MSABP is water purification technology based on a revolutionary biological treatment process in which a special biological carrier provides immobilization of microorganisms in a multi-stage aeration tank. Principles of treatment are as follows. 1. The effect of multi-stage changes the biota in each tank in an orderly manner thereby forming a food chain. 2. The biological carrier provides an environment in which microorganisms remain active and are able to treat highly concentrated effluent and hard to decompose effluent. MSABP can be used for the following applications. 1.