Law 4/1994 and its executive regulations stipulate that
handling of hazardous waste (HW) requires a license issued
by a competent administrative authority. The purpose of such
a license is to ensure that the movement of HW is carried
out in accordance to necessary safety conditions and that
proper measures are implemented to ensure the minimization
the potential to public health and the environment. An
additional integral component of permitting HW
transportation is monitoring the performance of licensees in
order to ensure their compliance with the set conditions,
This is to be carried out by the body (ies) issuing such
licenses. Figure(1) shows an overview of the HW transporting
system.
1. Permitting Requirements
Article 26 of the executive regulations of law 4/ 1994
identifies the requirements and conditions for permitting HW
handling.
(a) Transporter License
To be granted the license. The transporter must complete an
application form issued by the concerned authority and pay
the required permitting fees. The main components of the
application include the following:
Intended means of hazardous waste transport.
Hazardous waste description.
Training plans/ records.
Time schedule.
A copy of the application form for the HW transporter
license is included in the publication entitled. " hazardous
waste license requirements in the Egyptian law 4 / 1994"
(b) Means of Transport
Hazardous waste transportation can be carried out by road,
railways or vessels. The transporter license application
requires that the intended mode (s) of transportation be
specified. In this respect, the means of transport used (
vehicles, rail wagons or vessels) need to conform to set
technical and equipment.
Road Transport
Individual transporters can own and operate transportation
vehicles. The transporter is required to provide
documentation attesting that these vehicles meet the
required specification and are suitable for transporting the
types of HW designated in the license. This can be achieved
by attaching the manufacture's certificate indicating these
specification.
Current procedures for licensing transportation vehicles do
not discern the purpose for which the vehicles are used. It
is there for necessary that the essential HW documentation
be appended to the licensing papers to form a part of the
licensing application/ procedures.
Rail transport
Individual transporters would not have the possibility of
owing and operating rail wagons. And consequently no license
specific to individual wagons detailing the technical and
safety specifications would be needed. However. With the aim
of ensuring that wagons with the necessary specifications
are used to transport the HW types matching these
specifications. A plaque is to be attached to each of the
wagons. Specifying the type(s) of waste that could be
transported in it.
Transport by vessels
Similarly to road transport. Vessels can be owned and
operated by individual transporters. Necessitating that set
technical and safety specification be detailed in a license
specific to individual vessels used in HW transportation.
The transporter is also required to provide the necessary
documentation attesting that these vessels meet the required
specifications and are suitable for transporting the types
of HW designated in the license. This can be achieved by
attaching a manufacturer's certificate indicating these
specifications. Current procedures for licensing cargo
vessels do not discern the cargos for which the vessels are
to be used. It is therefore necessary that the HW
documentation be incorporated to form a part of the
licensing application/ procedures.
(c) Hazardous Waste Manifest
The tool used to track hazardous waste is the manifest
system. This system is composed of a set of forms and
procedures designed to track the waste from the time it
leaves the generator facility, to the point at which it
reaches the off- site facility that will store, treat, or
dispose of this waste.
The key component of this tracking system is the Hazardous
Waste Manifest, which is a legal form with multiple copies.
For transportation. This form is filled out with the
information on the type and quantity of the waste being
transported, instructions for handling. And signatures of
all parties involved in the transportation process (
generator delivering the waste to the transporters, the
transport operators, as well as the facility receiving the
waste for storage the waste for storage, treatment and/ or
disposal).
The Manifest System
The manifest form must contain information about types and
quantities of the transported waste, its hazardous class (es),
its packaging details and further important considerations
to be taken into account for safe handling of this waste.
The manifest is to be composed of seven copies of a single
form, a top original and six underlying carbon copies. Each
entitle that handles the waste must sign the manifest and
retain a copy for them selves. Once the waste reaches its
destination, the receiving facility returns a signed copy of
the manifest to the generator. Confirming that the transport
operators have delivered the waste to the designated
facility. Regulatory authorities receive two copies of the
manifest. One at the initiation of the transport process,
and one at its termination. In addition, one copy is
received by the Civil Defense Authority, the entity
responsible for intervention in cases of accidents or
spills, with the purpose of ensuring its knowledge of the
waste being transported for effectively intervening if needs
arise.
Completing The Manifest
The manifest form consists of three sections to be completed
by the waste generator, the transport operators and the
facility for storage/ treatment/ disposal as described
below:
The distribution of the manifest copies ensures that all
parties involved in the transportation process (i.e
generator, transporter, storage/ treatment/ disposal
facility and the concerned regulatory competent authorities)
receive matching copies confirming the proper transport and
storage, treatment, and/ or disposal of the hazardous waste.
Whenever waste is delivered from one entity to the other,
the entities always sign and data the manifest on the top
original copy. The six carbon copies are distributed as
follows:
carbon copy 1, the bottom copy, is sent by the generator to
the concerned competent authority.
carbon copy 2, the next copy up, is sent by the generator to
the Civil Defense Authority.
carbon copy 3, the next copy up. Is retained by the waste
generator as a record for the delivery of the waste.
Carbon copy 4, the next copy up. Is retained by the
transport operator after delivering the waste to the storage
treatment/ disposal facility.
Carbon copy 5, the next copy up. Is retained by the storage
treatment/ disposal facility as a record for the waste
received
Carbon copy 6, the next copy up, is sent back to the
generator by the storage/ treatment/ disposal facility.
The original is sent to the competent regulatory authority
by the storage treatment/ disposal facility. This copy
together with carbon copy 1, sent to the regulatory
authority at the initiation of the transport process,
provide a complete record of the HW transport operation in
order to facilitate this distribution, each of the copies
would be colored differently and the name of the entity to
keep it would be printed on it.
