In an unlined ET system, wastewater is disposed of primarily through which method?

In an unlined Evapotranspiration (ET) system, the primary method of wastewater disposal is indeed through evaporation, transpiration, and soil absorption. These systems are designed to allow wastewater to be treated naturally as it passes through the soil and interacts with vegetation.

Evaporation refers to the process where water is converted to vapor and released into the atmosphere. This is a key mechanism in unlined ET systems, as it helps to reduce the volume of wastewater being processed. Transpiration involves plants absorbing water through their roots and releasing it into the air through their leaves, further contributing to the reduction of liquid waste in the system. Soil absorption plays a crucial role in filtering out contaminants from the wastewater, allowing it to be naturally purified before it eventually becomes part of the groundwater system.

This combination makes unlined ET systems effective for treating and disposing of wastewater, especially in areas where traditional drainage or pumping systems may not be feasible or cost-effective. The other options, while relevant to wastewater management in certain contexts, do not directly describe the primary disposal method used in unlined ET systems.