Water containing selenium, for example flue gas desulfurization (FGD) blowdown water is treated with a combination of biological and chemical treatment and membrane filtration. The biologically treated water is dosed with a dithiocarbamate compound and flocculated prior to membrane filtration. Optionally, the treatment may be enhanced with one or more adsorptive agents prior to, or in conjunction with, membrane filtration. Membrane concentrate may be re-circulated to one or more biological treatment zones. The biological treatment may be by way of suspended growth, fixed growth on a moving bed, or both. One or more biological treatment zones may be controlled considering their oxygen reduction potential (ORP). Optionally, the biological treatment includes an aerobic zone following one or more anoxic or anaerobic zones. The non-aerobic zones remove selenium and optionally nitrogen and sulfur. The aerobic zone removes carbon, which may include carbon added as a nutrient in a non-aerobic zone.

A filter for a liquid purifier may include a filter housing having an inlet and an outlet; and a filter module provided in the filter housing, and configured to purify liquid introduced through the inlet, and to supply the purified liquid to the outlet. The filter module may include an electrostatic adsorption nonwoven fabric having a hollow portion. The filter module may be configured to receive the liquid introduced through the inlet is to pass through the electrostatic adsorption nonwoven fabric and then is to discharge out of the outlet of the filter housing.

Methods for removing anions from an aqueous solution include contacting the aqueous solution with an initial organic phase composition in a primary stage to form a first mixture, the initial organic phase composition including a quaternary amine and a weak organic acid; separating a nitrate-depleted raffinate from the first mixture; mixing the remaining organic phase (now containing nitrate) with a first basic solution to obtain a second mixture; separating an aqueous phase sulfate-containing scrub solution from the second mixture; mixing the remaining organic phase with a second basic solution to form a third mixture; and separating the third mixture into an aqueous phase nitrate-rich solution and a secondary organic phase composition. The secondary organic phase composition can be recycled. The raffinate, the sulfate-containing scrub solution, and the nitrate-rich solution can then be further processed.

Provided herein are processes for the removal and/or recovery of a target metal from a liquid sample, said process comprising: [1] applying acoustic cavitation to the liquid; and [2] adding an iron (II) salt, or a precursor form thereof, to the liquid sample and allowing Fenton oxidation reaction to occur between the iron and hydrogen peroxide in the liquid, thereby producing hydroxyl radicals; thereby producing a target metal salt or metal oxide having a reduced solubility in the liquid sample, leading to removal of the target metal from the liquid sample. The use of metal ligands in such processes is also described, as well as systems for performing such processes. Methods, processes, and systems for removing organic contaminants from a liquid sample are also described.

A method for efficiently removal of oxidised selenium from liquid, such as FGD wastewater. The method involves adding a non-iron-based reducing agent (e.g. sodium dithionite) and preferably Fe(II) ions to the liquid at a pH of above 7.5 or 8 and precipitating elemental selenium from the liquid.

A process for the treatment of contaminated water includes contacting the contaminated water with a cryptocrystalline magnesite-bentonite clay composite thereby to remove one or more contaminants from the water. The invention extends to a method for the manufacture of a cryptocrystalline magnesite-bentonite clay composite wherein an admixture of cryptocrystalline magnesite and bentonite clay is milled to a desired particle size with amorphization of the magnesite and bentonite clay in the resultant cryptocrystalline magnesite-bentonite clay composite, and to a cryptocrystalline magnesite-bentonite clay composite.

A system, a method and a process is provided for removing selenium from coal mine wastewater. The method and system include the steps of providing a quantity of ferric chloride in a predetermined relative ratio to a volume of mine wastewater, using sodium hydroxide to adjust the pH of the mine wastewater between 7.5 and 8, introducing the volume of mine wastewater into a sediment pond or tank having turbidity curtains.

Methods and systems for bioremediation of heavy metal contaminants in waste materials (e.g., sludge and combustion wastes from a coal-fixed power plant). The systems described in the present application include at least one waste treatment unit (e.g., a flue gas cleaner or a waste lagoon) that includes one or more selected bacterial strains disposed therein consume and/or reclaim at least a portion of the heavy metal in the combustion wastes. Methods include inoculating a waste treatment unit with one or more selected bacteria that consume and/or reclaim at least a portion of the heavy metal in the combustion wastes. Methods may include periodic reinoculation of the waste treatment unit with fresh bacteria and period recovery of the bacteria from the waste treatment unit.

The present invention is directed to a ligated metal-organic framework (MOF) for use in removing both anionic and cationic species from a liquid or liquid stream. The present invention also provides methods for placing the MOF on a substrate to form a MOF-containing product that can be used in the removal of certain species from a given fluid. The MOF may be a Zr-based MOF, such as NU-1000, for removal of certain anions, such as oxy-anions, or having an attached thiosulfonyl-thiol (—SO.sub.2—S—R.sub.2—SH, where R.sub.2 is an alkyl group) ligand for complexation with certain cationic species in addition to the anions. The substrate may be any substrate to which a given MOF may be attached, including inert polypropylene polymer resin beads, a macroscopic fabric such as a mesh material or mesh filter, and a molecular fabric.

The present application provides a waste water preconditioning system for limiting mercury concentrations in a waste water stream resulting from treatment of a flue gas. The waste water preconditioning system may include a wet flue gas desulfurization system for treating the flue gas with an aqueous alkaline slurry, a sulfite detector to determine the concentration of sulfite in the aqueous alkaline slurry, and to produce the waste water stream with a mercury concentration of less than about five micrograms per liter. The waste water preconditioning system also may include a waste water treatment system downstream of the wet flue gas desulfurization system.