Browsing by Author "Davey, Christopher J."
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Item Open Access Data supporting the publication "Transforming wastewater ammonia to carbon free energy: Integrating fuel cell technology with ammonia stripping for direct power production"(Cranfield University, 2022-03-08 09:18) Davey, Christopher J.; Luqmani, Benjamin A. ; Thomas, Navya; McAdam, EwanData File supporting article titled "Transforming ammonia to carbon free energy: Integrating fuel cell technology with ammonia stripping for direct power production"Item Open Access Data supporting: 'Downscaling reverse osmosis for single-household wastewater reuse: towards low-cost decentralised sanitation through a batch open-loop configuration'(Cranfield University, 2022-10-31 09:16) Thomas, Navya; McAdam, Ewan; Davey, Christopher J.There is a significant demand for water recycling in low-income countries. However, wastewater infrastructure is primarily decentralised, necessitating the development of affordable household-scale reclamation technology. In this study, a batch open-loop reverse osmosis (RO) system is therefore investigated as a low-cost clean water reclamation route from highly saline concentrated blackwaterItem Open Access Downscaling reverse osmosis for single-household wastewater reuse: towards low-cost decentralised sanitation through a batch open-loop configuration(IWA Publishing, 2022-04-15) Davey, Christopher J.; Thomas, Navya; McAdam, EwanThere is a significant demand for water recycling in low-income countries. However, wastewater infrastructure is primarily decentralised, necessitating the development of affordable household-scale reclamation technology. In this study, a batch open-loop reverse osmosis (RO) system is therefore investigated as a low-cost clean water reclamation route from highly saline concentrated blackwater. In a single-stage configuration, increasing feed pressure from 10 to 30 bars improved selective separation at water recovery exceeding 85%, whereas lower cross-flow velocity improved product recovery, reducing specific permeate energy demand from 21 to 4.8 kWh m−3. Rejection achieved for total phosphorous (99%), chemical oxygen demand (COD, 96%), and final pH (8.7) of the RO permeate was compliant with the ISO30500 reuse standard for discharge. However, the rejection of total nitrogen in the RO permeate was non-compliant with the reuse standard due to the transmission of low-molecular weight (MW) uncharged organic compounds. It is suggested that rejection may be improved by increasing feed pressure to rebalance selectivity but may also be controlled by reducing fluid residence time (storage) to constrain the hydrolysis of urea. The economic analysis identified that a high-pressure 1812 element cost of ∼US$30 meets the sanitation affordability index of US$0.05 capita−1 day−1. However, the unit cost of a high-pressure feed pump must be reduced to ∼US$500 to obtain an affordable system cost. These unit costs can be achieved by manufacturing 1812 elements at economies of scale, and by adopting pumping solutions that have been developed for other applications requiring high pressures and low flows. Overall, our findings suggest that RO in the batch open-loop configuration has the potential to deliver affordable and safe water production from blackwater in a decentralised (single-household) context.Item Open Access Figures and tables from "Hybrid membrane distillation reverse electrodialysis configuration for water and energy recovery from human urine: An opportunity for off-grid decentralised sanitation."(Cranfield University, 2019-05-15 14:12) Mercer, Edwina V.; McAdam, Ewan; Davey, Christopher J.; Pidou, Marc; Tyrrel, Sean; Williams, Leon; Jiang, Ying; Parker, Alison; Tierney, Ross; Azzini, Daniele; Eusebi, AnnaThis data compiles the dataset required to generate the tables and figures for the paper - "Hybrid membrane distillation reverse electrodialysis configuration for water and energy recovery from human urine: An opportunity for off-grid decentralised sanitation."Item Open Access Hybrid membrane distillation reverse electrodialysis configuration for water and energy recovery from human urine: an opportunity for off-grid decentralised sanitation(Elsevier, 2019-05-06) Mercer, Edwina V.; Davey, Christopher J.; Azzini, D.; Eusebi, Anna L.; Tierney, Ross; Williams, Leon; Jiang, Ying; Parker, Alison; Tyrrel, Sean; Pidou, Marc; McAdam, EwanThe integration of membrane distillation with reverse electrodialysis has been investigated as a sustainable sanitation solution to provide clean water and electrical power from urine and waste heat. Reverse electrodialysis was integrated to provide the partial remixing of the concentrate (urine) and diluate (permeate) produced from the membrane distillation of urine. Broadly comparable power densities to those of a model salt solution (sodium chloride) were determined during evaluation of the individual and combined contribution of the various monovalent and multivalent inorganic and organic salt constituents in urine. Power densities