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Increased recycling of water that has been contaminated during manufacturing processes would help to significantly reduce industry’s carbon footprint, according to research by De Montfort University.

Researchers have found a way to boost the energy efficiency of a method of recycling industrial wastewater that, if adopted by companies, would help them to reduce the overall amount of water they buy in.

The study marks the first time that the efficiency of membrane bioreactor plants has been assessed using computer-modelling techniques.

Academics leading the project believe initial results show plants can be made between 10 to 15 per cent cheaper to operate.

Industrial wastewater is water which has been contaminated while being used for a specific purpose, for example in the brewing process during the manufacture of alcohol, or in the cleaning of ingredients used for food products.

Contaminants typically include biological materials or industrial by-products and the wastewater is usually thrown away.

Parneet Paul, a senior research fellow within Process Control, Water Software Systems, and the project coordinator, said: ‘If the water is recycled, it can be reused, thereby reducing a company’s water utility costs and helping to reduce their energy footprint.

‘If this wastewater can be fully recovered in an efficient manner it not only has cost implications for industry as a whole, but could also be a way for industry to meet its targets to reduce its green house gas emissions.

He added: ‘Many industries in the UK currently do not use these advanced wastewater treatment systems for full water recovery since their performance has not been fully analysed to date by using computer-modelling techniques.’ The three-year, GBP402,000 project was funded by the Technology Strategy Board under the Technology Programme.

The aim of the project was to use the latest modelling techniques, coupled with measurements taken from electronic sensors and using biochemical laboratory testing, to make these advanced wastewater treatment plants more energy efficient and cost effective for industrial companies.

These advanced methods, which use ultra-filtration membranes, produce wastewater of excellent quality which is suitable for recycling and could potentially save industrial companies thousands of pounds in water utility costs.

Membrane bioreactors consist of a biological reactor containing a very high concentration of selective bacterial micro-organisms that ‘digest’ organic contaminants generated from the manufacturing processes.

The wastewater is then pumped through an ultra-filtration membrane to remove inorganic pollutants.

It is then clean enough to be reused as a secondary supply of water, or can be further purified using finer membranes and disinfection procedures.

The main operational energy costs are due to aeration of the micro-organisms in the bioreactor and having to pump liquid through the membranes at high pressures.

During the project, computer models were used to maximise the biological aeration processes that inject oxygen into the bioreactor and to minimise membrane fouling caused by the accumulation of solids during the filtration process, which can reduce clean water production rates and potentially damage the expensive membrane modules.

‘Using membrane bioreactors will help to improve upon the sustainable capabilities of any industries that use large volumes of clean water,’ Paul added.

The project was carried out by DMU’s Process Control – Water Software Systems (PC-WSS) research group in collaboration with industrial partners, including Aquabio Limited, ITT Sanitaire (UK) and Northern Ireland Water.

De Montfort University

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