Solid Waste & Hazardous Waste

Solid Waste & Hazardous Waste
Hikmat Al Salim
March 20123/9/2012 solid & Hazardous waste 1

Waste Classification
• Municipal waste
• Construction demolition debris
• Nonhazardous industrial waste
• Incineration ash
• Hazardous waste

Regulations
Solid waste is regulated under theResource
Conservation and Recovery Act (RCRA).
Classification of non-hazardous and hazardous
waste depends on the chemical constituents of
the leachate .

A waste is classified as a hazardous if it has a
hazardous characteristic listed below.
1. Hazardous Characteristics:
• Ignitable Hazardous Waste (TRIC)
– A liquid waste which has a flash point of less than or
equal to 140 degrees F (60 degrees C) as determined
by an approved test method.
– A non-liquid waste which, under standard
conditions, is capable of causing a fire through
friction, absorption of moisture or a spontaneous
chemical change and when ignited, the waste burns
so vigorously and persistently that it creates a hazard.
– An ignitable compressed gas or oxidizer.

2. Corrosive Hazardous Waste (TRIC)
– An aqueous waste with a pH of less than or equal
to 2 or greater than or equal to 12.5 is considered
to be a corrosive hazardous waste.
– A liquid waste that corrodes steel at a minimum
rate of .25 inch per year as determined by an
approved test method.

(TRIC)
3. Reactive Hazardous Waste
– A solid waste that is normally unstable, reacts
violently with water, or generates toxic gases
when exposed to water or other materials.
4. Toxic Hazardous Waste
– A waste that contains certain substances
determined to be harmful at or in excess of the
maximum concentration. Some of those
substances include lead, arsenic, and mercury.

Nature of Waste Problem
 Moisture within and flowing on the waste generates
leachate
 Leachate takes the characteristics of the waste
 Thus leachate is very variable and is site-specific -
there is no "typical" leachate
 Flows gravitationally downward into the leachate
collection system
 Enters groundwater unless a suitable barrier layer or
system is provided

Outlines
• Waste management methods
• Landfill design and regulations
• Function and usage of geosynthetics in landfill
systems
• Durability of geosynthetics
• Future trend of landfill management

Source Reduction
Source reduction involves reduction in the
quantity or toxicity of materials during the
manufacturing process via:
• Decrease the amount of unqualified products by
improving quality control
• Decrease the unit weight of the product by
using high quality material.

Combustion
• Combustion can reduce the volume of the solid waste
up to 90% at the same generate power.
• There are 140 combustion plants the US.
• Emission must meet the EPA Clean Air Act.
• Residual ash is hazardous material and should be
disposed accordingly.

• Destruction of wastes by Combustion
• The method is suitable for:
– – Gases
– – Liquids
– – Slurries
– – Sludge wastes
– – Solids
– – Containerized
• Incineration destroys molecular structure, thus
molecules with more stable structures and stronger
chemical bonds require longer residence times
and/or higher temperatures.

• Incinerator operating conditions must be monitored
continuously. The following are some parameters
affecting the efficiency of burning:
 Combustion temperature
 Residence time
Degree of mixing
 Presence of excess air
• The type of incinerator required depends on the
chemic and physical state of "waste" :

• Liquid injection
– Any pumpable waste
– Converts liquid waste to gas prior to combustion
Kilns
– Used on solids, liquids, and gases
– Many different types (e.g., rotary kilns, cement kilns, lime
kilns,
aggregate kilns).
Calcination or sintering
• – 1800oC and atmospheric pressure.
• – Destroys organics; reduces the volume of inorganics
• Incinerator Performance must be monitored, thus:

• Destruction and Removal Efficiency (DRE) must be
determined. This done by "monitoring" organization.
The higher the figure of DRE , the more efficient is
the incinerator. DRE of 99.99% for all “principal
organic hazardous constituents” (POHCs) is
required.
• – Example: Wastes containing dioxins and furans
requires 99.9999% DRE

• Incomplete combustion – afterburners must be installed
for exhaust
• – Combust the exhaust at higher temperature than the
combustion of primary waste stream. Example: dioxin
and furan creation, more toxic than precursors
• 75 dioxin congeners; 135 furan congeners
• Incinerators usually produce particulates; thus
particulate controls are important. Particulates can be
removed by using bag-houses, and water scrubbers
• Control of acid formation is also important e.g. HCl from
combustion of chlorinated organics. Acids corrode
metals and form "acid precipitates", and acid rain.
• .
Congeners are toxic chemicals that are formed during
incineration. A member of the same kind, class, or
group

Municipal Solid Waste Disposal
INCINIRATION

Landfill
– Landfill implies disposal of waste in the ground.
– 70% of the waste is disposed in landfill and the
percentage has been gradually decreasing.
– The amount of waste actually increased due to
population growth.

