WWTP Tour - Introduction

Wastewater treatment, and the associated control and prevention of water pollution, is closely tied to the water supplies of the community and industry. Proper treatment prepares the wastewater flow for return to the environment, so that the receiving waters will remain suitable for beneficial uses such as general recreation, and safe for use by our community.

Any natural water system contains dissolved gases normally found in air, which are in equilibrium with the atmosphere. In this way fish and other aquatic life obtain oxygen for their respiration. The amount of oxygen which the water holds depends on temperature and decreases with a temperature increase. Because water temperature is high during the summer, oxygen dissolved in the water is then at a low point for the year. Degradable or oxidizable substances found in wastewater also deplete oxygen through the action of bacteria and related organisms which feed on these waste materials, using available dissolved oxygen for their respiration. If this activity proceeds at a rate fast enough, it can seriously deplete the oxygen level, and the natural flora and fauna are affected. If the oxygen is entirely used up, a condition known as "oxygen exhaustion" occurs. Under such conditions the natural flora and fauna are destroyed.

Wastewater is generally classified into two categories, domestic and industrial. Domestic wastewaters result from the use of water in the home, and include both water after its use in the shower, sink or even watering the lawn, and the material it carries such as body wastes, kitchen wastes, household cleaning agents, and laundry soaps and detergents. In contrast to the general uniformity of substances found in domestic wastewaters, industrial wastewaters show increasing variation as the complexity of industrial processes rises. Because biological treatment processes are ordinarily employed in water pollution control plants, large quantities of industrial wastewaters can interfere with the processes as well as the total load of a treatment plant. This is why Industrial Pretreatment is performed.

Characteristics of wastewater vary. The solid content is numerically low and can amount to less than 1 lb. per 1000 lbs. of wastewater. Still, the character of these waste materials is such that they would cause significant degradation if discharged directly into the environment, and could spread waterborne diseases, notably typhoid and dysentery. Wastewaters usually have a dark grayish-brown appearance with floating trash apparent. Chemically, it contains the numerous and complex organic compounds in body wastes (i.e., proteins, carbohydrates, fats, oils, and urea), as well as soaps, detergents and other chemicals normally used in the household and industry. Biologically, bacteria and other microscopic life abound.

The volume of wastewater, that water which has been used water and must be disposed of or treated, depends on many factors. Household consumption, irrigation, industry, and a mutitude of other uses result in wastewater. In United States cities the average per capita contribution of wastewater quantities are from 75 to 150 gallons of wastewater per day. Of course, industrial consumption in larger cities increases per capita quantities.

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