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.
A vacuole is a membrane-bound sac that allows a plant cell to  maintain its form. It also acts as a sort of storage bin for  liquids, sustenance, or waste products. A sac-liâ¦ke organelle that stores water, food, and other materials.