MBR stands for Membrane Biological Reactor. This type of technology produces a class "A" water suitable for re-use in the irrigation of parks and golf courses, street washing, industrial cooling water and many other non-potable applications. A list of these can be found under Wastewater Documents, under "Wastewater Reuse Standards". It is a process of the biological removal of solids through nitrification which is similar to that found in nature. This environment is different in that it is all suspended in liquid and therefore air has to be introduced using blowers to meet the respiration needs of the bacteria.
Bacteria must be kept healthy and productive to consume the sewage and stabilize its effect on receiving waters. The membrane portion is a filter that either pulls or pushes liquid through while retaining the solids for recycle back to the biological tanks or to waste out of the system for solids handling and further reduction and stabilization. These filters are so small that all bacteria are trapped and the resulting permeate is virtually clear. Disinfection is still needed as viruses can make their way through the filter.