Halophilic or Halotolerant: Bacteria which thrive in a highly salt environment, up to 25% NaCl.
Headworks: The facilities where wastewater enters a wastewater treatment plant. The headworks may consist of bar screens, comminutors, a wet well and pumps. Heterotroph: A microorganism which uses organic matter for energy and growth. HRT: Hours of Retention Time.
House Sewer: The pipeline connecting the house and drain and the septic tank.
Humus: The dark organic material in soils, produced by the decomposition of soils. The matter that remains after the bulk of detritus has beenconsumed (leaves, roots). Humus mixes with top layers of soil (rock particles), supplies some of the nutrients needed by plants -increases acidity of soil; inorganic nutrients more soluble under acidic conditions, become more available, EX. wheat grows best at pH 5.5-7.0. Humus modifies soil texture, creates loose, crumbly texture, that allows water to soak in and nutrients retained; permits air to be incorporated into soil.
Hydraulic loading: Hydraulic loading refers to the flows (MGD or m3/day) to a treatment plant or treatment process.
Hydrogen sulfide gas: Hydrogen sulfide is a gas with a rotten egg odor. This gas is produced under anaerobic conditions. Hydrogen sulfide is particularly dangerous because it dulls your sense of smell so that you don't notice it after you have been around it for a while and because the odor is not noticeable in high concentrations. The gas is very poisonous to your respiratory system, explosive, flammable, and colorless.
Hydrolysis: The process in which carbohydrates and starches are simplified into organic soluble organics, usually by facultative anaerobes. Hydrophilic: Having an affinity for water and aqueous solutions. Hydrophobic: Cannot be wetted by aqueous and other high surface tension fluids.
Hygroscopic: Absorbing or attracting moisture from the air.
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