hazard waste space
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Hazardous Waste Management
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Introduction
Definition of hazardous waste
Risk and risk management,
Hazardous waste regulations andmanagement
Treatment technologies for hazardous waste
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Hazardous Waste
by reason of their chemical activity or toxic,
explosive , corrosive or othercharacteristics , can cause danger or likelywill cause danger to health or theenvironment , whether alone of when comingin contact with other wastes
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Dioxin Issues
Dioxin Issues
Dioxins are found over 20 different isomers of a basicchlorodioxin structure
The most common form, TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) is the most poisonous ofall synthetic chemicals
Dioxin are a contaminant by-product that may be
thermally generated during manufacture or burning ofchlorophenols, pesticides, algae-controllingherbicides, insecticides, etc.
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Risk
The concepts of risk and hazard
Hazard
Implies a probability of adverse effects in aparticular situation
Risk
Measure of the probability
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Risk Perception
People respond to the hazards they perceive. Iftheir perceptions are faulty, risk Management
efforts to improve environmental protectionmay be misdirected
Lay people rely on inferences based on theirexperience
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Risk Assessment
In 1989, the EPA adopted a formal processfor conducting a baseline risk assessment
This process includes Data collection and evaluation,
Toxicity assessment,
Exposure assessment, and Risk characterization.
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Data Collection & Evaluation
Gathering and analyzing site-specific datarelevant to human health concerns for the
purpose of identifying substances of majorinterest
A conceptual model of pathways andexposure points can be formed from thebackground data and site information
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Toxicity Assessment
Process of determining the relationshipbetween the exposure to a contaminant andthe increased likelihood of the occurrence or
severity of adverse effects to people Hazard identification determines whether
exposure to a contaminant causes increased
adverse effects towards humans and to whatlevel of severity
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Exposure Assessment
The objective of this step is to estimatethe magnitude of exposure tochemical of potential concern. Themagnitude of exposure is based on
chemical intake and pathways ofexposure
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Risk Characterisation
All data collected from exposure andtoxicity assessments are reviewed tocorroborate qualitative and quantitativeconclusions about risk
This includes the evaluation of compoundingeffect due to the presence of more than one
chemical contaminant and the combination ofrisk across all routes of entry
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Risk Management
Risk management is performed to decide themagnitude of risk that is tolerable in specific
circumstances This is a policy decision that weighs the
results of the risk assessment against costsand benefits as well as the public acceptance
Zero risk cannot be achieved !!
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Definition and Legislation ofHazardous Waste
The U.S EPA took nearly four years from thepassage of the nations first hazardous wastelaw in 1976 before promulgating regulationsthat define hazardous waste.
Hazardous
Waste??Not
Hazardous
Waste??
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The form of a waste is not important indefining whether it is hazardous.
The most critical part of any definition is toinclude those terms describing thecharacteristics that a waste to be consideredhazardous.
i.e. posing a substantial present or potentialdanger to human health or the environment
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Definition of hazardous waste preparedby the United Nations Environment
Program in December 1985Hazardous wastes mean wastes (solids, sludges,liquids, and container sized gases) other thanradioactive (and infectious) wastes which, by
reason of their chemical activity or toxic, explosive,corrosive, or other characteristics, cause danger orlikely will cause danger to health or theenvironment, whether alone or when come intocontact with other waste
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Cradle-to-Grave Concept
The EPAs cradle to grave hazardous waste managementsystem is an attempt to track hazardous waste from itsgeneration point to its ultimate disposal point
In Malaysia, toxic and hazardous wastes are defined asscheduled waste
DOE provide comprehensive regulations to themanagement of the scheduled waste that based on thecradle-to-grave principle
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Generator of hazardous waste can no longeravoid liability by contracting with a third partyto dispose of the waste
This compels generator to exercise care inthe selection of the disposal companies theyutilise
This procedure is designed to ensure thatwaste are directed to, and actually reach, apermitted disposal site
Cradle-to-Grave Concept
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Regulations
Environmental Quality(Scheduled Waste)
Regulations 1989
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Management Procedures
I. No tif ic at io n o f th e g en erat io n o fsch edu led w as tes
- Generation of any scheduled waste shallbe notified to the Director General inwriting
- Notification through form prescribed inthe Second Schedule
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Notification Form Prescribed in the Second Schedule
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II. Dis p o s al o f s c h ed u led was tes
- Scheduled wastes shall be disposed of at prescribedpremises only (for complete list of scheduled wastescontractors in Malaysia, please visit the DOEwebpage athttp://www.jas.sains.my/doe/port/bmport_frset.htm
- Prior to disposal, waste shall be rendered harmlessas far as is practicable
