Recent Achievements in Polymer Bio-Based Flocculants for Water Treatment

Abstract

Polymer flocculants are used to promote solid–liquid separation processes in potable water and wastewater treatment. Recently, bio-based flocculants have received a lot of attention due to their superior advantages over conventional synthetic polymers or inorganic agents. Among natural polymers, polysaccharides show many benefits such as biodegradability, non-toxicity, ability to undergo different chemical modifications, and wide accessibility from renewable sources. The following article provides an overview of bio-based flocculants and their potential application in water treatment, which may be an indication to look for safer alternatives compared to synthetic polymers. Based on the recent literature, a new approach in searching for biopolymer flocculants sources, flocculation mechanisms, test methods, and factors affecting this process are presented. Particular attention is paid to flocculants based on starch, cellulose, chitosan, and their derivatives because they are low-cost and ecological materials, accepted in industrial practice. New trends in water treatment technology, including biosynthetic polymers, nanobioflocculants, and stimulant-responsive flocculants are also considered.

Separation of Nano‐scaled Particles by Flocculation

“…In an attempt to achieve sustainable development, the flocculated nanoparticles must be recovered. This is to avoid generation of secondary waste (sludge) upon the separation 73. It would be interesting to test the feasibility to recover both the nanoparticles and the flocculant after the said separation.…”

“…In this context, microbial extracellular polymeric substances are good choice of bioflocculants since they are natural, biodegradable, and environmentally friendly 74. In fact, bioflocculants were actively researched in recent years for micro‐ or macro‐sized suspended solid removal 73, 75. On the other hand, an innovative approach using grafted copolymer flocculants such as combining starch and acrylamide proved to have better flocculation properties than the conventional flocculant 76, 77.…”

Synthesis and Characterization of Novel Hybrid Flocculants Based on Potato Starch Copolymers with Hollow Carbon Spheres

“…Various types of chemicals and water treatment agents are used for purifying water and sewage. Thus, coagulants and flocculants play the most important role in the field of waste water treatment [ 5 , 6 , 7 , 8 ]. However, simple coagulants and flocculating agents require high doses, which increase costs of the purification process.…”

“…They must be dosed in the right order to keep their proper effectiveness. Conventional coagulants are based on inorganic particles whereas flocculants are organic polymeric compounds [ 5 , 6 , 7 , 8 , 9 , 10 ]. Unfortunately, during application of traditional waste water treatment agents the remaining of metal ions originating from inorganic coagulants and unreacted monomers from polymeric compounds are of major concern [ 11 , 12 , 13 , 14 , 15 ].…”

Nanocellulose as a sustainable material for water purification

“…[4, 5] Studies in the recent past have focused on preparing bioflocculants based on modified polysaccharides. [ 6 ] Flocculants are commonly used materials for the removal of contaminants from wastewater by accelerating agglomeration of these contaminants, causing sedimentation, followed by contaminant removal. [ 7 ] Through the years, polysaccharides have become an attractive alternative option for fabricating a wide variety of high performance and low cost adsorbent membranes, attributed to the ease of their chemical modification.…”