New Wastewater Control System Means 25% Reduction in Carbon Emissions for Southern Water

A new advanced control system for wastewater treatment plants is being
introduced at six of Southern Water`s treatment plants in the United
Kingdom. This is one of the first applications of real-time control in the UK. It is the result of MWH and its joint venture organisation, 4 Delivery (4D), collaborating with SouthernWater to meet its AMP 4 wastewater standards. This will minimise capital expenditure, maximise performance and lead to carbon emission reductions of around 25% equivalent to taking 600 cars off the road.
Ajay Nair, MWH Principal Process Engineer seconded to the 4D JV explains, "Under traditional control systems, it is not possible to make use of the safety factors built into a treatment works to take account of the wastewater variability and seasonal changes. By controlling a treatment plant to match the actual conditions experienced at that time, rather than an "average" or minimum condition, optimum treatment and energy consumption can be
provided. The term "real time" control has been used to describe this
particular method of aeration control."
For AMP4, Southern Water was challenged with providing Total Nitrogen Removal at six of their treatment plants (Budds Farm, Peel Common,
Chichester, Sidlesham, Thornham and Bosham). The first three plants already use energy intensive activated sludge processes. If these processes had been combined with total nitrogen removal without `real time control` it would have resulted in at least a doubling of energy use plus significant additional carbon emissions due to the need for methanol dosing.
Therefore, to minimise the negative impacts on the environment and the company and to ensure it met the new regulatory compliance
requirements, Southern Water and 4D have worked towards reducing the carbon footprint associated with each of these new plants by using
real-time control. These will be amongst the first systems of this kind to use real time control in the UK, demonstrating Southern Water`s and
4D`s commitment to carbon savings and bringing innovation into the UK market.
David Craft, Principal Process Engineer of Southern Water explains,
"Currently treated wastewater standards are dictated by the short to medium term impact on the receiving water body. Until recently, no consideration was taken of the carbon impact of the more energy intensive processes needed to meet tighter standards - creating a regulatory vicious circle. However, it would have been irresponsible not to have chosen this innovative method as the increase in carbon emissions associated with the treatment plants to meet the new standards at Chichester, Peel Common and Budds Farm would have otherwise been the equivalent of 2,500 extra cars on the road."
He adds that in addition to significant carbon reduction through the use of real time control, an improvement in compliance is also achieved
at the same time as reducing operational costs, as the plant reacts instantly to changes in the influent and constantly operates under a very stable condition.
By implementing the control systems, it is anticipated that carbon emission savings that can be achieved on all three of the schemes will be around 25% (equivalent to 600 less cars). In addition to carbon reduction the cost benefit associated with the energy and methanol savings is also significant, providing additional financial incentives to install real time control systems. Currently, the partnership has selected a preferred supplier and a preferred method of the advanced control system to minimise capital expenditure and maximise performance. However, Nair is keen to stress that although, financial drivers are still very relevant, the sense of urgency around climate change is such that a greater emphasis is being placed upon carbon reduction techniques as the primary filter.
Narinder Sunner,MWH Principal Process Engineer leading this initiative says, "Both SouthernWater and 4D have demonstrated their commitment
to pioneering technologies that actively reduce carbon emissions to meet the compliance standards applied. The work conducted to date sets
the foundations for future energy reduction strategies not only for Southern Water, but for all UK water utilities if our national target of a 26 - 32% reduction in CO2 by 2020 is to be realistically achieved."