17 DEC 2003
Filter press--A dewatering device where water is forced from the sludge under high
pressure. (See ETL 1110-3-457 Plate and Frame Filter Press).
Filtrate--The liquid that passes through the filter medium.
Filtration Costs refer to the totality of costs associated with one filtration treatment option
over another. These costs include capital costs for equipment and design, including the
cost of floor space and equipment housing. Filtration costs also include operating costs
such as power, labor, maintenance and the costs associated with solids disposal. The
designer should be careful to include all costs associated with installing and operating a
filtration system when comparing solids removal options.
Filtration rate means a measurement of the volume of water applied to a filter per unit of
surface area in a stated period of time.
Head loss is the difference in water level between the upstream and downstream sides
of a treatment process attributed to friction losses. Sometimes called pressure drop.
HTRW means hazardous, toxic and radioactive waste, which is intended to include eve-
rything from petroleum contaminated soils and groundwater, to RCRA hazardous wastes,
to munitions waste and unexploded ordinance (UXO), to radioactive wastes. It does not
usually include domestic wastes or sanitary wastewater. However, HTRW can become
mixed with sanitary waste, in which case the filtration systems described in this Design
Guide can lend themselves to those applications as well. Code of Federal Regulations Title
40 PART 261- Sec. 261.3 (40 CFR 261.3) defines hazardous and toxic waste. Radioactive
waste is any waste material that spontaneously emits measurable quantities of ionizing
Influent means water or wastewater flowing into a basin or treatment plant.
Launder means a trough used to transport water.
Micron means one millionth of a meter. Another term meaning the same thing is a mi-
crometer. These terms will often be used to describe either particle size in a particular
waste stream or the filtering capabilities of a filter cartridge. The smaller the size, how-
ever, the less likely the described particle or medium is to be uniform with respect to the
dimension quoted and the harder it is to accurately measure that particle or pore size.
Therefore, when someone refers to a 5 micron particle, or a 5 micron cartridge, it is im-
portant to verify what exactly that dimension is intended to convey, how it was meas-
ured, and whether it is given as an absolute or nominal dimension.
Permeability is a measure of a liquid flow rate through a filter medium or a filtration
system. When manufacturers refer to a rated permeability they are often referring to the
permeability of that medium tested under laboratory conditions. The permeability of a
filtration system will not only vary under actual field conditions but will also change over
time during the filtration cycle as solids collect on the filter medium. Some manufactur-
ers may incorrectly report permeability as porosity.