Biomass for Water Treatment: Biosorbent, Coagulants and Flocculants
The number of studies on the use of biomaterials for the removal of hazardous compounds from aqueous solutions has risen sharply over the past few years. Technologies currently called biosorption (also biocoagulation and bioflocculation) have received considerable attention from numerous researchers working in water treatment field. They have many advantages over conventional methods because they use renewable and inexpensive materials, and possess good ability for the recovery of pollutants such as metals, dyes and phenolic compounds. This chapter presents the vast array of biomaterials—bacteria, fungi, seaweeds, some lignocellulosic biomass such as plants and agricultural by-products—that have been investigated for their performance for the removal of hazardous compounds as biosorbents, coagulants or bioflocculants. The biomaterial characteristics, the efficiency and mechanisms of removing different pollutants, and the various factors that influence this removal are reviewed. The reactions between the pollutant and the biomaterial are generally based on physico-chemical interactions between the pollutant and functional groups of the biomass. Thus, the uptake ability of some compounds (organic or inorganic) by a given biomass depends not only of its physico-chemical properties and the type of contaminant, but also on the environmental conditions (particularly pH, temperature and ionic strength).