Advances in Water Treatment and Enviromental Management

50 WATER TREATMENTThe rationale for the different standards for the individual substances isprovided in the appropriate Water Research Centre Technical Reports. Thesame methodology is also being applied to derive Preliminary EnvironmentalQuality Standards (PEQSs) for those ‘Red List’ substances (see Section 5)for which EQS values have not yet been adopted. The standards adoptedare periodically reviewed based on new information published in theliterature. Currently the standards set in 1984 for the six List II metals(arsenic, chromium, copper, lead, nickel and zinc) are being reappraised.5. CONTROL OF PARTICULARLY DANGEROUS ‘RED LIST’SUBSTANCESBy insisting on applying the EQS approach to the control of dangeroussubstances, whereas the other EC Member States opted for the uniformlimit value (UES) approach, the UK has been accused of being lax on thecontrol of environmental pollution. This is partly based on the misconceptionthat the EQS is being used to allow discharges to utilise the full capacity ofthe receiving water. In reality the EQS is used by the controlling authorityfor estimating the upper limit for a consent and, more importantly, as theindicator of acceptable water quality for a specified use-a factor which isnot included in the UES approach. In practice the controlling authority islikely to restrict the discharge for a new site to less than 20% of the residualavailable capacity to minimise the potential impact on the receiving water.In its report on the EC ‘framework’ Directive, the House of Lords SelectCommittee on the European Communities suggested that Member Statesshould re-examine the alternative use of limit values and quality objectives(House of Lords 1985). This proposal was endorsed by the House of CommonsSelect Committee on the Environment (House of Commons 1987).In the Ministerial Declaration following the Second Ministerial Conferenceon the Protection of the North Sea held in November 1987, the UK agreed toapply the dual approach to the control of certain particular dangeroussubstances (DoE 1987). The proposal recommends:– identification of a limited range of the most dangerous substances basedon scientific criteria—the ‘Red List’– setting of strict environmental quality standards for all ‘Red List’substances– progressive application of emission standards based on the concept of‘best available technology not entailing excessive costs’ (BATNEEC) forthe control of direct discharges of ‘Red List’ substances.The aim of the new proposals is that an effluent containing ‘Red List’substances will have to meet industry-wide effluent standards as well asthe EQS for the receiving water to ensure that the effluent discharged does