Patent ID: 7147777

Claim:
A sewage treatment system with a series of parallel main process lines including anoxic and aerobic zones and an MBR zone in series, with inflow means for receiving influent wastewater into the main process lines, and at least one additional, special process line having similar zones but being normally operated to receive a portion of M.L.S.S. from the main process lines, the special process line having means for internal recycling of sludge among the zones during normal operation, so as to produce a further thickened and stabilized or digested W.A.S. to be removed from the special process line during normal operation, and including means for recycling a majority of M.L.S.S. exiting the main process lines to re-enter the main process lines to mix with wastewater in the main process lines, whereby the system can be operated in a second, surge or storm mode of operation at more than twice normal design flow, wherein all process lines are operated in the same manner, with parallel streams of wastewater being processed serially through the anoxic, aeration and MBR zones, thereby maintaining equilibrium in the system by removing water via the MBRs at a rate equal to influent wastewater flow, without the need to remove W.A.S. during a period of such surge or storm mode.