OVERVIEW

A pilot plant consists of equipment and materials used to simulate a full-scale process or processes. It is built to collect process design and operations data, but it is constructed on a smaller scale for ease of operation, installation, and manipulation. A pilot plant s size can vary from bench-scale equipment to systems that can treat millions of gallons per day.

Each unit treatment process has a limited scale-down factor. If this limit is exceeded, the pilot unit process will no longer simulate the full-scale process. Most scale-down limits have been established empirically from previous pilot studies. For example, gravity filter operations can be simulated using filter columns as small as 4 in. (10 cm) in diameter. However, backwashing studies using the same size filter do not provide quality data. This is so primarily because the excessive ratio of sidewall area to surface area creates friction between the media and sidewall, short-circuiting washwater.

Pilot plant design and operations should be kept as simple as possible. Pilot plants should be operated manually to maintain control of the processes, to determine idiosyncrasies associated with unit processes and individual equipment pieces, and to rectify small problems as they occur. Problems not manually corrected could jeopardize the relevance of significant amounts of data. For example, flow can be controlled using rate controllers and variable-speed drives on pumps. With small flows, in-line flowmeter accuracy can be off by as much as 25% or more. Without a...