A vacuum truck is a truck mounted, heavy duty industrial vacuum loader designed to pneumatically convey solids, liquids, sludge or slurry through suction lines typically 2-4" in diameter with 3" being the norm. The typical pump used in the industry is the rotary vane vacuum pump. The truck can be configured to be a direct PTO/belt or a PTO/hydraulic drive system. There are two different ways to mount the pump either directly on the truck with PTO drive or on the trailer with a pony motor. Each application has different handling characteristics and each comes with pros and cons and each one has its own application depending on the services the company offers.

The trucks are often used by towns and municipalities for street cleanup, sewers and can also be used for cleanup of contaminated soil. The trucks are mostly used in the oil patch. They are used for the cleaning of storage tanks and spills. They are also a important part of drilling oil and natural gas wells, as they are located at(sometimes in very remote places)the drilling lease, on call 24 hrs a days. They are responsible for removing drilling mud, drilling cuttings, cement, cleaning up spills that occur, and they haul off brine water from production tanks. They dispose of this in sump pits, treatment plants or if within safe levels may be spread out in a farmer's field.

http://en.wikipedia.org/wiki/Vacuum_truck