Minimising the Impact of Heat Recovery on Wastewater Treatment Processes

By Madhu Murali

Our monitoring work at industrial and municipal wastewater treatment plants has found that they have a significant potential for heat recovery. However, there are some concerns regarding the impacts of heat recovery on the efficiency of treatment processes, particularly if a heat exchanger is introduced into the treatment area. To assess these potential impacts, we have replicated a common industrial treatment process, Dissolved Air Flotation, in the lab-scale at Trinity College Dublin. This setup will be used to both determine the scope for heat recovery from Dissolved Air Flotation Tanks and assess any subsequent impacts on their treatment efficiency.

Wastewater temperatures at industrial sites can be very high, particularly in the food and beverage industries where cleaning with high temperature water is often required. Our monitoring work at two meat processing plants showed that their peak wastewater temperatures were as high as 40°C with an average temperature of around 20-30°C. As the wastewater from these plants are treated on-site in treatment facilities, there is an opportunity to recover some of the embedded heat in the wastewater while it is treated. However, the potential negative impacts of heat recovery on the treatment efficiency of wastewater treatment processes should also be analysed to ensure they are minimal. A common treatment processes present in both on-site treatment facilities, Dissolved Air Flotation (DAF), has been selected to conduct a detailed analysis to determine the impacts of heat recovery on its operational efficiency.

Figure 1: A schematic diagram of the lab-scale dissolved air flotation tank

DAF is a physical treatment process by which suspended pollutants in water can be removed. Small bubbles (or microbubbles) are introduced into the wastewater in a DAF Tank, the bubbles aggregate around suspended particles in the water and lift them to the top of the tank where they can be skimmed off the surface. The microbubbles are formed by compressing air and water in a tank or vessel, called a pressure vessel, to a high enough pressure that the water is saturated with air. When this pressurised air and water mixture is released into the DAF tank through special valves that maintain pressure, the rapid change in pressure from the pressure vessel to atmospheric pressure causes the air to be released in the form of microbubbles. Flow patterns within the tank are controlled by the use of baffles, positioning of the inflow/outflow, and the volume of inflows such that the removal of suspended particles is improved. DAF is commonly used to treat wastewater from the meat processing industry, which have a lot of organic and suspended pollutants in them.

Figure 2: A photo of the lab-scale dissolved air flotation tank with microbubbles seen on the surface

A lab-scale DAF tank (Figures 1 and 2) has been set up at the Hydraulic Laboratory in Trinity College Dublin for experimentation related to heat recovery. The DAF tank is supplied heated water at a maximum temperature of 40°C from a supply tank and a pressure vessel supplies the water/air mixture to create microbubbles. The DAF tank also has two baffles near the inlet to control flow through the tank. Initially, the focus of our work with the lab-scale tank will be in identifying parameters to stably operate it and then characterising flow patterns in the separation zone of the tank to ensure that this is similar to that seen in other DAF tanks.

Future work will focus on identifying optimal locations for heat recovery in the DAF tank by measuring water temperature at different locations and identifying areas with optimal flow patterns. A heat exchanger can then be installed at a selected site to quantify the amount of heat recovery possible in our lab-scale tank. Another line of work will focus on determining any impacts on treatment efficiency in the DAF tank due to heat recovery.

This will involve examining the change in flow patterns and any significant changes in outlet wastewater temperature due to the introduction of the heat exchanger. A proxy suspended pollutant, such as clay, may also be used to determine if heat recovery impacts on its removal by the DAF tank.

How does a Pump as Turbine operate in a real water network?

Daniele Novara

Pumps As Turbines (shortened as “PAT”) consist of regular water pumps running in reverse as turbines, and therefore generating power from a stream of pressurized water. How do these devices operate when installed within a water network in parallel to a Pressure Reducing Valve (PRV)? And how to design a system able to cope with sudden variations in water pressure and flow rate?

Whether you are a regular visitor of the Dŵr Uisce website or just someone who occasionally checks the project updates, you may be already familiar with the concept of using “Pump as Turbines” (in short, “PAT”) to generate power from water networks. In short, these devices consist of regular water pumps which are utilized in reverse to generate electricity from a pressurized water stream as an alternative to conventional (and expensive) custom-made water turbines. These devices can be used to produce carbon-free, clean and renewable power with a low installation cost and ease of maintenance and they are particularly suitable for integration with existing water infrastructures.

