What type of process does an anaerobic biological treatment rely on?

Anaerobic biological treatment depends on the absence of oxygen as a key factor in its process. This method involves microorganisms breaking down organic matter without the presence of oxygen, which allows them to thrive and metabolize waste effectively. In anaerobic conditions, these microorganisms convert the organic pollutants into biogas, primarily methane, and carbon dioxide, along with other byproducts. This process is beneficial for treating high-strength wastewater and it results in the generation of energy in the form of biogas, making it an efficient and sustainable method of waste treatment.

In contrast, reliance on sunlight, aeration, or high-temperature environments would indicate processes that are not anaerobic. Sunlight is crucial for photosynthesis-based treatments (like algae treatment), aeration introduces oxygen for aerobic processes, and while high temperatures might speed up microbial activity, they do not define the anaerobic treatment process. Hence, the key characteristic of anaerobic treatment is clearly the absence of oxygen.