Glossary of Filtration Technologies: J

Joule

Joule is a unit of energy equal to 0.2389 calories. It can also be expressed as a unit of energy or work that is equivalent to one watt per second or 0.737 foot-pounds; a calorie is equal to 4.184 joules. In the US this definition is often used: 1055 Joules is equal to 1 BTU.

Joule's Law

The rate of heat production by a steady current in any part of an electrical circuit that is proportional to the resistance and to the square of the current, or, the internal energy of an ideal gas depends only on its temperature.

Juice

Juice is a fluid naturally contained in animal or plant tissue. For example, orange juice is the liquid extract of the fruit of the orange tree. Juice may be supplied in concentrate form, requiring the user to add water to reconstitute the liquid back to an approximation of the original juice. Juice will usually have a defined level of purity, in some countries of 100%. It should not be confused with a squash which is usually an artificial juice to be diluted with water. Common methods for preservation and processing of fruit juices include membrane filtration, freeze concentration, evaporation, separation (clarification), freeze drying, homogenization and pasteurization. GEA Filtration is a leading supplier of juice clarification systems.

The principles of membrane filtration are that the liquid to be filtered passes over the membrane at high velocity. Depending on the membrane pore size, different sizes of molecules are able to pass through the membrane. The feed is split into two streams, namely the permeate (containing the water (or solvent) and the particles smaller than the membrane pores) and the retentate (containing water (or solvents) and particles larger than the membrane pores).