Adsorption process is the capture of a substance, present in water solution, on an interface between two phases (generally liquid-solid phases). The substance on whose surface the adsorption reactions occur is called adsorbent. The adsorbing substances used for the treatment of waters are active carbons, ionic exchange resins and the iron and aluminium hydroxides.

The treatment by granular activated carbon is one of the most effective advanced treatments for the removal of the biodegradable and refractory organic compounds. The activated carbon adsorption can reduce the level of the synthetic chemical compound of a secondary effluent of 75-85%. This process, preceded by secondary treatment and filtration, can allow effluent with characteristics as good as BOD from 0.1 to 5.0 mg/l; COD from 3 to 25 mg/l and TOC (total organic carbon) from 1 to 6 mg/l. The treatment by activated carbon can also remove several metallic ions, particularly cadmium, chrome and selenium. This treatment can be used in conjunction with air stripping for removal of vapour-phase volatile compounds.

The ionic exchange resins are granular insoluble materials, that coming into contact with the electrolytes in solutions, are able to subtract the targeted cations or anions by exchanging equivalent quantities of different cations or anions. They are generally used for softening treatment and water demineralization.

The iron and aluminium hydroxides are strongly adsorptive substances used to remove colloids, from wastewaters, in a coagulation and flocculation treatment phase.

TREATMENT COSTS (ACTIVATED CARBON ADSORPTION)

Back