- Multiple Transportation
For cases of multiple transportation (i. e the involvement
of more than one transport operator during the
transportation process). The principal transport operator
(the one that receives the waste from the generator is the
one liable for the waste shipment unit it reaches its final
destination.
- How To Ensure Complying With The Manifest System
HW transporters must ensure that:
The name and address of the HW generators and the HW
receiving facility are clearly stated on the manifest.
The received HW properly identified.
The number of waste packages stated in the manifest
corresponds to the number of waste packages received/
delivered.
HW labeling is in accordance with hazardous classes stated
in the manifest.
Additional instructions for safe handling of waste are
included where applicable.
The signature of the HW generator. Or the HW receiving
facility is inscribed on the manifest.
2. Labeling
According to law 4/ 1994 and its Executive Regulations. HW
means of transport must have clear signs indicating the
hazardous characteristic (s) of the transported waste. Such
signs. When used on means of transportation are referred to
as "placards".
(a) Use of placards
During the transportation process, the placard corresponding
to the type of hazard associated with the transported waste
category must be used on the means of transport. For cases
of transportation of two or more categories of HW requiring
different placards, a "dangerous" placards is used on the
means of transport rather than the separate placards for
each hazardous category.
(b) Visibility of placards
The placards on the means of transport must be placed on the
sides as well as the rear of the vehicle. They must also be
clearly visible for inspection and emergency response
purpose. Moreover:
The placards must not be obscured by other labels or
markings ( such as advertising) and should be at least 76.0
mm from such marking.
Placards should be displayed on a background of sharply
contrasting color.
So far as practicable. Placards are to be located so that
dirt or water is not directed to it from the wheels of road
vehicles.
Placards should be durable and printed on or affixed to or
placed in a holder attached to the transport means.
Placards should be maintained in a condition so that the
format. Legibility, color, and visibility of the placard is
not reduced due to damage or deterioration.
(c) Specifications for placards
Placards must conform to the following:
A placard is to be made of plastic. Metal or other
material capable of withstanding. Without deterioration,
exposure to open weather conditions.
The hazard category number must be displayed in the lower
corner of the placard and must be shown in numerals
measuring at least 41mm in height.
Each placard must measure at least 273 mm on each side and
must have a solid line inner border approximately 12.7 mm
from each edge.
When text indicating a hazard is displayed on a placard,
the printing must be in letters measuring at least 41 mm in
height.
A placard may contain information including the name of
its maker, provided that information is printed outside of
the solid line inner border in no larger than 10- point
type.
(d) Other markings
In addition to the placards, the means of HW transportation
are to have stickers placed on all sides, visible from the
direction they are facing, indicating that these means are
approved and licensed for transporting HW the stickers
should also have the telephone numbers of the Civil Defense
Authority and the EEAA Contingency Plan Operation Room for
rapid contact in case of accidents.
The stickers should be circular, measuring at least 250 mm
in radius, and the text should be in bright green on a white
background. The HW transport operator should obtain them
from the authority licensing the means of transport.
1. Scope and Objectives
Improper storage of hazardous wastes can cause serious
accidents, health and safety problems, and damage to the
environment. The objective of this document is to provide
guidelines for safe, on-site storage and handling of
hazardous waste. Currently, solid hazardous wastes are
temporarily accumulated on-site and periodically transferred
to local dump sites for off-site disposal. Liquid hazardous
wastes are generally discharged into the sewers with or
without adequate treatment. Gaseous hazardous waste can be
in the form of "empty" cylinders containing residual gas
that is hazardous waste, or generated due to physical or
chemical reactions of other waste.
2. Regulatory Framework
Law 4 of 1994 is the overall legal instrument that regulates
environment pollution control in Egypt. Articles 1, 5, 29,
30 to 33, 85, 88, 95, 99 and 101 to 104 of this law and the
Executive Regulations for Law 4, Articles 25 through 33 are
the relevant articles for management of hazardous waste.
3. License For Handling Hazardous Waste
The applicant submits his application in writing containing
the data identified in Article 26, of the executive
regulation. The license shall be valid for a maximum of 5
years and subject to renewal (Article 27). It can be revoked
or suspended if:
It was obtained using false data.
Its conditions are violated.
Unforeseen dangerous environmental effects or new
technologies make the license invalid.
If EEAA concludes that it is unsafe to handle the waste.
4. Characterization of Hazardous Waste
According to Article 28 paragraph 1B of the Executive
Regulation of Law 4, every establishment must characterize
the waste generated in terms of both quantity and quality. A
new hazardous waste classification system has been put in
place.
5. Type of Storage Facilities
Hazardous waste storage facilities can be either on-site, at
the property where the waste is generated, or off-site, at a
common hazardous waste and disposal facility. EEAA
recommends the use of three types of on-site storage
facilities:
(a) Storage in drums
Containing small quantities of liquid or solid waste (easy
to handle and allows for easy segregation of incompatible
wastes such as corrosive and reactive wastes).
(b) Storage in tanks for bulk quantities of liquids
Tanks can be constructed above ground or buried underground.
EEAA does not recommend underground tanks because of their
complexity and the high risk of environmental damage.
Liquids should be periodically pumped to on-site treatment
systems or transferred to tankers for off-site treatment and
disposal.
(c) Storage in large containers
(generally of steel from 1 to 20 tons in capacity) for bulk
quantities of solids. The containers are designed to be
hauled by trucks to an off-site disposal facility and
returned for refilling.
6. Requirements for Storage Facility
(a) Location
Must be a secure site with limited admission.
Must be located away from storage areas particularly those
for hazardous chemicals, and from drinking water sources and
any residential areas.
Must have an access for loading, unloading, and responding
to emergency situations.
Must have electrical power, including emergency power
supply.
Must have a water supply for cleaning and firefighting.
