New Composite Materials and Processes for Chemical, Physico-Chemical and Biochemical Technologies of Water Purification

Abstract

In traditional methods of water purification, the use of chemical reagents leads to the appearance of toxic by-products and wastes that require complex energy-consumption processing technologies. In accordance with the principles of sustainable development and “green” technologies, a significant revision of existing water treatment methods is required. The review highlights the main trends of innovative development of water purification and disinfection technologies. Modifications of water treatment agents (flocculants, sorbents, membranes) by integration of nanoparticles, environmentally compatible materials and “smart” composites into traditional structures are described. The use of composite nanoparticles is promising, particularly the use of particles with the “magnetic core – shell” structure, in which functional elements are attached to the surface, that provide the selective capture of contaminants, including pathogenic microorganisms. The existence of the magnetic core makes it possible to manipulate particles by the applied magnetic field, which is important for their complete extraction from the water upon completion of their functions. The use of new composite flocculants containing inorganic and organic components capable of ensuring highly effective capture of contaminants from the water, significantly reduces the volumes of flocculants and generated sludges and therefore allows to reduce the cost of the sludges processing and the harm of their disposal in the environment. New carbon nanostructures and natural polymers have an important role to play. In the new generation membranes, the disperse nanoparticles may provide antibacterial and photocatalytic properties, resulting in the high efficiency of disinfection and purification. A novel trend is the development of hybrid structures of coagulants and membranes with the properties which are regulated by the external stimulus, which are temperature, pH, light, electric, magnetic and electromagnetic fields. The use of such «smart» structures will increase the purification efficiency, reduce energy consumption and water purification waste volumes, due to the decrease in membranes fouling. The use of biopolymers and composites based on plant raw materials for the water purification is attractive due to their natural decontamination under the influence of the components of the environment, such as air, soil micro-organisms and sunlight, but also due to the absence of the secondary pollution. Among innovative chemical water treatment technologies Advanced Oxidation Processes play an important role, in particular, by involving electromagnetic fields and ultrasonic activation. By these methods, harmful organic impurities and pathogens are destroyed without the intensive use of chemicals or the production of toxic by-products. The integration of biochemical wastewater treatment with a microalgae growing system can become a promising waste-free, cost-effective "green" technology.

REGENERATION OF ACTIVATED CARBON AFTER ADSORPTION OF DYE USING PERACETIC ACID. PART 1: EFFECTS OF METAL IONS, pH, REGENERATION TIME, AND ACID CONCENTRATION

“…The thermal method involves three stages: (1) drying at 105 C, (2) pyrolysis in inert gas, and (3) gasification of the remaining organic compounds. Stages 2 and 3 are usually performed at around 800 C, with an additional oxidizing agent (steam or CO gas) in stage 3 [4,5]. The drawback of this method is that it consumes a lot of energy to evaporate water in stage 1 and to heat up the system in stages 2 and 3.…”