5. Sludge treatment, reuse and disposal. Sludge is produced from the treatment of wastewater in on-site (e.g. septic tank) and off-site (e.g. activated sludge) systems. This is inherently so because a primary aim of wastewater treatment is removing solids from the wastewater.
Definition of central. 1  1 : containing or constituting a center. 2  2 : of primary importance : essential, principal the central character of the novel. 3  3a : situated at, in, or near the center the central part of the stateb : easily accessible from outlying districts a central location for the new theater.
A character who changes during the course of a story or novel. The change in outlook or character is permanent. Sometimes a dynamic character is called a developing character. A character who reveals only one, maybe two, personality traits in a story or novel, and the trait(s) do not change. Foil Character A character that is used to enhance another character through contrast.