An Article about Waste Water Management

Wastewater Treatment Process

The wastewater treatment process must be divided into different treatment stages to ensure good water and sanitation quality. The preliminary stage of the treatment process uses large filtering screens that remove large solid inorganic material such as paper, plastic, and metal. This is followed by the removal of the grit and silt which are abrasive to plant equipment.

In the primary stage, wastewater is passed through a primary sedimentation tank where solid particles of organic material are removed by gravity settling at the bottom of the tank. The resultant primary sludge is then raked to the center of the tank where it is concentrated and pumped away for further treatment.

The wastewater then undergoes a biological process known as activated sludge process, which uses natural occurring micro-organisms to break down dissolved and suspended organic solids. The settled wastewater then enters aeration tanks where air is blown into the water to provide oxygen promoting the growth of microorganisms. These microorganisms then consume the organic pollutants and nutrients in the wastewater. From the aeration tanks the mixture of wastewater and microorganisms is moved to a secondary sedimentation tank where the biomass settles to the bottom of the tank and is concentrated as sludge.

The clarified wastewater is then passed into a tank where the third stage of treatment, known as the Tertiary treatment stage, takes place. In this stage chlorine is used to remove any biological pathogens present in the clarified wastewater that could be a risk to human health.

In some instances this treatment is repeated more than once if the treated wastewater is reused for purposes such as irrigation of food crops or where close human contact may result. After all these treatment processes are complete, fresh water is produced.