1,720,980 research outputs found
Membrane-based technologies for the production of high-quality water from contaminated sources: from lab experiments to full-scale system design
Full text linkL'abstract è presente nell'allegato / the abstract is in the attachmen
Desalination of brackish groundwater and reuse of wastewater by forward osmosis coupled with nanofiltration for draw solution recovery
Full text linkCoupling loose nanofiltration and advanced oxidation for the abatement of micropollutants from wastewater effluents
No full textOptimization of physico-chemical and membrane filtration processes to remove high molecular weight polymers from produced water in enhanced oil recovery operations
Full text linkPolymer flooding is an enhanced oil recovery technique to extract the large portion of leftover subsurface oil following conventional extraction methods. In the flooding process, a long-chain polymer, such as partially hydrolyzed polyacrylamide (HPAM), is added to the displacing fluid to increase the mobility and extraction of the oil phase. Nevertheless, the challenge of managing produced water from polymer flooding operations is high because residual HPAM results in significantly high viscosity and organic content in the stream. Commonly used methods for produced water treatment, such as gravity settling and flotation, cannot be applied to obtain a purified stream efficiently, while innovative techniques are not yet feasible in practical operations. In this work, a simple method of polymer precipitation prompted by divalent ions is evaluated, optimized, and compared to membrane ultrafiltration. The physico-chemical properties of the HPAM are investigated and polymer precipitation tests are conducted by varying the main operational parameters, including pH, salinity, temperature, calcium and/or magnesium concentration, and polymer concentration. Response surface developed by central composite design method is used to optimize the process and identify the correct dosage of divalent cations coagulants and pH, the two main factors promoting HPAM separation. The removal of HPAM is well-described and maximized (>85%) by the model, which is also validated on three synthetic samples representing real wastewaters from polymer flooding applications. Optimized ultrafiltration, using ceramic membranes with surface pore size of 15 kDa, also shows the ability to remove HPAM effectively from water, but the precipitation method seems to be more versatile and easier to apply. The two processes, precipitation and ultrafiltration, may potentially be used in sequence as they complement each other in several ways
Design and performance of a nanofiltration plant for the removal of chromium aimed at the production of safe potable water
Full text linkEnvironmental impacts of detergents and benefits of their recovery in the laundering industry
No full textDetergents are important compounds in numerous industrial processes with laundering industry being among their largest consumers. Due to their wide application, detergents are continuously developed to meet higher quality and environmental standards. Following this trend, this study discusses a life cycle analysis conducted on different detergents and industrial washing systems. In particular, detergent production, use, and feasible recovery in the laundering industry is evaluated. Detergent production shows wide impact distribution related to the various detergent sources, with a large influence on the ecosystem compared to the other impact categories. Calculations of the primary energy demand and the global warming potential reveal the fundamental role of the application of renewable resources in the detergent production phase. The calculated contribution of detergents in the overall impacts of washing processes is also significant: detergent use and discharge represent crucial issues to be addressed to reduce the environmental burdens of the laundering industry. Two membrane-based processes are thus proposed to recover water and detergents coupling the washing cycle with wastewater treatment and partial reuse. Addition of membrane setups to existing washing systems has negligible environmental burdens and energy demand, but it results in significant environmental gains: up to 50% of the overall impact can be reduced thanks to the recovery of resources in situ
Ultrafiltration to reuse laundering wash water: evaluation of membranes and permeate flux
No full textLaundering industry consumes and discharges large amounts of water and surfactants, and the demand of surface active agents used for washing is increasing worldwide. Some of these substances are considered contaminants of emerging concern, as they persist in the environment. This work aimed at evaluating the feasibility of ultrafiltration as a method to treat the wash wastewater and possibly reuse the surfactant-rich permeate stream in laundry facilities. In particular, evaluation of surfactant recovery was performed through analysis of the permeate flux and properties obtained through polymeric and ceramic membranes. Wash water samples were collected at an industrial laundering facility for hospital linen and filtered through different ultrafiltration membranes with varying molecular weight cut-off. The critical micelle concentration of the detergent was quantified, and capillarity measurements were used to determine the concentration of free surfactants in water. The system was designed to comprise two filtration steps in series: a pre-filtration step did not allow recovery of surfactant or the production of a high quality permeate, but it was necessary to remove large contaminants and to minimize the amount of foulants in the feed water of the second filtration, from which reusable permeates were finally produced. Recovery of 43% and 39% of reusable surfactants were achieved using polymeric and ceramic membranes, respectively. Results suggest the existence of an optimal molecular weight cut-off, which for this work was equal to approximately 6 kDa. Since the operation temperature may have significant impact on the energy requirements of the washing process, the influence of feed water temperature on surfactant recovery was also preliminary investigated. Results suggested the possibility to recover water and surfactants by directly treating wastewater streams of high temperature and the potential of integrating an ultrafiltration system in large laundering facilities.</p
Ultrafiltration Membranes Functionalized with Polydopamine with Enhanced Contaminant Removal by Adsorption
Full text linkPromising chemical stable membranes developed through combined effect of radical polymerization and non – solvent induced phase separation of acrylic functionalized polysulfone
No full textAchieving low concentrations of chromium in drinking water by nanofiltration: membrane performance and selection
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