A Review of the Setting of Iron Limits for Wastewater Treatment Works Effluents
Iron dosing at wastewater treatment works is used mostly to reduce effluent phosphorus concentrations in order to meet the requirements of European legislation. The existing iron Environmental Quality Standard (EQS) is currently under review. If the EQS value is reduced, a subsequent tightening of surface water discharge permits may result, which would have significant implications for the Water Industry.
This project assessed the effectiveness of current iron permits to ensure compliance with the receiving water EQS including an assessment of downstream impacys on water chemistry, ecology and sediment. Am examination of how a reduction in the EQS value might affect the Water Industry, in terms of the ability of existing technology to meet tighter permits as well as the potentially increased costs and carbon emissions was also undertaken. The assessment of available data collected from across England in addition to SIMCAT modelling showed that there is no evidence of significant increases in total or dissolved iron concentrations due to dosing for phosphorus reduction. Water quality data was also supported by ecological data and sediment data.
The report recommends that the Environment Agency reconsider the use of widespread iron permitting and that where permits are to be used, a change from a maximum discharge value to the use of a percentile and look up table is considered (based on river needs and taking account of dilution). The impact assessment provides the Water Industry with a robust case for engaging with the Regulators on future iron permitting policies, in particular demonstrating the lack of impact of iron dosing on downstream water chemistry or ecology.
|UKWIR Reference :- 11/WW/20/4||Published Date :- 01/03/2011|
|Retail Price (£) :- 15||ISBN :- 1 84057 582 4|
Supporting Material and Reports
| A Review of the Setting of Iron Limits for Wastewater Treatment Works Effluents CD|