(b) Capacity
Several factors should be considered such as present and
projected waste quantities, types of wastes and their
incompatibility, storage time, and cost of bulk versus drum
storage including transportation and disposal.
(c) Layout
Outdoor storage is recommended for ease of accessibility,
handling, safety, and cost considerations. Indoors storage
is vital to protect stored waste from extreme heat or for
other considerations.
Storage space should be laid out to contain all types of
hazardous waste produced by the industry. It should provide
for:
Access from at least two sides for responding to fire and
other emergency situations.
Adequate separation of incompatible wastes, safe movement
of waste containers using mechanical equipment, and adequate
access for inspection.
Ignitable or reactive waste (solid or liquid) should be
stored at least 15 meters from the facility's property line.
Figure 3
shows the layout for such a facility.
(d) Security
The storage area should:
Be secured with a 3 meter wall or fence and have locked
gates. The keys to the lock should be properly labeled and
kept in a secured office. A duplicate or master key should
be available in case of emergencies.
Have at least two access gates: one for normal use, the
other for emergencies.
Have a person responsible for the security of the storage
area.
Be controlled: only trained personnel can enter the
hazardous waste storage area.
Have a restricted area sign: a hazardous waste storage
area.
Be well lighted for security at night.
Be designed to accommodate temporary containment of spills
and equipment to respond to spill incidences.
(e) Design
Drum Storage
The most common type for storage of liquid and solid
hazardous waste are the 200 liter steel drums. The drums
should be made of or lined with materials that will not
react with the hazardous waste to be stored. Liquid wastes
need an epoxy-based coating or anti-corrosive paint for
lining the inside of the drums. Solid waste requires a
polyethylene liner for corrosive wastes. Drums should be
stored upright on wooden pallets, as shown in
figure 4.
Each drum must be labeled and stacked so the label is
visible. The storage area should be divided into two
sections, one for drums containing liquids and the other for
drums containing solids. A containment system with a curb
sufficient to contain 10% of the total drums volume should
be built around the boundary of the storage area for
liquids. The floor should slope (2% minimum slope) to a
collection area to remove liquids resulting from spills and
leaks.
Tank Storage
Underground tanks require double walled construction,
excavation, shoring, and leak detection and monitoring
systems. They must have a corrosion resistant coating and
cathodic protection. Considering the complexity of
installation and operation and the high risk of environment
damage, it is not recommended to use underground tanks for
the storage of hazardous wastes. This document only provides
guidelines for above ground tanks. Tanks of steel or
fiberglass reinforced plastic (FRP) should be installed
above ground. All tanks should be clearly labeled and have
sufficient structural strength to hold contents, be
compatible with the wastes to be stored and have corrosion
protection.
The foundation for the tank should be a reinforced concrete
slab of adequate strength and thickness to prevent failure
due to settlement, compression, or uplift pressure.
Secondary containment can be provided by a double walled
tank or a vault around single-walled tanks or group of
tanks. Double-walled tanks should be designed as an integral
structure to contain any liquid releases from the inner
tank.
Vault systems consist of a wall enclosing the tank area and
should contain 100% of the capacity of the largest tank in
the enclosure, plus the estimated volume of the maximum
24-hours rainfall, as shown in
figure 5.
Bulk Container Storage
These are rectangular steel bins fitted with rigid covers to
keep out rain and ensure against wind disbursement of
materials. They could range in capacity from 1 to 20 tons of
solid hazardous wastes. The containers should be located on
a concrete pad with a minimum thickness of 7.5 cm. They
should be clearly labeled and marked.
Table 1 gives
specifications for both vertical and horizontal above ground
storage tanks.
Empty Chemicals/ Containers
Improper use of empty chemical containers can result in
serious risks. The owner of the facility should determine
chemicals that are harmful to human health, based on the
Material Safety Data Sheet supplied by the manufacturer.
Dispose of empty containers as follows:
- Cardboard boxes and paper and plastic bags should be
crushed on-site and disposal of along with solid hazardous
waste.
- Steel and plastic drums should be collected by the
supplier from the manufacturing facility. If not, they
should be crushed on-site and stored separately from bulk
storage for other hazardous wastes.
- Steel drums can be sold to a scrap metal reclamation
facility, after being thoroughly cleaned and decontaminated,
and crushed or cut up on-site.
- Disposable lines inside the drums, should be removed and
disposed of as hazardous solid waste.
Under no condition should an empty container of hazardous
chemicals be disposed of off-site without crushing the
container on-site.
7. Operation and management of storage facility
(a) organization and responsibility
Establish a team for management of hazardous waste with a
designated manager with overall responsibility and authority
from the point of generation to off-site disposal. Team
members should supervise operations during all shifts and in
every department. The team should have regular meetings.
(b) Training
Team should receive adequate training on waste handling
practices, personal health and safety measures, and
emergency response procedures for spills.
(c) Record-Keeping and The Hazardous Waste Register
Every establishment should maintain a register with the
following information:
Name and address of the establishment.
Name and job title of the person responsible for
maintaining the hazardous waste register.
The period covered by the current data
Any special conditions issued for the establishment by
EEAA.
A list of the types and quantities of hazardous wastes
generated by the establishment's activities.
Method of hazardous waste disposal.
The names of parties contracted for transportation and
disposal of the hazardous waste.
Date of reporting.
Signature of the person in charge at the facility.
(d) Waste Handling
Bulk liquid should be moved using pumps of material
compatible with and capable of handling the type of liquid
waste being stored.
During transfer of bulk solid hazardous waste, attention
should be paid to spillage as of the waste is moved to the
container. Drums should be transferred using forklifts,
which sometimes must be flame-proofed.
(e) Packaging and Labeling
Labels in Arabic should show:
Clear signs or symbols indicating the hazardous nature of
the contents.
