Mini compact MBR cassettes are designed for the treatment of domestic waste water to obtain a high quality effluent with minimal environmental impact. MBR mini cassette comprises: 10 membranes, stainless steel structure and a diffuser in the lower part for both cleaning the membranes and for biological aeration. Permeate of each membrane passes through a silicone tube to a PVC manifold where total water is collected. The mini cassette MBR has a total effective membrane area of 2.7 m2 and small size for easy inspection and placement.