 In fact, most water transport or distribution systems such as drinking water, irrigation or industrial cooling networks will typically have nodes at which pressure must be reduced in order to avoid leaks and pipe bursts. This is normally achieved via a Pressure Reducing Valve (PRV) which dissipates the excess water pressure as heat and noise. However, a Pump as Turbine can be inserted in parallel to such PRV and recover a portion of the dissipated pressure as useful electricity. As a consequence, the power generated by the PAT will offset the electricity consumed by the whole water network in a circular economy approach.

 The Dŵr Uisce research team over the recent years has focused extensively on several aspects of the PAT technology which were previously unknown, helping the scientific community as well as the general public to learn more about this class of devices and their application. These efforts culminated in the construction of a hydraulic test rig at Trinity College Dublin to test the performance of centrifugal PATs and eventually to the installation of two devices in Ireland and Wales. However, both these pilot plants are located at sites which offer a “conventional” hydropower layout where a portion of the water flow of a river is diverted into a pipeline and eventually across the turbine. Therefore, neither sites are located in a fully pressurized water network in parallel to a PRV as mentioned in the previous paragraph, which would pose additional challenges in the system design. Among these challenges, the main one is to ensure at any time that the water flow is never disrupted by the presence of the PAT even under exceptional circumstances. This translates into the need of a bypass pipeline which diverts from the turbine the water that can’t be processed by it. However, at the same time it is also important to minimize at all times the amount of water that bypasses the PAT since this results in an energy loss.Despite the fact that over the last decade there has been a number of scientific publications investigating the behaviour of PATs in water networks, most of them either did not include experimental data or utilized a sophisticated computer-operated bypass valve which greatly increased the complexity of the system. As opposed to this approach, what if a conventional PRV could itself be used as the bypass valve without the need of an additional element? How well can a PRV act as a turbine bypass valve, and how finely is it possible to tune it?

 In order to answer these questions, the existing hydraulic test rig at Trinity College Dublin has recently been upgraded with a PRV in parallel to a PAT (Figure 2) and tests are ongoing to evaluate the interactions between the two devices under varying flow and pressure conditions.

Figure 2: Upgraded test rig with PAT in parallel to a PRV

Richard shares his research at virtual EGU General Assembly 2021

Richard, a postdoctoral researcher in our Bangor team, has been attending the European Geosciences Union’s (EGU) 2021 General Assembly this week, as well as presenting and discussing his work. Usually held in Vienna, this year’s conference is being conducted online due to the ongoing global pandemic, providing a fantastic opportunity to disseminate Dŵr Uisce research to a wide global audience. Indeed, the event is one of the largest gatherings of geosciences related researchers in Europe, with the EGU having over 20,000 members.

Whilst participating in the conference, Richard has attended many sessions from various EGU divisions such as hydrological sciences, climate (past, present and future), and energy resources and the environment. The work presented here has been highly interesting, and has furthered Richard’s knowledge, research scope, and contacts, all of which will bring great benefit to his Dŵr Uisce research. In addition, new avenues of research have been explored, and ideas generated for future work and new methods.

Richard also presented his latest research which explores the impact of climate change on water abstraction for the purposes of public water supply and hydroelectric power in Wales. As with all contributions at this year’s assembly, Richard’s took the form of a vPICO (virtual Presentation of Interactive COntent), consisting a two-minute live presentation of a single slide, followed by a breakout room, allowing in-depth discussions of the work. This was a highly valuable experience, allowing for both the engagement of a broad audience and detailed discussions and conversations on the research, methods, and implications. In addition, a 15-minute pre-recorded presentation of the research has been available throughout the conference to EGU members, and will be accessible until the 30th May, allowing for even greater interaction with and comment on the research.

This has been a highly valuable opportunity for Richard and the Dŵr Uisce project, allowing access to some of the leading researchers in the field, enabling comment and opinions on the presented work and future plans. Thanks must go to the organisers of the General Assembly, as well as the funders of the Dŵr Uisce project, the European Regional Development Fund through Interreg Ireland-Wales Cooperation Programme.

Evaluating the potential for energy recovery in an industrial wastewater treatment plant

by Daniele Novara

Dairygold Co-Operative Society Ltd is an Irish dairy co-operative based in Mitchelstown, County Cork. A delegation from the Dŵr Uisce project visited the Dairygold Wastewater Treatment Works (WWTP) on 20/02/2020 to assess the potential for hydraulic energy recovery within the existing infrastructure.

