Experimental study on the mechanism and efficiency of a closed-cycle low-temperature evaporation system for treating high salt and high organic matter wastewater

With the rapid development of the economy and the increasingly strict environmental regulations, the treatment of high-salt and high-organic wastewater has received increasing attention. The development of a technology that can effectively treat high salt and high organic wastewater is necessary. In this paper, the mechanism and efficiency of a closed-cycle low-temperature evaporation system for treating high-salt high-organic wastewater were investigated. The system consists of a humidifier, two dehumidifiers and a heat pump unit. The operation mechanism and efficiency of the system were investigated using a laboratory configuration of high salt and high organic wastewater as the treatment target. The system performance was affected by two main operating parameters: (a) the increase in wastewater flow increased the productivity and GOR by 6.9 % and 4.1 %, respectively; and (b) the increase in airflow improved the heat transfer efficiency of the humidifier and the two-stage dehumidifier, which resulted in a significant improvement in the system performance, with an increase in productivity by 4.8 % and 4.9 %, respectively. The closed-cycle low-temperature evaporation system achieved 99.99 % and 100 % removal of the total dissolved solids (TDS) and chemical oxygen demand (COD) from wastewater, respectively. This system provides a new idea and method for the treatment of high salt and high organic matter wastewater, which has important theoretical and engineering application value.