The acidic nature of mine water results in elevated concentrations of heavy metals, implying significant pressures on aquatic ecosystems. Mine water treatment consists of objectives: reducing environmental harm by removing contaminants and providing alternative water sources and enabling metal recovery. This study employed forward osmosis to evaluate the treatment of simulated mine water, investigating the effects of draw solution concentration (0.5 and 1 M EDTA), pH levels (4, 7, and 9), ultrasonic parameters (frequencies of 28 kHz and 40 kHz with continuous and pulsed operation modes), and membrane orientation. The research specifically investigated the effect of time as a key factor in evaluating retention changes of heavy metals (Pb, Zn, Fe). The overall trend in metal retention efficiency exhibited a gradual decline over time, primarily influenced by various operational factors. Continuous ultrasonication enhanced performance when the support layer faced the feed solution, whereas pulsed mode was more effective with the active layer, yielding rejection efficiencies in the order Fe < Pb < Zn. Differential Scanning Calorimetry (DSC) revealed that ultrasonic vibrations during FO led to the highest glass transition temperature (Tg = 62.75°C), confirming a greater average water flow (AWF) in US-FO-28 compared to the baseline. Ultrasonication increased the crystallinity index (CI) of the membrane by 42% relative to the pristine membrane. Atomic Force Microscopy (AFM) further supported these improvements, showing a decrease in root mean square roughness (Rq) at 28 kHz.
Yazdani et al. (Wed,) studied this question.