Coarse bubble diffusers are a type of aeration device used in water treatment processes, particularly in wastewater treatment plants. They're designed to introduce large bubbles into water or liquid, aiding in the transfer of oxygen and mixing within the water body. These diffusers typically consist of larger apertures or openings through which air is released into the water. The bubbles produced are comparatively larger in size compared to fine bubble diffusers, which allows for more rapid ascent through the water column. This ascent facilitates mixing and helps in the aeration process by bringing oxygen from the air into contact with the water.

A rotameter, also known as a variable area flow meter, is a device used to measure the flow rate of a fluid in a closed conduit. It operates based on the principle of a variable area, where the area of flow passage changes in response to the flow rate of the fluid passing through it. The typical design of a rotameter includes a tapered tube, often made of glass or plastic, with a smaller diameter at the bottom and a larger diameter at the top. Within this tube is a float—a spherical or cylindrical object—positioned in the path of the flowing fluid. As the fluid flows through the tube, the float rises, indicating the flow rate.