Which system is primarily designed for the subsurface disposal of sewage effluent?

The ground absorption system is specifically designed for the subsurface disposal of sewage effluent, making it the correct choice. This system functions by allowing wastewater from a septic tank to be distributed through pipes into a series of soil trenches or beds. The soil acts as a natural filter, treating the effluent as it percolates through and allowing for the safe disposal of treated wastewater underground.

This design is crucial because it minimizes the potential for surface runoff and exposure to pathogens, while promoting the natural breakdown of organic materials by microorganisms present in the soil. By utilizing existing soil properties, ground absorption systems effectively reduce environmental impact and protect public health.

In contrast, wetlands treatment systems involve the use of man-made or natural wetlands to treat wastewater, relying on biological and chemical processes in surface water rather than subsurface disposal. Composting toilet systems focus on the aerobic processing of human waste into compost rather than discharging effluent into the ground. Above-ground oxidation systems typically involve treating wastewater in open aeration ponds, which is not the same as subsurface disposal. Each of these alternatives serves different purposes in wastewater management but do not primarily focus on the subsurface disposal aspect as the ground absorption system does.