In sewage treatment plant, activate sludge system depends on air compressor to transport the material, and stir the sewage slowly in the pretreatment pool, condense the oil particles. In deep ventilation pool, compressed air is used to violently stir the water to supply bacteria with oxygen.

Compressed air is very effective for important cleaning and operation job in water supply system. Water tank is cleaned rapidly by air jet and at the same time will check the corrosion point. Compressed air will also wash the rust stain from chlorinator and ammonia supply. The method of treatment for water with heavy metal is that using compressed air to remove the carbon dioxide and extract the iron. Compressed air is also used for drawing water, clean the pipes of boiler, piling and digging gutter, etc. So air compressors are necessary auxiliary machine for environmental protection equipments