The container's contents active substances, and
concentrations.
The original source of the waste.
Total and net weights.
Date when the container was filled and when the waste was
generated.
Name and contacts for the person responsible for filling
the container.
Safe storage method and warning about mixing with other
reactive substances or wastes.
Personal protective gear needed for handling.
The best manner for dealing with emergencies (leakage,
spills, fire etc)
Special precautions for opening and emptying.
(f) spill and fire prevention and emergency response:
An internal communications or alarm system.
A telephone or hand-held two-way radio.
Portable fire extinguishers, fire and spill control
equipment.
First aid stations to include emergency showers, eye-wash
facilities, basic first aid facilities, stretchers, fire
blankets, emergency lighting, and luminous tape.
Water at adequate volume and pressure.
(g) Facility should prepare a contingency and emergency
response plan that includes:
Description of actions to respond to spills fires, and
explosions.
Arrangements with the local police and fire departments
and hospitals to coordinate emergency services.
List of names , addresses and phone numbers of emergency
coordinators.
List of all emergency response equipment at the facility,
including first aid stations and where they are located.
Description of the evacuation plan for facility personnel
including details of the signals to use to start evacuation,
evacuation routes, and alternate evacuation routes. An
emergency coordinator should be designated for the facility.
In the event of an incident, emergency coordinator should:
Ensure that any hazardous wastes generated are disposed of
in the proper manner.
Ensure that all emergency equipment used and listed in the
contingency plan is cleaned and fit for its intended use
before operations are resumed.
Prepare a report on the incident that includes:
- date, time and location of the incident,
- type of incident,
- type and quantity of materials affected,
- an assessment of damage and extent of inquiries, if any,
- an assessment of actual or potential hazards,
- estimated quantity and type of wastes generated, and
method of disposal.
(h) Personal Protection and Health and Safety
Personnel should be provided with the proper clothing and
equipment to adequately protect them from exposure to the
hazardous waste: protective overalls, hard hats, safety
shoes/ work boots, safety glasses, gloves, dust and fume
protective masks, air purifying respirators with cartridges,
splash resistant aprons, and disposable coveralls.
(i) Inspection and Monitoring
Inspect at least once weekly, to look for leaking drums,
tanks, and containers, and for determining of any of the
containers. Also look for proper storage of the drums,
labeling, segregation, aisle space access, handling
equipment, personal protective equipment, and general
housekeeping requirements. The secondary containment system
also should be inspected at this time to ensure there is no
accumulation of debris or blockage of the liquid collection
and sump area. The walls of the secondary containment should
be inspected to ensure that its integrity is maintained. The
tanks should be inspected daily for overfill control
pressure, and temperature gauges.
View Sample inspection
checklist.
(j) Closure Plan
Every facility should have closure plan to ensure that all
hazardous waste is adequately removed. It should include:
A description of how each hazardous waste management unit
will be closed, details of removal of residual hazardous
waste, and decontamination of equipment structures , and
soils.
A description of the sampling and testing procedure for
all soils, and groundwater to identify existing
contamination.
An estimate of the total inventory of hazardous waste
stored, including types and quantities of different types of
waste.
A description of how and by whom the waste was
transported, and at which facilities the waste was disposed
of off-site.
Hazardous waste treatment and
safe disposal is the key element of hazardous waste
management. It is necessary for protection of human health
and the environment. However, in the management of hazardous
waste, it is important to consider another aspect, which is
pollution prevention and waste minimization of hazardous
waste. While in many cases it may not be possible to avoid
or eliminate generation of hazardous waste from some
industrial processes, it is recommended that hazardous waste
minimization opportunities shall be evaluated at industrial
facilities before implementing a waste treatment system.
Whether on-site or off-site treatment is considered, waste
minimization will reduce operating cost of industrial
facilities generating hazardous waste.
Depending on the situation, hazardous waste treatment is
either done at the industrial facility, where the waste is
generated, or at an off-site commercially operated
treatment, storage, and disposal facility (TSDF), In most
cases, a typical integrated TSDF consists of different
units, and a secured landfill.
1. Treatment technologies
Quantity of waste, characteristics, combined or segregated
wastes, degree of treatment required, and ultimate disposal
method. The treatment technologies can be categorized into
physical, chemical, biological, and thermal treatment.
Combinations of treatment technologies are often used to
develop the most cost-effective, environmentally acceptable
solutions for hazardous waste treatment.
(a) Physical treatment Physical processes for hazardous waste treatment include
screening, Sedimentation and Clarification, Centrifugation,
Flotation, Filtration, Sorption, Evaporation and
Distillation, Air or steam Stripping, and membrane based
processes. These processes are mostly applied to liquid
hazardous wastes, and involve the separation of suspended or
colloidal solids from the liquid phase. The selection of the
technology depends mainly on the concentration and
characteristics of the suspended solids relative to the
liquid phase. Physical processes segregate the waste from
one form to another, reduce the volume, and concentrate the
solids to facilitate further treatment, but do not detoxify
the waste. Whenever a waste containing liquids and solids
must be treated, physical separation of the solids shall be
considered first because it is generally cost-effective to
treat a low volume, high concentration waste. Usually
physical treatment is used in combination with other
treatment technologies for optimum waste treatment and
disposal.
(b) Chemical Treatment Chemical treatment involves the use of chemical reactions to
transform hazardous waste into a less hazardous waste, or
non- hazardous, or make it less mobile in the environment.
Chemical treatment can be useful also in volume reduction
and promoting resource recovery from hazardous wastes.
