NOVELTY - An anaerobic wastewater treatment system comprises a bioselector (80) comprising an overflow outlet, a tangential intake in communication with an overflow outlet of a bioreactor (50) for receiving treated wastewater and entrained microbial consortia particles (50A) from bioreactor and a recycle outlet in communication with a recycle tank (20). The bioselector has a circular cross section and a cone shaped lower end. The tangential intake causes the treated water to swirl such that suspended particles move toward the bioselector walls and sink to the bottom and return to the bioreactor.    USE - An anaerobic wastewater treatment system.    ADVANTAGE - The system fully exploits the potential capacity of a bioreactor tank and eliminates the constraint imposed by the need to retain microbial consortia particles. The addition of bioselector allows for an increase in the space loading capacity of bioreactor. The egress of microbial consortia particles from bioreactor tank is no longer a constraint in the system. With increased space loading, a higher chemical oxygen demand/biochemical oxygen demand (COD/BOD) feed rate for a bioreactor tank of a given volume can be accommodated. With a separate bioselector fulfilling the function of capturing and retaining active, viable, dense microbial consortia particles, complex structures inside bioreactor tank for retaining the particles are no longer necessary. The bioreactor tank may be optimized for the intimate interaction of granules and wastewater to accomplish wastewater treatment with little or no consideration of microbial consortia particle retention or selection in the bioreactor.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for capturing and returning dense anaerobic bacteria microbial consortia particles for digesting waste in wastewater.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of an anaerobic wastewater treatment system.    Recycle tank (20)    Intake (22, 52, 82)    Wastewater feed pipe (22A)    Recycle inlet (24)    Recycle outlet (26, 88)    Recycle feed pipe (26A)    Recycle feed pump (26B)    Bioreactor (50)    Microbial consortia particles (50A)    Gas disengagement portion (50E)    Overflow outlet (54, 96)    Biogas vent (56)    Bioselector (80)    Body (80A)    Conical lower portion (80B)    Effluent and recycle outlet portion (80C)    Return outlet (84)    Return pipe (84A)    Bioselector pump discharge pipe (84B)    Pump (86)    Recycle pipe (88A)    Recycle valve (92)    Vent (94)    Biogas collection pipe (94A)    Effluent discharge pipe (96A)    P elbow (96B)