Sanitation in Populated Areas

the system of organizational and technical measures for the collection, transport, and safe disposal of waste products from populated areas, as well as for cleaning streets, public squares, and yards in the summer and winter. Waste products pollute and contaminate man’s environment: the soil, air, water, and residential and public buildings. In addition to creating an epidemiological hazard and a sanitary problem, failure to remove waste products promptly and regularly detracts from the appearance of populated areas. As a result of the steady growth of cities and the increasing accumulation of refuse, sanitation services have become particularly important. They are inextricably linked with the problem of protecting and sanitizing the environment and safeguarding human health. In the USSR, planned city management makes it possible to furnish efficient sanitation services for populated areas and to provide for the maximum mechanization of the collection, removal, and safe disposal of waste products, as well as for the use of some of them.

A distinction is usually made between solid and liquid wastes and atmospheric forms of waste. Solid waste includes garbage from homes (food waste, trash, and salvageable material); slag and ash discharged by central boilers; street sweepings; leaves, grass, and fallen branches in parks and public squares; debris from the repair, construction, and demolition of buildings; and waste from public catering, trade, and industrial enterprises. Liquid wastes include sewage, used water from buildings without plumbing, and industrial wastes that cannot be released into the plumbing system (for example, by-products of petroleum refining, oils, and solvents). Atmospheric forms of waste products are rain, snow, and ice. Waste products, including the atmospheric forms, are hauled to special installations for safe disposal or recirculation and run through the pipes and ditches of the city sewage system.

The rational organization of the collection and removal of garbage from homes is very important for sanitation and hygiene. Garbage may be collected at buildings in one receptacle (the unitary method) or in several (the separate method). In most cities in the USSR all kinds of garbage and refuse are collected together. In the large cities, food waste is collected in separate receptacles and fed to pigs.

Garbage may be removed from buildings by garbage chutes, as well as by the hydraulic and pneumatic methods. In small populated areas and city districts with low buildings, garbage is removed by the inhabitants, who accumulate it in receptacles in their apartments and take it to movable garbage cans in the yard (maximum capacity, 100 liters [l]) or containers with capacities of 750 l. Garbage is removed by chute from buildings five or more stories high. It is hauled away by garbage trucks at one-or two-day intervals, in conformity with a plan. Usually, this requires 12–15 garbage trucks per 100,000 inhabitants. When considerable distances are involved, the garbage is delivered to transfer stations, where it is put into large garbage trucks with capacities of 30–50 cu m. Rail and water transport is also used. The system of hauling garbage away has a number of shortcomings: the pollution of yards, the use of manual labor, and garbage-truck traffic in the city.

The hydraulic method of garbage removal, in which the garbage is ground into small pieces and released into the sewage system, is not widely used. From the standpoint of sanitation and technology, garbage removal by the pneumatic method is better. The garbage is sucked through chutes into a system of removal pipes 500–600 mm in diameter and located in the street. Garbage is drawn into these pipes by means of a vacuum and moved in an air stream at a speed of 30 m per sec to the disposal or transfer site. Pneumatic garbage removal, which is used in certain cities abroad (in the USA and Sweden, for example), is in the planning stages for some Soviet cities.

Liquid waste from buildings without sewer connections is hauled away by sanitation trucks (tank trucks with capacities of 880–3,400 I) to sewage stations, where it is released into the sewage system, or to sanitation fields (plots of land on which agricultural crops are raised).

The sanitation system in populated areas provides for the safe disposal of garbage by various methods, using landfill areas, garbage-processing plants, and incinerators. In one widely used method, garbage (solid waste) is buried in landfill areas, compacted in layers, and covered with an insulating layer of earth (0.3 m for every 2 m of compacted waste). This method requires an area of 0.3 hectares per 100,000 inhabitants per year. Although the garbage is not recycled, parts of the landfill are planted. Garbage that presents an epidemiological hazard is burned at incinerator plants equipped with devices to decontaminate escaping gases. In one of the most effective methods of safe disposal, garbage is composted and biothermally processed by machines at special processing plants, for use as fertilizer and biological fuel.

Summer cleanup of streets, public squares, and yards differs from winter cleanup. During the summer, dust and refuse are swept from the surfaces of roads and sidewalks, which are then sprinkled and washed. Street sweepers, sprinklers, and washers are used for summer jobs. Winter cleanup involves clearing snow from the streets and sidewalks; sweeping and shoveling it into piles; hauling it to collection points and snow dumps, as well as to snow melters, so that it runs into the sewage system; and sprinkling surfaces with a mixture of sand and salt. Snowplows, snow loaders, snow melters, and sand spreaders are used in winter cleanup work.