Final answer:
Sludge digestion will ultimately develop as sludge becomes more concentrated. This process helps reduce the volume of sludge and destroys potentially disease-causing organisms.
Step-by-step explanation:
As sewage sludge becomes more concentrated, sludge digestion will ultimately develop. Sludge digestion is the process of treating the sludge removed in the primary treatment of wastewater. This can be done through anaerobic bacterial decomposition, which occurs in the absence of oxygen, and produces methane gas. Sludge digestion helps reduce the volume of sludge and also destroys any potentially disease-causing organisms.