This application is a Non-provisional Patent Application of U.S. Provisional Patent Application No. 62/596,029, entitled “MOVING BED BIOFILM REACTOR SYSTEM FOR SELENIUM REMOVAL FROM WATER AND WASTEWATER”, filed Dec. 7, 2017, which is incorporated herein by reference in its entirety.

The present invention relates generally to the field of wastewater treatment systems. More particularly, the invention relates to techniques for applying moving bed biofilm reactor systems (MBBR) for selenium removal and/or capture.

BACKGROUND OF THE INVENTION

Certain fluid discharges such drainage water from mining operations; flue gas desulfurization (FGD) blowdown from power plants; desalters and sour water stripper effluents from petroleum refineries; and petroleum refinery treated effluents are major sources of selenium in wastewater. While some selenium is a nutrient to living cells, selenium in water is considered a priority pollutant by the Clean Water Act. For example, the Clean Water Act mandates a selenium discharge limit of less than 5 microgram per liter for industrial discharges. Selenium may be removed, for example, through processes such as reverse osmosis, co-precipitation with ferric chloride, via electrocoagulation, through evaporation/crystallization, deep water injection, ion exchange, constructed wetlands, and so on. It would be beneficial to improve processes for selenium removal.

In a number of the processes used for wastewater treatment, particulate matter may be caused to precipitate from the wastewater and collect on the bottom of a vessel. Reactor vessels for secondary treatment, for example, may hold wastewater in a reactor vessel, along with biological support media. The biological support media includes bacteria that proliferate and serve to treat the water in the reactor vessel by circulation of the water over the support media

BRIEF DESCRIPTION OF THE INVENTION

In one embodiment, a system includes an anoxic moving bed biofilm reactor (MBBR) configured to receive a fluid containing oxy-ions of selenium and to process the fluid via a first biofilm disposed on a first media to produce a first MBBR fluid by removing nitrogen from the fluid. The system further includes a second anoxic MBBR fluidly coupled to the first MBBR to receive the first MBBR fluid and to process the first MBBR fluid via a second biofilm disposed on a second media to produce an elemental selenium enriched fluid. The system additionally includes a plurality of first sensors and first actuators disposed on the first MBBR, and a plurality of second sensors and second actuators disposed on the second MBBR. The system also includes a control system configured to derive one or more first MBBR conditions and one or more second MBBR conditions based on signals from the plurality of first and second sensors, and to actuate the first and second actuators to produce the first MBBR fluid and the elemental selenium enriched fluid based on the first and second MBBR conditions.

In a second embodiment, a method includes receiving wastewater having selenium-containing ions at a wastewater treatment system comprising a first anoxic moving bed biofilm reactor (MBBR) and a second anoxic MBBR fluidly coupled to the first MBBR. The method further includes treating the wastewater in the first MBBR to produce a treated wastewater by removing nitrogen from the wastewater, wherein the first anoxic MBBR comprises a first biofilm disposed on a first media. The method also includes directing treated wastewater to the second MBBR, and treating the treated wastewater in the second anoxic MBBR to produce an elemental selenium enriched fluid.

In a third embodiment, a control system includes a processor. The processor is configured to receive one or more first signals from a plurality of first sensors disposed in a first anoxic moving bed biofilm reactor (MBBR), the one or more first signals representative of a condition of a first fluid being processed by the first MBBR. The processor is further configured to receive one or more second signals from a plurality of second sensors disposed in a second anoxic MBBR reactor, the one or more second signals representative of a condition of a second fluid being processed by the second MBBR. The processor is additionally configured to actuate a first actuator disposed in the first MBBR to remove nitrogen from the first fluid based on the first condition, and to actuate a second actuator disposed in the second MBBR to produce an elemental selenium enriched fluid based on the second condition.

