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.
The central vacuole is a cellular organelle found in plant cells. It is often the largest organelle in the cell. It is surrounded by a membrane and functions to hold materials and wastes. It also functions to maintain the proper pressure within the plant cells to provide structure and support for the growing plant.
Vacuoles are usually organelles designed for the storage of wastes or water and other resources. The contractile vacuole, also known as the pulsing vacuole for its regular pumping action, is different. It stores its contents for only a few seconds before excreting them from the cell. They are crucial for the organisms that possess them, as without them the cells would expand with water, possibly even exploding.