News

Severn Trent choose te-ionTM Advanced Oxidation to reduce sludge bulking

Severn Trent has awarded Te-Tech a contract to install te-ionTM at its Chipping Campden wastewater treatment works. Like many activated sludge plants, Chipping Campden suffers from severe sludge bulking, that is poor sludge settleability and high suspended solids in the final effluent, during the summer period.

Sludge bulking is due to the prevalence of filamentous bacteria in the activated sludge, in small numbers these bacteria help flocculation, acting like polyelectrolytes to produce larger, stronger flocs. But, when they become too populous, the density of the flocs is reduced and they begin to float. The usual remedy is adding chemicals – nutrients, polyelectrolytes and selected bacteria supplements. But there’s another way. Filamentous bacteria are particularly susceptible to reactive oxygen species like peroxide, ozone and free hydroxyl radicals. The te-ion advanced oxidation process destroys the bacteria selectively, without the use of chemicals, by passing some of the aeration air through an electrical glow discharge, generating a non-thermal plasma which contains a wide range of reactive oxygen species. The plasma containing the reactive oxygen species is introduced into the aeration reactor along with the aeration air, via the diffuser system. The active oxygen destroys the bacteria and dramatically reduces sludge bulking without affecting the biological treatment process. “We were impressed by Te-Tech’s process knowledge and the te-ion technology’s track record. Their in-house control panel designand-build capability and their experience of system integration gave us confidence that this retrofit would be implemented successfully,” said Andy Harkin of Severn Trent Water

Design is underway and the project is on schedule for delivery and installation at the end of September and hand over at the beginning of October. For out more: www.te-tech.co.uk/products/ wastewater-treatment-products/te-ion

SEPTEMBER2021 DECEMBER2021

ISSUE20 ISSUE21

Improving Asset Health • Trenchless Technology • Wastewater Monitoring & AnalysisWastewater Treatment & Technology • Sludge Management • Pressure Sensors for Water Pipelines

Pipeline Rehabilitation • Data & Analytics in the Water Utility Sector • Clean Water Networks Pump Technology and Innovation • Wastewater Treatment and Technology

If you would like to participate in the December edition of Water Industry Journal we shall be featuring:

Pressure Sensors for Water Pipelines Digital Transformation Managing Sewer Networks Water & Wastewater Monitoring & Analysis Trenchless Technology Wastewater Treatment & Technology

Contact David Lancaster on 0191 580 5476 or email david.lancaster@distinctivegroup.co.uk for more information.

Digital technologies have key role in reducing pollution

British Water Chief Executive Lila Thompson says the water industry must embrace new technologies to combat increasing concerns over pollution.

The latest report from the Environment Agency calls for much stricter enforcement of water quality measures, as public, political and media pressure heighten around the issue of surface water pollution. So how should industry leaders respond to these regulatory pressures, and what role can the supply chain play in tackling the myriad reasons pollution happens? Thankfully there are plenty of proven solutions already available. As the UK’s leading water sector trade association, British Water works very closely with its membership - a vibrant supplier community that is continually researching, developing and innovating. Companies providing digital technologies, smart water monitoring, advanced membranes and flexible wastewater treatment systems can all help water utilities meet environmental and regulatory requirements, and avoid reputational harm,by reducing the risk of serious pollution incidents. While the water sector has traditionally lagged behind other industries in adopting digital technologies, it is now on the path to transformation. Examples include deployment of remote sensing equipment to improve the reliability of flood and drought predictions, realtime monitoring of water quantity and quality within watersheds, along with enhanced asset management tools and processes. Powerful tools

Internet of things (IoT) connected devices, predictive analytics, and artificial intelligence (AI), including machine learning, are also emerging as powerful tools in achieving sustainable, resilient, and equitable access to water. Used in combination, digital technologies have the potential to revolutionise every aspect of water and wastewater management, including maintaining and expanding water infrastructure, detecting leaks and anomalies in the water distribution system, as well as identifying emerging water contaminants and improving the water treatment process. In addition, the use of building information modelling (BIM) has had one of the biggest impacts on water services of any recent digital innovations. Its use in design and construction has enabled huge efficiencies in the way capital schemes are delivered, while leaving behind a legacy of better information which supports better asset operation, maintenance and upgrades.