The Largest Landfill
• Staten Island, NY
• 3,000 acres
• 2.4 billion cubic
feet of waste
• 25 times of the
great pyramid

Nature of Waste Problem
 Moisture within and flowing on the waste generates
leachate
 Leachate takes the characteristics of the waste
 Thus leachate is very variable and is site-specific - there
is no "typical" leachate
 Flows gravitationally downward into the leachate
collection system
 Enters groundwater unless a suitable barrier layer or
system is provided

Hazardous Waste Definition
• Waste is listed in Appendix VIII of Title 40, Code
of Federal Regulations, Part 251.
• Waste is mixed with or derived from hazardous
waste.
• Waste is not identified as municipal waste.
• Waste possesses one of the following
characteristics:
– ignitable; corrosive; reactive and toxic.

Minimum Technology Guidance (MTG)
for a Subtitle D Landfill
“Solid Waste”
150 mm
300 mm
600 mm
Filter (or GT)
Drain (or GN/GC)
Clay @ 1x10-7 cm/sec
Soil Subgrade
GT (opt.)
GM*
Composite
liner

MTG for a Subtitle C Landfill
300 mm Drain (or GN)
S-GM*
“Solid Waste”
150 mm
300 mm
900 mm
Filter (or GT)
Drain (or GN/GC)
(to highest groundwater level)
P-GM*
3.0 m
Composite
liner

Landfill Covers
(Non-hazardous landfill without
Geosynthetic on the bottom liner system)
Erosion Layer
Infiltration Layer
150 mm
450 mm

Cover Layers
• Erosion Layer
– Earthen material is capable of sustaining native
plant growth
• Infiltration Layer
– Permeability of this layer of soil should be less
than or equal to the permeability of any bottom
liner system or natural subsoils present, or
permeability less than 1x10-5 cm/sec whichever
is less

Landfill Cover System
(Subtitle C & D, and Corp of Eng.)
150 mm
150 mm
300 mm Drain (or GN)
600 to
900 mm
Topsoil
Filter (or GT)
”Solid Waste”
Varies
(frost depth)
Cover Soil
300 mm Gas Vent (or GT)
GM

Landfill Site
• Conforms with land use planning of the area
• Easy access to vehicles during the operation of the
landfill
• Adequate quantity of earth cover material that is
easily handled and compacted
• Landfill operation will not detrimentally impact
surrounding environment
• Large enough to hold community waste for some time

Geosynthetics
geomembranes (GM)
geosynthetic clay liners (GCL)
geonets (GN)
geotextiles (GT)
geogrids (GG)
geopipe (GP)
geocomposites (GC)

Primary Functions
Type S R F D B
GM - - - - Y
GCL - - - - Y
GN - - - Y -
GT Y Y Y Y -
GG - Y - - -
GP - - - Y -
GC Y Y Y Y Y
S = separation, R = reinforcement, F = filtration
D = drainage, B = barrier

Liner System
GT
GG
GN
GCL
GM
CCL
Gravel w/
perforated pipe

Composite Barriers
(Intimate Contact Issue)
Leachate
CCL
Clay Liner
(by itself)
Leachate
CCL
Composite Liner
(with intimate contact)
Does the GT compromise the composite
liner concept?
Ans: Generally no...
Leachate
Composite Liner
(GM + GCL)
GCL

Composite Barriers
(Theoretical Leakage)
GM alone (hole area “a”)
Composite liner (GM/CCL)
Leachate
ks
= 2
Q C a gh B
Q = 0.21 a0.1 h0.9 ks
0.74
(for good contact)
Q = 1.15 a0.1 h0.9 ks
0.74
(for poor contact)
Ref. Bonaparte, Giroud & Gross, GS ‘89)

Average Values of Leakage Quantities
Life Cycle Stage
Leakage Rate (lphd)
1 2 3
40
30
20
10
0
GM
GM/CCL
GM/GCL
Sand
Leak Detection

Average Values of Leakage Quantities
(cont’d)
GM/CCL
Life Cycle Stage
Leakage Rate (lphad)
1 2 3
20
15
10
5
0
GM
GM/GCL
Geonet
Leak Detection

Geomembranes
Widely Used Geomembranes Limited Used Geomembranes
High density polyethylene
(HDPE)
Chlorosulfonated
polyethylene (CSPE)
Linear low density
polyethylene (LLDPE)
Ethylene interpolymer alloy
(EIA)
Flexible polypropylene
(f-PP)
Ethylene propylene
trimonomer (EPDM)
Polyvinyl chloride-plasticized
(PVC-p)