In fact, Micro-hydropower schemes are an effective solution for energy recovery at the outfall of wastewater treatment plants and Pumps As Turbines (PATs) in particular are a hydropower technology particularly suitable on a small scale where a conventional turbine unit would not be economically viable.

The Dairygold WWTP is located at the foot of a hill just below the main industrial facilities, and next to the Mitchelstown municipal WWTP as shown in Figure 1. The main location investigated for energy recovery was the pipeline carrying pre-treated effluents from the industrial plant above head to the WWTP at the foot of the hill with a drop of around 12 m displayed in Figure 2. At the first step, flow and pressure data were gathered from the plant operators to provide a precise overview of the site conditions. Subsequently, the Pump As Turbine selection software developed at Trinity College Dublin as part of Dŵr Uisce research project has been applied to the selected site and helped to identify the ideal PAT and generator to be chosen.

Figure 1 the location of Dairygold Wastewater Treatment Works (WWTP)

Figure 2 the pipeline carrying pre-treated effluents

Eventually, the potential for energy recovery within the existing infrastructure of the Dairygold WWTP in Mitchelstown has been identified as 2 kW. The turbine may recover up to 7,400 kWh of electricity along a typical year, corresponding to a reduction of the electricity bill by nearly 1,200 €/year. However, given the low power output of the PAT the estimated payback time is between 11 and 14 years.

Recovering heat, saving space: Grease trap integrated heat recovery

By Jan Spriet

Wastewater from (commercial) kitchen drains can reach temperatures up to 55°C, consequently, they have a significant amount of embedded energy (that you paid for), that is currently being flushed down the drain. In commercial kitchens the installation of a pre-treatment system, to remove Fat, Oil & Grease (FOG) from the wastewater is mandatory, to avoid fatberg formation. In commercial kitchens, this pre-treatment is performed by a grease interceptor or grease trap. In the proposed prototype, this grease interceptor is used as a wastewater holding reservoir, avoiding temporal mismatches, and a heat exchanger is integrated into this grease interceptor. The heat recovered from the grease trap reduces the energy and fuel consumption of the kitchen’s traditional heating system. Integrating heat recovery in the grease trap would not only reduce the space requirements of heat recovery systems, and reduce their installation costs. It would also aid in the removal of FOG from the kitchen wastewater. In this article, we describe the operation of our prototype.

Figure 1. The working principle, in a nutshell.

Our previous research showed a technical heat recovery potential of 1.4 TWh (388 000 tons of carbon emissions) in the food and hospitality sector in the UK, each year, using currently available heat exchangers. However, it also showed that this potential was limited by temporal mismatches between supply and demand, a required vertical drop in the drain of 2m, and showed that these heat exchangers are not cost-effective for smaller kitchens. The idea of the developed prototype was to address these three bottlenecks. The solution was found by integrating heat recovery into grease interceptors. These grease interceptors are already a mandatory piece of equipment, this would thus not require additional space, and have a limited effect on costs.

Figure 2a. The grease trap with prototype DWHR device

Figure 2b. Picture of the prototype DWHR device

This prototype was tested in steady state conditions in the lab, using heated clean water to simulate the kitchen’s wastewater. This showed an effectiveness between 23% and 55%, and a recovered heat ranging between 600W and 1.8kW. It also reduced the temperature in the grease trap from around 41.5°C in normal conditions to 36.5°C at its lowest point

Figure 3. Heat recovery prototype in the lab set-up

The prototype is deemed profitable for kitchens with a consumption of more than 100 l/day, when complementing electric heating and 300-350 l/day when complementing traditional boilers (fuel oil, natural gas or bio-mass). Applying this prototype in the food and hospitality sectors results in over 150 000 food outlets, where installing the prototype is the most profitable solution. These outlets equate to 2348.52 GWH of heat recovery each year, the equivalent of 69 000 tons of greenhouse gas emissions.

The reduced temperature is expected to improve FOG removal efficiency, which in turn would increase the required emptying frequency of the grease interceptor, as more FOG would be collected. Collecting more FOG has the advantage that, when the removed FOG is treated in anaerobic digesters, additional bio-gas can be recovered.

