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Glossary

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Vacutug
The vacutug consists of a 0.5 m³ steel vacuum tank connected to vacuum pump, which is connected to a gasoline engine. On level ground, the vehicle is capable of around 5 km/h. The waste sludge can be discharged under gravity or by slight pressurisation from the pump. Synonyms: Mini-tug
Vacuum
A vacuum describes a space or container entirely devoid of air resulting in an under-pressure and an airflow towards the vacuum space.

Vacuum On Demand
A vacuum system where the system's pump generates vacuum in the piping only when a toilet is flushed or a greywater tank is discharged. Used in small systems with 4 to 10 toilets. Synonyms: VOD
Vacuum Sewers
Vacuum sewerage systems consist of a vacuum station, where the vacuum is generated; the vacuum pipeline system; collection chambers with collection sumps; and interface valve units. In contrast to conventional gravity sewerage systems with intermediate pumping stations, the pressure within the vacuum system is maintained below atmospheric pressure. Following the suction crated by the valve, batches of wastewater are forced to flow from the collection chambers towards the vacuum station. The valves are operated pneumatically and no electricity is needed. Vacuum sewerage is particularly advantageous where water is scarce; the natural slope is insufficient for gravity flow; in areas with poor subsoil conditions (e.g. rocky soil, high groundwater table); where operation is seasonal or water flow strongly intermittent; or in areas prone to flooding.
Vacuum Truck
A truck equipped with a pump and a storage tank. The pump is connected to a hose, which is lowered down into a septic tank or pit, and the sludge is pumped up into the tank. Generally, the storage capacity of a vacuum truck ranges between 4 and 6 m³.

Vault Composting Toilet
Composting toilet using an above vault as a composting chamber (e.g. continuous composting, concrete or brick double-vaults or movable containers).

Vector
An organism (most commonly an insect) that transmits a disease to a host. For example, flies are vectors as they can carry and transmit pathogens from faeces to humans.
Ventilated Improved Pit
The single VIP is a ventilated improved pit. It is an improvement over the single pit because continuous airflow through the ventilation pipe vents odours and acts as a trap for flies as they escape towards the light. See also double VIP Synonyms: Blair Toilet, Single Ventilated Improved Pit, Single VIP, Ventilated Improved Pit Latrine, VIP
Ventilation
The provision of fresh air to a room, building etc.

Vermicomposting
Vermicomposting is the process of using earthworms to break down organic waste in order to create a faster than normal composting. The worm population is self regulating and will increase to the point where available food and space constrain further expansion. The process must be monitored for such parameters as moisture content and temperature but is not labor-intensive. Compared to ordinary soils, the earthworm castings (the material produced from the digestive tracts of worms) contain much more nitrogen (N), phosphorus (P) and potassium (K). They are rich in humic acids and improve the structure of the soill if used as a soil conditioner. The worms are placed in bedding made of loose materials such as coconut husk or shredded paper in a shallow box or tub and fed with soft organic matter such as kitchen waste. After about two months the compost can be harvested by putting the compost in the shape of a cone and scrapping of the top layers. The worms go to the bottom of the cone as they run away from light. Vermicomposting is a popular sustainable low-cost treatment for organic solid wastes (kitchen wastes, plant wastes). It is also applied to treat fecal matter, such as human excreta in the form of sewage sludge, sieved blackwater or faeces. Vermicomposting is also used to produce Terra Preta. Synonyms: Vermicompost, Worm Compost
Vertical Flow Constructed Wetland
A vertical flow constructed wetland is a planted filter bed that is drained at the bottom. Wastewater is poured or dosed onto the surface from above using a mechanical dosing system. The water flows vertically down through the filter matrix to the bottom of the basin where it is collected in a drainage pipe. The important difference between a vertical and horizontal flow constructed wetland is not simply the direction of the flow path, but rather the aerobic conditions. See also constructed wetland. Synonyms: Sub-surface Flow Constructed Wetland, Sub-surface Vertical Flow Constructed Wetland, Vertical-Flow Constructed Wetland, VFCW
Vertical Garden
The term vertical garden refers to any kind of construction and support structure for growing plants in an upwards-directed, vertical way and thereby efficiently and productively making use of the existing space for food or other kind of plant production. A huge variety of different designs and concepts are available including greywater towers, green walls or living walls. The reuse of different composts (e.g. compost, vermicompost or terra preta) from household wastes and reclaimed water (e.g. greywater) or urine can be considered in vertical gardening allowing to enhance food production and to close the nutrient and water cycle at a local level. Synonyms: Green Wall, Living Wall

Virtual Water
The total water used for producing a good or service. This refers to both water used directly (e.g. drinking water for an animal when calculating virtual water of meat) and indirectly (e.g. the water used to produce the animal feed that eventually is needed to produce meat). Virtual water of any good can be divided into three different types of water, depending on the source of water and the type of pollution caused: blue, green and grey water.

Virus
An infectious agent consisting of a nucleic acid (DNA or RNA) and a protein coat. Viruses can only replicate in the cells of a living host. Some pathogenic viruses are known to be waterborne (e.g., the rotavirus that can cause diarrheal disease).
Vision
A vision is a desired future state.

VLOM pumps
A VLOM pump can be operated and sustained using Village Level Operation and Maintenance. The term VLOMM is also used, meaning Village Level Operation and Management of Maintenance. One of the basic aims of a VLOM hand pump is to make all the main wearing parts easy to reach and replace, and to reduce the wear and tear on the pump by good design.
References:
VLOM Pumps
Volatile Fatty Acid
Volatile fatty acids are fatty acids with a carbon chain of six carbons or fewer. They can be created through fermentation in the intestine. Synonyms: VFA
Abbreviation: VFA
References:
http://en.wikipedia.org
Volumetric Organic Load
The volumetric organic load is used to design wastewater treatment units. It can be calculated by multiplying the BOD (mg/L) of the raw water by the influent flow Q (m3/day) and then dividing this volumetric load by the pond volume. Synonyms: gBOD/m3/day
Abbreviation: gBOD/m3/day

Vyredox
The Vyredox method for water purification was developed in Finland and is now also used in Sweden and some other countries. It oxidises the ferrous ion, which is soluble in water, to the ferric ion, which is insoluble, before the water enters the well.