Sanitation Engineering

Sanitation (or “sanitary”) engineering emerged in the 19th century as a specialized form of civil engineering. Drinking water treatment and distribution, wastewater treatment and distribution, and solid and hazardous waste management are the principal traditional disciplines. Sanitation engineering is dedicated to the remediation of waste streams generated by human activity in an effort to preserve both environmental and public health. Public health has been defined as “community action to avoid disease and other threats to health and welfare to individuals and the community at large. “Environmental health is the extension of this concept beyond human settlements and into the larger natural world. The two concepts are inextricably linked.

Human wastes may be generated from municipal, commercial, and industrial sources. Sanitation engineering becomes increasingly important proportional to the density and activity of these sectors. Waste is traditionally defined as “a system by-product without inherent value,” but it is better described as a spent or displaced resource. Waste may be gaseous, liquid, solid, or even thermal in form. Accumulation of wastes can aggravate and distress ecosystems through the disruption of natural environmental equilibriums. This happens once a natural ecosystem's capacity to handle wastes is overloaded or incidentally diminished. Urbanization, industrial intensification, and agricultural expansion can be disruptive to both the immediate and global environment. The consequence if waste accumulation is left unchecked is disease, which may be derived either chemically (poisoning) or biologically (pathogenic microorganisms). The aim of sanitation is to return wastes back to the environment in a natural, harmless state. The more ambitious objective is to manipulate or transform a spent resource back into a desirable and useful commodity. A few examples are scrap-metal recycling and energy-from-waste programs (anaerobic digesters).

A waste stream must be treated from within the greater context of a complete system. A sanitation engineer must address a waste stream from its point of origin until final release and account for each intermediary step before it may be rendered “harmless.” In this respect, sanitation engineers must become masters of process engineering life-cycle analysis. The physical, chemical, and biological components of waste may change over time. Decomposition, degradation, or a change in the pattern of consumption can all influence the behavior of waste. For example, relatively harmless dissolved proteins in water contain proteins that can be reduced by bacteria to create toxic and corrosive hydrogen sulfide, which is potentially a safety concern at waste management facilities. Asbestos is only dangerous as a friable, airborne particulate. Water conservation programs may result in less volume of wastewater but yield a proportional increase in concentrations of contaminants.