This project has the following aims:

1) To investigate how drinking water quality is influenced by biogeochemical cycling of dissolved oxygen (O2) and manganese (Mn)

2) To investigate how engineered in-situ methods can be used for Mn reduction in drinking water supply reservoirs and improve source water quality

The objectives of this project are:

• Design and carry out field campaigns in aerated drinking water reservoirs

• Characterize the influence of natural and engineered mixing

• Assess the spatial and temporal distributions of Manganese on a reservoir-wide scale

Project outline

Within the UK, millions of £ are spent annually by drinking water utilities to address customer complaints with taste and odor problems stemming from Mn. Aesthetic problems associated with excess Mn often occur in water-supply infrastructure, e.g., brownish-coloured, metallic-tasting drinking water, staining of laundry and plumbing fixtures. Excessive Mn concentrations in water entering the distribution system can also lead to reduced flow in pipes as a result of Mn precipitate accumulation in the distribution system, reducing the pipe diameter and finally clogging the pipe. The primary research questions are:

1) how do aeration systems influence the distribution of Mn, O2 and mixing, the primary geochemical and physical controls on Mn cycling, within UK reservoirs, and

2) can aeration be optimised to reduce problematic levels of Mn in the source water prior to the treatment work?

These questions are being answered based on comprehensive physical and geochemical in situ measurements in two aerated drinking-water-supply reservoirs with two different aeration methods, Surface mixing and bubble plums aerations.

Science

This project uses an interdisciplinary, field-based approach to characterize how Mn and O2 levels vary in the sediment and water column on seasonal and reservoir-wide scales as a function of different aeration strategies as little is known on the influence of aeration strategies (e.g., the type of aeration system used, duration of aeration periods, and placement in the reservoir) on Mn transport and resulting water quality. The scientific outputs achieved so far include poster and oral presentations at Physical Processes of Natural Waters workshops 2016-2017 and the best poser prize at the Royal Society for Public Health conference on “What is the Future of Water and Public Health?” in December 2018.

Impact

Mn removal through conventional water treatment processes is frequently costly and difficult due to the complexity of Mn biogeochemical reactions, therefore, in-situ, source-based solutions are becoming extremely common as a way to improve drinking-water quality within reservoirs prior to it reaching the plant, thereby decreasing input Mn. In-situ aeration systems are being used more and more frequently by water utilities globally to improve water quality and ecosystem health via increased water-column O2 and mixing and suppression of sediment-water fluxes of reduced chemical species (e.g., Mn).

This is the PhD project of Mahan Amani, supervised by Dr Lee Bryant, Dr Thomas Kjeldsen and Dr Danielle Wain.