Determining the UK’s potential for heat recovery from wastewater using steady state and dynamic modelling - preliminary results

Abstract

By 2050, UK plans to create 'low carbon society'. To meet this ambitious target, UK's heating sector must be completely decarbonized. The identification and deployment of low carbon heating sources is thus an urgent policy and research priority. Recovering heat from sewage wastewater is relatively new and attractive option as it can help UK move towards its climate change targets while decarbonising the heating sector & reducing the reliance on fossil fuels. In the domestic context, wastewater is normally discharged at higher temperature than ambient (a carrier of heat/ thermal energy) losses its energy to (ground) environment before it reaches to WWTP. Recovering this heat from wastewater could be a considerable source of energy, revenue and is environmental friendly as it results in the reduction of GHG emissions, resource conservation and in increase share of renewable energy. In last decade, many cities around the world have successfully implemented wastewater thermal energy recovery but UK is lagging behind. Pilot project such as in Scotland is leading the way, but further research is needed to build the evidence base and replicate the concept elsewhere in UK. The Home Energy 4 Tomorrow (HE4T) project at London South Bank University (LSBU) was created to address this evidence gap. The project objectives include sizing the heat potential recoverable from wastewater at designated sites. The current paper forms part of the HE4T project and the second in series of output on wastewater heat recovery in UK. In this paper we present some initially measured data, variations in wastewater temperature and flow, steady state and dynamic model results wastewater temperature and the potential heat recovery of the designated site. Early results, their limitations and possible routes to address these limitations are discussed along with policy implications for UK heat strategy.

Optimising the Hydraulic Retention Time in a Pilot-Scale Microbial Electrolysis Cell to Achieve High Volumetric Treatment Rates Using Concentrated Domestic Wastewater

“…This suggests that much of the COD was anaerobically digested, with the resulting methane released from the open anode section. This is surprising: the reactor was run at ambient UK temperatures (wastewater remained between 10 and 20 degrees [44]), which would normally prohibit anaerobic digestion; it was fed wastewater deemed too liquid to be suitable for the anaerobic digestion process; and it was operated at residence times much lower than typical anaerobic digestion [45]. Intriguingly, this suggests that the BES reactor facilitates high rates of anaerobic COD removal, yet this COD is not being converted into current, or subsequently hydrogen.…”

The heat recovery potential of ‘wastewater’: a national analysis of sewage effluent discharge temperatures

“…Importantly, our suggestion of recovering 2.2°C from FSE on a national scale is physically based on over a million temperature measurements and is not an arbitrary temperature as appears to be sometimes used in wastewater heat recovery potential estimates. 14…”

“…Wastewater heat recovery systems implemented in sewers or at WWTW discharge locations have their own advantages and disadvantages. 8,14 In sewers, wastewater temperatures may be higher than at discharge because of closer proximity to source, which is also an advantage in minimising heat loss before reuse. However, sewer flow rates are less consistent than WWTW discharges, wastewaters are much less clean which may negatively affect heat exchangers, retrofitting (and then maintaining) developed complex sewer networks would be a highly disruptive and costly activity, and temperature decreases prior to treatment might negatively affect biological processes within WWTW (a maximum cooling limit of 0.5°C has been suggested).…”

“…8,26 However, the study is only available in German and was only possible because of the provision of private discharge and temperature data for 296 WWTW. An annual 20 TW h of sewer heat recovery potential in the UK has been claimed, 14 but this was only based on a seemingly arbitrary heat recovery temperature of 3°C. Considering the advantages of FSE heat recovery over sewer heat, we use publicly available water quality monitoring records of the English Environment Agency (EA) and air temperature records of the UK Met Office to quantitatively compare FSE, crude sewage, river and air temperatures across England.…”

Opportunities to decarbonize heat in the UK using Urban Wastewater Heat Recovery

“…All the sites considered were collector sewers and trunk sewers collecting the domestic wastewater, rainwater, surface water, etc. Some data have been analysed by the authors forming the series of outputs 5,6,7 on wastewater heat recovery. Further detailed analysis is ongoing and is subject of future publications in this series.…”