_____ are flows generated within the plant, usually from solids processing that has been recycled back through the plant.

• A. Sidestreams
• B. Mainstreams
• C. Upsream
• D. Downstreams

Answer: (A)

Flows that originate inside the plant during solids handling and are recycled back into the process are called sidestreams. These streams come from operations like digestion, thickening, and dewatering and are often returned to the main treatment train to help maintain solids balance and treatment efficiency. Sidestreams usually carry higher solids or concentrations than the main flow, so they’re managed separately and reintegrated at appropriate points rather than simply flowing along the primary path. This distinguishes them from the main flow, which is the continuous, primary treatment stream, and from upstream/downstream terms, which describe location along the process rather than recycling behavior.