Managing Emissions to the Water Environment Flashcards
What are the general classifications of water pollutants?
> physical - eg litter, suspended solids, heat and radioactivity
> chemical - eg acids, alkali, pesticides, etc
> biological - eg harmful pathogens, in water that cause disease, eg viruses and intestinal parasites
What is Oxygen Stress?
effluents that contain a high level of organic matter (human sewage - strip oxygen from receiving waters.
Substances,( such as iron) will combine with oxygen in water, thus reducing the amount of freely available oxygen for wildlife.
What are the main effects of Solids in water?
main effects are aesthetic as you can see, smothering plants and animals on the bed of the watercourse, damaging fisheries, and interfering with self-purification.
How can Acids and Alkalis effect water bodies?
changes in pH leads to change in the biodiversity of the water course and the release of secondary pollutants such as metals.
What can Phosphorus and Nitrogen Compounds do to water bodies ?
Can indirectly remove oxygen from the water by the process of eutrophication.
What can Hydrocarbons do to water bodies ?
Oil may coat the leaves of aquatic plants and other organisms such as birds, in addition to impacting on oxygen exchange.
What can Pesticides do to water bodies ?
Acute release of pesticides into water has been found to kill aquatic life and may cause thyroid disruption.
Persistent Organic Pollutants?
These are a group of substances that can accumulate in fatty tissues of any organism and, as they degrade very slowly, can bioaccumulate in food chains posing a high risk to human health and the environment (eg a number are carcinogenic)
What is the effect of Thermal increase in water?
raised temperature can have the effect of reducing the amount of oxygen in the water and altering bio-diversity.
Pathogens and Parasites?
sewage and animal waste contain pathogenic micro-organisms (viruses, bacteria, protozoa, and intestinal paretic eggs) which may cause disease.
Chlorine and Chlorine Containing Compounds?
Tricholorethylene (TCL) is a common industrial solvent. Ingestion of which in drinking water may lead to liver damage and increase the risk of various types of cancer.
Heavy Metals?
Such as mercury and cadmium have the ability to bioaccumulate in food chains. The effects of this bioaccumulation will vary depending upon the substance, eg mercury may cause nervous system impairment, dizziness, coma and death.
Explain Point and Diffuse Sources of Pollution.
> Point Sources of water pollution are those where there is a distinct controlled discharge into the watercourse
> Diffuse sources are those that do not enter a watercourse through controlled sources
Detail the practical Methods of Pollution Prevention.
> Identifying, Marking and Maintaining Drains
Binding
Pipework
Deliveries
Drum and IBC Storage
Spill Kits
Spillage Control Management
Identifying, Marking and Maintaining Drains
A drainage plan of the site is necessary for effective pollution control.
Education of the different uses of the different drains is also important.
Recommended that surface water drains are marked as blue and foul water drains as red.
Practical Means of Pollution Prevention - Binding.
> should be constructed of sturdy material, or lined with sturdy material, impervious to the material to be contained.
> they should comprise a base and surrounding walls (with no damp course
> The capacity of the bund should be the whole capacity plus 10% as a minimum.
> ice there is more than one tank in the bund it should be at least 120% of the combined capacity
> even if tank is double skinned should still follow the same requirement as traditionally bounded tanks
Practical Means of Pollution Prevention - Pipework
> Should be above ground where possible
> Filler pipes should be within the bund and vent, overflow pipes should be positioned to overflow into the bund
Practical Means of Pollution Prevention - Deliveries
Deliveries should be isolated from surface water drains in the event of a spillage
> automatic cut-off valves should be fitted to oil delivery points to prevent over-filling.
Practical Means of Pollution Prevention - Drum and IBC Storage
> bunding of an oil-containing drum are a drip tray of a capacity of 25% of the volume of the drum
> for IBC containing oil, the requirements are 110% of the largest container or 25% of the total of the containers (whichever is the greater)
Practical Means of Pollution Prevention - Spill Kits
provision of a spill kit is sound practice
they should be appropriate to the substances used on site and training must be given.
Spill kits should be accessible - so their location is important
Practical Means of Pollution Prevention - Spillage Control Management
A pollution incident control plan should be prepared based on the spillage control hierarchy:
- contain at source
- contain close to the source
contain on the surface
- contain in the drainage system
- contain on or in the watercourse
All spillages must be cleaned up and disposed of in line with legal requirements for waste
What are the elements of Mitigating the Effect of Fire Water Run Off?
control methods to be implemented include:
- containment lagoons and sacrificial area
- penstock valves
- consulting enforcement authorities
- fire-fighting strategies
What is the Purpose of Effluent and Water Monitoring?
- legislation often dictates requirements to sample and monitor effluent discharges (permits and consents to discharge will identify Emission Limit Values (ELV)
- monitoring of water use by a site is normally undertaken as part of a water minimisation scheme (to assist in the reduction of costs and environmental impacts associated with water use)
- standard tests using accredited laboratories is essential if results are to be relied upon and for legal purposes
Explain the Role of the Environmental Practitioner in Water Pollution Monitoring
-specific competencies are required for monitoring standards which are dictated by law
- MCERTS standards state competency requirements for those undertaking the chemical testing of sewage and trade effluents
- those undertaking sampling should be deemed to be competent to do, falling in line with any competence standards that may be set in permits/consents and/or assocaiated guidance
Explain the Biotic Index
the Biological Monitoring Working Party (BMWP) attaches a score between 1 and 10 to specify of aquatic invertebrates, depending upon their tolerance to pollution (the less tolerant the higher the score)
What are the Key Monitoring Perimeters?
