WATER POLLUTION ASSESSMENT
Environmental Standards
and
Discharge Consents.
Environmental Regulation
• Regulation of impacts on the environment is now a
crucial area of public policy.
• Over $500 billion p.a. is spent globally on
compliance.
• Environmental impact without any regulation would
cost many times that sum.
Setting Standards.
• Scientific Understanding
– The starting point for setting environmental standards.
– Essential to determine dose-effect relationships.
– Uncertainties and limitations in the data must be recognised.
– the science must provide a firm basis for policy decisions
• Precautionary Principle
• Mechanism*
– identify problem, policy, set standard, monitor
*see 21st Report of Royal Commission on Environmental Pollution
“Setting environmental standards”
Environmental Standards
• Forms of Environmental Standard.
– Biological. Limits of physiological change.e.g.
lead in blood.
• Biomarkers of exposure, not effect.
• Inform after exposure has occurred, hence do
not prevent the effect.
• Exposure from a number of routes, hence no
indication of course of action.
Environmental Standards
•
Forms of Environmental Standard.
• Exposure. Acceptable doses at the point of entry to an
organism.
– Tolerable Daily Intakes (TDIs)
• International Programme on Chemical Safety (IPCS)
• UNEP, ILO, WHO
• Often standards not set (due to lack of information).
– Acceptable Daily Intakes (ADIs)
• Mainly internationally based health standards.
• Food and Agriculture Organisation/WHO
• e.g. pesticides, medicines and max residue levels
(MRLs)
Environmental Standards
•
Forms of Environmental Standard.
• Environmental Quality.
– Acceptable concentration of substance in the
environment (air, soil, water)
– Water Quality Objectives (WQO), Water Quality
Standards (WQS)
• benefit the natural environment.
– Freshwater fish, Shellfish
• benefit human health
– bathing waters
– quality of water abstracted for use as
drinking water
Environmental Standards
•
Forms of Environmental Standard.
• Emission
load of pollutant discharged to the environment
– car exhaust
• but BATNEEC probably better (e.g. legislate for
catalytic converters)
– Effluent Discharges
• main basis for controlling organic pollution and
toxic substances in Europe
• UK also uses WQO
Environmental Standards and
Objectives
Therefore, two different approaches to tackle water pollution:
1. The Water Quality Objective (WQO) approach
• defines the minimum quality requirements of water to limit the
cumulative impact of emissions.
• Achieves a certain quality level of the water not harmful for the
environment and human health (even after discharges of polluted
water).
• E.g. early EU water directives (1970-1980) such as:
– the Surface Water (Abstraction) Directive (1975),
– the Bathing Water Quality Directive (1976),
– the Freshwater Fish Directive (1978),
– the Shellfish Water Directive (1979)
Environmental Standards and
Objectives
• 2. The Emission Limits Value (ELV) approach
• maximum quantities of pollutants allowed to be discharged from a
particular source into the aquatic environment.
• Specifies the efficiency of wastewater treatment
• Specifies what quantities of pollutants may be released
•
Subsequent EU directives (1990s)
– the Urban Waste Water Treatment Directive (1991)
– the Nitrates Directive (1991)
– the IPPC Directive (Integrated Pollution Prevention and Control,
1996)
Future - Environmental Standards and
Objectives
3. Future approach
• Water Framework Directive (2000/86/EEC)
• aims
– expanding the scope of water protection to all waters, surface
waters and groundwater
– achieving "good status" for all waters by a set deadline (2015)
– water management based on River Basins
– “combined approach" of emission limit values and quality
standards
– getting the prices right
– getting the citizen involved more closely
– streamlining legislation
Reviewing Standards.
• Key Changes in the Policy process.
– Numerical standards.
• Maturity of toxicology and ecotoxicology
• Advances in measurement science.
• Improved understanding of the behaviour of
substances in the environment.
– Pan European Policies
Discharge Consents
• basis for setting discharge consents.
– water quality objectives (WQO)
• river ecosystem classification scheme (RE1 - 5)
– Statutory Water Quality Objectives (SWQO)
(currently under consideration in UK for use in
planning)
– Statutory Emission Standards
• UWWT Directive 1991
• Dangerous Substances Directive 1976
Discharge Consents
Aim - provide adequate monitoring of compliance
with standard
– Numerical standards should always incorporate
protocols for sampling and measurement.
– Laboratories should be accredited to appropriate
proficiency testing schemes.