Chemical treatment is commonly used before sending a
hazardous waste to an off-site landfill for disposal. Also
since liquid hazardous wastes should not be disposed in a
landfill without prior treatment, chemical treatment is
often used to either make it non- hazardous, or at least
convert it to a solid or semi-solid, that makes the
contaminants chemically stable, and not mobile in the
landfill environment. Chemical treatment therefore offers a
number of options for hazardous waste treatment.
Many types of chemical treatment processes are used in
hazardous waste management such as Neutralization,
Precipitation, Coagulation, Flocculation, Oxidation and
Reduction.
(c) Chemical Neutralization Neutralization of acidic or alkaline waste streams is an
example of chemical treatment to mitigate liquid wastes
characterized as corrosive and hazardous. Wastes that have a
PH less than 2.5 or greater than 12 are considered
characteristically hazardous waste based on Hazardous Waste
Regulations (ER 338/1995 ER 1741/2005).
Neutralization of a waste that is an acid or Alkali involves
the addition of a neutralizing chemical to change the pH to
a more neutral level in the range of 6 to 8. Industrial
wastewater frequently requires neutralization prior to any
other treatment or release to municipal sanitary sewer
system.
Alkaline wastewater may be neutralized with a strong mineral
acid, such as sulfuric acid (H2 SO4) or hydrochloric acid (HCL),
or with carbon dioxide CO2 . The reaction with mineral acids
is rapid. Agitator vessels with pH sensors that control the
acid feed rate are used. Flue gas from a combustion process
is often used as a source of CO2, for neutralization, thus
making the neutralization process more economical.
Liquid acidic wastes may be neutralized with lime
[Ca (OH)2], caustic soda (Na OH), or soda ash (Na2 CO3),
Since lime is less expensive than other alkalis or soda ash,
it is most commonly used. The lime is added to the acidic
wastewater in an agitator vessel with a pH sensor to control
the lime feed rate.
The end products of neutralization are salt and water. Some
salt may precipitate, and will have to be disposed.
(d) Chemical Precipitation
The usual method for removal of dissolved heavy metals in
liquid wastes is chemical precipitation at selected pH
levels, depending on the metal ion, resulting in the
formation of an insoluble compound. Generally, most metals
precipitate in alkaline pH conditions. Hence, neutralization
of an acidic waste stream may cause precipitation of heavy
metals and allow them to be removed as a sludge residue. The
hydroxides of heavy metals are usually insoluble, so lime or
caustic is commonly used to precipitate heavy metals. Metals
can also be precipitated as sulfides. The solubility of
metal hydroxides and sulfides is influenced by pH, and shall
be taken into consideration to optimize metals
precipitation.
Precipitation of heavy metals can be enhanced with the
addition of various watersoluble chemicals and polymers
that promoted coagulation and flocculation. These processes
are used to separate suspended solids from liquids when
their normal sedimentation rate are slow to provide
effective clarification. Coagulation is commonly used for
removal of fine and colloidal solids in liquid wastes.
Coagulation is the addition and rapid mixing of a coagulant
to neutralize charges and collapse the colloidal particles
so they agglomerate and settle. Colloidal solids require
coagulation to achieve an effective size and settling rate,
to enhance settling time in removing suspended and colloidal
solids. Lime, alum and iron salts are common coagulants.
(e) Chemical Oxidation and Reduction The chemical process of oxidation and reduction is used to
convert toxic pollutants to harmless or less toxic
substances. Oxidation is a reaction in which valence
increases from a loss of electrons. Reduction is a reaction
in which valence decreases from a gain of electrons.
Chemical reactions that involve oxidation and reduction are
known as redox reactions.
An example of oxidation -reduction reaction in hazardous
waste treatment is the treatment of hazardous liquid wastes
from the tannery industry. Hexavalent chromium generated
from tanning industry is highly toxic and its presence in a
waste requires careful management to avoid harm to human
health and environment, Hexavalent chromium is first reduced
to trivalent form under low PH (2-2.5) conditions, followed
by increase in PH (approximately PH 8-9) by adding lime or
caustic to be precipitated as chromium hydroxide. Treatment
of cyanide liquid waste using alkaline chlorine is another
example of chemical oxidation, in which the toxic cyanide is
oxidized to a less toxic form as cyanate, and then further
oxidized to carbon dioxide and nitrogen.
Chemical oxidation-reduction is also used commonly to
stabilize chemical sludges to make the hazardous waste less
mobile before being disposed in a landfill. Lime, fly ash,
or pozollonic materials, like cement are often used for
chemical stabilization process.
(f) Biological Treatment Biological treatment can be used for contaminated
wastewater, landfill leachate, and contaminated soil.
Biological treatment is often referred to as bioremediation.
Biological treatment may be categorized according to the
oxygen utilization , into aerobic processes and anaerobic
processes. In the aerobic processes, oxygen is required to
decompose organic matter using aerobic bacteria. Anaerobic
processes, use anaerobic bacteria, in an oxygen deficient
atmosphere, to decompose organic matter. Aerobic organisms
are most commonly used to treat industrial wastewater.
Anaerobic systems are generally used for the treatment of
concentrated organic waste or organic sludges.
Bioremediation is often used for treatment of soil
contaminated with petroleum compounds. Bioremediation is a
relatively low cost treatment option. However, the treatment
is dependent on type and concentration of compounds, oxygen
availability, temperature, moisture, and other factors.
Bioremediation systems shall be designed by professionals
with specialized experience in this type of treatment
technology. (g) Thermal Treatment (Incineration) Thermal treatment using incineration offers a technology
that results in breaking down complex organic compounds in
hazardous waste into carbon dioxide and water. Incineration
enables detoxification of combustible hazardous wastes,
which may contain toxic compounds that are carcinogens,
mutagens, and teratogens. Incineration is generally
recognized as one of the common treatment technologies in
hazardous wastes management.