Changing river water quality under a worst-case climate change scenario: Implications for drinking water supply

By Richard Dallison

Water service providers in the UK face a vast array of challenges when it comes to planning their future operations and services; the impact of climate change on the quality of water arriving at drinking water treatment plants (DWTPs) is just one of these. Changes in water quality are induced by a variety of factors, when considering non-point source inputs. Large or prolonged rainfall events, for example, can lead to greater washing of pollutants from the land in to rivers. Additionally, large streamflow events provide rivers with greater stream-power, enabling more erosion of river banks and the movement of larger particles. Very low streamflow events can also cause spikes in water quality issues, as there is less water available to dilute any pollutants. Therefore, any changes in future climate, and subsequent alterations in streamflow regime could have far reaching consequences in terms of water quality, this in turn could cause problems at DWTPs if they are unprepared for any such changes.

Using the Soil and Water Assessment Tool (SWAT) hydrological model, we have projected and analysed future (2021-2080) streamflows and water quality under a worst case scenario of future emissions, that being representative concentration pathway 8.5, as laid out by the Intergovernmental Panel on Climate Change. To account for uncertainty in future modelling, an ensemble of 12 regionally downscaled models derived from the Met Office Hadley Centre Global Environmental model (HadGEM3), and supplied by UK Climate Projections 2018, have been used as the future climate inputs to SWAT. Five catchments have been studied, the Clwyd and Conwy in north Wales; the Dyfi in mid Wales; and the Teifi and Tywi in south Wales; these systems represent a variety of catchment characteristics in terms of land use, soil types, underlying geology and topography. We have investigated annual and seasonal average changes for four water quality aspects, suspended sediment (SS); total phosphorous (TP); total nitrogen (TN); and dissolved oxygen (DO). Mann Kendall trend analysis was performed on the model outputs, in order to detect any statistically significant trends.

Figure 1. Study area and catchments showing streams larger than third order as defined by Strahler method.

Previous work by the Dŵr Uisce project has shown that extreme streamflow events will become more frequent in the future, with winter and spring seeing more very large events, and summer and autumn seeing much lower streamflows. This is reflected in the water quality outputs, with increases in SS loads seen in winter and spring in four of the five catchments each. At annual average level, SS loads are increasing significantly (p <0.01) in all catchments except the Tywi, were a non-significant increase is seen. TP and TN display broadly similar trends, with concentrations increasing in all seasons, in all catchments except the Dyfi, where a decline is shown in winter, spring and annually on average. Summer concentrations of TP and TN in particular show a statistically significant increase in all catchments (except TP in the Tywi). DO levels show the most variation, although a decline is seen in all catchments in summer. The Teifi catchment is the most divergent, with a statistically significant increase in winter and spring DO levels, compared to declines seen in all other catchments for winter.

Figure 2. Overview of the direction and significance of annual and seasonal average trends in projected future (2021 – 2080) water quality concentrations, as detected by Mann Kendall trend analysis, based on the average of all 12 RCM model outputs.

Given the trends seen in river water quality, it is clear that for the vast majority of the time in the future, water quality will be worse than it is currently. This is an issue that needs to be managed at DWTPs in particular, to ensure that current operating systems, procedures, and technologies will be able to cope with more contaminated water in the future. This adaptation need comes hand-in-hand with the need to also ensure future water security, especially in summer and autumn, when lower precipitation and streamflows, as well as higher temperatures, are projected for Wales. It is clear that the projected changes in climate will have a large impact on catchments in Wales, this will have a significant knock-on impact on a variety of aspects of drinking water supply. Work is therefore needed now to plan and mitigate against these potential changes in order to maintain continued high-quality supplies in to the future.

Eco-code posters in English, Welsh and Gaelic languages

Szu-Hsin Wu

Previously, we have designed an English language version of eco-code poster which shares many water-saving tips. The poster was firstly published on our website and social media and posted across campus in both hard copies and digital format.

Due to the COVID19 pandemic, over the past months, we have all been adjusting our routines and behaviours to slow down the spread of the coronavirus. During the period, we also experienced water shortages in Ireland. We had only 25% of normal rainfall in April and decreased 5% of normal rainfall for May. We thought the sharing of these water-saving tips could also remind everyone making a small effort to collectively create a positive impact on our environment. To further promote these water-saving tips, we converted the poster into a Gaelic language version. These tips circulated to the mailing list of the Sustainability Network at Trinity College Dublin and were well received on many social media such as Twitter, Facebook and Instagram.

Following a positive response from social media, we also designed a Welsh language version of the eco-code poster. Now, these water-saving tips are communicated in three languages.

