CH3 SCH2 CH(NH2 )COOH CH3SH+ CH3 CH2 CH2(NH2 )COOH (14-12) The methyl mercaptan can be hydrolyzed biochemically to methyl alcohol and hydrogen sulfide CH3SH+H2O→CH4OH+H2S (1413) Breeding of Flies In the summertime and during all seasons in warm climates, fly breeding is an important consideration in the on-site storage of wastes. Flies can develop in less than two weeks after the eggs are laid. The life history of the common house fly from egg to adult can be described as follows 8-12 hours First stage of larval period 20 hours Second stage of larval period 24 hours Third stage of larval period 3 days Pupate stage 4-5 days Total The extent to which flies develop from the larval (maggot)stage in on-site storage containers depends on the following facts: If maggots develop, they are difficult to remove when the containers are emptied. Those remaining may develop into flies. Maggots can also crawl from uncovered cans and develop into flies in the surrounding environment 144 Physical, Chemical, and Biological Transformations of Solid Waste The purpose of this section is to introduce the reader to the principal transformation processes that can be used for the management of MSW. These transformations can occur either by the intervention of people or by natural phenomena. Solid waste can be transformed by physical, chemical, and biological means(Table 14-4). One must understand the transformation processes that are possible and the products that may result because they will affect directly the development of integrated solid waste management plans Physical Transformations The principal physical transformations that may occur in the operation of solid waste management systems include(1)component separation, (2)mechanical volume reduction, and(3)mechanical reduction. Physical transformations do not involve a change in phase (e.g, solid to gas), unlike chemical and biological transformation processes ponent Separation Component separation is the term used to describe the process of separating, by manual and/or mechanical means, identifiable components from commingled MSw. Componen separation is used to transform a heterogeneous waste into a number of more-or-less homogeneous components. Component separation is a necessary operation in the recovery of reusable and recyclable materials from MSW, in the removal of contaminants from separated materials to improve specifications of the separated material, in the removal of hazardous wastes from MSW, and where energy and conversion products are to be recovered from processed wastes Mechanical Volume Reduction. Volume reduction(sometimes known as densification) is the term used to describe the process whereby the initial volume occupied by a waste is reduced, usually by the application of force or pressure. In most cities, the vehicles used for the collection of solid wastes are equipped with compaction mechanisms to increase the amount of waste collected per trip. Paper dboard, plastics, and aluminum and tin cans removed from MSw for recycling are baled to reduce storage and handling costs and shipping costs to processing centers. Recently, high-pressure compaction systems have been developed to produce materials suitable for various alternative uses ch as production of fireplace logs from paper and cardboard. To decrease the costs associated with the transport of waste materials to landfill disposal sites, municipalities also may use transfer stations equipped with compaction facilities. To increase the useful life of landfills, wastes are usually compacted before being covered 14-614-6 CH3SCH2CH2CH(NH2)COOH → CH3SH + CH3CH2CH2(NH2)COOH (14- 12) The methyl mercaptan can be hydrolyzed biochemically to methyl alcohol and hydrogen sulfide: CH3SH + H2O → CH4OH + H2S (14- 13) Breeding of Flies In the summertime and during all seasons in warm climates, fly breeding is an important consideration in the on-site storage of wastes. Flies can develop in less than two weeks after the eggs are laid. The life history of the common house fly from egg to adult can be described as follows: Eggs develop 8-12 hours First stage of larval period 20 hours Second stage of larval period 24 hours Third stage of larval period 3 days Pupate stage 4-5 days Total 9-11 days The extent to which flies develop from the larval (maggot) stage in on-site storage containers depends on the following facts: If maggots develop, they are difficult to remove when the containers are emptied. Those remaining may develop into flies. Maggots can also crawl from uncovered cans and develop into flies in the surrounding environment. 14- 4 Physical, Chemical, and Biological Transformations of Solid Waste The purpose of this section is to introduce the reader to the principal transformation processes that can be used for the management of MSW. These transformations can occur either by the intervention of people or by natural phenomena. Solid waste can be transformed by physical, chemical, and biological means (Table 14- 4). One must understand the transformation processes that are possible and the products that may result because they will affect directly the development of integrated solid waste management plans. Physical Transformations The principal physical transformations that may occur in the operation of solid waste management systems include (1) component separation, (2) mechanical volume reduction, and (3) mechanical size reduction. Physical transformations do not involve a change in phase (e.g., solid to gas), unlike chemical and biological transformation processes. Component Separation. Component separation is the term used to describe the process of separating, by manual and/or mechanical means, identifiable components from commingled MSW. Component separation is used to transform a heterogeneous waste into a number of more-or-less homogeneous components. Component separation is a necessary operation in the recovery of reusable and recyclable materials from MSW, in the removal of contaminants from separated materials to improve specifications of the separated material, in the removal of hazardous wastes from MSW, and where energy and conversion products are to be recovered from processed wastes. Mechanical Volume Reduction. Volume reduction (sometimes known as densification) is the term used to describe the process whereby the initial volume occupied by a waste is reduced, usually by the application of force or pressure. In most cities, the vehicles used for the collection of solid wastes are equipped with compaction mechanisms to increase the amount of waste collected per trip. Paper, cardboard, plastics, and aluminum and tin cans removed from MSW for recycling are baled to reduce storage and handling costs and shipping costs to processing centers. Recently, high-pressure compaction systems have been developed to produce materials suitable for various alternative uses such as production of fireplace logs from paper and cardboard. To decrease the costs associated with the transport of waste materials to landfill disposal sites, municipalities also may use transfer stations equipped with compaction facilities. To increase the useful life of landfills, wastes are usually compacted before being covered