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.
the answer to a main character is a person or living thing that is talked about mostly or has a great part in the book,play.movie ect. the main character on a story can be one â¦ person or a group of people, the main character usually leads to the introduction of the story then to the climax and the to the end.o in other words the main character in a story is a leader. well usually the main character is the one who is most mentioned The main character in a story is the character who the story is mostly talking about.