In the face of new environmental legislation, two key U.K. governmental agencies have implemented operator self-monitoring requirements to improve wastewater quality and to provide greater protections for the environment.
The Environment Agency (EA) is responsible for carrying out England's and Wales' government policies to protect and improve the environment and to promote sustainable development. In Scotland, the regulating authority is the Scottish Environmental Protection Agency (SEPA).
Effluent monitoring
In order to comply with consents and regulations covering effluent quality, wastewater must be regularly tested to ensure that those consents are being met. The monitoring of effluent discharges and the impact of such discharges on the environment are key elements of regulatory control. Under current U.K. regulations, the EA or SEPA collects "end-of-pipe" samples of effluent from wastewater plants to check compliance with the conditions of consent to discharge. The costs associated with this sampling and analysis are levied on the operators under the "polluter pays" principle. These charges are primarily determined by the size of the discharge, rather than the actual risk to the environment from what is being discharged.
Consent parameters at a wastewater treatment plant typically include pH, temperature, suspended solids, chemical oxygen demand, biological oxygen demand and ammonia. The use of these parameters is outlined in Table 1.
Table 1: Typical wastewater monitoring parameters
| Parameter |
Test usage |
| Biological Oxygen Demand |
A measure of the dissolved oxygen consumed during an incubation period at a stated temperature (5 Days at 20 °C in the United Kingdom). |
| Suspended Solids |
A measure of solids removal. |
| Chemical Oxygen Demand |
A measure of the amount of oxygen required to chemically oxidize organic substances present in the sample. |
| Ammoniacal Nitrogen (NH3-N) |
This indicates the amount of nitrogenous organic matter, which has been converted to ammonia. |
| pH |
The pH of a liquid is a measurement of its acidity or alkalinity. The average pH of crude domestic sewage is 7.2 (slightly alkaline). |
Operator self-monitoring
Throughout the European Union, the need for self-monitoring is expected to increase as:
- the complexities and sophistication of measurement techniques advance and costs rise
- industry adapts Eco Management and Audit Scheme (EMAS) and International Standards Organization (ISO) 14000 environmental standards
- the European directive on Integrated Pollution Prevention and Control (IPPC) is implemented
- the "polluter pays" principle is applied, particularly under regulatory regimes that do not provide for the recovery of competent authorities' monitoring costs from operators
- voluntary commitments of the operator are undertaken or mandatory obligations are initiated
In the United Kingdom, regulators (i.e., the competent authority) have introduced Operator and Pollution Risk Appraisal (OPRA) and Operator Self Monitoring (OSM) requirements for water quality. OPRA assesses the environmental risks of effluent discharges based on a number of different attributes including size and location of the discharge and the performance by the wastewater plant operator. OSM passes the responsibility for collecting, analyzing and reporting discharge quality to the wastewater plant operators.
In April 2009, the EA and SEPA began introducing the OPRA and OSM for water quality. The EA and SEPA use the information from the assessment to levy charges that operators will need to pay to cover the costs of regulation. OSM passes the responsibility for collecting, analyzing and reporting discharge quality to operators.
The operator is in a better position to deploy monitoring, and it is believed that regular self-monitoring activity will provide more information on effluent quality than may be obtained by periodic inspection and monitoring by the competent authorities. All the costs associated with self-monitoring will be met by the operator.
Monitoring techniques will vary depending upon consents and may include the use of:
- on-site continuous reading instruments
- portable discontinuous reading instruments
- laboratory analysis of samples taken by online or flow proportional samplers
- laboratory analysis of spot or composite samples
Whatever measurement technique is employed, it must conform to a relevant national, European (CEN) or international (ISO) standard and where considered necessary, should be carried out within a qualified measurement infrastructure conforming to the European Standard 45000.
A report prepared by the European Union Network for the Implementation and Enforcement of Environmental Law cautions that self-monitoring does not constitute self-regulation. "Self-monitoring provides additional information on which the competent authorities can judge whether an operator is complying with relevant legislation and conditions of permits. It does not change the duty of the competent authorities to assess compliance by means of inspection, and by using its own monitoring data or by reliance on operator self-monitoring – or a combination of both. The competent authorities also continue to be responsible for enforcement. Similarly, it does not in any way diminish the duty of the operator to ensure that all necessary measures are taken to comply with relevant legislation and conditions of permits."
For more information, e-mail info@severntrentservices.com.
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