Waste Management Flashcards
Draw the Waste Hierarchy
How are UK Landfills classified?
~ Hazardous
~ Non-hazardous
~ Inert
But legal requirements state that some level of pre-treatment of waste must be undertaken prior to going to landfill for final disposal.
What are the elements of responsible waste management?
~ raw material reduction
~ corporate image
~ pollution minimisation
~ morale
~ energy reduction
~ cost
~ employment
Role of Design in Reducing Waste
cleaner design can be defined as the design of a product to minimise its environmental impacts over its entire life-cycle by considering:
~ reduced raw material use
~ elimination of hazardous substances
~ reduced use of energy and waste
~ less pollution and waste
~ increased service life
~ greater potential for recycling
What are the Steps to Responsible Waste Management?
~ Prevention of
corrosion or wear of containers
accidental spills or leakages
breach of containment by weather
blowing away or falling from vehicles or storage
scavenging by ASB (anti social behaviour) or animals
~ protection of waste while it is held (store liquids in bunded enclosures/covered skips)
~ ensuring that waste reaches the next holder intact - which may be a waste transfer site
~ segregating incompatible wastes (preventing cross contamination)
~ ensuring security - so waste should be secured and left for the minimum of time
~ labelling waste where appropriate and in accordance with the hazardous substance legislation
Transportation and Disposal of Waste?
must be transported by an authorised/licensed company and taken to a permitted landfill site/incinerator/treatment works
What are the Economic Reasons for Waste Management?
~ reduced taxation
~ reduction in raw material use
~ improved corporate image
~ less chance of prosecution
~ improved H&S standards
~ increased employment opportunities
What are the Common Areas for Waste Objectives?
~ waste minimisation
~ waste recovery rates
~ amount of waste diverted from landfill/incineration
Why do you Monitor Waste?
many reasons, such as compliance with an integrated environmental permit; best technique to monitor:
~ the physical and chemical composition of the waste
~ its hazard conditions
~ handling precautions and substances with which it cannot be mixed
Waste Reporting as part of ISO14001 may include what?
~ what should be monitored and measured
~ the methods for monitoring, measuring, analysing and evaluating
~ what criteria the organisations performance is compared against
~ the frequency of monitoring
~ when monitoring results should be analysed and evaluated
Waste Audit - what are the six steps?
- Assessing Scope for Savings
- Gaining Management Commitment
- Mapping of Activities/Processes
- Quantifying and Cost Determination
- Understanding and Generating options
- Opportunity Assessment
What are the Techniques to Treat Waste?
> Chemical
Physical
Biological
What are common ways of managing waste?
> Incineration
What re some areas of Advanced Thermal Technologies
Mechanical Biological Treatment (MBT)
Composting
Anaerobic Digestion
Landfill
what are some Areas affecting the Economics of Incineration?
> Increase in cost of Landfill Disposal
Economic Instruments eg, Non-Fossil Fuel Obligation (energy from waste is classified as a renewable energy source and therefore receives grants/subsidies from Government)
What are the Benefits of Incineration?
> Reduction in Volumne
Destruction of Hazardous Components
Creation of Easily Disposed Ash
Small Size of Plant
Immediate and Measurable Effects
Can be Used to Raise Energy by Using Calorific Value of Waste
What are the Limitations of Incineration?
> High Capital Cost and Monitoring Requirements
High Fuel Costs on Start Up
Need to Carefully Control Inputs
Not Suitable for
. aqueous waste
. wastes containing heavy metals
. chlorinated materials (unless special controls in place)
. combustible solids
What are Advanced Thermal Technologies?
Pyrolysis
Gasification
Plasma Arc
Similar to thermal incineration, but very high temperatures.
Key difference is that they use limited amount of oxygen (compared to traditional incinerators)
What are the key stages of Pyrolysis and Gasification?
- Preparation of Waste feedstock - materials with no calorific value are to be removed
- Heating the Waste - in a low oxygen atmosphere to produce gas, oil and ash
- Scrubbing the Gas - removes particulates, hydrocarbons and soluble materials
- Using Scrubbed Gas to generate electricity or heat - may be achieved via gas engines or steam turbines
How is Plasma Arc used for Waste Disposal?
the waste is heated using plasma arc (an electric arc is used to heat the waste)
What are the Benefits of Advanced Thermal Technologies?