(h) Advantages of Incineration Incineration is particularly desirable when dealing with
large quantities of highly toxic organic hazardous wastes,
since it can achieve high destruction and removal efficiency
(DRE) of organic wastes, and produces an inorganic residue,
which is non-toxic. Incineration is a suitable option when
there is a mixture of different kinds of hazardous wastes.
Another advantage of incineration is that since organic
hazardous wastes often have high calorific value, the waste
provides a fuel source for incineration, in addition to
destroying the toxicity of the waste, incineration reduces
the volume of hazardous waste. Reduction in volume makes
management of hazardous waste much more economical, and
reduces the space required for landfills. Another advantage
on incineration is the reduction of leachability of the
wastes after it is incinerated, thus making landfilling an
acceptable method of final disposal, with significant
reduction in potential for release of contaminants for
groundwater contamination.
(i) Disadvantages of Incineration
While incineration of hazardous wastes offers many
advantages. It also has some disadvantages. The initial
capital investment for an incineration system is generally
higher than that for some of the other treatment
technologies. Incineration technology also requires highly
trained operators. Incineration results in release of
particulates, and other undesirable compounds in air
emissions.
(j) The Chemistry of Incineration Incineration represents a combustion process applied to the
destruction of toxic substances present in hazardous wastes.
Simply stated, incineration is the controlled
high-temperature oxidation process to produce carbon dioxide
and water, and inert residues.
The chemistry of combustion and the chemistry of
incineration may be considered interchangeable. Both terms
are used to define a thermal oxidation process. The
distinction between combustion and incineration lies in the
application of the chemistry and its relation to the
desirable effects of resource conversion versus the
desirable effects of resource conversion versus the
destruction of undesirable substances. For example, in
combustion, typically a valuable material, such as coal or
oil, is oxidized in the presence of a flame to produce a
desirable end product, energy, and undesirable gas
emissions. On the other hand, in incineration an undesirable
waste, such as hazardous wastes, is thermally destroyed to
produce acceptable air emission products, such as carbon
dioxide and water, and a solid ash residue. Some air
pollutants are emitted in incineration of hazardous waste.
(k) Design of an Incinerator Several factors are necessary to be considered in the design
of an incineration system. Any incinerator design must
consider the three critical parameters, which are often
referred to as the three T's of incineration. Time,
Temperature, and Turbulence. Specifically, these are the
temperature at which the furnace is operated, the Time
during which the combustible material is subject to that
temperature, and Turbulence required to ensure that all the
combustible material is exposed to oxygen to ensure complete
combustion. In addition to the three T's, the pressure in
the oxidation chamber and the air supply for oxygen are also
parameters for design. The optimal combination of all these
parameters can significantly affect thermal destruction and
removal efficiency (DRE). The efficiency of an incinerator
is typically measured in terms of the DRE of the principal
organic hazardous contaminants (POHC). For example, typical
DRE requirements are 99.99% for most hazardous wastes, and
99.9999% for FCB and dioxin wastes. The design of the
incinerator plays a key role in ensuring adequate
destruction of the hazardous waste and shall include the
following factors:
Temperature one of the most significant factors in ensuring proper
destruction of the hazardous waste in any thermal
destruction process. The destruction and removal efficiency
(DRE) in any incineration operation depends on the
incinerator temperature. Depending on the type of waste, and
design of the incinerator, and DRE required, temperature for
hazardous waste incineration varies generally from 800° C to
1500° C.
Residence Time The residence time for any given flow rate, can be
determined by the dimensions of the incinerator. Optimal
combination of residence time and temperature is necessary
to ensure compliance with destruction and removal efficiency
(DRE) requirement of the regulations.
Turbulence The degree of turbulence is used in design to attain
desirable DRE to destroy the POHC of the hazardous waste,
and lessen the severity of opening temperature and residence
time requirements. The configuration of the incinerator
affects the ability to create turbulence, and destroy
hazardous waste. Pumps, blowers, and baffles shall be
selected based on the type of waste and required DRE.
Air supply Incineration involves the reaction of combustible components
with air, which normally provides the oxygen required for
complete combustion. Products of incomplete combustion (PIC)
are undesirable, and results in air emissions of compounds
such as carbon monoxide if optimal combination of residence
time temperature, or air is not maintained.
Pressure
It is common practice to design the hazardous waste
incinerator to operate at slightly negative pressure to
reduce fugitive emission. However, thermal destruction
systems operating at a positive pressure, requires
non-leaking enclosures.
Material of Construction The materials of construction of an incinerator must be
designated conservatively to handle a wide variety of
hazardous wastes, and the high temperature conditions.
Materials of construction can vary from ordinary steels to
alloys. Incinerators are generally lined with refractory
materials to withstand the high temperature, and aggressive
chemicals.
Material Feed System Material feed system is one of the important parameters to
consider in the design of incinerators, particularly those
used for treating a wide variety of hazardous wastes of
different chemical composition, and physical
characteristics. Experience has shown that many incinerators
with well designated optimal process conditions had
problems in operation and performance due to inadequately
designed material feed systems.
Emissions Control System Incinerators have undesirable air emissions that have to be
controlled. Air emissions can be particulate matter, oxides
of nitrogen, and sulfur, acidic vapors, carbon dioxide,
metals and other products of incomplete combustion, The
design of incinerator must consider treatment and control of
the emissions. Bag filters, electrostatic precipitators, dry
and wet scrubbers, and carbon adsorption systems, are common
devices used for control of air emissions.
