Encyclopedia of Environmental Science and Engineering, Volume I and II

352 ENVIRONMENTAL HEALTH

treatment unit processes are shown in Figures 10 and 11;

their effi ciencies are shown in Table 6.

There are two major factors which can determine the

success or failure of a sewer and treatment plant construc-

tion program once completed. First is the positive exclusion

of surface water, ground water, roof leaders, and rooting

drains by ordinance and inspection. Many a sewage treat-

ment plant constructed has been so hydraulically overloaded

as to render it almost useless as a stream pollution abatement

facility. Next is proper operation of the treatment plant by

competent adequately paid personnel. Here the consulting

engineers and the regulatory agencies share a joint respon-

sibility to ensure that public offi cials are properly informed

and that the huge investments in water pollution control

accomplish the intended objectives.

SOLID WASTES

General

Aesthetic, land use, health, water pollution, air pollution, and

economic considerations make proper solid waste storage,

collection, and disposal municipal, corporate, and individ-

ual functions which must be taken seriously. Indiscriminate

dumping of solid waste and failure of the collection system

in a populated community for two or three weeks would soon

cause many problems. Odors, fl ies, rats, roaches, crickets,

wandering dogs and cats, and fi res would dispel any remain-

ing doubts of the importance of proper solid waste storage,

collection, and disposal.

The complexities of proper solid waste management are

not readily appreciated. There are numerous sources and

types of solid wastes ranging from the home to the farm and

from garbage to radioactive wastes, junked cars, and indus-

trial wastes. Handling involves storage, collection transfer,

and transport. Processing includes incineration, densifi ca-

tion, composting, separation, treatment, and energy con-

version. Disposal shows the environmental inter-relation

of air, land, and water, and the place of salvage and recyl-

ing. All these steps introduce constraints—social, political,

economic, technological, ecological, legal, information, and

communications which must be considered in the analysis of

the problem and in coming up with acceptable solutions.

All these factors show the need for comprehensive plan-

ning. It is necessary to come up with alternative solutions

together with the environmental and social impact of each.

In this way one is more likely to come up with a practical

and acceptable plan that will have a good chance of being

implemented.

Composition, Weight, and Volume

The solid waste of a municipality may consist of garbage,

rubbish, ashes, bulky wastes, street refuse, dead animals,

abandoned vehicles, construction and demolition wastes,

industrial solid wastes, special hazardous wastes, animal

and agricultural wastes, sewage treatment plant residues,

and septic tank cleanings. Garbage is the putrescible organic

material discarded or remaining as a result of the storage,

processing, preparation, and consumption of food. Rubbish

includes paper, wood, glass, metal, leaves, plastics, tin cans,

stones, and dirt. Bulky wastes include stoves, refrigerators,

auto parts, furniture, large creates, trees, and tree branches.

Various estimates have been made of the quantity of solid

waste generated and collected per person per day. The amount

of municipal solid waste generated in 1968 was estimated to

be 7 pounds per capita per day and expected to increase at

about 4% per year. The amount collected was found to aver-

age 5.32 pounds. The fi gures given in Tables 7a and 7b are

averages, subject to adjustment dependent upon many local

factors, including time of the year, habits and economic status

of the people, whether urban or rural, education, and location.

The estimates should not be used for design purpose. Each

community should be studied by itself and actual weighings

made to obtain representative information.

TABLE 7a

Average solid waste collected, 1968 (pounds per person per day)

Solid waste type Urban Rural National

Household 1.26 0.72 1.14

Commercial 0.46 0.11 0.38

Combined 2.63 2.60 2.63

Industrial 0.65 0.37 0.59

Demolition, construction 0.23 0.02 0.18

Street and alley 0.11 0.03 0.09

Miscellaneous 0.38 0.08 0.31

Totals 5.72 3.93 5.32

Anton J. Muhich, “Sample Representativeness and Community Data,”

Proceedings, Institute for Solid Wastes, APWA, Chicago, IL., 1968.

TABLE 7b

Approximate composition of domestic solid wastesa

Component % by weight

Food waste 15

Paper products 50

Plastics, rubber, leather 3

Rags 2

Metals 8

Glass and ceramics 8

Wood 2

Garden wastes 5

Rock, dirt, miscellaneous 7

a Moisture content approximately 30%.

C005_009_r03.indd 352C005_009_r03.indd 352 11/18/2005 10:24:51 AM11/18/2005 10:24:51 AM