What’s the best way to use distillery by-products?

By Isabel Schestak

Cattles in Scotland, photographed by Isabel Schestak

By-product use from malt distilleries has a long tradition in Scotland, where it has probably been fed to cattle and sheep for more than 500 years (Crawshaw, 2001). Recently though, a shift from feed to bioenergy use has been observed, as incentives by the UK and Scottish government for renewable energy technologies have been taken up by the distillery sector (Bell et al., 2019). Though energetic use of by-products brings benefits for a distillery’s carbon footprint, from a water use perspective, also feed use might deserve recognition as environmentally favourable, when the protein rich by-products replace imported feed such as soybean meal. This has been shown already for greenhouse gas emissions, but not been looked at from a water perspective yet.

To find out which by-product use option performs best in terms of water use and to which extend it can improve the water footprint of spirits, we applied a recently developed methodology to the operations of a Scottish distillery. The method called AWARE (Available water remaining) does not only take into account the volume of water consumed for a process or product, but also the water availability or scarcity in the geographical area where the consumption takes place (Boulay et al., 2018). Water consumed in an arid region therefore is weighted stronger than that in a fairly water abundant area such as the UK. It is therefore not just a water, but a water scarcity footprint.

We looked at different scenarios for using spent grains and pot ale: 1) direct use as cattle feed in its fresh form and replacing a mix of imported soybean meal and domestic barley, 2) processing them first to dried distillers grains, thus producing a better conserving and more flexible to use feed before also replacing soy and barley, 3) processing to dried distillers grains but only replacing pure soy protein as feed and 4) anaerobic digestion to biogas, with subsequent combustion of the biogas to electricity and heat, and using the leftover digestate as fertiliser i.e. in total replacing grid electricity, heating fuel and fertilisers.

In the feed scenarios, both soy and barley were replaced in order to substitute an equal amount of protein and metabolisable energy found in the by-products.

First results showed that the water scarcity footprint of whiskey can be reduced by about 20% by using the by-products as either direct cattle feed (scenario 1) or generating biogas (scenario 4). Thus, there is no clear benefit for the use of by-products for renewable energy purposes, in contrast to the suggested reduction of GHG emissions through the government incentivised bioenergy option. The water savings are partially “invisible”, indirect savings though, achieved outside the distillery or even abroad and therefore do not directly improve a distillery’s footprint.

Similar observations have been made by Leinonen et al. (2018), who conducted an assessment on greenhouse gas emissions from different by-product use scenarios from single malt whiskey: in terms of percentage reduction of burdens through by-product use, higher reductions were achieved when by-products were used as feed in form of dried distiller’s grains, replacing soybean and barley feed (40%) than through biogas production and digestate application (27%). Again, these were partially indirect savings connected to land use change for the cultivation of soy abroad.

The study will be expanded to include other water footprint methods and data from further distilleries to enhance the reliability of the results. But already now we may question the environmental benefit from incentivising biogas production from distillery by-products.

References:
Bell, J., Farquhar, J., Mcdowell, M., 2019. Distillery by-products , livestock feed and bio-energy use in Scotland, Sruc.
Boulay, A.M., Bare, J., Benini, L., Berger, M., Lathuillière, M.J., Manzardo, A., Margni, M., Motoshita, M., Núñez, M., Pastor, A.V., Ridoutt, B., Oki, T., Worbe, S., Pfister, S., 2018. The WULCA consensus characterization model for water scarcity footprints: assessing impacts of water consumption based on available water remaining (AWARE). Int. J. Life Cycle Assess. 23, 368–378. https://doi.org/10.1007/s11367-017-1333-8
Crawshaw, R., 2001. Co‐product feeds: animal feeds from the food and drinks industries, 1st ed. Nottingham University Press, Nottingham.
Leinonen, I., MacLeod, M., Bell, J., 2018. Effects of alternative uses of distillery by-products on the greenhouse gas emissions of Scottish malt whisky production: A system expansion approach. Sustain. 10. https://doi.org/10.3390/su10051473

Testing explanatory factors and proxy variables in economic and energy efficiency benchmarking

By Nathan Walker

Evaluating efficiency has many advantages to companies, such as enabling assessment of explanatory factors however, the process of doing so is not always easy. Sometimes missing data leads whoever is conducting the research to utilise proxy variables, which replace the ideal choices.

