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First Name: Carlos
Surname: Pestana
Position: Research Student
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Research Title: Monitoring and regulating cyanobacterial metabolites (microcystin, geosmin and 2-MIB) in aquatic systems

Project start date: September 2008

Cyanobacteria are one of the oldest types of bacteria and are capable of producing a wide variety of secondary metabolites that can be harmful to human beings and can have a significantly impact on the economy (cost of water treatment and loss of harvest in aquaculture). Generally cyanobacterial secondary metabolites can be divided into two broad categories: toxins and taste & odour compounds. 

Due to the fact that cyanobacteria traditionally contain secondary metabolites within the cells, traditional water treatment methods cause more harm than good, because most treatment options lead to the bacterial cells to be lysed (broken up), which in turn leads to the release of the metabolites. Within the bounds of this project a number of alternative treatment options are investigated. Firstly a biological approach was chosen, it was found that non-toxin-producing food competitors (other cyanobacteria) can inhibit toxin production in toxin producers. Furthermore the effect of adding small amounts of one of the cyanobacterial toxins (microcystin-LR) also lead to decreased toxin production. The second approach is the removal of cyanobacterial metabolites by chemical means. To this end photocatalysis was employed. A catalyst (titanium dioxide, TiO2) that is activated by UV light breaks down undesirable compounds like toxins and taste & odour compounds. A novel product, TiO2 coated, hollow silica (glass) spheres were tested and compared to the photocatalytic properties of other TiO2 presentations (pellets and powder) in the destruction of both toxins and taste & odour compounds).

Close collaboration with the industry was achieved on two projects as well (Pisces Engineering Ltd. and Nanoparticulate Surface Adhesion Ltd.).    

Supervisors:

  • Prof. Linda A. Lawton
  • Dr. Christine Edwards
  • Dr. Radhakrishna Prabhu