Knowledge sharing

With utilities ready to harness the benefits of digital water solutions - collaboration and knowledge sharing will be key to its success moving forward. In order to help facilitate this necessary shift, on 3 November 2022 British Water will be hosting its annual Data Conference in London.

This year’s event will continue the discussion on ways to realise digital transformation for the water industry. It will provide an excellent forum for discussion around how collaboration can boost the use of data and analytics to drive efficiency and sustainability. This is all the more pressing as the UK moves towards the next regulatory asset management period - AMP8, which runs from 2025-30, and the water sector seeks to embrace a progressive culture of consultation, collaboration and digital innovation.

Public awareness of the way water is managed in the environment may be a point of pain for the industry as it scrambles to catch up with expectations, but the focus is long overdue, and should be welcomed as an opportunity to drive innovation. New technologies and ways of working will deliver multiple benefits, not only for utilities and suppliers but also – crucially - for the environment and wider society. To find out more visit britishwater.co.uk/events/eventdetails.

Wessex Water has proven that a nature-based alternative to chemical dosing reduces phosphorus in treated wastewater

Constructed wetlands could successfully deliver a natural alternative to chemically treating wastewater before it is returned to the environment, according to the pioneering project by Wessex Water.

The company’s unique 0.8 hectare wetland site at Cromhall Water Recycling Centre started operating last year to ensure water quality and ecology in nearby Tortworth Brook was protected and enhanced. The investigation into the effectiveness of the rural South Gloucestershire site – the first of its kind in the water industry designed to remove phosphorus from sewage effluent – assessed how the wetland removed nutrients, organic pollutants and chemicals and delivered biodiversity enhancement following its construction.

Findings revealed that such wetlands can keep the concentration of phosphorus in effluent within permitted limits. Further ongoing academic research demonstrates that the wetlands also help to effectively remove microplastics and more than 70 per cent of some compounds from the water, and reduced bacteria released into the environment by more than 95 per cent. Ruth Barden, Director of Environmental Solutions at Wessex Water said: “Essentially, Cromhall is the first example of using a sustainable alternative to chemical dosing to achieve phosphorus reductions at sewage works and there has been a high level of interest as companies look to achieve net zero carbon and identify opportunities for wider environmental gains. “As well as phosphorus removal, wetlands address other water quality parameters, such as bacterial reduction and their resistance to diseases and infections, as well as microplastics, which have implications for discharges to areas such as inland bathing waters.’’

The Cromhall investigation was included in the WINEP (Water Industry National Environment Programme), with outcomes reported to the Environment Agency earlier this year. It’s part of Wessex Water’s drive to deliver wider environmental benefits, including net zero carbon, biodiversity gains, improved river water quality and a reduction in flood risk. The company’s pioneering approach focuses on research into the effectiveness of nature-based solutions. The outcomes of this investigation are likely to be closely monitored as water companies address their own environmental challenges and tackle government guidance which advocates using similar measures to achieve water quality and wider environmental targets.

The site showed a 111% increase in biodiversity value (Biodiversity Metric 3.0)

Findings

The wetland appeared to be most effective in the summer months, with lower water flows, warmer temperatures, more daylight and significant macrophyte growth contributing to the positive findings. On average, annual concentrations of phosphorus were reduced to within the proposed permit limit of three milligrammes of phosphorus per litre at Cromhall WRC. The report concluded: “To allow naturebased solutions such as Cromhall ICW (Integrated Constructed Wetland) to become viable alternatives to ‘traditional’ treatment approaches, there needs to be acceptance that the performance will vary due to the natural processes involved.’’ Included in the findings on water quality were a 27.5 per cent reduction in total phosphorus, a 62 per cent reduction in ammonia and more than 60 per cent in nitrogen. The investigation also determined a 111 per cent increase in biodiversity value, with the projected increase expected to continue significantly over a 30-year period. “These findings will help to inform how the site should be managed going forward to ensure the best balance between water quality removal performance and biodiversity value,” Ruth added.

