Glossary
The technical terms used in this site and the general terms of water treatment are explained on this page. The terms are listed in alphabetic order. Select the term you are looking for from the index on the left.
- Laminar flow
- This is a state of current that each part of the fluid flows sequentially and adjacent layer of fluid slip on each other in the direction of flow when a fluid flows in a smooth watercourse at a small flow velocity. When the flow velocity exceeds a certain limit, the flow shifts to a turbulent state. The limit can be estimated by acquiring the Reynolds number of the fluid.
- Limulus test
- This is the most sensitive and reliable method for detecting endotoxin. This is a test method which uses a component extracted from the blood cells of a limulus (LAL) and its characteristic that it gels when it contacts endotoxin.
- Measurement of the number of live bacteria
- This is a method to calculate the number of live bacteria based on the 2 principles that all live bacteria form colonies and that 1 bacterium form 1 colony. The tested solution or the microfilter with which the tested solution was filtered is cultured in aseptic culture medium, and the number of live bacteria is calculated based on the number of formed colonies. There are pour plate dilution method, membrane filter method, liquid culture medium step dilution method, etc. according to the number of bacteria.
- Membrane area
- The surface area of the membrane which directly contacts the feed water in the membrane module.
- Membrane filtration
- A method to separate solvent from dissolved matter, low-molecular dissolved matter from high-molecular dissolved matter, fine particles, etc. by pressurizing solution via semipermeable membrane.
- Membrane separation
- General term of separation processes which use semipermeable membrane.
- Membrane surface washing
- To wash off the dirt such as deposits on the membrane surface in order to recover the performance of the membrane which has decreased caused by fouling and adsorption of dissolved matter. There are physical washing methods such as washing by scrubbing with sponge balls, flashing with undiluted solution or water, back washing with permeate, etc., and chemical washing methods which use chemicals including oxidizers, detergents and chelating agents such as acid, lye and hypochlorous acid.
- Mixed liquor suspended solids (MLSS)
- The amount of activated sludge in the mixed liquor in the aeration tank
- Module
- This is a structure created by processing membrane and assembling the components for efficiently performing membrane separation. It is a unit for use which has a structure that can be used if it is connected to piping.
- Molecular cutoff
- It means the minimum molecular cutoff which can be stopped by a semipermeable membrane, which is UF membrane in general. In other words, the dissolved matter which has a molecular mass higher than the molecular cutoff is stopped by the membrane. However, note that it is difficult to strictly compare the molecular cutoffs described in the catalogs of different companies because the type of the standard dissolved matter, the measurement conditions, the value of the rejection rate which is considered to be stopped by the membrane vary among companies.