Disinfection of water used for domestic and potable purposes is still a challenge for developing and under developed countries. Disinfection of water can be done physical, chemical and biological methods.In second chapter use of membrane separation for better water purification facilities is discussed.Water reuse and recycle is becoming important for conservation of water resources. The physico-chemical treatments are widely used for water treatment and removal of organic matter. Use of membrane separation can be done for water purification. The presence of natural organic matter affects the membrane performance. This is followed by review on sulphide removal. Removal of selective gases from exhaust gas stream can be done by various gas liquid mass transfer operations. Gas absorption and adsorption are two important gas liquid separation operations. Gases like carbon dioxide, sulphur dioxide are products of combustion of fuel. sulphide gases are the commonly existing gases in coal, natural gas and synthesis gas processing. CS2 has detrimental effect on industrial heterogeneous catalysts. Methods like hydrogenation, oxidation, and hydrolysis can be used for removal of carbon disulphide.
Fourth topic deals with biological phenol removal. Removal of phenol from wastewater can be carried out by using various biological and non biological methods. Biological phenol removal can be carried out by biosorption and various suspended and attached growth processes. Adsorption and ion exchange are also important methods for phenol removal.Fifth chapter deals with hazardous waste treatment. The solid waste disposal is generally done by using sanitary land fill method. In developing countries open dumping is done. Open dumping is dangerous option due to odour and dispersion of waste in the form of particles in the air. Sanitary landfill is relatively safer option. The solid waste buried in the land contaminates groundwater. The bio composting of the waste provides additional benefits like manure for agriculture and reduction in the volume of waste. The other option of treating solid waste is incineration. Incineration has disadvantage of exhaust gases.
Chapters 6,7,9,12 and 13 deals with metal recoveries. Manganese and iron are two such heavy metals. Manganese removal is difficult because of its high solubility. The electronic waste and waste jewelries, catalyst industry waste and catalytic converters contain considerable amount of platinum. The platinum removal and recovery is necessary from ecological and economical point of view. The use of heavy metals in the various components of mobiles, computers, remote, chips and other components calls for effective solid waste management. The electronic waste includes used components and electronic goods. These electronic materials and goods contain various valuable metals like gold, silver, platinum etc. These wastes are normally treated unscientifically. These methods are inefficient and at times hazardous. The need for effective method for removal of cobalt calls for studies on various methods and aspects of wastewater treatment for cobalt removal.Common methods used for iron removal includes chemical precipitation, coagulation–flocculation, flotation, ultrafiltration, nanofiltration, reverse osmosis, electrochemical treatment techniques like electro dialysis, membrane electrolysis, electrochemical precipitation, electroextraction.
Eighth chapter deals with phosphorus removal .Nitrates and phosphates enter the water bodies as they are important nutrients for plants. Various causes for presence of phosphorus in water bodies include use of fertilizers, domestic and industrial wastewater, and atmospheric deposition. Various processes for phosphorus removal include electrochemical treatment, coagulation, aeration, sorption and simultaneous sludge minimization and enhanced biological phosphorus removal.Process intensification is a field which aims at increasing effectiveness of processes in terms of cost, space, efficiency and conversion. Coupling of two unit operations or processes can exhibit excellent results in some processes. Combination of membrane separation with reaction is found to be very effective in many applications. The membrane bioreactors find application in dehydrogenation, hydrolysis and enzyme catalyzed reactions.Advanced membrane separation is discussed in chapter 14.Chapter eleven deals with noise pollution. Normally undesired and irritating sound is termed as noise. The noise in industrial, residential and silence zones need to be monitored and controlled. The traffic noise is a major problem in cities and populated areas. The noise of horns is major deterrent. Sound level is alarming during festivals also. It is very important to educate industrial workers, citizens and students about effects of noise pollution and its control methods.
Membrane separation methods are becoming more and more important in the era of rapid industrialization. The industrialization in inevitable for meeting the demand of rapid urbanization and increased living standard. The undesirable side effect of this industrial growth is water pollution. Many industries discharge effluents with high pollutant loading. Membrane separation methods give the product with uniform quality. Reverse osmosis, ultrafiltration, microfiltration and nanofiltration are few important membrane separation methods. Many modifications in these processes are also tried by various investigators to overcome the disadvantages.Chapters 15 and 16 deals with advanced treatments such as latest biological techniques and ozonation and U.V. irradiation. Disinfection of water can be carried out by ozonation and U.V. irradiation. U.V. irradiation with ozonation can exhibit synergic effect and can treat the water more effectively. Many investigators have studied ozonation- UV irradiation- hydrogen peroxide treatments in combination and separately and compared them.Biological treatment can be either attached growth or suspended growth. The selection of biological treatment depends on quality of effluent and the percentage removal required. Biological treatments are also used for selective removal of many heavy metals, phosphorous and other pollutants. Chapter seventeen deals with reviews dissolved oxygen, its importance and effect. Last chapter deals with reviews on rain water harvesting.