Utility Week

30 | SEPTEMBER 2021 | UTILITY WEEK Analysis on a circular economy strategy to "build a strong economy, protect resources and support the environment". It is a tenet of Scottish Water's objectives for its current regulatory cycle, SR21, which runs to 2027, to assess the potential for resource recovery from sewerage. The biological treatment processes to clean wastewater generate nitrous oxide and methane equivalent to 43k of CO2 each year. The top contributors for the company's pro- cess emissions are from wastewater aeration (nitrous oxide 34 per cent); wastewater sludge treatment (nitrous oxide 22 per cent); and sludge storage (methane 20 per cent). Over the coming decades the company has fore- cast it can cut these by 20 per cent through process optimisation and it aims to maximise the energy it recovers from bioresources. Mark Williams, business strategy and climate change manager at Scottish Water, said: "It is crucial to get to grips with energy intensity and drive it down. To be as efficient as possible, move away from energy-intense activities, explore how to maximise energy recovery and other value from bioresources, sludges and other products wastewater treat- ment centres have." He told the audience the company has been working with its assets to add more efficient pumps and reduce power as well as installing more monitoring equipment to understand how the kit is working and find ways to make it more efficient. The company is now involved in a num- ber of projects focused on reducing energy consumption – and recycling where pos- sible. At the moment, aeration is around 70 per cent of total site energy used at acti- vated sludge plants. Driving down the energy used here is key so the company has begun replacing blowers and systems with more efficient ways of getting air into the treat- ment processes. Williams explained the next step: "One of the biggest individual energy saving oppor- tunities is moving to real-time control of the process and looking at how to manage aeration levels and at various stages within the process, managing biomass to mini- mise the input to achieve the same levels of performance. At some of the largest works energy con- sumption has been reduced by about 15 per cent and is now being applied to the wider asset base. "This is adding up to an ambitious pro- gramme of energy efficiency over the next 10 years to try to take 30, 40, 50GWh of energy out of all the water treatment processes," Williams said. "Sludge has been a source of energy and value across the sector for a number of years and Scottish Water has done a lot to advance [anaerobic] digestion technology. This is where our investment over the next 10 years hopes to move this forward for Scottish Water and we hope to increase the amount of power we're getting to around 90GWh." Williams said innovation is needed to develop recovery of ammonia from waste- water to avoid process emissions and then to find opportunities to use that recovered ammonia in line with circular economy intentions. Overcoming barriers At present there are more questions than answers as companies work to update cen- tury old techniques. Lack of regulatory incentives was identified as a stumbling block and workshop participants called for these to be strengthened to drive innovation in wastewater treatment. Seminar discussions on how to strengthen regulatory incentives noted there is something of a grey area around creating value out of energy resources: should it be Ofwat or Ofgem regulating? One person said: "It's important to mod- ernise the regulatory environment, including the incentives for the next phase of decar- bonisation and resource recovery." Modernisation, it was suggested, would need to address the misalignment between funding and regulatory cycles. One person commented that five-year regulatory cycles inevitably lend themselves to "short- termism of regulation", and suggested longer time frames, as have been adopted for water resource management plans, would be more relevant. Likewise, any incentives that are offered "appear for an AMP cycle then evaporate aŸer year five", making it harder to create a business case to get energy-from-waste pro- jects off the ground. Another participant countered that cre- ating a viable revenue stream could be one approach to funding projects if regulatory incentives aren't sufficient. However, this value would then need to be distributed between customers and shareholders. One participant proffered a time frame of 10-15 years to get waste heat recovery projects off the ground, which they suggested should be factored into the periodic review period with longer-term incentives added to create certainty while such schemes are launched. They said taking a long-term view and con- sistent approach, with alignment between Ofwat and Ofgem, "would help a lot". Providing an essential service means wastewater treatment can never be paused, so trials or new approaches must be in addition to core business and that will not happen overnight. Ofwat has actively encouraged innovation through its fund as a way to enable companies to share risk. This may allow them to overcome the dilemma that people demand innovation, something no-one has done before, but they also want to know for sure it will work. The societal and environmental benefits may outweigh the financial benefits but the economics still must stack up or projects will never progress. The sector is facing monu- mental challenges but the opportunity to reimagine century-old processes with a focus on decarbonisation will lead to step changes in treatment for the 21st century. Ruth Williams, water correspondent continued from previous page The biological treatment of wastewater generates the equivalent of 43k of CO2 each year

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