Machines for sewage disposal plants, namely, machines which convey and compact grit and sand in wastewater and sewage; machines for sewage disposal plants which remove mechanical and biological materials and sludge in wastewater and sewage by means of separation and conveyance; mechanical graters and screens for cleaning, namely, machine graters also incorporating screens which screen and cleanse solid materials in wastewater and sewage; feeding and transporting machines, namely, waste materi...