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III. Treatment of scheduled wastes
- Scheduled wastes shall be treated atprescribed premises or at on-site treatmentfacilities ONLY
- Export of scheduled wastes governed by
Guidelines for the Export of Scheduled Waste EG 1/93
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- Since 1996, DOE has stopped the issuance ofapprovals to export scheduled wastes for finaldisposal but the export of scheduled wastes forrecovery and recycling were still allowed on a case-to-case basis
- Export of scheduled wastes monitored through Form AS15A/rev3 and notified in accordance with BaselConvention for transboundary movement of wastethrough a notification form
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Form AS15A/rev3
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Notification Form for Transboundary Movement of Waste
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V. Reduction in the generation of scheduled wasteby best practicable means
- The generation of scheduled wastes by everywaste generator shall be reduced to themaximum extent practicable using the bestpracticable means
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VI. Storage of scheduled wastes
- Scheduled wastes shall be stored in durablecontainers that are able to prevent spillage orleakage
- The containers shall be clearly labelled in
accordance with the Third Schedule foridentification and warning purposes
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Third Schedule : Labelling Requirements for Scheduled Waste
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- Incompatible scheduled wastes shall be stored inseparate containers (please refer to the Fourth
Schedule for potential incompatibilities ofscheduled wastes
- Areas for storage of containers shall be designed,constructed and maintained to prevent spillage or
leakage to the environment
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Fourth Schedule : Scheduled Wastes of Potential Incompatibilities
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VII. Waste generator shall keep an inventory ofscheduled wastes
- Accurate and up-to-date inventory of thequantities and categories of wastes beinggenerated, treated and disposed of (inaccordance with the Fifth Schedule ) shall bekept by the waste generator
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VIII. Information to be provided by wastegenerator, contractor and occupier of
prescribed premises- Six (6) copies of Part I of the Sixth Schedule
shall be completed by the waste generatorand be given to the contractor to whom the
waste are delivered
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Sixth Schedule : Consignment Note for Scheduled Wastes
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- Upon receipt of scheduled wastes from wastegenerator, the contractor shall complete all six (6)
copies of Part II of the Sixth Schedule and shallhand over immediately two (2) copies of theSchedule to the waste generator [who in turn shallsubmit one (1) copy to the Director General]
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- Upon delivery of the scheduled wastes to theoccupier of any prescribed premises, a contractorshall hand over the remaining four (4) copies of theSixth Schedule to the occupier
- Upon receipt of the scheduled wastes from thecontractor, the occupier of any prescribed premisesshall complete Part III of all remaining four (4)
copies of the Sixth Schedule
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- The occupier shall retain one (1) copy of the SixthSchedule and return one (1) copy each to thecontractor, waste generator and the DirectorGeneral
- The waste generator shall notify the DirectorGeneral immediately upon failure to receive thecopy of the Sixth schedule from the occupier within
30 days from the date of delivery- The waste generator shall also investigate and
inform the D-G of the investigation results
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IX. Scheduled wastes transported outside wastegenerators premises to be accompanied byinformation
- Information in accordance with the SeventhSchedule shall be provided by every wastegenerator in respect of each category of scheduledwastes to be delivered to the contractor
- The Schedule shall be given to the contractor upondelivery of the waste from the waste generator tothe contractor
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Seventh Schedule : Information on Scheduled Wastes
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Waste Minimisation &Pollution Prevention
The term waste minimisation applied to anymanagement technique or process modification thatultimately reduces the mass or toxicity of waste senton to treatment and disposal facilities
The somewhat broader term pollution preventionhas an evolving definition that includes:-
Managing chemicals to reduce risk
Identifying and estimating all releases
Waste minimisation
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Pol lu t ion Prevent ion Tech niqu es
Pollution Prevention techniques
Source reduction Recycling(on- and off-site)
Product changesProduct substitutionProduct conservationChgs. in prod.composition
Source Control Recovery and reuseReturn to originalprocessRaw materialsubstitute for anotherprocess
Reclamation
Processed for resourcerecoveryProcessed as a by-product
Input materialchanges
Material purificationMaterial substitution
Technology changesGood operating practices
Procedural measuresLoss preventionManagement practicesWaste stream segregationMaterial handling improvementsProduction scheduling
Process changesEquipment, piping, orlayout changes Addition automationChanges in operationconditions
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Key elements necessary to the success ofa waste-minimisation program
Top-level organisational commitment
Financial resources
Technical resources
Appropriate organisation, goals, and strategy
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Waste A ud i t
Identify waste streams
Identify sources
Establish priority of waste streams for waste-
minimisation activity Screen alternatives
Implement
Track
Evaluate progress
The key question "why is this waste being generated?"
