Wastewater treatment system with membrane separators and provision for storm flow conditions
First Claim
1. 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.
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Accused Products
Abstract
In a wastewater treatment system and process utilizing membrane bioreactors (MBRs), multiple, parallel series of tanks or stages each include, an MBR stage. Under conditions of normal flow volume into the system, influent passes through several parallel series of stages or process lines, which might be, for example, an anoxic stage, an aeration stage and an MBR stage. From the MBR stages a portion of M.L.S.S. is cycled through one or more thickening MBRs of similar process lines, for further thickening and further processing and digesting of the sludge, while a majority portion of the M.L.S.S. is recycled back into the main process lines. During peak flow conditions, such as storm conditions in a combined storm water/wastewater system, all of the series of stages with their thickening MBRs are operated in parallel to accept the peak flow, which is more than twice normal flow. M.L.S.S. is recycled from all MBR stages to the upstream end of each of all the parallel process lines, mixing with influent wastewater, and the last one or several process lines no longer act to digest the sludge. Another advantage is that with the thickened sludge in the last process line of basins, which ordinally act to digest the sludge, there is always sufficient biomass in the system to handle peak flow, the biomass being available if needed for a sudden heavy flow or an event that might bring a toxic condition into the main basins.
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Citations
21 Claims
- 1. 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.
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14. A method for operating a sewage treatment system, the system including a series of parallel main process lines each including anoxic and aerobic zones and an MBR zone in series, with influent wastewater received in the main process lines, and at least one additional, special process line having similar zones, comprising the steps of:
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in the normal operation mode in which influent wastewater is approximately at design flow, normally operating the system to deliver a portion of M.L.S.S. from the main process lines to the special process lines, and internally recycling sludge among the zones of the special process line during normal operation, so as to produce a further thickened and stabilized or digested W.A.S., in the normal operation mode, removing stabilized or digested W.A.S. from the MBR zone of the special process line, in the normal operation mode, recycling effluent M.L.S.S. from the main process lines back to re-enter the main process lines to mix with wastewater in the main process lines while delivering said portion of M.L.S.S. to the special process line wherein further thickening and digestion or stabilization of sludge occur, and in a surge or storm mode of operation when influent wastewater flow rate is more than twice design flow, receiving the influent wastewater in all process lines and operating all process lines in the same manner, with parallel streams of influent wastewater being processed serially through the anoxic, aeration and MBR zones similarly and in parallel through all process lines including the special process line, and in the surge or storm mode of operation, recycling effluent M.L.S.S. from all process lines back to enter the process lines to mix with wastewater in the process lines, thereby, in the surge or storm mode, maintaining equilibrium in the system by removing water via the MBRs of all process lines at a rate essentially equal to influent wastewater flow, without the need to remove W.A.S. during such surge or storm mode. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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Specification