Sustainable future that’s becoming reality

The water industry has to embrace green solutions to improve energy efficiency and cut emissions. Barry Oliver explains the best approaches

Part way through the first year of AMP5 and already everyone working in the water industry is noticing a marked change – both from within the industry, but also external factors that are influencing the upcoming trends and challenging the way we do business. These changes are being brought about for many micro and macro factors including the impact from climate change, the challenging economic environment and the regulator pressure to improve service and efficiency.

We all recognise the need to become more sustainable in everything that we do.

With the escalating cost of energy, the water companies all signed up to the Carbon Reduction Commitment (CRC) programme, and recognised the need for improved sustainability. One of the key emerging trends is the need for wastewater treatment works (WwTW) to become power self sufficient.

The challenge of minimising the amount of power actually required for wastewater treatment and maximising power generation from the advanced digestion of sewage sludge is delivering results.

Already there has been notable examples of power self sufficient wastewater treatment which proves it is not just an idea, but reality. These include Anglian Water’s new AD plants at Kings Lynn and Great Billing, where power generation has exceeded power requirements, and has also led to surplus power being exported to the grid.

Dwr Cymru Welsh Water has achieved power self

sufficient service at Eign (Hereford) and is in the commissioning stages with two schemes in South Wales at Cardiff and Afan, where the forecast for renewable power generation is anticipated to be 6.5MW.

During AMP5, a further 15 to 20 AD schemes at least are planned across

the UK.

To date, power self sufficient service has normally been achieved by treating additional fuel in the form of imported sludges from other sites. There is potentially other fuel available with growing examples of food waste and FOG (fats, oils and grease) digestion, which together provide the potential for increasing renewable power generation by 50%.

Maintenance activities are no longer replacing like for like but replacing inefficient old assets with high efficiency assets such as pump stations with monitoring and control systems to ensure ongoing efficient operation. Similarly, there are now many good examples of improving process performance to deliver significant efficiency savings.

A good example is the Anglian Water ‘SOOP’ initiative to optimise performance and opex savings at its latest Advanced Digestion plants.

Solar power

Linked to the recognition of power self sufficient wastewater service is the trend to explore new and innovative ways of delivering sustainable power generation. There are a number of alternative methods that are currently being explored and form part of the future for the industry.

Water treatment needs more efficient pumping systems, and there are examples of turbines being used in place of pressure regulators to generate electricity from surplus pressure. There is an increasing use of wind turbines to harness natural renewable resources to generate power.

Thames Water is currently installing wind turbines to generate electricity at its WwTW at Crossness. This is an example where this low level technology is being used within the water industry and, when complete, it will help generate up to half the energy needed to power the site.

PV cells, which utilise solar power to generate renewable energy, is another area that is increasingly being developed, and at Imtech Process we forecast significant take-up of this across water company assets over the next few years.

These PV cells represent excellent economic benefits, while helping to reduce power consumption. However, innovation in the design of buildings to accommodate the PV cells will be required.

So renewable fuel, water pressure, sun and wind are now being increasingly harnessed to help sustainably provide the energy we need into the future, but we also have to continue to explore new ways of maximising power generation from renewable resources.

A currently underdeveloped area is the potential power from the sea. Tidal power needs to be exploited, particularly as there are so many marine outfalls already associated with wastewater treatment works. The basis of design is moving towards the lowest whole life carbon footprint. Including carbon embedded in new assets, used in manufacture and construction as well as operational footprint.

We need to build assets that embrace Low Impact Design (LID), remove rainwater from overloaded drainage networks, encourage natural, free drainage solutions with the local community and not resort to forced aeration systems because they are quick, easy and low capex.

We are seeing changes in the climate, which are impacting on everything we do from accurate modelling through to operational issues around water and wastewater management and treatment. More frequent, intense storms will require upgrading and more real time control of drainage systems. We need to upgrade our drainage, storage and treatment assets in a sustainable manner with long term planning and phased improvements as climate forecasts are confirmed. One area that can potentially alleviate the associated problems is further investment in UV disinfection of storm discharges.

Dwr Cymru Welsh Water has successfully delivered a scheme at Cog Moors in South Wales providing UV disinfection of storm discharges in place of a conventional storm storage system. This solution has achieved the environmental need and promoted a sustainable economic solution with significant carbon savings.

The successful introduction of UV treatment in Cog Moors was only achievable by working closely with the Environment Agency and Ofwat to show that different, innovative practices were able to provide the results required for bathing water quality.

Not only are we likely to be subjected to increases in intense storms over the next few years, but also there is a high probability of having to face water supply challenges of less rainfall or prolonged dry periods, which will ultimately require improved storage, reduced water use, water re-use, together with optimum treatment and water distribution.

Smarter solutions

Then there is the pressure on food supply and increased fertilizer costs – 90% of global demand for phosphorus is for food production, currently around 148 million tonnes of phosphate rock is mined per annum, which at its current usage could be depleted within just 30 years.

Fertilizer costs will continue to rise, however this is an issue the water industry may be able to ease through the ability to recover nutrients from wastewater treatment, which can then be used in agriculture. An example is the production of struvite from AD liquors, which has been proven to be possible at pilot scale and Thames Water is constructing a full scale plant.

The future is a challenging one for the water industry, but it also represents some exciting possibilities if we are able to embrace long-term sustainable planning and seek smarter asset solutions. No longer can we continue to deliver high energy solutions to achieve water and wastewater treatment requirements, but we can be leaders in the delivery of sustainable solutions for a sustainable future.

Barry Oliver is technical director at Imtech Process.

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