Substitution of Chloride Chemicals with Degradable Bioflocculants for Sedimentation of Suspended Particles in Water

Chlorine-based flocculants are commonly used to enhance the flocculation and sedimentation of particles in suspension in water and other liquids, while chlorine is the major element used for disinfection of drinking water. The chlorine chemicals which are highly effective and low cost are also nondegradable and after use the compounds and their derivatives can be detected in the environment and in estuaries. In the case of pretreatment of seawater for RO desalination, a plant producing 100 million m3 of water per year could discharge with the filter backwash water up to 1500 ton/year (1.362 kt·a-1) of spent ferric chlorinated chemicals forming a nonesthetic red-brown mat, affecting light penetration and biological productivity, as well as being a potential eutrophication agent of coastal water. The likely replacement of inorganic chloride salts with environmentally friendly biodegradable and food-grade flocculants for use in food and water treatment process is discussed together with a description of a comparative coagulation-flocculation experiment testing patented bioflocculants (Seleno-X) as against traditional chemical flocculants for the destabilization of colloidal and particulate matter in seawater feeding RO membranes. The bioflocculants were found to yield comparable results in terms of NTU and silt density index (SDI). But, the results are inconclusive to validate the practical application and commercial use of bioflocculants in water, and further research is required in an attempt to substitute and reduce the use of chloride chemicals in general and in water treatment in particular.