The principal objective of wastewater treatment is to reduce or remove pathogenic micro-organisms, organic matter, nutrients, and possibly toxic compounds from the wastewater before it is returned to the receiving waters, to land or reused.
The ultimate purpose for wastewater treatment is to protect public health and the environment. In this chapter, a broad range of wastewater treatment alternatives is provided from which one particular system will be selected for the Al-Esmaieleia & Al-Rastan plant based on a set of criteria. Wastewater treatment can be categorised into primary, secondary and advanced or tertiary treatment.
In primary treatment, physical operations are used to remove floating and settleable materials found in the wastewater, whereas, for secondary treatment, biological and sometimes chemical processes, are used to remove most of the organic matter.
Advanced treatment involves additional combinations of unit operations and processes that are introduced only when it is necessary to remove other constituents not reduced by conventional secondary treatment. Figure 3-1 below shows the schematic of a conventional wastewater treatment facility providing primary and secondary treatment processes.