were improved through raising feed-side temperature and increasing concentration in the concentrate, without observation of limiting behaviour imposed by non-ideal salt and water transport. A further unique contribution of this application is the limited volume of salt concentrate available, which demanded brine recycling to maximise energy recovery analogous to a battery, operating in a ‘state of charge’. During recycle, around 47% of the Gibbs free energy was recoverable with up to 80% of the energy extractable before the concentration difference between the two solutions was halfway towards equilibrium which implies that energy recovery can be optimised with limited effect on permeate quality. This study has provided the first successful demonstration of an integrated MD-RED system for energy recovery from a limited resource, and evidences that the recovered power is sufficient to operate a range of low current fluid pumping technologies that could help deliver off-grid sanitation and clean water recovery at single household scale.Item Open Access Impact of fouling, cleaning and faecal contamination on the separation of water from urine using thermally driven membrane separation(Taylor & Francis, 2018-02-12) Kamranvand, Farhad; Davey, Christopher J.; Sakah, H.; Autin, Olivier; Mercer, Edwina V.; Collins, Matt; Williams, Leon; Kolios, Athanasios; Parker, Alison; Tyrrel, Sean; Cartmell, Elise; McAdam, EwanIn this study, membrane distillation is evaluated as a technology for non-sewered sanitation, using waste heat to enable separation of clean water from urine. Whilst membrane fouling was observed for urine, wetting was not evident and product water quality met the proposed discharge standard, despite concentration of the feed. Fouling was reversible using physical cleaning, which is similar to previous membrane studies operating without pressure as the driving force. High chemical oxygen demand reduction was achieved following faecal contamination, but mass transfer was impeded and wetting occurred which compromised permeate quality, suggesting upstream intervention is demanded to limit the extent of faecal contamination.Item Open Access Integrating crystallisation into transmembrane chemical absorption: Process intensification for ammonia separation from anaerobic digestate(Elsevier, 2020-05-15) Davey, Christopher J.; Hermassi, Mehrez; Allard, E.; Amine, M.; Sweet, N.; Schmieder Gaite, T.; McLeod, A.; McAdam, Ewan J.In this study, reactive crystallisation is introduced into a liquid-liquid membrane contactor for the selective separation, purification and recovery of ammonia from concentrated waste. Whilst liquid-liquid membrane contactor technology has been previously demonstrated for ammonia absorption, further process intensification can be achieved by incorporating crystallisation into transmembrane chemisorption to recover the ammonia as crystalline ammonium sulphate. Reactive crystallisation occurred in the draw solution (sulphuric acid) which was supplied to the lumen-side of the polypropylene hollow-fibre. The ammonium sulphate concentration in the draw solution increased through ammonia mass transfer to supersaturation, at which time induction (the onset of nucleation) commenced. Ammonia mass transfer at draw concentrations above the solubility limit was not limited provided sufficient ‘free’ sulphate was available. This resulted in nucleation which occurred at a low level of supersaturation (C/C*, 1.03) to produce small crystals of around 2.5 μm, which indicated that nucleation was favoured. The nucleation rate was found to be proportional to the ammonia flux in the draw solution. As the solution became more saturated, crystal number increased but crystal growth was comparatively small; this is symptomatic of reactive crystallisation, where the rate of reaction exceeds the rate of mass transfer. Due to the large difference in the ratio between the lumen internal diameter and the mean crystal diameter (dfibre/dmean,CSD, ∼180), no fibre clogging was observed despite facilitating crystallisation on the lumen-side of the membrane. Transmembrane chemisorption crystallisation presents a feasible process intensification for the selective separation of ammonia from environmental applications. For its integration into environmental applications, solutions to wetting and fouling remain due to associative interactions with the complex organic matrix that are practically achievable through engineering intervention. Subsequent transformation of ammonia into a crystalline phase of ammonium sulphate presents a new product which is of commercial interest.Item Open Access Integrating crystallisation into transmembrane chemical absorption: Process intensification for ammonia separation from anaerobic digestate(Cranfield University, 2020-05-04 11:24) Davey, Christopher J.Underlying data for figures in manuscript:Integrating crystallisation into transmembrane chemical absorption: Process intensification for ammonia separation from anaerobic digestateItem Open Access Managing power dissipation in closed-loop reverse