The rejection of emerging trace organics by a variety of commercial reverse osmosis (RO), nanofiltration (NF), and ultra-low-pressure RO (ULPRO) membranes was investigated using TFC-HR, NF-90, ...NF-200, TFC-SR2, and XLE spiral membrane elements (Koch Membrane Systems, Wilmington, Massachusetts) to simulate operational conditions for drinking-water treatment and wastewater reclamation. In general, the presence of effluent organic matter (EfOM) improved the rejection of ionic organics by tight NF and RO membranes, as compared to a type-II water matrix (adjusted by ionic strength and hardness), likely as a result of a decreased negatively charged membrane surface. Rejection of ionic pharmaceutical residues and pesticides exceeded 95% by NF-90, XLE, and TFC-HR membranes and was above 89% for the NF-200 membrane. Hydrophobic nonionic compounds, such as bromoform and chloroform, exhibited a high initial rejection, as a result of both hydrophobic-hydrophobic solute-membrane interactions and steric exclusion, but rejection decreased significantly after 10 hours of operation because of partitioning of solutes through the membranes. This resulted in a partial removal of disinfection byproducts by the RO membrane TFC-HR. In a type-II water matrix, the effect of increasing feed water recoveries on rejection of hydrophilic ionic and nonionic compounds was compound-dependent and not consistent for different membranes. The presence of EfOM, however, could neutralize the effect of hydrodynamic operating condition on rejection performance. The ULPRO and tight NF membranes were operated at lower feed pressure, as compared to the TFC-HR, and provided a product water quality similar to a conventional RO membrane, regarding trace organics of interest.
Summary form only given. Electrical discharge plasma is an effective and versatile advanced oxidation process due to the formation of reactive species such as hydroxyl radicals and hydroperoxyl ...radicals. The technology requires no chemical additions, can degrade a broad range of contaminants, and produces no residual waste. Plasma treatment also includes a broad range of other treatment mechanisms, including electron-based reduction, UV radiation, cavitation, and thermal degradation. Despite the obvious benefits and advantages of Plasma-based Water Treatment (PWT), the technology has not yet reached a level of development where it can be commercially used. This study determined the main obstacles hindering the implementation of PWT and developed design principles for overcoming the process limitations through control of the plasma-liquid interphase dynamics. We have determined the efficacy of the plasma process for treatment of a wide range of different compounds and used the results of this investigation to construct a model to predict the approximate treatability of any compound based on just a few of the compound's physical properties. Using particle imaging velocimetry we have further characterized the dynamic nature of the plasma-liquid interface and bulk liquid flow as a function of selected design and process parameters. Insights gained from this part of the study provided design guidance in scaling up of the plasma reactor, which features several novel design aspects to exploit bulk liquid and interfacial flow phenomena to enhance the exposure of chemical contaminants to the plasma. The scaled-up reactor was then tested on a few of the compounds deemed most treatable by the predictive model, including perfluorooctanoic acid and perfluorooctanesulfonic acid. The efficiency and relative competitiveness of the scaled-up plasma process.
Brine Management Bellona, Christopher
A Multidisciplinary Introduction to Desalination,
2018
Book Chapter
The need for desalination in regions with few disposal options has led to the development of approaches to minimize brine or concentrate volumes mainly through treatment and optimizing product water ...recovery. Juby et al. performed a study for the Eastern Municipal Water District in California to determine the best brackish water desalination brine management strategy to increase potable water recovery and decrease the volume of brine requiring disposal. A water reuse facility in Southern California added a secondary reverse osmosis (RO) system to allow for plant expansion while maintaining the same concentrate flow rate that is subsequently sent to a wastewater treatment plant. A number of treatment schemes using electrodialysis and electrodialysis reversal have been proposed for desalination, RO brine/concentrate minimization, zero liquid discharge applications, and salt production from brine and concentrates. As an alternative to solar evaporation/precipitation, several researchers have suggested that potassium could be produced from RO concentrate using an evaporation/crystallization process.
Nanofiltration (NF) and reverse osmosis (RO) for drinking water augmentation are compared. Because of the relatively high fouling potential of the feedwater, the initial high specific flux (SF) rates ...of the TMG 10 and NF-90 membranes, as observed during both laboratory- and pilot-scale testing, are reduced to values similar to those for the commonly used ultra low-pressure RO (ULPRO) membrane ESPA2, but exceed those for the conventional RO membrane TFC-HR. Rejection performance for unregulated trace organic contaminants is similar among membranes tested and monitored at pilot and full scale, indicating that certain NF membranes, ULPRO membranes, and RO membranes are an effective barrier for the pharmaceutically active compounds (PhACs), PCPs, and endocrine disrupting compounds (EDCs).
