Classification of Wastewater

Classification of WastewaterWastewaters atomic number 18 numerous in kind and defy easy definition. It is difficult to evolve a universal compartmentalisation for drop. However, roughly there atomic number 18 three basic classification methods, which atomic number 18 combined to form a waste classification system (Hagerty., 1973). They are animal(prenominal) classification, chemical classification and thermic classification. The last one is directly related to thermal touch on requirements and focuses on the information needed to select, design, and operate a thermal functioninging system.5.1 Physical ClassificationThis classification identifies the physical state of waste. It is needed for the weft and design of waste handling systems and the choice of processing equipment. Based on physical characteristics, typical waste materials are classified as vapourific, liquid, slurry, sludge, solid and mastererized waste. In the present context, solid and liquid wastes will be di scussed in this section. unscathed waste is wastes those which arise from human and animal activities that are normally solid and are usually discarded as useless or unwanted. The term as used in this context is all inclusive, and it encompasses the heterogeneous mass of throw aways from the urban community as well as the more homogeneous accumulations of agricultural, industrial and mineral wastes (Tchobanoglous, 1977). In discussing solid waste, generally and traditionally certain categories of wastes are well recognized as they are very common. For example, solid wastes include domestic, commercial, industrial, (due to reflexion and demolition) agricultural, institutional and miscellaneous. Many times domestic and commercial wastes squirtnot be differentiated and are considered together as urban wastes. Included in this category are the garbage materials which result from food preparation both in the homes and restaurants, and also the frill which is produced in residences and commercial establishments. Generally, the garbage consists of rapidly decomposable materials while the rubbish is either s basely decomposable or non-degradable. A second major category of waste is industrial, the disavow produced by industrial processes. Generally the character of the refuse produced in any manufacturing or processing operation will depend very much on the type, amount, or the character of wastes produced by the industry. Obviously, the wastes produced by stain manufacturers will differ considerably from those produced in the chemical industry. Usually the wastes produced by any food processing operation, the study and plastics industries are almost similar to the paper and plastic packaging materials found in domestic rubbish. On the other hand, the metal processing industry will obviously generate metallic wastes, that in addition will also produce large quantities of slags, processing chemicals, and other residues, many of which are used in air pollution u nderwrite and water pollution control activities. The wastes produced by chemical industries or other more specialized industries will in general depend upon the specific disposition of the end product of the manufacturing process (Waste Classification Guidelines Part 1 Classifying Waste , 2009).5.2 Chemical ClassificationIt is the key to selection of proper process design parameters, selection of materials of construction, choice of concentration equipment, design of incinerator hardware, the possibility of bye-product recovery, and the requirement of fuel gas and discharge water treatment systems. Based on this classification, the waste materials are in the main classified as clean waste and hazardous waste.5.2.1 Clean WasteThis group covers hydrocarbons which contain alone carbon, hydrogen and oxygen. The oxidation products are considered clean and can be discharged into the environs.5.2.2 Hazardous WasteThe problem with hazardous wastes is that there is still no internationa lly accepted definition of a hazardous waste. However, technical foul criteria such as toxicity, flammability, corrosivity, ignitability and reactivity have been proposed and used to some extent to identify and designate the waste as hazardous. Though the hazardous wastes account for only a small proportion of all wastes generated by the industries, their impact can be disastrous as they not only affect the physical environment but also the biotic components. The United States alone generates well-nigh 60 million tons of hazardous waste every year, and the European Economic association about half of that quantity. Roughly 10 to 20 per cent of the total waste produced can be considered as potentially hazardous. In general, there are industries like metallurgical, iron and steel, fertilizers, thermal power production, etc. generating large quantities of solid and liquid wastes containing low concentration that is at the trace level of hazardous constituents. On the other hand, there is another group of industries such as chlor alkali, pesticides, dyestuffs, electroplating, photographic chemicals, fine chemicals, etc. which generate comparatively small quantity of wastes, but they are highly toxic and hazardous. Approximately one million tons of solid waste is generated annually by the 131 industrial units surveyed. Nearly 22% of wastes from these industries are hazardous. It has been estimated that about 94% of these wastes are generated by process oriented (generating during the processing of raw materials to get the finished products) industries and 6% of it is pollution control oriented (generated from the treatment of gaseous and liquid effluents) industries. Maximum amount of hazardous waste is generates by chlor-alkali, dyes and pigment, organic fertilizer chemicals, pesticide and plating industrial sectors. The inorganic chemical sector on the other hand, generated low volume-high toxic wastes. The synthetic drug manufacturing units in drugs and pharma sector generate maximum quantity of hazardous wastes. Thus, hazardous waste may be foster classified into waste generating gaseous contaminants, waste containing alkali and alkaline earth metals and waste containing heavy metals.5.3 Thermal ClassificationThis is used in the determination of faculty requirements for processing and in the selection of system configuration. Based on the thermal properties, typical waste materials are classified as follows, where combustible wastes are a group that includes wastes which will sustain oxidation reaction without additional energy requirements, noncombustible wastes are groups that represent low-Btu value wastes, which will not sustain oxidation reaction without additional energy supply. These wastes may be further classified into following two categories which are the noncombustible wastes with no low the volatiles (the organics in the wastes contain no low volatiles which, when heated, will evaporate) and the noncombustible waste with l ow volatiles (the organics in the waste are heat sensitive and readily vaporized when heated). These two categories tolerate important information for the designing of evaporation and steam stripping systems. They are also important factors in the selection of pre-concentration equipment of wastes. For the successful application of thermal processing systems accurate and reliable information about the composition and characteristics of any waste to be processed is essential. Such data are necessary to understand the process and for the selection of process equipment.Classification of a wastewater by toxicity or hazard is important for safety and also to comply with legislation (Mumford, 1973). In practice, it is better to use the characterization hazardous and non-hazardous having regard to both toxicity and the environmental implications of the waste on disposal. Therefore the Control of Pollution Act distinguishes waste as poisonous, noxious or polluting and whose presence on lan d is likely to give rise to an environmental hazard. It also encompasses highly flammable or volatile materials which may have little toxicological significance (Agency, n.d.).Classification may be further expanded taking into consideration individual chemicals. Chemical outline will usually give the proportion of each chemical present, except that of organics which may be characterized by one or more physical properties as listed in Table 2.Table 2 Physical properties of liquid wastes.Alternatively the description may be limited to synthetic organic materials, natural organic materials, and inorganic materials and this characteristic corresponds to classification by origin. Finally, wastewater is usually wastes because it consists of unusable and often unpleasant mixture of chemicals.BibliographyAgency, T.E.P. About Hazardous Non-Hazardous Waste by The environmental Protection Agency, Online, Available http//www.lonestar.edu/16715.htm 19 February 2014.Hagerty., D.J.P.J.L.a.H.J.E. (1973) Solid Waste Management, New York Van Nostrand Reinhold Co.Mumford, C.J. (1973) Industrial Pollution Control, Bussiness Books.Tchobanoglous, G.T.H.a.E.R. (1977) Solid Wastes Engineering Principles and Management issues, New York McGraw Hill.