The explanatory factors* analysed in the study were: leakage, per capita consumption, number of sources, proportion of water through size 5-8 water treatment plants (the largest 50%) and average pumping head height. Leakage and number of abstraction sources were concurrent in their negative effect and significance across both the energy and economic assessments. These results were expected to an extent since for leakage the more water that is lost, the more water needs abstracting, treating and delivering, which all require energy and money. Although diversifying abstraction sources can be a positive attribute for companies to make their supply more resilient, it appears as though this is at the expense of a significantly increased energy consumption owing to more pumping being required through a larger network of piping. Average pumping head height displayed a significant negative effect for energy, whereas the variable proportion of water passing through the largest four treatment works was deemed to have a significant negative effect on economic efficiency. These exogenous factors, therefore, need to be corrected for in future benchmarking activities and have the potential to inform water companies about factors to prioritise in order to improve efficiency.

The proxies that were tested were population served for drinking water and length of water mains, which replaced the output volume of drinking water produced and the input of CAPEX, respectively. These were chosen as they are frequently used as proxies in the academic literature. We found that the proxy population served for drinking water can adequately replace the volume of water produced as an input variable (Figure 1) in efficiency benchmarking when leakage and per capita consumption ranges are minimal since companies stayed at the same rank and explanatory factors displayed the same significance. Conversely, length of water mains performed poorly when replacing CAPEX as an economic input (Figure 2), implying companies were on average 12.6% more efficient, resulting in 10 companies changing their rank compared to the original variable and causing some explanatory variables to differ in direction of influence and significance. Further research is recommended on the energy and economic efficiency of WoCs and WaSCs, considering a wide range of exogenous variables and careful selection of (proxy) indicators.

Figure 1. The energy efficiency results with the primary set of variables, and a volume of water produced proxy (population served for drinking water). WoCs are featured as triangles and WaSCs are displayed as circles. 1 Is the optimum efficiency rank and everything above that is classed as the degree to which companies are inefficient.

Figure 2. The economic efficiency results with the primary set of economic variables, and a capital expenditure (CAPEX) proxy (kilometres of water mains network). WoCs are featured as triangles and WaSCs are displayed as circles. 1 Is the optimum efficiency rank and everything above that is classed as the degree to which companies are inefficient.

The full research with more details on the background, methodology and discussion is available here: https://doi.org/10.1016/j.jenvman.2020.110810

*Only explanatory factor results that showed significant results are discussed here.

Learning in action: Generating actionable knowledge with stakeholders

Szu-Hsin Wu

In the Dŵr Uisce project, it is part of our innovative culture to working with stakeholders on co-designing, co-developing and co-implement green innovation which mitigate impacts on the environment.

In collaboration with National Trust (UK) and National Federation of Group Water Scheme, Dŵr Uisce researcher and stakeholders have installed micro-hydropower energy recovery system at two demonstration sites: Tŷ Mawr Wybrnant  and Blackstairs Group Water Scheme. The process of achieving green innovation has never been easy and straightforward. We encountered numbers of unknown problems and challenges. Without our valuable stakeholders being patience and continuously engaged in the collaboration process, we could not have achieved what we have today. Various forms of actionable knowledge were generated and accumulated from the process. For example, engineering researchers learned insights from realizing the system design in a controlled setting. Researchers from the management discipline also learned how to communicate innovation performance and commercialise the technology to stakeholders and a wider audience. All stakeholders obtained the codified processed experience from designing in the system, communicating with stakeholders and installing the system that can be used for the next cycle of green innovation.

Generating and accumulating new actionable knowledge was through intuiting, interpreting, integrating and institutionalizing. Through intuiting, engineers identified patterns, possibilities, similarities and differences between the two sites. Through interpreting the results of feasibility studies, we selected suitable energy recovery possibilities within specific domains or environments. Through integrating the knowledge, both the academic researchers and the practitioners developed a shared understanding of the objectives, engineering choices and criteria for evaluation and installed the system. This integration took place through direct interaction among group members in order to attain coherence. The Dŵr Uisce team then institutionalised the learning from Blackstairs Group Water Scheme demon site and leveraged it for Tŷ Mawr Wybrnant site and consolidating the learning for further application.

We know that innovation is rarely a linear process and rarely stop at a point of time. We work continuously and closely with stakeholders on innovation. And in the near future, we hope to share more insights from implementing our Wastewater Heat Recovery Systems at other demonstration sites.