Adsorption properties of some low cost adsorbents and their possible use for the removal of heavy metals from industrial wastewater

Abstract

The thesis is divided into 7 chapters. Chapter-1, include the general introduction of pollution and particularly emphasized on water pollution. The addition of any organic, inorganic, biological or radiological substance to water which changes its physical and chemical properties is known as water pollution. These pollutants come in contact with water by rapid and unplanned industrial progress, over population, discharge of sewage into water bodies etc and such water is unfit and very harmful to public health, animals, plants and aquatic life. Water pollution due to heavy metals and organic pollutants has been a major concern since long. Heavy metals are non biodegradable and are the cause of many dreadful disorders on long run; on the other hand many organic pollutants are carcinogenic in nature. Sources, toxicity and hazardous effects of some important heavy metals are also summarized. For the treatment of industrial wastewater, there are various methods which include preliminary treatment, primary treatment, secondary treatment and tertiary treatment.The main objective of preliminary treatment and primary treatment are the removal of gross solids such as large floating and suspended solid matter, grit, oil and grease if present in considerable quantities. Secondary treatment is a biological process involving bacteria and other microorganisms remove the dissolved and colloidal organic matters present in the wastewaters. Tertiary treatment is the final treatment, meant for polishing the effluent from the secondary treatment processes to improve the quality further. As a result of increasing industrialization more and more heavy metals are being continually released to environment and this has prompted environmental engineers and scientists to investigate methods by which heavy metals-bearing wastewaters can be treated effectively and economically. These methods are evaporation, reverse osmosis, precipitation, ion-exchange, electrolysis and adsorption.