Global human activity is responsible for the production of 105 billion tonnes of organic wastes per year. Organic waste sources include food waste, crop and animal residues (including manures) and sewage sludges from wastewater. The unsupervised decomposition of this material results in the release of substantial greenhouse gases (GHG) to the atmosphere. It has been estimated that extensive deployment of existing anaerobic digestion (AD) technologies for the biological treatment of organic wastes could reduce global GHG emissions by 10% by 2030 and produce 10,100 to 14,000 terawatt hours of energy. That is, 16-22% of global electricity consumption, or 26-37% of natural gas usage. Thus, AD could play a critical part in global efforts to reach Net Zero. AD is a bio-based technology that uses communities of hundreds of different species of microbes to recover resources from waste. The microbes found in anaerobic digesters facilitate the decomposition of organic materials into biogas, a mixture of carbon dioxide (CO2) and methane, two greenhouse gases that contribute to climate change. In contrast to fossil sources of these gases, the carbon liberated by AD comes from CO2 that has been recently fixed from the atmosphere by plants. By cycling CO2 fixed from the atmosphere rather than adding CO2 from fossil fuels, AD can be considered a Net Carbon Zero technology. The biogas generated by AD is usually captured before being burned to generate heat, electricity and Net Zero CO2, or upgraded to biomethane, sometimes referred to as Renewable Natural Gas, which can be injected into the grid as a Net Zero drop-in replacement for natural gas. Methane can be used as a building block for a range of important chemicals, including plastics, and so AD could potentially contribute to the displacement of fossil fuels for plastics and other products that are currently petroleum-based. Anaerobic digestion is the UK government's preferred disposal route for the 9.5 million tonnes per annum of domestic food waste. Segregated food waste collection legislation is due to be rolled out in the UK this year (2023) so that more resources can be recovered from waste more easily. In addition, UK water companies treated 801,721 tonnes of sewage sludge in 2021, a decarbonisation saving of 563,200 tonnes CO2 equivalent. There are numerous benefits to the work we propose to carry out with Yorkshire Water, which aims to reach Net Zero by 2030, with the primary impacts including: - Near-term solutions that can be deployed before 2025; - Providing medium-term options that can be planned for implementation over the five year Asset Management Period from 2025 (known as AMP8 or PR24 - the Ofwat 2024 Price Review that will consider whether Water Companies are performing as expected); - A long-term consideration of the opportunities offered by AD, including but not limited to: - recovery of volatile fatty acids (building block molecules) from sewage sludge for the production of bioplastics; - treatment of microplastics; - the future of wastewater treatment eg. genetic manipulation of biology to enable zero aeration (low energy) wastewater treatment in 10 years, wastewater treatment for carbon capture, and as an exemplar for biorefining.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Flows found in many situations including gravel bed rivers, overland flows, and in partially filled pipes are turbulent. Such depth-limited flows always have patterns of small waves on the air/water boundary. We believe that the dynamic behaviour of these small waves carries information about the turbulent mixing and energy losses within that flow. Normally in engineering calculations the water surface is assumed to be flat and so this source of potentially very valuable information is ignored. This project will use laboratory observations and a complex 3D numerical model to study and predict the turbulent flow structures that are created by turbulent flows over rough solid boundaries. These flow structures then rise to the water surface and cause it to oscillate and create a distinct pattern of small waves. The numerical model will be able to predict the generation, growth and transport of these flow structures in 3D, and capture their effect on the water surface pattern. It is believed that by measuring the wave pattern it will be possible to predict the mixing and energy losses within the flow. The numerical model will be used to simulate this process for a wide range of physical scales, bed roughness types and flow depth to width ratios, so that a very wide range of flow regimes will have been examined.The wave pattern on a water surface can be measured using a number of methods; e.g. optical, eletromagnetic and acoustic. Acoustic measurements are particularly suited to hydraulic applications because they are fast, low-cost, non-invasive, and can be easily used at both small and large scales. An airborne acoustic sensor that can project sound energy onto the moving water surface pattern will be placed above the water surface in a channel or pipe. By examining the acoustic reflections, the behaviour of the air-water boundary will be measured. New methods of acoustic signal analysis and sound propagation theory are needed to re-construct the fine detail of the water surface patterns from the measured acoustic reflections. The processed acoustic data will then be combined with the knowledge gained from the laboratory and 3D numerical studies to provide engineers with relationships to estimate energy losses and turbulent mixing solely from measurements of the air-water boundary. Information on energy losses and turbulent mixing is needed to predict water levels for flood studies and to predict the mixing of pollutants and sediments accidentally released into rivers and pipes. This system will be able to improve flood prediction and warning, so providing better protection for people and their property. Better assessment of turbulent mixing in water bodies will help to protect better the natural environment and sensitive habitats. In the final part of the project, a prototype sensor system will be manufactured and tested at full scale in the River Taff, at an Environment Agency test facility. The results will be used to demonstrate the practical applicability of the concept and the technology to end users.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Water companies manage extensive networks of clean and waste water pipes. Sometimes these pipes fail catastrophically, resulting in; loss of supply to properties, public highway closures and potentially long-term inconvenience to business and the general public. Pipes also frequently suffer leakage resulting in loss of pressure, increased demands on water treatment works (increasing carbon emissions) and water-related ground instability for example. The potential for pipe failure is, to some extent, controlled by ground conditions, in particular soil corrosion and stresses resulting from ground movement. This project is concerned with understanding the relationship between ground conditions and pipe failure so that we can attempt to predict where pipes are more likely to fail. The project will focus on the Yorkshire Water region and will take advantage of their pipe failure database. Locations where pipe failure has occurred will be analysed against data on ground stability, terrain and soil corrosivity sourced from the British Geological Survey. A conceptual model of pipe failure and a map showing predicted failure rate will be developed. The results of this project are anticipated to improve the ability of Yorkshire Water to plan their asset investment strategies for repair and maintenance. This will allow them to target investment to pipes that are most susceptible to fail, and thus use customer's money more efficiently. It will also reduce the frequency of catastrophic pipe failures, long-term leakage and reduce diffuse pollution caused by leaking sewerage pipes and infiltration of groundwater into pipes (causing combined sewers to overflow). Whilst this project is specifically concerned with the Yorkshire Water region, the results and/or methodology tested during this project are anticipated to be transferable to other water companies.