One of the practices for dealing with water pollution from point and non point pollution sources is the use of on-line purification lakes. The Lea Marston lakes were built in the early 1980' s to reduce the pollution load transported by the River Tame to the River Trent. The lakes operate on the principle of particle bound contaminant sedimentation. The lakes were observed to be efficient at reducing suppressed (ATU) biochemical oxygen demand (BOD(ATU)), suspended solids (SS) and metals under dry weather flow and wet weather flow conditions. However, ammoniacal-nitrogen (ammonia) is observed to increase across Lake 1. The dominant mechanism of removal is via sedimentation with greater removal occurring under higher inlet concentrations. The addition of ammonia occurs possibly via diffusion with the bed sediments providing a source of ammonia. The bed sediments were identified as a potential pollution source and processes such as diffusion and resuspension could adversely affect the water quality across Lake 1. Porewater and surface water profiles identify the significance of the bed sediments as a sink for dissolved oxygen and a source of ammonia. A modelling study showed that a River Quality Objective (RQO) of River Ecosystem Class (RE) 2 could be achieved at the lakes inlet by improvements in nearby wastewater treatment works effluent quality and water quality from the upper catchment. However, the outlet water quality would probably be adversely influenced by ammonia released from the lake sediments.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:564485 |
| Date | January 2002 |
| Creators | Upadhyay, Neerja |
| Publisher | University of Birmingham |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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