Urban runoff Storm water from city streets and adjacent domestic or commercial
properties that may carry pollutants of various kinds into the sewer systems and
from there to rivers, lakes, or oceans.
Vacuum filtration This sludge dewatering process consists of a cylindrical drum
which rotates partially submerged in a vat of sludge. The filter drum is divided
into compartments by partitions or seal strips. A vacuum is applied between the
drum deck and filter medium, causing filtrate to be removed and filter cake to be
retained on the medium during the pickup and cake drying cycle. The filter
medium may be a cloth made of natural or synthetic fibers, stainless steel wire
mesh, or coil springs. Dewatered sludge is ordinarily removed by a fixed scraper
blade.
Vector (a) In environmental science, an organism, typically a biting insect or tick,
that transmits a disease or parasite from one animal or plant to another. (b) A
quantity having direction as well as magnitude, especially as determining the
position of one point in space relative to another. (c) In mathematics and physics,
a vector is an element of a vector space. For many specific vector spaces, the
vectors have received specific names, which are listed below. Historically,
vectors were introduced in geometry and physics before the formalization of
the concept of vector space.
Vegetable oil An oil derived from plants, e.g., canola oil, olive oil, sunflower oil.
Ventilated improved pit latrine (VIP) It is a pit latrine with a black vent pipe
going from the pit to above the superstructure with a fly screen on top. VIP
latrines have the advantage over simple pit latrines of removing flies and odors if
designed, built, and used properly.
Volatile fatty acids (VFAs) Fatty acids containing fewer carbon atoms, and are
dissolvable in water. When organic material undergoes fermentation reactions,
smaller and more readily available organic molecules are formed known as
volatile fatty acids (VFAs). VFAs typically found in wastewater are acetic acid
(acetate) and propionic acid. VFAs provide the food for PAOs.
Volatile solids Those solids in water, wastewater, or other liquids that are lost on
ignition of the dry solids at 550
C.
Volcano A vent in the Earth that, when pressure builds and it erupts, releases
dangerous molten rock and gases.
Vulnerability The degree to which a system is susceptible to, or unable to cope
with, adverse effects of climate change, including climate variability and
extremes. Vulnerability is a function of the character, magnitude, and rate of
climate variation to which a system is exposed; its sensitivity; and its adaptive
capacity.
Warning A notice issued when a hazardous weather event is occurring, is imminent, or has a very high probability of occurring. A warning is used for conditions
posing a threat to life or property.
WASH It is an acronym that means Water, Sanitation, and Hygiene. Access to
WASH usually includes safe water, appropriate sanitation, and hygiene education. Adequate access to WASH can greatly reduce water-borne diseases in a
community.
12 Glossary of Natural Resources and Environmental Pollution Control
491
properties that may carry pollutants of various kinds into the sewer systems and
from there to rivers, lakes, or oceans.
Vacuum filtration This sludge dewatering process consists of a cylindrical drum
which rotates partially submerged in a vat of sludge. The filter drum is divided
into compartments by partitions or seal strips. A vacuum is applied between the
drum deck and filter medium, causing filtrate to be removed and filter cake to be
retained on the medium during the pickup and cake drying cycle. The filter
medium may be a cloth made of natural or synthetic fibers, stainless steel wire
mesh, or coil springs. Dewatered sludge is ordinarily removed by a fixed scraper
blade.
Vector (a) In environmental science, an organism, typically a biting insect or tick,
that transmits a disease or parasite from one animal or plant to another. (b) A
quantity having direction as well as magnitude, especially as determining the
position of one point in space relative to another. (c) In mathematics and physics,
a vector is an element of a vector space. For many specific vector spaces, the
vectors have received specific names, which are listed below. Historically,
vectors were introduced in geometry and physics before the formalization of
the concept of vector space.
Vegetable oil An oil derived from plants, e.g., canola oil, olive oil, sunflower oil.
Ventilated improved pit latrine (VIP) It is a pit latrine with a black vent pipe
going from the pit to above the superstructure with a fly screen on top. VIP
latrines have the advantage over simple pit latrines of removing flies and odors if
designed, built, and used properly.
Volatile fatty acids (VFAs) Fatty acids containing fewer carbon atoms, and are
dissolvable in water. When organic material undergoes fermentation reactions,
smaller and more readily available organic molecules are formed known as
volatile fatty acids (VFAs). VFAs typically found in wastewater are acetic acid
(acetate) and propionic acid. VFAs provide the food for PAOs.
Volatile solids Those solids in water, wastewater, or other liquids that are lost on
ignition of the dry solids at 550
C.
Volcano A vent in the Earth that, when pressure builds and it erupts, releases
dangerous molten rock and gases.
Vulnerability The degree to which a system is susceptible to, or unable to cope
with, adverse effects of climate change, including climate variability and
extremes. Vulnerability is a function of the character, magnitude, and rate of
climate variation to which a system is exposed; its sensitivity; and its adaptive
capacity.
Warning A notice issued when a hazardous weather event is occurring, is imminent, or has a very high probability of occurring. A warning is used for conditions
posing a threat to life or property.
WASH It is an acronym that means Water, Sanitation, and Hygiene. Access to
WASH usually includes safe water, appropriate sanitation, and hygiene education. Adequate access to WASH can greatly reduce water-borne diseases in a
community.
12 Glossary of Natural Resources and Environmental Pollution Control
491