– Numerical standards should consider the extent of
statistical variation (look-up tables)
– Self regulation - EA has passed sampling
responsibility to water undertaker
Discharge Consents
• History
– mid 19C Typhoid, TB, Cholera
– epidemics , mortality 46/1000
• Royal Commission on Sewage Disposal
– nine reports 1901 -1915
– recommended a discharge standard
– 20 mg/l BOD, 30 mg/l SS
Discharge Consents
Recent legislation
• Water Industry Act (1991)
– water undertakers can charge, and set consents
to sewer
• Water Resources Act (1991)
– EA authorised to set discharge consents to
watercourses
• Urban Wastewater Treatment Directive (1991)
i.e UWWTD
– pan-european standards
Discharge Consents
•
Apply to “Controlled Waters”
– virtually all freshwaters, groundwaters, tidal and coastal
waters
1. Descriptive consents
– Discharges that are small, have a low potential to impact
the environment (c. 50,000 in UK)
2. Numeric Consents
– Discharges having most potential to affect the quality of the
receiving water (i.e. large flows, Industrial, STW)
–
may apply to an individual substance or group of
substances (c. 30,000 in UK)
–
based on Royal Commission Standards, and EU
Directives (UWWT Directive)
Discharge Consents
Water Companies
•
Water plc’s set their own consents for sewer
discharges
– For Commercial and Industrial discharges
– Ensures the performance of Municipal WWT
Plant (compliance)
– Review of existing consents
• appeals
– Granting of new consents
UWWT Directive (1991)
• Size of plant
– < 2000 pe are exempt
– > 2000 pe before 2006 to comply
• Sensitive waters
– EA and English Nature interpret the definition of
“sensitive waters”
– Habitats Directive(1992)
• Special Protection Areas (SPAs)
– Birds Directive (1979)
• Special Areas of Conservation SAC
UWWT Directive (1991)
Samples
• 24h composite
– for 95%ile comparison
– for Upper tier
• usually 2 X 95%ile limit
• waived for exceptional weather conditions
• Parameters
– BOD5, COD, Suspended Solids (optional)
– N&P
UWWTD Monitoring for BOD
Is Final Effluent
< 25 mg/l ?
YES
PASS
NO
Is BOD removal
> 70% ?
YES
PASS
NO
Is Final Effluent
< 50 mg/l ?
NO
Upper-Tier
FAIL
YES
Look-up
table
FAIL/Pass
UWWTD Monitoring for COD
Is Final Effluent
< 125 mg/l ?
YES
PASS
NO
Is COD removal
> 75% ?
YES
PASS
NO
Is Final Effluent
< 250 mg/l ?
NO
Upper-Tier
FAIL
YES
Look-up
table
FAIL/Pass
UWWTD Monitoring for Phosphorous
• STWs discharging to Sensitive waters (inland) must also
demonstrate Phosphorous removal.
The measurement criteria is different:
– Based on annual “average concentration”
– average for year (1st January to 31st December)
< 2 mgP/l, or minimum 80% removal (<100,000 pe)
< 1 mgP/l, or minimum 80% removal (>100,000 pe)
e.g. A STW <50,000 pop. has 12 samples taken, meaning that
the ‘total’ for the year must not exceed 12 x 2 = 24, (2mg/l
average) or must have achieved 80% removal.
UWWTD Monitoring for Nitrogen
• STWs discharging to Sensitive waters (inland) must also
demonstrate Nitrogen removal.
– Sum Individual sample results.
– Divide by the number of samples taken to give an average.
– average for year (1st January to 31st December)
< 15 mgN/l, or minimum 70 - 80% removal (<100,000 pe)
< 10 mgN/l, or minimum 70 - 80% removal (>100,000 pe)
UWWTD Monitoring
• Key Points
– UWWTD uses the same Look-up Table as Water Resources
Act.
12 samples taken - maximum number of parameter failures
permitted = 2
24 samples taken - maximum number of parameter failures
permitted = 3
– UWWTD samples are based on a fixed 12 month
programme running from 1st January - 31st December.
(Spot Water Resources Act compliance is based on a rolling
12 month programme)
– All works are sampled (24 h composite) on pre-determined
dates agreed with the Environment Agency.
Coastal Sites
• Bathing Water Directive
– typically enterovirus critical
– Modelling dispersion & dilution
– Standard
0 PFU/10litres
• typically need 5 log removal
• treatment & dispersion/dilution (typ. 4 log)
• UV disinfection (typ. 1 - 2 log)
Future Improvements
• WQOs Continually Reviewed
– LEAPs
– Asset management Plans (AMP4,2005)
• Undertaker / EA / DEFRA
• capital investment for “best ecological effect”
• Upgrading works
– Relaxation of Consent (typ. 6 months)
– interim measures
• better primary settlement
• supplementary oxygen