2. Types of Incineration Systems
A number of different types of incineration systems are
available which successfully treats hazardous waste. Some
are better suited for liquid wastes, while others can handle
solid and liquid wastes. The two most common types of
incinerators systems, based on liquid feed and the solid
feed types are as follows:
Liquid Feed Incinerator A large number of hazardous waste incinerators used today
are of this type. The waste is burned directly in a burner
or injected into a flame zone or combustion zone of the
incinerator chamber through atomizing nozzles. Liquid
injection-type incinerators are usually refractory lined
chambers, generally cylindrical in cross-section, and
equipped with a primary burner (waste and/ or auxiliary fuel
fired). Often secondary combustors are required where low
heating value waste liquids are to be incinerated. Liquid
incinerators operate generally at temperature from 1000°C to
1500°C. Residence time in the incinerator may vary from
milliseconds to as much as 2.5 seconds. The method of
injection of the liquid waste is one of the critical factors
in the design and performance of these incinerators. Organic
liquids pass through these phases before oxidation takes
place. The liquid droplets are heated, vaporized, and
superheated to ignition temperature. Proper mixing of air
with the atomized droplet is very important for complete
oxidation. Inorganic particles carried in the liquid waste
stream may become molten and agglomerate into molten ash.
The ash can be landfilled.
Rotary Kiln Incinerator
The rotary kiln is often used in hazardous waste
incineration because of its versatility in processing solid,
and liquid, and containerized wastes. The kiln is
refractory-lined. The shell is mounted at a slight incline
(about 5 degrees) from the horizontal plane to facilitate
mixing the waste materials. A conveyor system or a ram
usually feeds the solid and containerized wastes. Hazardous
liquid wastes are injected through a nozzle(s).
Noncombustible metals and other residues are discharged as
ash at the end of the kiln.
Rotary kiln incinerators are cylindrical, refractory-lined
steel shells supported by two or more steel trundles that
ride on rollers, allowing the kiln to rotate on its
horizontal axis. The refractory lining is resistant to
corrosion from the acid gases generated during the
incineration process. Rotational speeds range from 0.5 -2.5
cm/sec. The kilns generally range from 6 to 14 feet in
diameter and 25 to 100 feet in length. The burners for the
kilns range from 10 million British Thermal Units (BTU) per
hour, to 120 million (BTU) per hour.
The advantages of the rotary kiln include the ability to
handle a variety of wastes, high operating temperature, and
continuous mixing of incoming wastes. The disadvantages are
high capital and operating costs and the need for trained
personnel. Maintenance costs can also be high because of the
abrasive characteristics of the waste and exposure of moving
parts to high incineration temperature. Both stationary and
mobile type kiln incinerators are available.
Figure 6 shows a
typical rotary kiln incinerator. Cement kiln incinerator, which can be used to incinerate
most hazardous waste. Rotary kilns used in cement industry
are much larger in diameter and longer in length than the
previously discussed hazardous waste rotary kiln
incinerator. The manufacturer of cement from limestone
requires high kiln temperatures (1400°C) and long residence
times, creating an excellent opportunity for hazardous waste
destruction. Further, the lime can neutralize the hydrogen
chloride generated from chlorinated hazardous wastes without
adversely affecting the properties of the cement. Liquid
hazardous wastes with high heat contents are a supplemental
fuel for cement kilns and promote the concept of recycling
and recovery. As much as 40 percent of the fuel requirement
of a well-operated cement kiln can be supplied by hazardous
wastes such as solvents, paint thinners, and dry cleaning
fluids. However, if hazardous waste is burned in a cement
kilns, attention has to be given to determine the compounds
that may be released as air emissions because of the
combustion of the hazardous waste. The savings in fuel cost
due to use of hazardous waste as a fuel, may offset the cost
of additional air emission control systems required in a
cement kiln. Therefore with proper emission control systems,
cement kilns may be an economical option for incineration of
hazardous waste.
3. Secured landfill Disposal Facilities
Industries in Egypt most commonly send their hazardous
wastes off-site for landfill disposal, since this is the
only alternative available. These landfills are essentially
dumpsites used for non-hazardous waste disposal, and do not
have any waste treatment facilities, or the liner system
necessary for hazardous waste landfills. The practice of
disposing hazardous waste in non-hazardous waste landfills
and without prior treatment poses a serious threat to the
environment, because the leachate containing high
concentration of hazardous and toxic compounds easily
migrate underneath the landfill and contaminate the
subsurface soil and groundwater.
A secured landfill can be defined as an engineered facility
for land disposal of hazardous wastes. A secured landfill
can be defined as an engineered facility for land disposal
of hazardous wastes. A secured landfill facility is often a
treatment, storage and disposal facility (TSDF). It shall be
carefully planned and constructed to ensure efficient, long
term operation without adverse environmental impact.
Optimal use of the landfill capacity is necessary to ensure
the long-term operations of the TSDF. Treatment of the waste
prior to landfilling minimizes the potential for leachate
migration, and reduces the volume of waste for disposal.
Development of a new hazardous waste landfill project
entails several phases over lifetime of the landfill as
follows:
Site selection phase
Designing phase
Construction phase
Operation and management phase
Closure phase
Post closure monitoring phase
Site Selection Selecting a hazardous waste landfill site requires taking
into consideration of a number of factors as follows: - Groundwater - Flood plains - Surface water - Air quality - Operational safety
- Endangered species - Climate The geological structure below the landfill is important in
establishing the design parameters. Critical design
parameters include the depth to groundwater, characteristics
of subsurface soils, and groundwater transmissibility.
Groundwater aquifers underlying the landfill site must be
located. Hazardous waste landfills must also be located
outside historic floodplains. In order to address surface
water impact issues, the landfill should consider adjoining
surface water bodies on to which drainage of runoff may
occur from the landfill. The air quality in the vicinity of
a hazardous waste landfill must be monitored and controlled
to ensure compliance with applicable standards for emission
of toxic compounds. Endangered species must be considered in
the sitting process. Other considerations in landfill site
selection include climate, the topography and hydrogeology
of the area. Soil is an important determinant in the choice
of an appropriate hazardous waste landfill site. Rocky soil
must be avoided, wherever possible for excavation problems
and due to high permeability, soil permeability at the site
is generally the major factor affecting the rate of
contaminant transport through the soil. An ideal native soil
underlying, and in vicinity of the landfill shall have a
maximum permeability of 1 x 10-7 cm/sec.