> dissolved oxygen
> Chemical Oxygen Demands (COD) - the test measures materials in a water sample that can be chemically oxidised
> Biological Oxygen Demands (BOD) - measures all the materials in a water sample that can be broken down by the action of microbes
> Total Oxygen Demand (TOD) - measures all the organic and inorganic compounds present in a sample of water that can be oxidised
> pH Scales - identifies the acidity or alkalinity of an aqueous sample
> Total Suspended Solids - the dry weight of particles trapped by a filter
> Total Dissolved Solids (TDS) - constant salts, metals and other substances that are dissolved in water
> Turbidity - cloudiness of a fluid which is caused by particles in the water that are individually invisible to the naked eye
What is sewage?
it is a complex mixture of suspended and dissolved materials
what two parameters may characterise sewage?
> suspended solids (SS)
> biological oxygen demand (BOD)
Conventional wastewater treatment process can be described as consisting of what three processes?
> preliminary sewage treatment
secondary biological sewage treatment\
tertiary treatment
followed by:
> sewage sludge treatment and disposal
the objectives of water treatment are to produce an adequate and continuous supply of portable water which is what?
> clear - no turbidity or suspended matter
palatable - no unpleasant taste
safe - no disease or other organisms or harmful mineral content
reasonably soft
What are the main methods of treatment?
- screening
- aeration
- coagulation
- clarification
- Filtration
- pH adjustment
- Disinfectant
- Softening What is aeration
What is aeration?
- elimination of certain ordours
- remove objectionable dissolved gas
- oxidise some metal salts to enable them to be filtered out
what is coagulation?
the enable finely divided matter to be settled out in order to entrap bacteria and absorb colour
what is clarification?
twho settle out sediment to provide clear water
what are the three techniques to treat sold and liquid wastes?
> chemical
physical
biological
what are examples of physical treatment?
- screening
- sedimentation
- activated carbon
- air stripping
- filtration
- centrifuging
- reverse osmosis
- flotation
- evaporation
- sumps
- oil-water separation
what are examples of chemical treatment?
most chemical treatments apply to both liquid and solid wastes
- neutralisation
- oxidation
- coagulation and flocculation
- metal precipitation
- disinfection
what re examples of biological treatment?
THERE ARE FOUR MAIN TYPES:
- percolating filter treatment
- rotating biological contactor (RBC)
- activated sludge treatment
- oxidation ponds
what is desalination?
the removal of minerals (largely salt) from saline water to produce water fit for human consumption with salt as a by product
what are the methods of desalination?
- multiple stage flash distillation
- vapour compression distillation
- reverse osmosis
what re the advantages of desalination?
> provides clean freshwater for drinking and agriculture
uses tried and tested technology
habitat protection - as less impact on land based aquatic systems is sea water is used
what are the disadvantages of desalination?
> energy consumption is great
significant cost
chlorine and other chemicals can be let behind in a brine which, when dumped, may cause harm to saline
what are the impacts of over-abstraction on rivers and aquifers?
> reduction in river flow - reducing the size of aquatic species that can be supported
wetland habitats supported by the rivers may dry up
aquifers drying up may remove important sources of water for human consumption and agriculture
what is water neutrality?
a process by which participants try to balance their water usage by reducing water usage and investing introjects that increase the supply of freshwater
a water balance is used to what?
- understand and manage water use and effluent production
- identify areas that have a significant cost saving potential
- detect areas of leakage
what are the stages of water balance?
- water using activities
- water saving ideas
- analyse different options
- maintain momentum
what are some examples of reducing water usage?
- toilets - dual flush system
- water meter - direct correlation between use and charged amount
- drpiinjg taps - fix dripping taps or leaking pipes. a dripping tap wastes at least 5500lts of water per year (Waterwise UK)
- water garden plants in the evening
- fit diffusers on taps
grey water recycling - fit low flow shower heads
what is water stress?
defined as being when demand for water resources exceeds the amount available for usage
warning threshold of water stress is 20%.
severe water stress is over 40% - which indicates significant competition for water
what is the Water Exploitation Index (WEI)?
(or withdrawal ratio)
is a measure of the vulnerability of water abstractions to over exploitation
What are the direct consequences of flooding?
- damage to property/equipment/stock
- business continuity issues
- increased insurance premiums
- pest infestations
- health issues
what are the indirect consequences of flooding?
- damage to roads and other infrastructure
- cleanup costs and removal of debris
- general health and safety issues
what are the key risk factors when determining the risk of flooding?
- identification of sources of flooding
- historical site data
- typical climate in an area
- location of floodplains
- severity of damage to property and local habitats/eco-systems
- climate change
what measures can be implemented to reduce the chances of being affected by a flood?
- maintenance of existing controls such as pumping stations
- emergency plans covering flood risk
- monitoring flood updates
- flood defences
what are SuDS?
sustainable drainage systems in urban areas which have a reduced capacity to hold water
aim to mimic natural drainage processes to decrease the effects of quality and quantity of runoff from development, providing biodiversity and amenity benefits
in terms of buildings designed to reduce the impact of flood, what are the techniques?
- avoidance - construct buildings to avoid it being flooded
- resistance - construct to prevent water entering the building and causing damage
- resilience - construct so that floodwater may enter but its impact is minimised
