What type of treatment is primarily focused on removing dissolved and suspended solids from wastewater?

The focus of the treatment method that primarily targets the removal of dissolved and suspended solids from wastewater falls under secondary treatment. This stage of wastewater treatment is specifically designed to use biological processes to degrade organic matter, resulting in the significant reduction of dissolved and suspended solids. Secondary treatment typically employs microorganisms to consume organic materials, effectively clarifying the wastewater.

In this stage, aeration processes may be utilized to enhance the biological degradation of contaminants, leading to the production of a clearer effluent. Following this biological treatment, primary effluent undergoes further sedimentation, which helps separate remaining solids from the treated wastewater.

While primary treatment does remove some solids and settleable materials, it primarily focuses on physical separation. Advanced or tertiary treatments involve additional processes aimed at further purifying wastewater beyond the secondary level, often targeting specific contaminants or nutrients. Therefore, secondary treatment stands out as the correct choice for its specific role in addressing dissolved and suspended solids effectively.