Can be employed on-site. These systems require regular supervision and maintenance to be effective. An aerobic bacteriological farm can digest 90% to 95% of the solid wastes that are deposited into the septic tank. Typically, oxygen is supplied to a septic system when there is a problem with pumping frequency or the overall effectiveness of the system. The typical design of these systems is such that a small compressor is located near the sewer line as it exits the house, which provides oxygen for the tank.