CQUniversity researchers have addressed a problem facing fish farming, which is crucial for averting hunger as the world population grows beyond seven billion people and there are pressures on sustainability of fish stocks in our seas.

Doctoral student Sadia Khan, Professor Rob Reed and Dr Mohammad Rasul have researched ways for fish farms to prevent bacterial infection, and their latest findings are published in BioMed Central's open access journal BMC Microbiology.

LINK for the journal article via Sunny prospects for aquaculture purification

Sadia Khan, Professor Rob Reed and Dr Mohammad Rasul display their research equipment

The CQUni research demonstrates that a prototype water purification reactor containing a thin film of titanium dioxide (TiO₂) is able to enhance the sun's natural disinfection properties. This device could reduce the need for expensive antibiotics or poisonous chemicals.

Outbreaks of infectious diseases by bacteria and other microbial pathogens can cause substantial losses of stock in aquaculture. While antibiotics, biocides and conventional disinfectants can be used, they are expensive and leave behind chemical residues. Using sunlight for disinfection is not a new idea, however conventional solar disinfection is slow and inefficient. 

The CQUni researchers addressed this problem by adapting thin-film fixed-bed reactor (TTFBR) technology to provide treated water. In the reactor, water contaminated by Aeromonas hydrophila was slowly passed over a sloping film of TiO₂ at a fixed rate and in full sunlight. Results showed that using TiO₂ as a photocatalyst increased the effectiveness of solar disinfection by over 10 times.

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Professor Reed explained, "Other people have looked at using TiO₂ as an enhancer of solar disinfection, but they either used a suspension of TiO₂ particles in water, or artificial UV to test their reactors. Our TTFBR technology is very effective at killing pathogens at high levels of natural sunlight and consequently is particularly suited to countries with sunny climates and is especially useful to developing countries where sunlight is abundant but other resources are scarce."

Former Bangladesh student Sadia Khan has been carrying out her research under Professor Reed's supervision, with CQUniversity engineer Dr Mohammad Rasul supervising the structural side of the project.