1-4 IMPROVEMENT OF ENVIRONMENTAL QUALITY

Vitally concerned with the improvement of environmental quality, the environmental engineer plays an important role in environmental management programs. Such programs might be said to involve two distinct aspects--environmental strategies and enviromnental tactics. [1-1] Environmental strategies are comprehensive plans that usually address a variety of problems that confront a single area. Typical environmental strategies might be a program to improve the quality of Lake Erie, to improve the air quality of the Los Angeles basin, or to collect and properly dispose of the solid waste from the city of Philadelphia.

Environmental strategies are usually worked out in public and political arenas. Considerations must include economic, social, and demographic factors. Historically, enviromnental engineers have not played a highly visible role in devising environmental strategies. Nevertheless, the environmental engineer should be a important member of a management team that includes persons drawn from a wide variety of disciplines. The input of the environmental engineer, especially in assessing the likely response of the environment to various levels of contaminant loading and in weighing the various technical solutions that may be proposed, is a necessary component of any environmental strategy.

Environmental engineers are usually more directly associated with the implementation of the environmental tactics that are the means for achieving the goals set forth in a specific portion of a given environmental strategy. The engineer's part in this implementation consists primarily of the design, construction, and operation of treatment facilities for water, air, and solid waste. For example, the environmental engineer would be involved directly in the addition of tertiary processes to remove phosphorus from the effluent of a wastewater-treatment facility emptying into Lake Erie, the installation of a hydrocarbon removal system at a gasoline refinery system in Los Angeles, or the design of a solid-waste processing plant in Philadelphia.

1-5 THE ROLE OF THE ENVIRONMENTAL ENGINEER

As pollutants enter air, water, or soil, natural processes such as dilution, biological conversions, and chemical reactions convert waste material to more acceptable forms and disperse them through a larger volume. Yet those natural processes can no longer perform the cleanup alone. The treatment facilities designed by the environmental engineer are based on the principles of self-cleansing observed in nature to handle larger volumes of pollutants and to treat them more rapidly. Engineers adapt the principles of natural mechanisms to engineered systems for pollution control when they construct tall stacks to disperse and dilute air pollutants, design biological treatment facilities fo the removal of organics from wastewater, use chemicals to oxidize and precipitate out the iron and manganese in drinking-water supplies, or bury solid wastes in controlled landfill operations.

Occasionally, the environmental engineer must design to reverse or counteract natural processes. For example, the containers used for disposal of hazardous materials from the environment in order to prevent the onset of the natural, but highly undesirable, processes of dilution and dispersion.

As will be demonstrated throughout this text, an understanding of natural and engineered purification processes requires an understanding of the biological and chemical reactions involved in these processes. Thus, in addition to being knowledgeable in the mathematical, physical, and engineering sciences, the environmental engineer must also be well grounded in the subject areas of chemistry and microbiology, subject areas not usually emphasized in engineering curricula. Indeed, an understanding of biological and chemical principles is as essential to the environmental engineer as the understanding of statics and strength of materials is to the structural engineer.

The environmental engineer's unique role is to build a bridge between biology and technology by applying all the techniques made available by modern engineering technology to the job of cleaning up the debris left in the wake of a indiscriminate use of that technology. The delicate balance of our biosphere has been disturbed, and the state in which we now find ourselvbes is a direct consequence of our having been ignorant of the constraints imposed by the limits of the self-cleansing mechanisms of our biosphere.

A keen awareness of these natural constraints plays an important role in the work of enviromnmental engineers. For example, the laws of conservation of mass and energy prevent the destruction of pollutants, and the engineer is bound by these limits. The principles of waste treatment must therefore be to convey the objectionable material to other, less objectionable forms; to disperse the pollutants so that their concentrations are minimal; or to concentrate them for isolation from the environment.

In all instances, the end products of the treatment of polluted water or air or of the disposal of solid wastes must be compatible with the existing environmental resources and must not overtax the assimilative powers of hydrosphere, atmosphere, or lithosphere. In structural engineering, the engineer can simply specify a larger or stronger beam to carry a heavier load. The environmental engineer, on the other hand, must accept the carrying capacity of a stream, an airshed, or a landmass because these can seldom be changed.

It is the purpose of this text to demonstrate how the environmental engineer, working within these constraints, uses all available technological tools to design efficient control and treatment devices that are modeled after the natural processes that have so long preserved our biosphere. For only by bringing technology into harmony with the natural environment can the engineer hope to achieve the goals of the profession--the protection of the environment from the potentially deleterious effects of human activity, the protection of human populations from the effects of adverse environmental factors, and the improvement of environmental quality for human health and well-being.