> by using less oxygen, were air emissions may be generated inn comparison to thermal incineration
plants are modular and consist of small units that can be added to or taken away as volume or waste streams change
plant is relatively quick to construct
produces more useful products than conventional incineration (eg syngas)
Syngas can generate energy more efficiently than a conventional incinerator (using steam turbine)
What are the Limitations of Advanced Thermal Technologies?
> unless they use residual waste as a feedstock they may undermine waste minimisation efforts further up the waste hierarchy
feedstock is limited in order for them to work effectively and is unlikely to break truly residual waste
an ash produced that requires disposal
fuel produced will be less than the energy needed to manufacture new products
What are the Two Types of MBT (Mechanical Biological Treatment)?
Type 1 - mechanical then biological treatment
Type 2 - biological then mechanical treatment (BMT)
What are the Benefits of MBT?
> Consists of Technologies that are proven and used internationally
removes a greater proportion of waste that can be recycled from the residual waste stream
produces waste material that may be used as a source of energy
can capture waste containing recyclable material in residual waste (kerbside schemes are not 100% successful)
significantly reduces waste disposed of to landfill
waste disposed of to landfill from MBT will have much lower biodegradability and as such reduce methane and leachate production in a landfill
can recover items that are not always collected for recycling
sorting will ensure that hazardous items do not reach landfill sites
plants are modular and with units added or removed as waste streams or volumes fluctuate
Limitations of MBT?
> market for output may be small
some wastes will still need to be disposed of to landfill
higher operational costs in comparison to alternative techniques
plants are often large and draw in waste from a wide geographical area with resultant transport impacts
due to cost, plants often operate on long term contracts and need a fixed amount of waste - this can undermine waste minimisation schemes
MBT waste is generally mixed rather than kerbside sorted material, so it can fetch a lower price in the market
What is composting?
biologically treating solid waste.
it is a process which stimulates the decay of organic materials by aerobic means.
The waste is composted under controlled conditions including aeration and mechanical turning of the material.
What are the Benefits of Composting?
> lower capital investment required than for most other alternative techniques
produces a solid fertiliser
less environmental impact than spreading unprocessed waste on land
improves the physical, chemical and biological properties of the soil (eg water retention)
What re the Limitations of Composting?
> requires large energy input to turn and aerate compost piles
if inefficient may cause order nuisance
compost plant will require a large area to run efficiently
composted material may retain a heavy metal content, with potential contamination problems
What is Anaerobic Digestion?
the biological process that happens naturally when bacteria break down organic matter in environments with little or no oxygen.
Methane fermentation is part of the anaerobic digestion process, being a system to extract biological gas (60% Methane and 40% CO2) from waste by the action of methane bacterium.
This gas can be burnt.
What is Digestate?
AD produces a solid and liquid residue called digestate which can be used as a soil conditioner to fertilise land.
What are the benefits of Anaerobic Digestion?
> produces energy in the form of biogas
produces a by product of a solid and liquid fertiliser
can sanitise waste if temperature held at required level for a predefined time period
reduces odour compared to unprocessed waste (eg landfill)
reduced risk of pollution in comparison to land spreading of unprocessed waste
fertiliser produced is of a higher quality and longer lasting than untreated organic waste
diverts waste from alternative techniques lower on the waste hierarchy
requires little energy to operate an AD plant
What are the Limitations of Anaerobic Digestion?
> requires a high level of investment to build AD plants
if an AD plant is inefficient may cause odour nuisance
operating costs of an A~D is greater than those for aerobic digestion (eg composting)
will not remove non-organic pollutants
What are Principles of Landfill Site Selection?
must be classified as inert, non-hazardous, or hazardous.
Must have a detailed:
geological survey
engineering survey
hydrogeology
solids
water
groundwater
etc
Specifications of a Landfill Site?
Location
Control of Water
What bare the Major Problems concerned with Landfill Sites?
Landfill gas
Leachate
Nuisance
What are the site Management controls for a Landfill Site?
Control of Gas
Control of Nuisance
Access Control
Landfill site Gas Control details
measures must be taken in order to control the accumulation and migration of landfill gas
landfill gas must be collected from all landfills receiving biodegradable waste and must be treated and, to the extent possible, used
Landfill Site Nuisance Control
> Measures must be taken to minimise the nuisances arising from landfill in relation to:
emissions of odours and dust
wind-blown materials
noise and traffic
birds, vermin and insects
the formation of aerosols
fires
Landfill Access Control Measures
> must be secured to prevent free access to the site
the gates must be locked outside operating hours
must discourage to detect and discourage illegal dumping in, or near, the facility
