatives

for the closed landfill


1 year 5 year 10 year 15 year 20 year

CO

D (

mg

/L)

0

100

200

300

400

500

1st

2nd

3rd

4th

5th

6th

7th

8th

Washing Test for Specimen Excavated Solids

from a Closed Landfill

Fig. 9. Changes of Extracted COD with washing times

- Soil washing test showed that only one time of water washing could

remove almost 70% out of water-extractable COD.

- Soil washing has a great potential as a pretreatment to reduce the

organics which produce odor, gas, settlement, strong leachate, et al.

Soil:Water = 1:10 (by wt.)

Agitated for 6 hours at 200rpm

Centrifuged for 20 min at

3,000rpm

Analyze the supernatant


A Washing Method for Remediation of Dumping Sites

(with permission of the Hyundai Engineering & Construction Co., Ltd.)

Excavated

materials

Vibrating

feeder

Wet

vibrating

screen

Air

turbulencing

pipe

Sedimentation tank

Centrifuge

Thickener

Clean

materials

(> 3.0mm)

Clean

materials

(> 0.065mm)Dewatering

screen

Hydrocyclone

Clean

materials

(< 0.065mm)

Sludge

Coagulants

Clean Water

Clean

materials

(< 0.065mm)

Recycled water

Discharge

(or to WWTP)


In-situ Aerobic Biological Stabilization

- Advantages: Simple design and operation, less odor

generation (less public complaints), etc.

- Disadvantages: questionable performance, only for

organic fraction, etc.


In-Situ Solidification

(with permission of the Geoworks Co., Ltd.)


Impermeable Barriers


Permeable Reactive Barriers (PRBs)

(with permission of

the Geoworks Co., Ltd.)

PRBs based on the chemical reactions

(e.g., Fe0, Fe2+, Pd/Fe, zeolite, ZanF, etc.)

NO3-N

Contaminated

groundwater

Clean

groundwater

NO3-

N2

Denitrifiers

SO42-

S0

Elemental

sulfur

Lime stone

55S + 20CO2 + 50NO3- + 38H2O + 4NH4

+

4C5H7O2N + 25N2 + 55SO42- + 64H+

PRBs based on the biological reaction

“Biobarriers”, “Biological PRBs” etc.


Site of Sky Mound, USA


Site of Sky Mound (Nancy Holt, 1985)

Fukuoka City, Japan

Refresh Citizen’s Agricultural Park

IMAZU Sports Park - Parking lot


Nanji-Do, Korea (1/2)

- Najido site had been used

as a waste dumping site

for 20 years.

- No engineering as a

landfill facility

- Serious problems such as,

odor, fire, groundwater

contamination, land use,

etc.

- Finally, it was planned to

be remediated.


Nanji-Do, Korea (2/2)

- Vertical cut-off wall for

leachate and gas migration

control (slurry wall and

sheet piles)

- Gas extraction and

utilization (heat recovery)

- Leachate pumping wells

and treatment facility

- Final cover and ecopark

construction


Hickory Ridge Landfill, USA


Hickory Ridge Landfill (Atlanta, USA)

Considerations of building solar panels

on closed landfills

- Maintaining the integrity of the cap

and the gas management systems

- Limiting the depth of excavation

- Avoiding the use of heavy equipment

- Restrictions on laydown areas

- Maintaining erosion and surface

water run-off controls

- Robust safety measures and capping

system repair plans

design, operation and management of solid waste … short course...scharff, h., afvalzorg holding,...

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