electrodialysis to maximise energy recovery during thermal-to-electric conversion(Elsevier, 2020-09-09) Hulme, A. M.; Davey, Christopher J.; Parker, Alison H.; Williams, Leon; Tyrrel, Sean F.; Jiang, Ying; Pidou, Marc; McAdam, EwanWhilst the efficiency of reverse electrodialysis (RED) for thermal-to-electrical conversion has been theoretically demonstrated for low-grade waste heat, the specific configuration and salinity required to manage power generation has been less well described. This study demonstrates that operating RED by recycling feed solutions provides the most suitable configuration for energy recovery from a fixed solution volume, providing a minimum unitary cost for energy production. For a fixed membrane area, recycling feeds achieves energy efficiency seven times higher than single pass (conventional operation), and with an improved power density. However, ionic transport, water flux and concentration polarisation introduce complex temporal effects when concentrated brines are recirculated, that are not ordinarily encountered in single pass systems. Regeneration of the concentration gradient at around 80% energy dissipation was deemed most economically pragmatic, due to the increased resistance to mass transport beyond this threshold. However, this leads to significant exergy destruction that could be improved by interventions to better control ionic build up in the dilute feed. Further improvements to energy efficiency were fostered through optimising current density for each brine concentration independently. Whilst energy efficiency was greatest at lower brine concentrations, the work produced from a fixed volume of feed solution was greatest at higher saline concentrations. Since the thermal-to-electrical conversion proposed is governed by volumetric heat utilisation (distillation to reset the concentration gradient), higher brine concentrations are therefore recommended to improve total system efficiency. Importantly, this study provides new evidence for the configuration and boundary conditions required to realise RED as a practical solution for application to sources of low-grade waste heat in industryItem Open Access Managing power dissipation in closed-loop reverse electrodialysis to maximise energy recovery during thermal-to-electric conversion(Cranfield University, 2020-07-14 11:05) Hulme, Anna; Davey, Christopher J.; Parker, Alison; Williams, Leon; Tyrrel, Sean; Jiang, Ying; Pidou, Marc; McAdam, EwanUnderlying data for the manuscript: Managing power dissipation in closed-loop reverse electrodialysis to maximise energy recovery during thermal-to-electric conversionItem Open Access Membrane Distillation for Concentrated Blackwater: Influence of Configuration (Air Gap, Direct Contact, Vacuum) on Selectivity and Water Productivity(Cranfield University, 2021-02-09 17:16) Davey, Christopher J.Underlying data for associated manuscriptItem Open Access Membrane distillation for concentrated blackwater: Influence of configuration (air gap, direct contact, vacuum) on selectivity and water productivity(Elsevier, 2021-01-30) Davey, Christopher J.; Kamranvand, Farhad; Williams, Leon; Jiang, Ying; Parker, Alison; Tyrrel, Sean; McAdam, Ewan J.Water recovery from concentrated blackwater has been studied using air gap (AGMD), direct contact (DCMD) and vacuum membrane distillation (VMD) to deliver decentralised sanitation. Whilst good water quality was achieved with each configuration, differences in the rejection of volatile compounds was observed. VMD exhibited the highest rejection of volatiles, specifically ammoniacal nitrogen, of all the configurations but fouling inhibited total flux. DCMD exhibited a temperature dependent volatile rejection which resulted in poor rejection at lower feed temperatures (≤40 °C). AGMD was identified as the most promising configuration for application within decentralised sanitation, since the rejection of volatiles was consistent over a range of operating temperatures with ammonia rejection directly related to solution pH. An increase in organic colloids and particles due to faecal contamination reduced COD removal due to the induction of wetting, but was shown to be offset by adoption of a smaller pore size (0.1 μm), and when complemented with upstream solid-liquid separation within a fully integrated system, will provide a robust sanitation solution. Importantly, this work has shown that AGMD can recover water from concentrated blackwater close to international discharge and reuse regulations in a single stage process; this is significant as blackwater consists of only urine and faeces, and is thus 40 times more concentrated than municipal sewage. It is proposed that the water quality produced reflects a step change to delivering safe sanitation, and is complemented by a simple method for heat recovery integration this is similarly advantageous for resource constrained environments common to decentralised sanitation solutions.Item Open Access Membrane distillation of concentrated blackwater: effect of temperature, solids concentration and membrane pore