What treatment method first conditions the solids with chemicals and later separates them?

The correct method for conditioning solids with chemicals before separating them is the centrifuge process. In a centrifuge, the solid waste is first treated with chemicals to enhance the separation of solids from liquids. This conditioning can help break down the structures of the solids or agglomerate particles, making them easier to separate.

Once the solids are conditioned, the centrifuge uses centrifugal force to separate the solids from the liquid phase efficiently. This method is widely used in wastewater treatment for its effectiveness in dewatering sludge.

Other options, such as thermal treatment and incineration, involve high temperatures to reduce waste volume or destroy pathogens and do not focus on chemical conditioning. Gravity thickening relies on natural gravitational force to separate solids from liquids, but it does not use chemical agents for conditioning prior to separation. Understanding this is crucial for grasping the different steps involved in wastewater treatment processes.