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Waste Exchange
Consignment of excess unused materials toan independent party for resale to a thirdparty
SaveWasteProduction Cost
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Recycling
When it is not possible to reduce thevolume or toxicity of a waste
Recycle to another process or anotherplant
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Zero Emission Concept
Before Pollution control at the end-of-pipe
High cost to meet strict emission and effluent
standards Rise in energy input
Rise in resource consumption
Present Zero Emission
Reduce the amount of pollutant and make theprocess less energy intensive
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Zero Emission Approach
Networking :-
Enables the use of waste from an industry asraw or starting material in othermanufacturing process and vice versa.
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Treatment Technologies
Physical Treatment
Chemical Treatment Biological Treatment Incineration
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Physical Treatment
Not detoxify but only concentrate waste for furthertreatment or recovery
Carbon Adsorption Distillation Ion Exchange Reverse Osmosis Solvent Extraction
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Carbon Adsorption
Adsorption is a mass transfer process in which gasvapors or chemicals in solution are held to a solid byintermolecular forces
Adsorbents Activated carbon
Molecular sieves
Silica gel
Activated alumina
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u 1: Schematic of a carbon contactor
Figure : Schematic of a carbon contactor
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Distillation
Separation of more volatile materials fromless volatile materials by a process of
vaporisation and condensation. The larger the vapor pressures differences,
the more efficient the separation process
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Ion Exchange
Metals and ionised organic chemicals can berecovered by ion exchange
Ion to be removed is passed through a bed of resin
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Reverse Osmosis
Solvent is forced to pass through a semi-permeablemembrane from concentrated medium to lessconcentrated medium
Semi-permeable membrane
HighConcentration
LowConcentration
Solvent
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Figure 2: Reverse osmosis systems
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Solvent Extraction
Liquid extraction and liquid-liquid extraction
Contaminants migrate from the wastewaterinto the solvent
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Chemical Treatment
Convert the waste to another form which are lesshazardous than the starting material
Spectrum of chemical methods:
Neutralisation
Oxidation
Precipitation Reduction
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Neutralisation
Application of the law of mass balance to
bring the waste to acceptable pH
pH between 6 to 8
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Oxidation
The cyanide molecule is destroyed by oxidation
Electrolytic oxidation
Carried out by anodic electrolysis at hightemperatures
Wet air oxidation
Zimmerman process Oxidized by oxygen at sufficient temperature and
pressure
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Precipitation
Removal of metals from platingsolutions
Application of the solubility productprinciple
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Reduction
Some metals have to be reduced before itcan be precipitated
Example:Hexavalent chromium (Cr 6+) used in platingsolutions must be reduced to trivalentchromium (Cr 3+)
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Biological Treatment
Biodegradation
Novel microorganisms for biological treatment ofanthropogenic compounds is a new concept
Certain organisms biodegrade certain waste
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In an incinerator, chemicals are decomposed byoxidation at high temperature (800 C and greater)
The waste, or at least its hazardous components,
must be combustible in order to be destroyed The primary product: CO 2, water vapor, inert ash
The percentages of carbon, hydrogen, oxygen,nitrogen, sulfur, halogen, phosphorus and moisturecontent in the waste should be known
why? To determine stoichiometric combustion airrequirement and to predict combustion gas flow andcomposition
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Actual incineration conditions generally requireexcess oxygen
- to maximize the formation of produ c t o fcom plete com bus t ion (POCs)
- to minimize the formation of produc t o fincom plete com bus t ion (PICs)
Hazardous waste incinerator must be designed toachieve a 99.99% des t ruc t ion and remo valefficiency (DRE)
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Permitting of Hazardous WasteIncinerators
Complex process
Due to variety of state and local regulations for thehandling, transportation, treatment, disposal &
operation of incinerators. Hazardous waste incinerators must meet 3
performance standards: Principle Organic Hazardous Constituents (POHC)
Hydrochloric acid
Particulates
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The DRE is determined for each designated POHCfrom a mass balance of the waste introduced into theincinerator and in the stack gas:
Where:
W in - mass feed rate of one POHC in the waste streamWout - mass emission rate of the same POHC present in exhaust
emission prior to release to the atmosphere
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2. Hydrochloric acid
An incinerator burning hazardous waste andproducing stack emissions is no greater than 1.8 kg/hor 1% of the HCl emissions
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3. Particulates Stack emissions of particulate matter are limited to
180mg/dry standard cubic meter (mg/dscm) for 7% O 2 The adjustment is made by calculating a corrected
concentration:
WhereP c corrected concentration of particulate, mg/dscmP m measured concentration of particulate, mg/dscmY percent oxygen in the flue gas
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Example 10-8 (page 883 885)
MUST TRY!!!!!
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