Experimental study of multi-effect membrane distillation (MEMD) for treatment of water containing inorganic salts

Abstract

A novel multi-effect membrane distillation (MEMD) process has been implemented to treat water containing four different inorganic solutes. The 4-stage MEMD module was developed based on the air-gap configuration. The influence of operating parameters like concentration, feed temperature, flow rate and operating time on permeate fluxes of zinc sulfate, sodium fluoride, magnesium chloride and sodium carbonate solutions was observed. Concentration had negligible effect on the MEMD's permeate flux, while its performance increased with increasing feed temperature and flow rate. Its separation efficiency was stable at more than99.91% throughout the experiment. In addition, its specific energy consumption after the recovery of the latent heat of vaporization and sensible heat of brine was measured at different component concentrations and found to be independent of the type of component.

Ti/RuO2-IrO2-SnO2 Anode for Electrochemical Degradation of Pollutants in Pharmaceutical Wastewater: Optimization and Degradation Performances

“…As shown in Figure 6b, in the process of enhancing the current density from 1 to 8 mA/cm 2 , the degradation efficiency showed the simultaneously increasing trend. With the increase in current density, the rate and intensity of charge transfer also increase, thereby promoting the formation of active intermediates and increasing the degradation efficiency of pollutant in wastewater [34,35]. It may be that the side reactions also occur on the electrode surface under too high current density, and the concentration of the active group decreases, thereby reducing the efficiency of reaction electrolysis and increasing energy consumption.…”

Gray water treatment by air-gap multi-effect membrane distillation with pre-treatment by electrocoagulation

“…To overcome the above limitations requires the implementation of the multi-effect concept in a traditional MD module. As referred by Liu et al (2012), Zhao et al (2013), Lu et al (2012) and Pangarkar & Deshmukh (2015), Pangarkar et al (2016b), the following are the advantages of MEMD over traditional MD: (i) Less energy is required for heating the feed water due to internal latent heat recovery, (ii) low grade waste heat or solar energy can be used efficiently, (iii) high rate of water production due to the number of stages, (iv) less cooling water consumption, (v) the MEMD process has a high thermal efficiency, gain output ratio (GOR), and is stable and reliable, (vii) it has lower maintenance cost and 24 hours continuous operation with minimum supervision.…”