Abstract: This specification describes a process and apparatus for treating water comprising selenium. A process is described having the steps of treating the wastewater influent using a biological reduction process to produce an intermediary stream and reducing the concentration of unconsumed constituents in the intermediary stream by means of filtration optionally with upstream coagulation or flocculation. When compared to the wastewater influent, the intermediary stream preferably has reduced concentration of the selenium species when compared to the wastewater influent. When compared to the intermediary stream, the effluent preferably has reduced concentration of one or more of the inorganic non-metallic constituents (such as nitrogen, phosphorous and sulphur), metallic constituents or organic constituents. An apparatus is described herein having a fixed film reactor configured to receive a wastewater influent, and a membrane filter configured to receive effluent from the fixed film reactor.

Abstract: Systems and methods are described for treating flue gas, for example from a coal fired power plant. The systems and methods include control of a wet flue gas desulfurization (WFGD) system to manage sulfite concentration in a slurry produced by the WFGD system. Oxygen is added to the slurry in an amount sufficient to produce a sulfite concentration in the slurry in the range of about 5 to 75 mg/L, an oxidation reduction potential in the range of about 100-250 mV, or both. The systems and methods also include the biological treatment to remove selenium from a liquid fraction of the slurry. The liquid fraction is treated in a biological reactor maintained under anoxic or anaerobic conditions to reduce its selenium concentration.

Abstract: A bioreactor has a biofilm supporting bed with at least two types of media. An upper media is relatively porous, preferably porous enough to admit particles of a lower media. In use, wastewater flows downwards through the bed. Soluble nitrogen is reduced in the upper media and converted into nitrogen gas. Nitrogen gas bubbles rise through the upper media and escape from the bed. Selenium is reduced in the lower media and converted into elemental selenium. The elemental selenium is released periodically by backwashing the bed, which may cause fluidization or other expansion of the lower media into the upper media.

Abstract: This specification describes a process and apparatus for treating water comprising selenium. A process is described having the steps of treating the wastewater influent using a biological reduction process to produce an intermediary stream and reducing the concentration of unconsumed constituents in the intermediary stream by means of filtration optionally with upstream coagulation or flocculation. When compared to the wastewater influent, the intermediary stream preferably has reduced concentration of the selenium species when compared to the wastewater influent. When compared to the intermediary stream, the effluent preferably has reduced concentration of one or more of the inorganic non-metallic constituents (such as nitrogen, phosphorous and sulphur), metallic constituents or organic constituents. An apparatus is described herein having a fixed film reactor configured to receive a wastewater influent, and a membrane filter configured to receive effluent from the fixed film reactor.

Abstract: A bioreactor has a biofilm supporting bed with at least two types of media. An upper media is relatively porous, preferably porous enough to admit particles of a lower media. In use, wastewater flows downwards through the bed. Soluble nitrogen is reduced in the upper media and converted into nitrogen gas. Nitrogen gas bubbles rise through the upper media and escape from the bed. Selenium is reduced in the lower media and converted into elemental selenium. The elemental selenium is released periodically by backwashing the bed, which may cause fluidization or other expansion of the lower media into the upper media.