Online Microbial Fuel Cell biofilm-based BOD sensor

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The project aims to manufacture and develop an online Microbial Fuel Cell-based biosensor for rapid, online detection of Biochemical Oxygen Demand (BOD) to be used at wastewater treatment plants. The BOD provides a measure of the amount of biodegradable carbon, a constituent that is regulated to protect water quality. Current techniques for measuring BOD are either time-consuming and resource-intensive, or provide over-estimates of true BOD. Bioelectrochemical Systems (BES, a type of Microbial Fuel Cell) offer a potential solution for BOD sensing, in which the concentration of biodegradable material consumed by the anodic biofilm is proportional to the electrical current generated. Monitoring that current provides a measure of BOD in real time (or close to real time).

The online BOD sensor developed in this project will enable water treatment companies, and other industries that discharge effluent containing organic matter, to continuously monitor BOD. For the first time, they will be able to use real time, continuous monitoring to economically optimise various treatment protocols to control BOD. Real time monitoring is currently not possible, as for each variation in operating parameters a large number of expensive and time consuming off-line BOD tests would have to be performed. Improved monitoring will also bring direct benefits by alerting operators as the discharge BOD approaches the consent limits, allowing action to be taken before the limits are breached and a fine is incurred, a situation that is not currently possible. There are clear environmental benefits to having improved control of the BOD in discharged water, where areas downstream of the treatment plants are no longer subject to wild fluctuations in BOD and a stable ecology can be managed.

Economic Impact - Market Opportunity
The market for a BOD sensor includes water companies dealing with wastewater on a range of different sized plants. For small-scale plants (2,000 - 9,999 population equivalent (p.e.)) after an initial regime of 12 samples/year only 4 samples/year are required for BOD analysis. Whereas, for medium- (10,000 - 49,999 p.e.) and large-scale (50,000+ p.e.) plants, 12 and 24 BOD samples/year are required respectively. In the UK alone, sewerage systems receive over 11 billion litres of wastewater per day which feed into approximately 1,900 treatment plants with 2,000+ p.e. and across the UK there are 588 (19,466 km) designated sensitive discharge areas. In addition to dedicated wastewater treatment plants, other companies dealing with wastewater must monitor their discharges including processing plants for: Milk, Fruit and vegetable product, Soft drink, Potato, Meat, Breweries, Alcoholic beverage, Animal feed, Gelatine and glue, Malt, Fish.
Currently there are about 1,900 waste treatment plants with 2,000+ p.e. in the UK, if these were to have only a single sensor each, then if a cost per sensor of £1,000 is targeted there is a potential market of about £2,000,000 in this industry in the UK alone, with further substantial markets in the processing industries outlined above. Expanding into Europe and North America the market would be expected to be over £20,000,000. There is also scope to exploit the technology in as a simple low cost alerting device to show when BOD levels have been breached, meaning the technology could be of significant benefit in developing countries.
Economic Impact - Reduced costs to Wastewater industries
The current BOD test that the waste water industry is required to undertake is expensive and time consuming. Companies are keen to have a low cost, robust sensor. As well as reducing monitoring costs, the online sensor will enable companies to carefully manage and optimise their industrial processes to control BOD, avoiding any fines associated with a breach in discharge limits and any associated bad publicity.
Regulatory/Policy Impact - The current BOD test is lengthy (and hence expensive) and delivers results many days too late to correct any faults within the system under test. This has driven the regulatory landscape towards a very infrequent testing regime that may miss infringements that lead to fines to companies if detected. The online sensor developed in this project will enable water quality to be monitored more closely, and thus enhancing information available to the regulator (Environment Agency), and improving the safeguarding of water quality. The sensor could be an important tool in ensuring compliance with the Water Framework Directive.
Environmental Impact - There are clear environmental benefits to having improved control of the BOD in discharged water, where areas downstream of the treatment plants are no longer subject to wild fluctuations in BOD and a stable ecology can be managed. Better control of BOD will lead to health benefits for those people who live downstream of waste treatment plants, where unexpected BOD breaches will no longer risk the environment or release of noxious materials. On a global scale, water quality is a top priority and as populations and industrialisation increase, maintaining good water quality and tracing pollution sources will continue to grow in importance.