What do wastewater treatment facilities depend upon for the breakdown of pathogenic organisms and organic materials in secondary treatment of wastewater

Removal of grit by flowing the influent over/through a grit chamber. Fine grit that finds its way into the influent needs to be removed to prevent the damage of pumps and equipment downstream (or impact water flow). Too small to be screened out, this grit needs to be removed from the grit chamber. There are several types of grit chambers (horizontal, aerated or vortex) which control the flow of water, allowing the heavier grit to fall to the bottom of the chamber; the water and organic material continue to flow .

Thats just a thought though. O^O

answer:

sequence 1- deletion

                  2- duplication

                  3- insertion

                  4- substitute

                  5- inversion