In this research, a novel heat-localized solar thermal membrane distillation system is developed to produce drinking water from untreated surface water, wastewater, and seawater. The system is mainly comprised of a feed water chamber, a nanoparticle-coated membrane, and a distillate chamber. The membrane absorbs solar thermal energy and localizes it in the pores and near region of the membrane where the feed water is efficiently vaporized without losing much heat to the bulk water. This system relies solely on the solar radiation and does not require any electrical energy. Experiments were conducted under both simulated and natural sunlight. Under the simulated sunlight, the distillate production rate was up to 1.48 kg/(m2 h) at an irradiance of 900 W/m2. Under natural sunlight, the distillate production rates were 4.51 and 8.56 kg/(m2 day) at daily average irradiances of 386 and 578 W/m2, respectively. The distillate had low turbidity (0.11~0.21 NTU), electrical conductivity (51~400 µS/cm), chemical oxygen demand (2.3~9.2 mg/L), and no bacteria or protozoa, in spite of the type of feed water (i.e., wastewater, canal water, and seawater). The formation of fouling on the feed side of the membrane and the effect of fouling on the distillate production rate and water quality was assessed in long-term experiments. The results show that the fouling was insignificant in reducing production rate after 23 days of distillation of seawater or 13 days of distillation of canal water. The production rate of distillate from municipal wastewater declined significantly with time due to severe fouling after 8 days. However, the turbidity and electrical conductivity of the distillate remained satisfactory for all types of feed water throughout the long-term experiments. Having a high production rate, good distilled water quality, and operational simplicity, this device could be an affordable solution for providing farmers with potable water in underdeveloped areas.

Nanoparticle-enabled integrated solar thermal membrane distillation system

2019 Spring National Meeting

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