Tributyl tetradecyl phosphonium chloride for biofouling control in reverse osmosis processes

Secondary effluent reclamation and reuse has been considered as an alternative for agricultural irrigation water. Whilst all constituents in the reclaimed wastewater could affect plant growth and soil characteristics, the most important parameters for agricultural irrigation are salinity and SAR (Sodium Adsorption Ratio). Salinity affects the availability of crop water and sodium causes clay soils to disperse. Membrane technologies, especially NF (Nano-Filtration) and RO (Reverse Osmosis), have played in a key role reclaiming the secondary effluent. RO can remove monovalent and divalent cations simultaneously. However NF processes reject preferably divalent cations and most monovalent ions are allowed to pass through the NF membranes. This could make them have different SAR values for both NF and RO processes. Therefore the primary objective of this study is to examine if the SAR values of the reclaimed water could be changed while they undergo NF and RO processes. The measured SAR values of the secondary effluent, NF permeate, and RO permeate were 1.78, 4.67, and 0.72 respectively. The SAR value after NF (4.67) increased to more than twice that of the feed solution, whereas the SAR of the RO permeate decreased to 0.72. In general, the higher SAR the water has, the greater risk the soils have. Although the SAR value after NF was within the safe range, this increased SAR value will affect permeability of soil, thus limiting the reclaimed wastewater use for as agricultural irrigation water. Consequently, when the NF system is used for the reclamation of the secondary effluent, SAR has to be examined first because potentially it tends to increase the SAR value.

Reverse osmosis uses nonporous membranes and can separate down to the ionic level, e.g. seawater in the rejection of dissolved salt. This chapter focuses on reverse osmosis because of its widespread use in desalination applications. The reverse osmosis process and membrane principles and applications are addressed through a review of the role of osmosis, reverse osmosis equipment, describing equations, other membrane processes, and membrane process applications. The membranes used for reverse osmosis processes are characterized by a high degree of semi-permeability, high water flux, mechanical strength, chemical stability, and relatively low operating and high capital costs. Ultrafiltration, microfiltration, and gas permeation are also briefly reviewed. Six illustrative examples of concepts and implementation of reverse osmosis and membrane desalination processes are provided at the end of the chapter.

Performance of a pilot-scale reverse osmosis process for water recovery from biologically-treated textile wastewater

Influence of microbubble two-phase feed flow on reverse osmosis desalination using different salt concentrations

Fuzzy logic control of a brackish water reverse osmosis desalination process

Energy efficiency of batch and semi-batch (CCRO) reverse osmosis desalination

Integration and optimization of pressure retarded osmosis with reverse osmosis for power generation and high efficiency desalination

Unlocking the potential of thin-film composite reverse osmosis membrane performance: Insights from mass transfer modeling

Recently, there has been a special research focus on the bioconversion of glycerol to 1,3-propanediol (1,3-PD) due to its significance in the chemical industry. However, the treatment and separation of fermentation broths is a great challenge. Currently, the reverse osmosis (RO) process is a reliable state-of-the-art technique for separation of biological solutions. This study (as the first to do so) investigated the feasibility of separation of 1,3-PD broths with the use of cellulose acetate (CA) membrane by the RO process. The experiments were carried out using the installation equipped with the plate module, under the transmembrane pressure (TMP) and temperature of 1 MPa and 298 K, respectively. It was found that the used membrane was suitable for broth separation. Indeed, it was noted that 1,3-PD, as a target product, migrated through the membrane; meanwhile, other broth components were rejected in various degrees. Moreover, it was proven that retention of carboxylic acids tended to increase with increasing molecular weight, according to the following order: succinic acid > lactic acid > acetic acid > formic acid. With regards to ions, retention degree increased with the increase of ionic radius and decrease of diffusion coefficient. Finally, it was demonstrated that the CA membrane is resistant to irreversible fouling, which has a positive effect on the economic viability of the process.

After a brief introduction to membrane processes in general, and the reverse osmosis process in particular, the structure and properties of membranes and membrane transport theory are described. The mechanism of salt rejection and transport properties of membranes are discussed in detail. Solubility, diffusivity, and permeability of membranes to solutes and solvents are reviewed critically and compared with each other. Special attention is given to two particular types of membranes, cellulose acetate (CA) and aromatic polyamide (AP) membranes, which are often used for water desalination. The major portion of this article is devoted to the review and discussion of membrane transport theory with application to the reverse osmosis and ultrafiltralion processes. It is shown that the solvent flux can be represented reasonably well by linear models such as the solution-diffusion model (Lonsdale, et al., 1965). The contribution of pore flow to the solvent flux is small. The solute flux, however, is not ...

This work focuses on Specific Energy Consumption (SEC) in batch and semi-batch reverse osmosis (RO) processes. It is proved from optimal control theory that the minimal SEC in semi-batch RO occurs at constant flux conditions, similar to conclusions in both batch RO and continuous, infinite-stage RO. While semi-batch RO is comparable to two- or three-stage RO at the thermodynamic limit (i.e. zero flux), its performance may be severely compromised by finite flux applied in desalination and efficacy of flushing before the next filtration step. Batch RO is even more susceptible to salt retained during flushing. On the basis of typical flux used in industrial desalination and a 95% flushing efficacy, semi-batch RO at the cyclic steady state is only similar to one-stage RO at low recoveries (e.g. 30 and 40%) and excels slightly at high recoveries (e.g. 50 and 60%). Batch RO may outperform one-stage RO but is still not as good as two-stage RO. Reducing salt retention and operating at a reduced flux are ways to make batch and semi-batch ROs energy advantageous over their continuous counterparts.

This study experimented with the novel approach of using a microfiltration (MF) and reverse osmosis (RO) treatment train to treat the effluent of a primary settling tank at the Inland Empire Utility Agency in Chino, CA. The pilot used polyvinylidene fluoride hollow-fiber MF modules as pretreatment for an RO skid, which used Hydranautics ESPA2 membranes in a two-stage configuration with a feed capacity of 6 gallon per minute (gpm). In this pilot configuration, researchers monitored the removal of 38 most prevalent contaminants of emerging concerns (CECs) through the MF/RO process. To investigate how operating the RO process at two fixed recovery rates of 55% and 80% would affect the performance of the MF/RO membranes, researchers applied different fluxes (8, 10, 12 and 14 gal/d/ft2 (gfd)) and evaluated the removal of CECs in 1-stage and 2-stage RO configurations. The occurrence of CECs in the MF influent, MF effluent, RO permeate, and RO concentrate were analyzed and studied. In the first phase (1-stage the RO process), flux of 14 gfd showed a better rejection value of inorganics (95.2%) when compared with those of other fluxes. Meanwhile, in the second phase (2-stage RO process), flux of 12 gfd showed a better rejection of inorganics (93.7%) when compared with those of other fluxes. Although concentrations of CECs slightly decreased in the RO permeate as the flux has increased, statistical analysis showed no significant differences between different fluxes in terms of CEC rejection.

Experiments on RO process for production of boiler make-up water from sea water

Coupling reverse osmosis and osmotic distillation for clarified pomegranate juice concentration: Use of plasma modified reverse osmosis membranes for improved performance

Toward a combined system of forward osmosis and reverse osmosis for seawater desalination