Electrodeionization (EDI), also known as continuous deionization (CDI), is a hybrid separation process combining ion-exchange resins with ion-exchange membranes. The EDI gained increasing attention for removal/recovery of ions from water. There are different types of applications for the EDI on the removal and concentration of various species from effluent streams. The aim of this paper is to give a brief overview of those studies. The presented examples of applications have shown that EDI process is very efficient in environmental protection, production of ultra pure water, and for the recovery of some valuable species. Normally, weakly-ionized species, such as carbon dioxide and boron are difficult to remove via such membrane processes as reverse osmosis and electrodialysis reversal (EDR).