ABSTRACT
The demand to effectively treat medical wastewater has escalated with the much greater use of antiviral drugs since the COVID-19 pandemic. Forward osmosis (FO) has great potential in wastewater treatment only when appropriate draw solutes are available. Here, we synthesize a series of smart organic-inorganic polyoxomolybdates (POMs), namely, (NH4)6[Mo7O24], (PrNH3)6[Mo7O24], (iPrNH3)6[Mo7O24], and (BuNH3)6[Mo7O24], for FO to treat antiviral-drug wastewater. Influential factors of separation performance have been systematically studied by tailoring the structure, organic characteristics, and cation chain length of POMs. POMs at 0.4 M produce water fluxes ranging from 14.0 to 16.4 LMH with negligible solute losses, at least 116% higher than those of NaCl, NH4HCO3, and other draw solutes. (NH4)6[Mo7O24] creates a water flux of 11.2 LMH, increased by more than 200% compared to that of NaCl and NH4HCO3 in long-term antiviral-drug wastewater reclamation. Remarkably, the drugs treated with NH4HCO3 and NaCl are either contaminated or denatured, while those with (NH4)6[Mo7O24] remain intact. Moreover, these POMs are recovered by sunlight-assisted acidification owing to their light and pH dual sensitivity and reusability for FO. POMs prove their suitability as draw solutes and demonstrate their superiority over the commonly studied draw solutes in wastewater treatment.
Subject(s)
COVID-19 , Water Purification , Humans , Wastewater , Sodium Chloride , Pandemics , Membranes, Artificial , Osmosis , Solutions/chemistry , Water/chemistryABSTRACT
In dental clinics, the infections may be acquired through contaminated devices, air, and water. Aerosolized water may contain bacteria, grown into the biofilm of dental unit waterlines (DUWLs). We evaluated a disinfection method based on water osmosis and chlorination with chlorine dioxide (O-CD), applied to DUWL of five dental clinics. Municipal water was chlorinated with O-CD device before feeding all DUWLs. Samplings were performed on water/air samples in order to research total microbial counts at 22-37 °C, Pseudomonas aeruginosa, Legionella spp., and chlorine values. Water was collected from the taps, spittoons, and air/water syringes. Air was sampled before, during, and after 15 min of aerosolizing procedure. Legionella and P. aeruginosa resulted as absent in all water samples, which presented total microbial counts almost always at 0 CFU/mL. Mean values of total chlorine ranged from 0.18-0.23 mg/L. Air samples resulted as free from Legionella spp. and Pseudomonas aeruginosa. Total microbial counts decreased from the pre-aerosolizing (mean 2.1 × 102 CFU/m3) to the post-aerosolizing samples (mean 1.5 × 10 CFU/m3), while chlorine values increased from 0 to 0.06 mg/L. O-CD resulted as effective against the biofilm formation in DUWLs. The presence of residual activity of chlorine dioxide also allowed the bacteria reduction from air, at least at one meter from the aerosolizing source.