V
volatile acids: these are present in the feedstocks and also produced in the digester by acid-forming bacteria and then used by the methane-forming bacteria to produce methane.
volatile solids: the organic matter which can be converted to gas.
wastewater: water that has been used for domestic or industrial purposes.
wastewater treatment: physical, chemical, and biological processes used to remove pollutants from wastewater before discharging it into a water body.
waterborne disease: a disease spread by contaminated water.
water conservation: practices which reduce water use.
water cycle: see hydrologic cycle.
water pollution: the act of making water impure or the state of water being impure.
water quality: the condition of water with respect to the amount of impurities in it.
watershed: land area from which water drains to a particular water body.
water system: a river and all its branches.
water table: the upper surface of the zone of saturation of groundwater.
W
Glossary
V-Z