size(Wiley, 2020-11-06) Kamranvand, Farhad; Davey, Christopher J.; Williams, Leon; Parker, Alison; Jiang, Ying; Tyrrel, Sean; McAdam, Ewan J.This study has elucidated the mechanisms governing water recovery from blackwater using membrane distillation, and has clarified the role of the organic particle fraction on membrane performance. Whilst fecal pathogen growth was initially observed at lower temperatures, pathogen inactivation was demonstrated over time, due to urea hydrolysis which liberated ammonia in excess of its toxic threshold. During the growth phase, membrane pore size <0.45 µm was sufficient to achieve high log reduction values for Escherichia coli, due to size exclusion complimented by the liquid–vapor interface which enhances selective transport for water. Higher feed temperatures benefitted rejection by promoting thermal inactivation and suppressing urea hydrolysis. Whilst the mechanism is not yet clear, suppression of hydrolysis reduced bicarbonate formation kinetics stabilizing the ammonia‐ammonium equilibrium which improved ammonium rejection. Blackwater particle concentration was studied by increasing fecal content. Particle fouling improved selectivity for coarse pore membranes but increased mass transfer resistance which reduced flux. Particle fouling induced wetting as noted by an eventual breakthrough of feed into the permeate. We propose that by incorporating upstream solid–liquid separation for particle separation to limit wetting and mass transfer resistance, membrane distillation can be a reliable solution for the recovery of high‐quality permeate from blackwater.Item Open Access Membrane technology for water reuse in decentralised non-sewered sanitation systems: comparison of pressure driven (reverse osmosis) and thermally driven processes (membrane distillation and pervaporation)(Royal Society of Chemistry (RSC), 2024-11-01) Mercer, Edwina V.; Davey, Christopher J.; Bajón Fernández, Yadira; Septien, Santiago; Tyrrel, Sean; Cartmell, Elise; Pidou, Marc; McAdam, Ewan J.Membrane processes are an established barrier technology for water reclamation from wastewater. Applied at a household scale to improve sanitation practice, membrane technology can disrupt the source–receptor pathway, alleviate water scarcity through eliminating flush water and recover clean water for reuse. However, blackwater comprises a distinct composition compared to municipal wastewater, and there is only limited understanding on whether membrane selectivity is sufficient to produce water of sufficient quality for reuse. In this study, pressure driven and thermally driven membranes are evaluated for their potential to treat blackwater, by relating selectivity to relevant water quality standards (ISO 30500) and the transmission of volatile organic compounds (VOCs) that are primarily associated with faecal odour, and thus constitute a critical challenge to water reuse. Both pressure driven (reverse osmosis) and thermally driven (membrane distillation and pervaporation) membranes were able to produce water that conformed to category B of the ISO 30500 standard for the majority of determinants. A critical limiting factor was in the selectivity for ammonia and odorous VOCs which were generally poorly removed by reverse osmosis and membrane distillation. The high ammonia transmission was accounted for by the elevated pH of blackwater which shifted the ammonium equilibria toward volatile ammonia which is poorly separated by RO polymers, and is free to diffuse through the gas-filled micropores of the membrane distillation membrane. In contrast, greater ammonia and VOC separation was evidenced for the pervaporation membrane due to advanced polymer–solute interactions. In a preliminary assessment, the hydrophilicity exhibited by the membrane was also advantageous to withstanding fouling. If complemented with a polishing step to target the residual COD and VOCs (that may be of similar origin), pervaporation could deliver to category A standard for non-potable reuse. This is particularly advantageous for water scarce regions where solar or liquified fuels may be applied in favour of electricity for off-grid sanitation.Item Open Access Quantification of liquid phase faecal odourants to evaluate membrane technology for wastewater reuse from decentralised sanitation facilities(Royal Society of Chemistry, 2018-11-29) Mercer, Edwina V.; Davey, Christopher J.; Campo Moreno, Pablo; Fowler, Dawn; Williams, Leon; Kolios, Athanasios; Parker, Alison; Tyrrel, Sean; Walton, Christopher; Cartmell, Elise; Pidou, Marc; McAdam, Ewan J.Public willingness to use decentralised sanitation facilities or arising water products is discouraged due to malodour, preventing improved sanitation practices or water reuse opportunities in low income countries Whilst odour is characterised in the gas phase, it originates in the liquid phase. Consequently, controlling odour at source could prevent gas-phase partitioning and limit produced water contamination. This study therefore developed an analytical method for the quantitation of a range of liquid phase