Compositions
(approximate percentage)
Type Resin Carbon
Black
Plasticizer Anti-oxidant
Filler
HDPE 95-97 2-3 0 1-0.5 0
LLDPE 95-97 2-3 0 1-0.5 0
PVC-p 50-70 1-2 25-35 1-0.5 5-10
fPP 95-97 2-3 0 1-0.5 0
CSPE 40-60 5-40 0 1-0.5 5-15
EPDM 25-30 20-40 0 1-0.5 20-40

Material Properties
• Mechanical property
• Density
• Melt flow
• Carbon black
• Plasticizers
• Antioxidant

Tensile Behavior
• Test method varies according to the resin type and
style of the geomembrane.
• Each test method consists of unique shape of
specimen and strain rate.
• Methods:
– HDPE, LLDPE and fPP – ASTM D 638 Type IV
– PVC-p – ASTM D 882
– All reinforced geomembranes – ASTM D 751

Design Concept
FS
Allowable (Test) Property
Required (Design) Property
=
Where:
• Test methods are from ASTM, ISO, or others
• Design models from the literatures
• Factor-of-Safety is site specific

Function of Carbon Black
• The primary function is as an ultraviolet light
stabilizer to protect polymer being degraded.
• Carbon black absorption coefficient increases
with loading up to ~ 3%.
• In elastomeric materials, carbon black also
functions as an reinforcement, and loading can be
as high as 30-40%.

Addition of Carbon Black
• The masterbatch technique is utilize to dispersing
carbon black in plastic.
• A masterbatch is a resin containing a high
concentration of carbon black.
• The masterbatch is blended with polymer resin to
achieve the desire percentage.

Carbon Black
• Carbon black content is measured according
to ASTM D1603.
• Carbon black dispersion is evaluated
according to ASTM D 5596.

Plasticizers
• Plasticizers is used in PVC to lower the glass
transition temperature (Tg).
• An addition of 30% plasticizer in PVC can lower
the Tg from 80oC to –20oC.
• The plasticized PVC behaves rubbery at normal
ambient temperature.
• However, plasticizer can slowly leach out with
time.

Antioxidants
• The function of antioxidants is to protect polymers
from being oxidized during the extrusion process
and service lifetime.
• For polyolefines, antioxidants is vital to the longevity
of the product.
• Antioxidant will be the focus of the second part of
this class.

Degradation of
HDPE Geomembranes
Chemical Related:
– Thermal-oxidation
– Photo-oxidation

Linear PE Structure
• Linear PE is a graft copolymer
• Each co-monomer creates one branch
• Co-monomer can be butene, hexene, or octene

Density of Geomembranes
• Density decreases as the amount of
co-monomer increases
• Density range of PE (ASTM D883)
–> 0.940 g/ml for HDPE
– 0.926 - 0.940 g/ml for MDPE
– 0.910 - 0.925 g/ml for LLDPE
–<0.909 g/ml for VLDPE or ULDPE

II. Oxidation Degradation
• Polyolefins, such as HDPE, PP and PB are susceptible
to oxidation.
• Oxidation takes place via free radical reactions.
• Free radicals form at the tertiary carbon atoms (i.e.,
at branches).
• Oxidation leads to chain scission that results in
decrease of Mw and subsequently on mechanical
properties.

Reactions during Induction Period
RH R H 
R O  ROO 2
ROORHROOH R

Reactions during
Acceleration Period
OH  RH  H O R 2
ROOHROOH
RORHROH R

Functions of Antioxidants
• Primary antioxidants react with free radical
species
• Secondary antioxidants decompose ROOH to
prevent formation of free radicals

Types of Antioxidants
Category Chemical Type Example
Primary Hindered phenol Irganox 1076 or 1010
Santowhite crystals
Hindered amines Various of Tinuvin,
Chemassorb 944
Secondary Phosphites Irgafos 168
Sulfur compound Dilauryl thiodipropionate
Distearyl thiodipropionate
Hindered amines Various of Tinuvin,
Chemassorb 944

Effective Temperature Range
0 50 100 150 200 250 300
Phosphites
Hindered Phenols
Thiosynergists
Hindered Amines
Temperature (oC)

Depletion of Antioxidants
Two mechanisms:
a. Chemical reactions – by reacting with free
radicals and peroxides
b. Physical loss – by extraction or volatilization

Arrhenius Model
Rate of reaction = X * Y * Z
Where:
X = collision frequency (concentration or pressure)
Y = energy factor
Z = probability factor of colliding particles
(temperature dependent)

