A novel zero-liquid discharge desalination system based on the humidification-dehumidification process: A preliminary study

As a byproduct of desalination plants, brine is increasingly becoming a threat to the environment, and the design of zero-liquid discharge (ZLD) systems is gaining increasing attention. Existing ZLD systems are limited by a high energy intensity and high plant costs of their crystallizers. This study proposes a novel crystallization method based on the humidification-dehumidification (HDH) process, which exhibits the advantages of a low energy consumption, low component costs and a reduced scaling and fouling potential. A simple experimental setup is first designed to demonstrate the feasibility of the proposed system. Brine concentration and salt crystallization are successfully achieved with air heated to 40 degrees C as the heat source. Afterwards, a thermo-economic analysis is conducted for the whole system. The specific thermal energy and electricity consumption levels are found to range from 700-900 and 5-11 kJ, respectively, per kg of feed brine. The energy consumption is 56% lower than that of a conventional evaporative crystallizer, and the initial plant cost is reduced by 58%.

Automated summary

This study proposes a novel crystallization method based on the humidification-dehumidification process, which has advantages of low energy consumption, low component costs, and reduced scaling and fouling potential. Experimental results show the feasibility of the proposed system, with energy consumption 56% lower than that of a conventional evaporative crystallizer.