volatile organic compounds (VOCs) classified into eight chemical groups, known to be primary indicators of faecal odour, to provide characterisation of real fluids and to permit evaluation of several potential membrane separation technologies for liquid phase odourant separation. The gas chromatography mass spectrometry method provided quantitation in the range of 0.005 mg L-1 to 100 mg L-1 with instrument detection limits ranging from 0.005 mg L-1 to 0.124 mg L-1. Linear calibration curves were achieved (r2 >0.99) with acceptable accuracy (77-115%) and precision (<15%) for quantitation in the calibration range below 1 mg L 1, and good accuracy (98-104%) and precision (<2%) determined for calibration in the range 1-100 mg L-1. Pre-concentration of real samples was facilitated via solid phase extraction. Subsequent application of the method to the evaluation of two thermally driven membranes based on hydrophilic (polyvinyl alcohol) and hydrophobic (polydimethylsiloxane) polymers evidenced contrasting separation profiles. Importantly, this study demonstrates the methods utility for liquid phase VOC determination which is of use to a range of disciplines, including healthcare professionals, taste and odour specialists and public health engineers.Item Open Access Scale-up of reverse electrodialysis for energy generation from high concentration salinity gradients(Elsevier, 2021-03-05) Hulme, Anna; Davey, Christopher J.; Tyrrel, Sean; Pidou, Marc; McAdam, EwanWhilst reverse electrodialysis (RED) has been extensively characterised for saline gradient energy from seawater/river water (0.5 M/0.02 M), less is known about RED stack design for high concentration salinity gradients (4 M/0.02 M), important to closed loop applications (e.g. thermal-to-electrical, energy storage). This study therefore focuses on the scale-up of RED stacks for high concentration salinity gradients. Higher velocities were required to attain a maximum Open Circuit Voltage (OCV) for 4 M/0.02 M, which gives a measure of the electrochemical potential of the cell. The experimental OCV was also much below the theoretical OCV, due to the greater boundary layer resistance observed, which is distinct from 0.5 M/0.02 M. However, negative net power density (net produced electrical power divided by total membrane area) was demonstrated with 0.5 M/0.02 M for larger stacks using shorter residence times (three stack sizes tested: 10 × 10cm, 10 × 20cm and 10 × 40cm). In contrast, the highest net power density was observed at the shortest residence time for the 4 M/0.02 M concentration gradient, as the increased ionic flux compensated for the pressure drop. Whilst comparable net power densities were determined for the 10 × 10cm and 10 × 40cm stacks using the 4 M/0.02 M concentration gradient, the osmotic and ionic transport mechanisms are distinct. Increasing cell pair number improved maximum current density. This subsequently increased power density, due to the reduction in boundary layer resistance, and may therefore be used to improve thermodynamic efficiency and power density from RED for high concentrations. Although comparable power densities may be achieved for small and large stacks, large stacks maybe preferred for high concentration salinity gradients due to the comparative benefit in thermodynamic efficiency in single pass. The greater current achieved by large stacks may also be complemented by an increase in cell pair number and current density optimisation to increase power density and reduce exergy losses.Item Open Access Scale-up of reverse electrodialysis for energy generation from high concentration salinity gradients(Cranfield University, 2021-02-11 09:50) Hulme, Anna; Davey, Christopher J.; Tyrrel, Sean; Pidou, Marc; McAdam, EwanUnderlying data for manuscript.Item Open Access Transforming wastewater ammonia to carbon free energy: Integrating fuel cell technology with ammonia stripping for direct power production(Elsevier, 2022-03-07) Davey, Christopher J.; Luqmani, Benjamin A. ; Thomas, Navya; McAdam, Ewan J.The transformation of ammonia from pollutant to energy rich carbon free fuel presents an opportunity for the transition of wastewater services to net zero. However, there is only limited knowledge of how the product quality of ammonia recovered from real wastewater might impact on its downstream exploitation in fuel cells. This study therefore exploited vacuum stripping to produce an aqueous ammonia concentrate from real wastewater that was then evaluated within a direct ammonia fuel cell, as a reference technology for energy generation. A 17 g L−1 aqueous ammonia product was created by vacuum stripping centrate from a full-scale anaerobic digester (2 gN L−1). The pH of the product was lower than expected due to the mild-acidification of solution by the co-transport of low MW volatile organic compounds. This reduced power density in the fuel cell, due to the incomplete deprotonation of ammonia (lowering oxidation potential at the fuel cell anode) and a decrease in [OH–] which is required for complete electrochemical conversion. We