“They also offer evidence towards our future investment decisions as we strive for a more sustainable approach towards improving water quality and local biodiversity of our water courses and achieve lower carbon and more cost-effective solutions for both sewage works discharges and storm overflows. “We hope that this report will inform government policy and the evidence base to enable more wetland solutions to be implemented in the future by all water companies, not just Wessex Water.’’ An executive summary of the Cromhall Wetland Investigation report that was submitted to the Environment Agency is available at Cromhall wetlands trial (wessexwater.co.uk)

A perfect storm: Responding to new legislative pressures around storm overflows

Nick Barker, of Weightmans law firm, explains what the major new legislation means for water companies, the imperative of ensuring regulatory compliance in the short term, and steps that can be taken to do so.

Over recent weeks water companies have faced further scrutiny over excess sewage and rainwater discharges, caused by flooding, into the seas around Britain. This adds to a sustained period over which discharges into waters have come under review.

The issue of storm overflows is not a new one; its current status reflects the complexity of the problem. Like many, water companies have long regarded the situation as unacceptable but lacked the necessary statutory and regulatory framework to act. This has changed with the passing of the Environment Act 2021 and the publication of the Storm Overflows Discharge Reduction Plan (the Plan), marking a watershed in the industry’s approach to the issue.

The Environment Act sets out a requirement for sewerage undertakers to secure a progressive reduction in the adverse impacts of storm overflow discharges, while the Plan provides clear and unambiguous requirements for what is needed.

Regulatory shifts

The Plan sets out ambitious targets requiring water companies to participate in a mandatory £56bn investment project to fix the long-standing issue of storm overflow discharges. Two clear targets are:

By 2035, water companies must have improved all overflows discharging into or near all designated bathing water, and improved 75% of those discharging to high priority sites

By 2050, no storm overflows will be permitted to operate outside of unusually heavy rainfall or cause any adverse ecological harm Progress against this plan will be scrutinised by Ofwat, the economic regulator for the water industry, and the Environment Agency (EA), the environmental regulator in England. Supporting them to do so are strengthened monitoring and reporting requirements, including: 100% coverage of Storm Overflows through

Event Duration Monitoring (EDM) by 2023, requiring companies to report the frequency and duration of spills Storm Overflow data to be published annually, with frequency and duration data required in near real time Monitoring the water quality impact of assets that discharge sewage into river systems

Nick Barker is a Principal Associate at national law firm Weightmans. He is a specialist environmental lawyer in environmental compliance, regulatory investigations and enforcement action. Nick is a key member of the firm’s water group and has good insights into water companies having worked on secondment for a well-known water/ wastewater company.

What should water companies be doing in the short term?

Water companies will be reviewing the Plan and carefully considering what it means for long-term planning and future investment. The scale of this project cannot be understated. The immediate challenges presented by storm overflows will not, however, go away. Where water companies aren’t meeting existing legal obligations, the EA have a range of options available to them, including issuing enforcement notices, prosecuting companies in the criminal courts and in extreme cases even jailing individuals whose companies are responsible for the most serious incidents (although that hasn’t happened to date). These risks have increased following recent public scrutiny, including an investigation by the Office for Environmental Protection into the roles of Ofwat, the EA and Defra in the regulation of combined sewer overflows, alongside active investigation by the EA. In addition to the long-term measures required to tackle storm overflows, water companies will be looking to: 1. Strengthen compliance Water companies will be regularly reviewing their environmental management systems to ensure they are proactively monitoring compliance with existing legislation such as the Environmental Permitting Regulations and the Urban Wastewater Treatment Regulations. 2. Take commitments seriously Monitoring conditions and reporting requirements are already included within discharge permits for each storm overflow identified. However, a wider approach to investigation and reporting can provide insight into common causes and demonstrate proactivity to regulators and stakeholders. 3. Harness the potential of data - knowledge is power Improving EDM data provides a robust and consistent way of monitoring storm overflows. Water companies should consider the potential of data generated by increased monitoring responsibilities, with opportunities to: engage real-time data analytics solutions to support operational decisions; provide elevated insight into operational risk management; inform investigations into discharges; and engage with stakeholders. The Plan will help water companies bring much needed improvement to Britain’s antiquated Victorian sewer infrastructure and have a positive impact on the environment. Alongside a commitment to achieving its longterm objectives, a key focus will be ensuring current legal obligations regarding storm overflows are being complied with.