Abstract

Globally, freshwater consumption has increased for many reasons, including industrialisation, which is especially complex in areas affected by water scarcity. An example of this is the scallop culture industry, which uses potable for washing systems and generates wet sludge. The water contained in this waste evaporates and is released into the atmosphere in the form of unused steam. In order to evaluate the recovery of this water, the use of two sizes of heat exchanger (10- and 16- tube configuration) and Peltier modules (2 and 4 plates) to condense the vapour was studied. For this, an adapted humidification-dehumidification process (HDH) with a closed water-open air cycle was used in areas of water scarcity, such as northern Chile, where scallops are farmed. The volume of water recovered with the heat exchanger was higher with the 16-tube system than with the 10-tube system, obtaining total volumes of 2000 mL and 1680 mL, respectively. The highest gained output ratio (GOR) values achieved with the 10- and 16-tube heat exchangers were 2.2 and 2.6, respectively. In the case of the Peltier modules, the GOR values were 0.27 and 0.25 with 2 and 4 plates, respectively. The electrical conductivity of the condensate was 163 mu S/cm. The condensation performance of the processes was 0.915 and 1 for the heat exchangers with 10 and 16 tubes, respectively and, 0.063 and 0.145 for Peltier modules with 2 and 4 plates, respectively. Economically, HDH with Peltier plate dehumidifiers required a lower investment than tube heat exchangers: Peltier modules with 2 and 4 plates required 0.00058 and 0.00054 US$/L, respectively, and heat exchangers with 10- and 16- tubes required an investment of 0.00029 and 0.00027 US$/L, respectively. However, when the investment, operational costs and recovery time were referred to as reclaimed water units, the performance was better for tube heat exchanger dehumidifiers.