WASTEWATER TREATMENT

Wastewater Treatment

Wastewater Treatment

Wastewater Management

The water that has lost its quality because of human related activities is known as wastewater. Therefore, wastewater management is intrinsically related to water quality management. The activities mentioned in the definition of wastewater management can be broadly summarized as the activities that a person or a group of individuals or entities carry out to protect public and environmental health from the adverse effects of contaminants found in wastewater.

Managing wastewater encompasses several important areas that can be summarized as follows:

The collection and transportation of the wastewater away from highly populated or environmentally sensitive areas via sewerage networks (sewerage is the infrastructure used to collect and transport wastewater, including pipes, pumps, screens, channels, and combined sewer overflows, used to move sewage from its origin to the point of eventual treatment or disposal) (Biswas, et al, 2006).

Treatment Prior to Discharge

•Releasing wastewater again into the environment (land, rivers, lakes, and oceans) or reusing the treated wastewater for beneficial purposes (e.g., cooling of power-generating facilities, groundwater recharge augmentation).

•Ensuring that the concentrations of contaminants found in the receiving water bodies or land do not harm people and the environment (Bartlett, 1979).

Sources of Wastewater

Wastewater is collected in sewerage networks (if available) or in small decentralized systems such as privy houses, pit latrines, septic tanks, and so on. Most cities, throughout the world, have sewerage systems that allow for the collection of both wastewater and runoff resulting from rain. Runoff carries a mixture of water, sediments, oil, and grease from streets that is combined with wastewater from human-related activities that produce liquid wastes (Melosi, 2008).

Sources of wastewater from human-related activities are classified as point source or direct, and non-point source or diffuse. Examples of direct sources are the discharges from domestic residences, public properties such as governmental buildings, private commercial properties, industrial and mining facilities, and livestock farms. Examples of diffuse sources are agricultural areas. Each of these sources can add different types and concentrations of contaminants to water (Glennie, 2002).

Constituents of Wastewater

Wastewater is composed primarily of water. Alongside water, there are high concentrations of chemicals, toxic compounds, and organic and inorganic matter. When wastewater is accumulated and is left untreated, the decomposition of the organic matter that it contains leads to nuisance conditions, including the production of malodorous gases. Untreated wastewater contains a large number of pathogenic organisms (bacteria, viruses, parasitic worms, etc.) that come from human and animal intestinal tracts (Cech, 2005). These organisms are the leading causes of epidemics such as typhoid, cholera, hepatitis A, dengue fever, among others and bacteriological and viral diseases. Wastewater also contains nutrients, such as nitrogen and phosphorus that exist naturally in the environment. However, the high concentrations of these nutrients in wastewater can stimulate unwanted growth of algae and other aquatic invasive species (McDonald, 1988).

Wastewater may also contain heavy metals and different types of toxic compounds that are known carcinogens. Because of these reasons, the highest priority of wastewater management has been to adequately remove potential nuisance conditions that can severely affect public ...