Potential Energy
Eact
DH
transition state
products of
reaction
Separate
Reactants
Potential Energy
Progress of Reaction

Distribution of Energy
dN
dE
Energy
Fraction is
-E act
RT
exp( )

Arrhenius Equation
E
RT
act
R =
X e Z r

( )( )( )
R A e r
E
RT
act
=

( )( )
(9)
(10)
E
RT r
act =  (11)
ln R ln A

Arrhenius Plot
A
ln R
E act
R
r 1
high temperature
(lab tests)
low temperature
(site temperature)
Inverse Temperature (1/T)

Experimental Design
• Incubation environment should simulate the field
(i.e., landfill environment)
– Limited Oxygen
– Some degree of liquid extraction
• Utilize elevated temperatures to accelerate the
reactions.
– 55, 65, 75, and 85oC

Incubation Device
Piezometer
Insulation
Perforated steel loading plate
Sand
Sand
Heat tape
Geomembrane
Load
1 10

Tests Performed
• Oxidative inductive time (OIT) for antioxidant
content.
• Melt index for qualitative molecular weight
measurement.
• Tensile test for mechanical property

OIT Tests
• OIT is the time required for the polymer to be
oxidized under a specific test condition.
• OIT value indicates the total amount (not the
type) of the antioxidant remaining in the
polymer.

OIT Test for Evaluation of
Antioxidant (AO)
• OIT Tests:
– ASTM D3895-Standard OIT (Std-OIT), or
– ASTM D 5885-High Pressure OIT (HP-OIT)
• HP-OIT test is used for AOs which are
sensitive to high temperature testing

Test Results
0 5 10 15 20 25 30
150
100
50
0
Std-OIT
HP-OIT
Density
Melt Index
Yield Stress
Yield Strain
Break Stress
Break Strain
Incubation Time (month)
Percent Retained
Changes in Eight Properties with Incubation Time at 85°C

Analysis of OIT Data
a. Determine OIT depletion rate at each
temperature.
b. Utilize Arrhenius Equation to extrapolate the
depletion rate to a lower temperature.
c. Predict the time to consume all antioxidant in
the polymer.

a) - OIT Depletion Rate
4.5
4
3.5
3
2.5
2
1.5
1
55°C
65°C
75°C
85°C
0 5 10 15 20 25
ln OIT (min.)
Incubation Time (month)

b) –Arrhenius Plot
-1
-2
-3
-4
-5
Standard OIT
HP-OIT
0.0027 0.0028 0.0029 0.0030 0.0031
1/T (°K)
ln (OIT Depletion Rate)
y = 17.045 - 6798.2x R^2 = 0.953
y = 16.856 - 6991.3x R^2 = 0.943

c) Lifetime of Antioxidant
• Use the OIT depletion equation to find “t”
ln(OIT) = ln(P) – (S) * (t)
• The OIT value for unstabilized PE is
0.5 min.
• For this particular stabilization package
t = 200 years

Lifetime of Geomembrane
• Induction time and degradation period (Stages B &
C) can be established by using unstabilized polymer
in the experiment.
• It was found by Gedde et al. (1994) that the duration
of Stages B and C is significant shorter than that of
Stage A.
• Antioxidants are critical to the long-term
performance of polyethylene and other polyolefines.

Future of Waste Containment
• Current waste containment technique is defined
as “dry dome” method by eliminating leachate
from being generated after closure.
• Waste will not degrade since moisture is a critical
component of the biodegradation process.

Bioreactor Landfill
“……a sanitary landfill operated for the purpose of
transforming and stabilizing the readily and
moderately decomposable organic waste
constituents within five to ten years following
closure by purposeful control to enhance
microbiological processes. The bioreactor landfill
significantly increases the extent of waste
decomposition, conversion rates and process
effectiveness over what would otherwise occur
within the landfill.”

Why Operate a Landfill as a Bioreactor?
• to increase potential for waste to energy conversion,
• to store and/or treat leachate,
• to recover air space, and
• to ensure sustainability

Status
• 1993 - less than 20 landfills recirculating leachate
• 1997 - ~ 130 landfills recirculating leachate
• My estimate - ~ 5% of landfills

Aerobic Bioreactor
• Rapid stabilization of waste
• Enhanced settlement
• Evaporation of moisture
• Degradation of organics which are recalcitrant
under anaerobic conditions
• Reduction of methane emissions

Research Issues - Aerobic Bioreactor
• How much air is needed?
• How can air be delivered?
• What is the impact on the water balance?
• How are landfill fires prevented?
• What are the economic implications?

Solid Waste & Hazardous Waste

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