Other factors to consider in locating a landfill include
distance from the points of waste generation, availability
of space for current and projected waste quantities,
infrastructure in the area to transport for waste, and wind
direction relative to population and ecological receptors.
Designing a Landfill A properly designed and constructed landfill should
incorporate proven technology to guard against the release
of contaminants into air, surface water, and groundwater,
reducing environmental concerns over its entire operating
and post- closure life. Proper landfill design is most
effective when it is considered an integral part of the site
selection process. In designation the landfill, the
following key design parameters should be considered:
- Type and volume of hazardous waste - Topography and soil characteristics of the site and
vicinity - Climate conditions - Surface water bodies in the area
- Groundwater characteristics - Selection of liner system for the landfill - Quantity and characteristics of the leachate
- Selection of leachate collection and treatment systems - Closure and post-closure plans
Some of the key components of a landfill are as follows:
- Liner system A landfill for hazardous wastes must include a liner and
drainage system that is chemically resistant to the types of
wastes and the leachate produced. The purpose of the liner
is to provide an impermeable barrier layer under the waste
to prevent leachate migrating into the groundwater below the
landfill. A wide variety of materials are available for
liners in hazardous wastes landfill construction. Synthetic
flexible membrane liners are generally considered to offer
the best long term containment of leachate. The chemical and
physical properties of these liners should be weighted
carefully to ensure both long life and cost effectiveness
of the liners system. Common materials used for synthetic
liners include high density polyethylene (HDPE) polyolefins,
and poly vinyl chlorine. Selection of the appropriate liner
material is a critical design parameter that affects
long-term performance of the landfill. Depending on the
application, liner thickness generally varies from 40 to 100
mils. Figure 7 shows
a landfill with a liner system. Depending on the
site-specific conditions, a single or double liner system
may be used in the landfill. It is recommended that a double
liner system be used in hazardous waste landfills to protect
the groundwater. In case where the groundwater is quite
deep, the soil below the landfill is a thick layer of low
permeability clay material, a single liner system may be an
option. In either a single or double liner system, it is
important to have a compacted clay liner (at least one meter
thick) at the bottom of the landfill. This clay liner shall
have a permeability not exceeding 1 x 10-7 cm/sec. If the
natural underlying clay in a landfill is a deep layer, and
has a similar low permeability, additional clay liner,
although still preferable, but may not be essential.
- Leachate Collection System A leachate collection and removal system must be installed
above and below the liner. A riser pipe extending from the
sump in the leachate collection system to the ground surface
facilities removal of leachate. This pipe allows the
leachate to be pumped to the surface for subsequent
treatment and disposal. The leachate collection system must
remain operational during the entire post-closure period.
The material of construction for the leachate collection and
monitoring system must have high chemical resistance to the
anticipated constituents in the leachate.
- Cover System A significant source of leachate generation at hazardous
waste landfills is the infiltration of water through the top
of the landfill from rainfall precipitation. Some of this
precipitation flows off the landfill as runoff, carrying
contaminants. In order to minimize leachate generation and
runoff contamination, hazardous waste landfills must have a
cover system. The final cover for the landfill is intended
to minimize infiltration of surface water, prevent runoff
contamination, prevent erosion of the soil, and generally
maintain the integrity of the hazardous waste landfill long
term over the post closure period, which may be 30 years.
- Slope stability Landfills must be stable during construction, operations,
and for many years after closure. Landfill failure due to
inadequate slope stability sometimes occurs, and can be a
major problem. Special attention by an experienced
geotechnical engineer to address slope stability of the
landfill is essential during the design of the landfill.
Landfill Construction Construction of a landfill involves several steps, which
must be followed with close supervision, quality control,
and attention to details. Steps for landfill construction
are as follows: - The natural soil is excavated to the planned depth and the
excavated material is often used for constructing the
lateral embankment for the portion of the landfill above
ground. - At the bottom of the landfill an impermeable compacted
clay layer, is placed. The layer should be minimum 1 m
thick. The permeability of this layer should nor exceed 1 x
10-7 cm/sec. - A layer of non-woven fabric (geo-textile) is placed above
the clay. The purpose of the geo-textile is to smooth out
the unevenness of the clay layer, and protect the
geomembrane synthetic liner against any damages due to sharp
stone edges that may puncture the liner. - A geomembrane liner is laid on the top of the geotextile
layer. Since the liner is one of the critical components of
the landfill construction, particular attention must be paid
to liner installation. One of the key aspects of laying the
liner is the location and seaming of the joints. The liner
should be overlapped at the joints such that the leachate
would drain as away from the joint. Special care shall be
taken to use manufacturer's recommended techniques for
seaming the joints, and testing for integrity. - On top of the liner layer, a layer of sand is laid to form
the drainage layer. In the sand, a system of perforated
drainage pipes is installed for collecting the leachate. The
hydraulic conductivity of the drainage layer should
generally be equal to 1x10 cm/sec or more. The minimum
thickness of the drainage layer should be 30 cm. Slope of
the drainage layer should be a minimum of 2% - On top of the drainage layer, a filter layer is
recommended with minimum thickness of 20 cm. The filter
layer can be made of gravel or crushed rock. The waste is
placed on top of this layer. - When the landfill is filled and covered, a cover system is
installed. The cover system is composed of a geomembrane
layer over the soil cover on the waste, with a drainage
layer about it, and finally a vegetative layer of topsoil.
