2 - Definitions
2.1Annex IV – the revised Annex IV of the International Convention for the
Prevention of Pollution from Ships, 1973, as modified by the 1978 and 1997 Protocols
(MARPOL), as amended by resolutions MEPC.115(51) and MEPC.200(62).
2.2Convention – the International Convention for the Prevention of Pollution
from Ships, 1973, as modified by the 1978 and 1997 Protocols (MARPOL).
2.3 Dilution (Qd) – is dilution water, grey water, process water,
and/or seawater introduced to the sewage treatment plant after the influent sample
point and after the influent flow measurement device, see figure 1.
2.4Effluent (Qe) – treated wastewater produced by the sewage treatment plant,
see figure 1.
2.5 Flush water – transport medium used to carry sewage or other
wastes from toilets or urinals to the treatment system.
2.6Geometric mean – the nth root of the product of n numbers.
2.7Grey water – is drainage from dishwater, galley sink, shower, laundry, bath
and washbasin drains and does not include drainage from toilets, urinals, hospitals,
and animal spaces, as defined in regulation 1.3 of MARPOL Annex IV and does not
include drainage from cargo spaces.
2.8Hydraulic loading – system design flow rate of waste water (Qi) into the
sewage treatment plant.
2.9Influent (Qi) – Liquid containing sewage, grey water or other liquid
streams, to be processed by the treatment plant, see figure 1.
2.10Sample point – A point for manual collection of a representative sample of
influent and effluent without opening tanks, voids or vents, see figure 1.
2.11Testing on board – testing, for the purpose of type approval, carried out
on a sewage treatment plant installed on a ship.
2.12Testing ashore – testing ashore, for the purpose of type approval, carried
out on a sewage treatment plant.
2.13Thermotolerant coliforms – the group of coliform bacteria which produce gas
from lactose in 48 hours at 44.5°C. These organisms are sometimes referred to as
"faecal coliforms"; however, the term "thermotolerant coliforms" is now accepted as
more appropriate, since not all of these organisms are of faecal origin.
Figure 1 - System diagram of a sewage treatment plant