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EHSIMS
  EHSIMS Hazardous Wastes

 Identification and Classification
 Management System for Handling
 Environmental Measurements
 Law Number 4/1994
 Basel Convention
 Internet Resources


 


New Management System for Hazardous Waste Handling

Hazardous waste transportation
Hazardous waste storage
Hazardous waste treatment and disposal


A. Hazardous waste transportation:


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:

- Generator section
- Transport section
- Storage/ treatment/ disposal facility section

• Using The Manifest

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.
 


B. Hazardous waste storage:


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.


C. Hazardous waste treatment and disposal:


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 water–soluble 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.