Articles & Case Studies

“AQUABIO TAKES THE STRESS OUT OF WATER REUSE”

Posted: Tuesday 28th October 2014

Water stress is a hot topic on the agenda for the UK water industry and the impact is already felt and reacted to by the UK’s major food & drink producers. We are used to thinking of England as a wet country, making the assumption that there is plenty of water but it is a finite resource and by no means guaranteed. Parts of the UK receive less rainfall per person than some Mediterranean countries. Seasonal variations can rapidly change the stores of UK surface waters from drought to flood, with groundwater supply often taking much longer to recharge.

Of the 24 water company areas in England & Wales, the Environment Agency “Water Stressed Classification report 2013” reports 9 areas to be at a level of current serious water stress. According to DEFRA (2008) Future Water report, 23% of the public water supply in the UK is non-household use and this does not account for private water supply via abstraction licence by many industrialists.

Water supply is critical for food & drink manufacturers, be it for product manufacturing, cooking, cleaning or heating. Without it businesses would grind to a halt. This risk to business is in many cases already present and due to increased demand for water and climate change it is almost certainly going to increase. Across industry sectors water minimisation strategies have reduced water consumption per unit production significantly and in recent years many have turned to water reuse. Forward thinking companies are paving the way in water reuse, using innovative technology and boosting consumer confidence in safe recovery of water. This has led to reduced ‘stigma’ of recycling water into food factories.

Whilst water minimisation and reuse offers environmetal benefits to business and the surrounding area, it can also be attractive economically. In times of rising incoming water charges, outgoing effluent disposal costs, plus limitations on borehole or surface water extraction and tightening of discharge conditions, recycling is increasingly an attractive option. With recent development in treatment technology the payback on capital investment has reduced significantly, in many cases to below 3 years. These motivating factors can be exacerbated by business growth and factory expansion and benefit scompanies through reduction in carbon footprint and improvement to environmental credentials. The UK Government is supporting this activity offering an Enhanced Capital Allowance Tax Incentive Scheme (ECA) for water reuse investments where 100% of capital expenditure can be offset against corporation tax in the first year following start-up of an eligible efficient plant reusing > 40% of the factory wastewater. Aquabio was the first company to provide an eligible wastewater reuse plant under the ECA scheme (G’s Beetroot, 2006) and have added to this, 6 further schemes completed to date, the most recent being at Wyke Farms, Somerset.

Wyke Farms are the largest independent cheese maker and milk processor in the UK. They provide an example of a company taking a forward thinking approach to both their business and the environment, having just opened their new Aquabio water recovery plant as part of their ‘100% Green’ strategy. Wyke Farms has been producing award-winning farmhouse cheddar cheese in the heart of the Somerset countryside since 1861. Family-run Wyke Farms is the third largest cheddar brand in the UK and the cheese is still made from a recipe passed down from their grandmother, Ivy. The ‘100% Green’ strategy is an ongoing part of the Wyke Farms business which has so far seen the installation of solar panels across the family owned farms and cheese dairy, using electric vehicles for delivery, reducing packaging waste and last year the installation of an on-site biogas plant making the company 100% self-sufficient in green energy.

The water recovery plant, officially opened by Baroness Verma (Parliamentary Under Secretary of State for Energy and Climate Change) was designed and built by Aquabio and is now fully operational providing reuse water to the factory. The Wyke Farms factory is based in a rural location outside Bruton in Somerset and doesn’t have supply of mains water or sewerage. Water supply is by abstraction from local boreholes and wastewater is treated and discharged to a local watercourse. The site were under pressure from the Environment Agency to meet more stringent effluent discharge conditions from their effluent plant and it was identified that an extension to the plant would be required. The Environment Agency recognise Membrane Bioreactors (MBR) as best available technology, offering high quality effluent without the need for subsequent clarification, having a smaller space requirement and membranes as being suitable for water recycling.

L-R John Clothier (chairman), Rich Clothier (managing director), David Rowswell (dairy manager), Baroness Verma (DECC), Tom Clothier (green energy director)

Dependant on water for their production, Wyke Farms also identified their borehole supply as a risk to security of operation. This was particularly highlighted in the dry periods of 2010-2012 when the groundwater table reduced to alarmingly low levels across the UK. The cause was the lowest levels of rainfall in over 100 years, over a prolonged duration of 18 months. This led to the selection of water reuse to reduce the sites water consumption and improve business security for the future.

Aquabio AMBR LETM with tertiary Reverse Osmosis (RO) was selected by Wyke Farms as the best solution to meet their needs. This technology has been successfully operated for wastewater treatment and water reuse in numerous applications since 2001, offering Wyke Farms the security of well proven technology, which has already been accepted by suppliers to all major UK supermarket retailers.

Aquabio have over the past 15 years developed their AMBRTM and AMBR LETM technologies with the focus on the industrial wastewater reuse market place. Aquabio uses its own crossflow MBRs as the core process in its wastewater recycling plants, and through the development of the technology, can offer its clients the most cost effective alternative for their particular circumstances. All Aquabio MBR plants have true ultrafiltration (UF) membranes mounted on the outside of the bioreactor in dry conditions with no parts immersed in the biomass, which leads to hygienic operation, ease of maintenance and well managed safety. The AMBR LETM utilises intermittent back flushing for the control of membrane fouling and hence allows a reduction in crossflow velocity and a significant saving in energy when compared to traditional crossflow UF plant.

For Wyke Farms this process selection offered a number of key advantages:

· The AMBR LETM is operated at high MLSS concentrations offering a small footprint to fit within the boundaries of the existing effluent treatment plant without disruption to the old plant operation during construction.

· The UF membrane system is designed to optimise energy consumption at average flow conditions and can ramp up to deal with peak flow without additional membrane area being required.

· The pressurised biomass recirculation system can take advantage of the small footprint, deep bioreactor tank to provide additional trans-membrane pressure and enabling a further reduction in energy consumption.

· High flux performance combined with optimised installed membrane area offers long membrane life and reduced membrane replacement costs.

· The AMBR LETM system offers the most flexible flux rates of any MBR process with high levels of turn-up, turn-down and optimised energy consumption. This ensures that throughput can be constantly met and minimises disruption upstream, or production of reuse water even in the event of maintenance and membrane cleaning.

The installed plant is designed to treat a peak flow of 750m3/day arising from the dairy and a peak load of 1,275kgCOD/day passing to biological treatment following the sites dissolved air floatation (DAF) plant. The RO is designed to provide 300m3/day of reuse water to the site meeting drinking water quality. The discharge to watercourse, including the reject water from the RO, will meet the consent condition of <30mg/l suspended solids, <10mg/l biological oxygen demand, <5mg/l ammoniacal nitrogen and pH 6-9.

With ever increasing water & wastewater costs, tightening water extraction and discharge limitations combined with developments in treatment technology and acceptability of reuse, water recycling has become a high priority subject food & drinks producers around the world. Aquabio is at the forefront of implementing proprietary plants which enable food & drinks companies to take greater control over their own water cycle. This saves considerable amounts of operating expenditure, improves corporate image and promotes environmental credentials. Today Aquabio’s portfolio of plants has the capacity to reuse nearly 2 billion litres of water per year and this figure is continuing to rise.




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