Glossary (S)

Sludge dewatering technology based on conveying sludge along the length of a cylindrical screen using an Archimedean screw

Decay and putrefaction under anaerobic (i.e. oxygen-depleted) conditions

The velocity of a particle settling in water under gravity

Factor expressing the rate of increase and intensity of heat

Rate of imposed shear, the force associated with water flowing parallel to the particle or floc surface

Non-oxidative thermochemical treatment employing low heating rates and moderate temperatures favouring bio-char as the main product

Removal of water from sludge by evaporation at elevated temperatures

Reduction of odour, putrescence (i.e. decay) and pathogenic organism content of sewage sludge

Equipment for removing water from sludge through its evaporation at elevated temperatures

Sludge drying bed housed in a glass-based structure to allow control of the drying atmosphere

Centrifuge based on a rotating horizontal cylinder with a conical end where the sludge cake exits

Amount of solids fed into the reactor per volume per unit time

Percentage solids content or mass of solids per unit volume of sludge

Reduction of solids content of sludge through its decomposition to thermal products

Period of time the solids are retained in the reactor

Dissolving of matter in water

Hydraulic resistance of the cake formed from sludge solids to the passage of water through it

Measure of hydraulic resistance

See 'Sludge stabilisation'

Phase of the drying cycle where the sludge becomes sticky and challenging to manipulate

Region of the water temperature:pressure phase diagram above 218 bar pressure and 374 °C temperature in which water exists as a supercritical fluid or plasma

Another term for 'hydrothermal gasification'

Oxidation taking place in the supercritical region of the temperature:pressure water phase diagram (above 218 bar pressure and 374 °C temperature)

Diluted (water) upper layer produced when solids settle

Water associated with solid particles and bound to their surfaces by hydrogen bonding

Primary product of hydrothermal gasification (HTG), containing gaseous hydrogen and carbon monoxide as the primary constituents

A biochemical symbiotic relationship