Glossary

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u
Ultra Violet Radiation
Ultraviolet radiation spans wavelengths from about 10 nm to 400 nm and is an important component of sunlight although the ozone layer prevents much of it from reaching the earth's surface. It is seperated in UV-A, UV-B and UV-C light. UV-C and UV-B light have a damaging effect on DNA and can therefore act as a desinfectant (killing microbes) or cause skin cancer and genetic mutation. Synonyms: Ultra Violet, Ultraviolet, UV
Abbreviation: UV

Ultrafiltration
A kind of low-pressure membrane filtration process in which hydrostatic pressure forces a liquid against a semipermeable membrane. Suspended solids and solutes of high molecular weight are retained, while water and low molecular weight solutes pass through the membrane (typically with a pore size of l 0.1–to 0.01 micrometres). Synonyms: Ultra-filtration

Unimproved Drinking Water Sources
As defined by the Joint WHO & UNICEF Monitoring Programme (JMP), an unimproved drinking-water source is one that by the nature of its construction does not adequately protect the source from outside contamination, in particular with faecal matter. Unimproved drinking-water sources include: Unprotected (dug) well; unprotected spring, cart with small tank or drum; tanker truck-provided water, surface water (river, dam, lake, pond, stream, canal, irrigation channel); bottled water (because of potential limits on the quantity of water available to a household through this source, not the quality). Synonyms: Unimproved Drinking Water, Unimproved Drinking-Water, Unimproved Water Source
Unsaturated Zone
The unsaturated zone is the portion of the subsurface above the groundwater table. The soil and rock in this zone contains air as well as water in its pores. In some places the unsaturated zone is absent, as is common where there are lakes and marshes, and in some places it is hundreds of meters thick, as is common in arid regions. Hydrologically, the unsaturated zone is often the main factor controlling water movement from the land surface to the aquifer. Flow rates and chemical reactions in the unsaturated zone control whether, where, and how fast contaminants enter groundwater supplies.
Upflow Anaerobic Sludge Blanket Reactor
Upflow anaerobic sludge blanket (UASB) reactors are anaerobic centralized or decentralized industrial wastewater or blackwater treatment systems achieving high removal of organic pollutants. The wastewater flows upwards in a vertical reactor through a blanket of granulated sludge. Bacteria living in the sludge break down organic matter by anaerobic digestion transforming it into biogas. Solids are also retained by a filtration effect of the blanket. Upflow and the motion of the gas bubbles allow mixing without mechanical assistance. Baffles at the top of the reactor allow gases to escape and prevent outflow of the sludge blanket. As all aerobic treatments, UASB require a post-treatment to remove pathogens, but due to low removal of nutrients, the effluent water as well as the stabilised sludge can be used in agriculture. Synonyms: UASB
Abbreviation: UASB

Upstream-Downstream Water Conflict
The upstream / downstream conflict over water consists of diametrically opposed demand patterns for water resources, in space and in time. Furthermore, downstream communities often suffer from upstream induced pollution. Synonyms: Upstream-Downstream Conflict over Water, Upstream/Downstream Conflict over Water, Upstream/Downstream Water Conflict

Urea
Urea is the main nitrogenous breakdown product of protein metabolism in mammals and is excreted in urine as a way of ridding the body of excess nitrogen. With time, the urea in urine breaks down into carbon dioxide and ammonia, which is readily used by organisms in soil.
Urinal
A urinal is a specialised toilet for urinating only. It has the shape of a container or simply a wall, with drainage and automatic or manual flushing.
Urine
Urine is the liquid produced by the body to rid itself of urea and other waste products (TILLEY et al. 2008). Urine is virtually sterile. It makes up less than 0.5 % of the household wastewater (TETTEY-LOWOR n.y.), but contains most of the essential plant nutrients accounting for about 80 % of the nitrogen (N), 50% of the phosphorous (P) and 60% of the potassium (K) from all nutrients excreted per year per person (JOHANSSON 2000). A human being excretes about 500 litres of urine per year accounting for 2 to 4 kg nitrogen (N) and 0.2 to 0.4 kg Phosphorus (P). P and K from urine are directly plant available. N from urine is transformed into ammonium during storage. Hence, urine has properties similar to commercially available chemical fertilisers.
Urine Diversion
Urine diversion devices collect urine separately from faeces and from water (or with minimal flush water). A urine diversion toilet has two outlets with two collection systems: one for urine and one for faeces in order to keep these two excreta or wastewater fractions separate. Synonyms: UD
Urine Diversion Components
Urine diversion components allow toilet users to separate urine from faeces. There are urine diversion components for all kind of toilet systems, cultures and climates. Synonyms: UD components
Abbreviation: UD components

Urine Storage
Urine storage is the simplest and cheapest way to hygienise separately collected urine in order to reuse it safely in agriculture. Urine is generally sterile but contains most of the plant nutrients excreted by humans. To hygienise urine, it is stored for one up to six or more month, depending on estimated risk of cross-contamination with faeces. The sanitising effect comes from a combination of the rise of pH (due to the transformation of urea to ammonium by the naturally present enzyme urease), the raise of temperature and time.

User Interface
User interface describes the type of toilet, pedestal, pan, or urinal that the user comes in contact with; it is the way that the user accesses the sanitation system. In many cases, the choice of user interface will depend on the availability of water.
UV-A Radiation
The longest ultraviolet radition, UV-A, lies within 315 and 400 nm. Most of it passes through the atmosphere and reaches the earth surface. Synonyms: UV-A, UVA
Abbreviation: UV-A

UV-B Radiation
Ultraviolet radiation within 280 and 315 nm. UV-B can be directly absorbed by DNA and is therefore carcinogenic and can kill microorganisms. Most of it in natural sunlight is filtred out by the ozone layer and only some few percent of the solar spectre contain UV-B. Synonyms: UV-B, UVB
Abbreviation: UV-B

UV-C Radiation
Ultraviolet radation within 100 and 280 nm. Almost all of UV-C light from the natural solar light is filtred out in the atmosphere. Synonyms: UV-C, UVC
Abbreviation: UV-C