Perfluorooctane sulfonate (PFOS) and related substances are persistent, bioaccumulative, and toxic, and thus of substantial environmental concern. PFOS is an essential photolithographic chemical in the semiconductor industry with no substitutes yet identified. The industry seeks effective treatment technologies. The feasibility of using reverse osmosis (RO) membranes for treating semiconductor wastewater containing PFOS has been investigated. Commercial RO membranes were characterized in terms of permeability, salt rejection, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and membrane surface zeta potential (streaming potential measurements). Filtration tests were performed to determine the membrane flux and PFOS rejection. Over a wide range of feed concentrations (0.5 - 1500 ppm), the RO membranes generally rejected 99% or more of the PFOS. Rejection was better for tighter membranes, but was not affected by membrane zeta potential. Flux decreased with increasing PFOS concentration. While the flux reduction was severe for a loose RO membrane probably due to its higher initial flux, very stable flux was maintained for tighter membranes. At a very high feed concentration (about 500 ppm), all the membranes exhibited an identical stable flux. Isopropyl alcohol, present in some semiconductor wastewaters, had a detrimental effect on membrane flux. Where present it needs to be removed from the wastewater prior to using RO membranes.

No abstract

No abstract

Desalination of seawater, brackish water, and reclaimed water is increasingly utilized worldwide to augment and diversify fresh water sources. The lack of economically and ecologically feasible concentrate management options, however, is a major barrier to widespread implementation of desalination, in particular at inland sites. This paper critically reviews strategies and technologies for concentrate management, including disposal, treatment, and beneficial use. Development of energy-efficient, cost-effective, and environmentally benign concentrate management systems is critical if desalination is to become a major part of a sustainable water future. This paper examines the limitations and advantages of a range of concentrate management tools, including emerging and novel technologies for minimization of concentrate volume, enhancement of water recovery, removal of organic contaminants, and recovery of valuable products and energy.