Encyclopedia of Environmental Science and Engineering, Volume I and II

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INSTRUMENTATION: WATER AND WASTEWATER ANALYSIS

INTRODUCTION

In the observation of our pollution problems there seems

to be an attitude of separation on the part of the human

observer from the polluted lake or stream. In reality water

is so pervasive in our life; it is such a large part of our

bodily mass and surrounds us in clouds, fog, rain, snow,

lakes, rivers, and oceans. We seem to accept its presence

without much thought. However, we all are part of the eco-

system and, therefore, pollution is an intimate condition

of our lives—not something unconnected to us. Much of

the human population appears to have been separated from

their ecological heritage and membership. Perhaps this

is the reason pollution is so endemic to our world; many

people had seen pollution as something displaced from

their intimate reality.

In the last thirty years the threat and cause of damage

to ecological and human health from polluting surface and

ground water and acid rain and snow, as well as air pollution,

global warming, and the destruction of the ozone layer has

increasingly occupied our consciousness and our everyday

life. The society from young school children to adults read-

ing newspapers and watching television are aware that we

are heirs to serious environmental problems. Polls indicate

the great extent of this concern. Recently the concerns of

various national governments have led to international con-

ferences dealing with the ozone problem and discussion of

global warming. Perhaps the convergence of several envi-

ronmental conditions that threaten to change planet earth’s

ecological system have awakened the irresponsible amongst

the citizenry, government administrators, scientists and engi-

neers, and the industrial establishment to finally realize that

we are all part of the ecological system and have a vital inter-

est in the control of pollution.

The Clean Water Acts of the U.S. Congress and envi-

ronmental action of various States and similar actions in

Canada have resulted in some improvement in natural

water quality in North America. The role of the Green par-

ties and the citizenry has had a similar effect in Western

European nations. In Eastern Europe there is increasing

concern about pollution problems. Much remains to be

done in the areas of irrigation, non-point source pollution,

acid rain and snow, the effect of air pollution on water

pollution, protection of ground water from hazardous

wastes, and the further reduction of pollution from indus-

trial sources. Extensive human effort and resources have

been dedicated to detect and measure water pollutants and

understand their effect on human populations and on the

ecological system, as well as on the collection and rec-

tification of wastewater in treatment facilities. However,

much more remains to be done.

A realistic primer may help us to visualize the overall

effects of water pollution. Sitting by an ecologically healthy

lake or stream, we observe a proliferation of life—plants and

animals familiar and cherished by us. Comparing that to our

experience of being next to a polluted water body, we would

notice different plants, not attractive to us and the presence

of foul offensive odors. (However for a lake acidified by acid

rain, very clear waters, devoid of life, are observed.) The

system has changed from being aerobic (presence of dis-

solved oxygen) to anaerobic (lack of dissolved oxygen). The

water body has changed so that it is no longer attractive to

us nor can it serve as a water resource. A lack of dissolved

oxygen in the water has changed the living conditions so that

anaerobic fauna and flora can reside there. Two conditions

can cause this situation: i.e., an excess of nutrients (such as

nitrates or phosphates) serving to facilitate the growth of

plants and an excess of biodegradable organic matter serv-

ing as food for the microbial population. These pollutants

originate from human biological waste and human activities

such as agriculture and industry.

An excess of biodegradable organic matter leads to an

accelerated growth of the microbial population. Since they

are aerobic and require dissolved oxygen in the water for

respiration, a large population could deplete the dissolved

oxygen supply leading to the asphixiation of fish, other ani-

mals and insects and the death of plants. Then anaerobic

fauna and flora will flourish producing reduced gaseous

substances, such as ammonia and hydrogen sulfide. These

gases are toxic and unpleasantly odiferous. Although water

can be reaerated by the air above its surface to provide a

supply of dissolved oxygen, the process is very slow allow-

ing for the conditions of oxygen depletion to exist for long

periods of time.

Another mechanism leading to the same result is caused

by an excess of nutrients. The presence of excessive amounts

of nitrates and phosphates spur algae growth in the water

body. The upper layers of algae shield the lower layers from

sun light. This situation causes death of the lower layers

of algae adding large amounts of biodegradable organic

matter to the water body and an explosion in microbiologi-

cal growth. Thus, through the action described above the

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