propose that improved vacuum stripping design can increase the distillate ammonia concentration and produce a more alkaline product, yielding markedly higher fuel cell power density by enhancing ammonia oxidation at the anode (through concentration and deprotonation) and reducing [OH–] mass transfer limitations. As the separation energy for ammonia is dominated by the latent heat demand of water vapour, a synergy exists between creation of a concentrated ammonia product (that improves power density) and reducing the energy demand for separation. The energy balance from this research evidences that despite the high latent heat demand for separation, the low cost of heat coupled with the power produced from ammonia yield a favourable economic return when compared to conventional biological treatment. This study also identifies that revaluing ammonia as a carbon free fuel can help reposition wastewater treatment for a zero-carbon future.Item Open Access Transitioning from electrodialysis to reverse electrodialysis stack design for energy generation from high concentration salinity gradients(Elsevier, 2021-07-08) Hulme, A. M.; Davey, Christopher J.; Tyrrel, Sean; Pidou, Marc; McAdam, Ewan J.In this study, stack design for high concentration gradient reverse electrodialysis operating in recycle is addressed. High concentration gradients introduce complex transport phenomena, which are exacerbated when recycling feeds; a strategy employed to improve system level energy efficiency. This unique challenge indicates that membrane properties and spacer thickness requirements may differ considerably from reverse electrodialysis for lower concentration gradients (e.g. seawater/river water), drawing closer parallels to electrodialysis stack design. Consequently, commercially available electrodialysis and reverse electrodialysis stack design was first compared for power generation from high concentration gradients. Higher gross power densities were identified for the reverse electrodialysis stack, due to the use of thinner membranes characterised by a higher permselectivity, which improved current. However, energy efficiency of the electrodialysis stack was twice that recorded for the reverse electrodialysis stack at low current densities, which was attributed to: (i) an increased residence time provided by the larger intermembrane distance, and (ii) reduced exergy losses of the electrodialysis membranes, which provided comparatively lower water permeance. Further in-depth investigation into membrane properties and spacer thickness identified that membranes characterised by an intermediate water permeability and ohmic resistance provided the highest power density and energy efficiency (Neosepta ACS/CMS), while wider intermembrane distances up to 0.3 mm improved energy efficiency. This study confirms that reverse electrodialysis stacks for high concentration gradients in recycle therefore demand design more comparable to electrodialysis stacks to drive energy efficiency, but when selecting membrane properties, the trade-off with permselectivity must also be considered to ensure economic viability.Item Open Access Ultrafiltration pretreatment enhances membrane distillation flux, resilience and permeate quality during water recovery from concentrated blackwater (urine/faeces)(Elsevier, 2020-08-08) Kamranvand, Farhad; Davey, Christopher J.; Williams, Leon; Parker, Alison; Jiang, Y.; Tyrrel, Sean; McAdam, Ewan J.In this study, the pretreatment of concentrated blackwater using ultrafiltration (UF) was shown to improve the permeability, selectivity and robustness of membrane distillation (MD) for application to wastewater treatment. Concentrated blackwater comprises urine and faeces, with minimal flushwater added. The faecal contribution increased the soluble organic fraction and introduced coarse and colloidal particles into the urine, which increased resistance to filtration during dead-end UF. Ultrafiltration removed the particulate and colloidal fractions (MW > 500 kDa) from the blackwater, which permitted similar permeability and robustness for MD to that observed with urine (29.9 vs 25.9 kg m−2 h−1), which comprises a lower colloidal organic concentration. Without UF pretreatment, a higher density organic layer formed on the MD surface (197 vs 70 gCOD m−2) which reduced mass transfer, and transformed the contact angle from hydrophobic to hydrophilic (144.9° to 49.8°), leading to pore wetting and a dissipation in product water quality due to breakthrough. In comparison, with UF pretreatment, MD delivered permeate water quality to standards satisfactory for discharge or reuse. This is particularly timely as the ISO standard for non-sewered sanitation has been adopted by several countries at a national level, and to date there are relatively few technologies to achieve the treatment standard. Membrane distillation provides a robust means for concentrated blackwater treatment, and since the energy required for separation is primarily heat, this advanced treatment can be delivered into areas with more fragile power networks.