A feasibility study of municipal wastewater desalination using electrodialysis reversal to provide recycled water for horticultural irrigation

A membrane desalination system based on electrodialysis reversal (EDR) has been evaluated for its capacity to remove salt from treated municipal wastewater to provide a source of recycled water for horticultural applications. Economic and technical feasibility was determined using data collected from a pilot scale plant, from which the following parameters were calculated: salt removal, water recovery and overall process economics. The pilot plant consisted of a pre-treatment multimedia filtration unit (MMF) and an EDR system with a capacity of approximately 144. kL/day. Treated effluent from a wastewater treatment plant (WWTP) was used as feed water for the desalination pilot plant. Water quality guidelines for horticulture specify an upper limit for total dissolved solids (TDS) of 375. mg/L. The EDR process reduced the TDS from 1104. mg/L to 328. mg/L. Additionally, the process reduced the conductivity of recycled water by 72%, including the removal of 84% calcium, 76% chloride, 59% fluoride, 64% alkalinity and 60% phosphate, demonstrating that the EDR treated water is a viable alternative supply. The power consumption of the EDR plant was found to be 0.6. kW. h/kL and the media filtration 0.4. kW/kL. The total operating cost was estimated to be 18. cents/kL to deliver 82% water recovery.</p

Post-Synthetic Annealing: Linker Self-Exchange in UiO-66 and Its Effect on Polymer–Metal Organic Framework Interaction

Post-synthetic exchange (PSE) and defect engineering have emerged as powerful techniques for tuning the properties and introducing novel functionality to metal organic frameworks (MOFs). Growing evidence suggests that each technique plays a key role in the mechanism of the other: linker coordination chemistry is pivotal to defective frameworks, while defect sites can help initiate PSE. Here, the intersection of these approaches is explored by exchanging an MOF with linkers already present within the framework. Post-synthetic annealing (PSA) modifies an MOF’s properties by redistributing the framework’s mixture of bound linker/modulator species. Using changes to the polymer-additive interactions in poly-1-trimethylsilyl-1-propyne nanocomposites observed through aging, we demonstrate that PSA causes one linker species to preferentially accumulate on the MOF’s crystal surface. Reaction conditions are shown to affect molecular composition of the resulting annealed UiO-66 MOFs, a finding explained through established reaction constants. This work simultaneously reveals intricacies of post-synthetic modification chemistry and presents a facile means of tuning MOFs and MOF nanocomposites