Land-Based Disposal of Wastewater

Disposal onto land takes the form of effluent from on-site and off-site treatment systems being permitted to percolate by the ground. For a septic tank, for instance, this occurs by the soakage of overflow from the septic tank within a leach drain. Disposal onto land commonly pollutes groundwater, and might reach surface water although groundwater eventually discharges within surface water. The impact of BOD and nutrients in the wastewater on the surface water has been attenuated through soil processes and is, thus, not as severe as direct disposal within surface water. A Disposal from an off-site treatment plant for groundwater recharge to control encroachment of seawater within coastal fields is a form of reuse.

Injection of wastewater within a deep confined aquifer through a borehole is a possibility. Only treated wastewater along with extremely low content of suspended and colloidal solids could be injected within a deep aquifer to avoid blockage of the pore spaces surrounding the borehole. The long-term effect of deep well injection is still unclear and the method is not commonly recommended.

Use of treated wastewater is considered to be disposal techniques as opposed to a reuse method. This keeps wastewater from being discharged within bodies of water (rivers, streams, groundwater and the ocean). Nutrients (nitrogen and phosphorus) are taken up through the crop, therefore protecting the groundwater. This system has several advantages as follows:

(a)        Nutrients act as a fertiliser therefore reducing amounts from traditional categories of fertilizers.

(b)       Reduces surface water and groundwater pollution potential.

(c)        It is an environmentally better scheme that is more likely to get approval of regulating bodies.