Ion exchange membranes: State of their development and perspective

To support a sustainable industrial growth, chemical engineering today faces a cru-cial challenge of meeting the increasing demand for materials and energy. One possi-ble solution is to decrease the equipment size/productivity ratio, energy consumption,and waste generation via process integration and optimization. This review focuses onthe integration of electrodialysis with traditional unit operations and other membraneseparations. Such integrations, due to their diversity and practicability, can be versa-tile tools to meet speciﬁc needs from chemical, biochemical, food, and pharmaceuticalindustries.

Electrodialysis‐based separation technologies: A critical review

Research developments in environmental electrochemistry and their potential to contribute to a cleaner environment are reviewed here for wastewater treatment applications. Most environmental pollutants can be successfully eliminated or converted to non-toxic materials by one or more processes, including electrochemical oxidation, electrochemical reduction, electrocoagulation and electrocoagulation/flotation, electrodialysis, and electrochemical advanced oxidation processes. Specific examples of applications for pollutant removal and reclamation of wastewater are given for the different processes, along with research needs and improvements for commercial application of these electrochemical processes.

Electrochemical technologies for wastewater treatment and resource reclamation

Removal of anionic pollutants from liquids by biomass materials: A review

This paper is designed to provide an overview of the main membrane-assisted processes that can be used for the removal of toxic inorganic anions from drinking water supplies. The emphasis has been placed on integrated process solutions, including the emerging issue of membrane bioreactors. An attempt is made to compare critically recently reported results, reveal the best existing membrane technologies and identify the most promising integrated membrane bio/processes currently being under investigation. Selected examples are discussed in each case with respect to their advantages and limitations compared to conventional methods for removal of anionic pollutants. The use of membranes is particularly attractive for separating ions between two liquid phases (purified and concentrated water streams) because many of the difficulties associated with precipitation, coagulation or adsorption and phase separation can be avoided. Therefore, membrane technologies are already successfully used on large-scale for removal of inorganic anions such as nitrate, fluoride, arsenic species, etc. The concentrated brine discharge and/or treatment, however, can be problematic in many cases. Membrane bioreactors allow for complete depollution but water quality, insufficiently stable process operation, and economical reasons still limit their wider application in drinking water treatment. The development of more efficient membranes, the design of cost-effective operating conditions, especially long-term operations without or with minimal membrane inorganic and/or biological fouling, and reduction of the specific energy consumption requirements are the major challenges.

Toufik Cherif

Papers

Use of a membrane bioreactor for denitrification of brine from an electrodialysis process