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 is any person, animal, or figure represented in a literary work. Characters are essential to a good story, and it is the main characters that have the greatest effect on the plot or are the most affected by the events of the story. character is any person, animal, or figure represented in a literary work. Characters are essential to a good story, and it is the main characters that have the greatest effect on the plot or are the most affected by the events of the story.