The hydrothermal solution for self-sustaining drinking water purification at point of use

Decentralized drinking water purification complements water supply in areas with unreliable or absent infrastructure. The exacerbating consequences of climate change in form of droughts and floods force remote households to tap various water sources. Hence, household-based processes must be versatile to cope with e.g. contaminated ground water and turbid surface waters. Purification at household level must be self-sustaining in order to enable independence from continuous supply of power and consumables. In this study, we design a process accordingly and we prove its technical feasibility on pilot scale. The two-step process utilizes gravity-driven ultrafiltration and activated carbon adsorption to purify water, whereas the process regeneration is accomplished by combining Temperature Enhanced Backwash and Temperature Swing Adsorption to clean the membrane and adsorber, respectively. We obtained stable operation over >40 days with a sustained flowrate of ∼5 Lh^-1 and consistent product quality (turbidity ≤0.2 NTU) for all relevant water matrices: synthetic ground water, river water and even secondary effluent. We achieved a high removal of the spiked model micropollutant amitrole, environmental endocrine disruptors and bulk dissolved organics of ∼93%, >65% and ∼69%, respectively, at the optimal water recovery for river water of ∼80%. In-situ regeneration promises long-term, self-sufficient operation without exhaustion.