A biological reactor system treats concentrated contaminated water with a combination of upflow and downflow bioreactors that are downstream from a reverse osmosis or other concentrator. The system may have a fail safe configuration where flush water may be introduced to the reactors in the event of a power failure or when taking the reactors offline. Many reverse osmosis systems introduce antiscalant treatments upstream so that the reverse osmosis filters do not scale. However, such treatments result in superconcentrated conditions of the antiscalants in the contaminated water processed by the bioreactors. A flushing system may deconcentrate the bioreactors to prevent the antiscalants from precipitating and fouling the bioreactors.

A method for removing selenium according to the present invention comprises: a valence change step of adding an oxidant to a wastewater from a facility that gasifies a fuel containing selenium in a reducing atmosphere, and oxidizing the selenium to change the valence of the selenium, and a solid-liquid separation step of adding a flocculant to the wastewater, forming a floc containing the selenium for which the valence has been changed in the valence change step, and subjecting the floc to solid-liquid separation.

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.

Implementations of the present disclosure relate to an apparatus and a method for reducing a selenium-content of a fluid-input stream. The present disclosure includes components and steps for performing chemical modifications of a fluid-input stream and further components and steps for performing physical modifications of a chemically-manipulated fluid stream. When the fluid-input stream has a selenium content the chemical modification of the fluid-input stream drives at least a portion of the selenium content into a selenium-containing solids phase. The chemical modifications include at least oxidation, coagulation, chelation and flocculation. The present disclosure also includes components and steps for performing physical modifications that separate and remove some or all of the selenium-containing solids phase from the liquid phase, which reduces the selenium content of the liquid phase.

A process for treating mine impacted water containing one or more reduced selenium species by an advanced oxidation process (AOP) including ozone and ultraviolet light, or ozone and hydrogen peroxide is disclosed. The process oxidizes the one or more reduced selenium species to selenate and thereby produces AOP treated water. Residual oxidants are removed from the AOP treated water.

The description relates to a composition and a method for reducing the concentration of selenium in water. Contaminated water is contacted with a kaolinite clay characterized by a removal efficiency for selenatearsenate of at least 40 wt % at ambient temperature. The adsorption process is fast. Following sufficient contact, the water is separated from the kaolinite clay. In a preferred form, the kaolinite clay has high surface acidity.

This disclosure provides polyamine sorbent compositions for the separation of metals from aqueous solutions. The polyamine sorbent compositions comprise a silica support, an aminosilane bound to the silica support, an epoxysilane bound to the silica support, and a polyamine where the polyamine is chemically tethered onto a solid silica support through via the epoxysilane. The polyamine may be further stabilized within the bulk sorbent through hydrogen bonding interactions with the aminosilane. The sorbent compositions resist leaching by H.sub.2O in an aqueous stream containing heavy oxyanion-based (and other) metals and demonstrate stability over a pH range of 2-14. The sorbent compositions are useful for the separation of metals from aqueous solutions. The cationic heavy metals are captured by the co-existing amine groups (NH.sub.2, NH, N) from the polymeric network while additional metal capture capacity is derived from the introduction of a secondary silane linker.

A method of binding a target metal in solution. The method of binding a target metal comprises contacting a solution containing i) a target metal with ii) an encapsulated exudate of a culture of algal flagellate, or a fraction thereof; or an encapsulated dried Euglena biomass or a fraction thereof, to form a complex between the target metal, and the encapsulated exudate or fraction thereof, or the encapsulated dried Euglena biomass or the fraction thereof; and optionally separating the complex from the solution. The disclosure also relates to a biosorbent element, as well as methods of using same in binding a metal in solution.

This disclosure provides polyamine sorbent compositions for the separation of metals from aqueous solutions. The polyamine sorbent compositions comprise a silica support, an aminosilane bound to the silica support, an epoxysilane bound to the silica support, and a polyamine where the polyamine is chemically tethered onto a solid silica support through via the epoxysilane. The polyamine may be further stabilized within the bulk sorbent through hydrogen bonding interactions with the aminosilane. The sorbent compositions resist leaching by H.sub.2O in an aqueous stream containing heavy oxyanion-based (and other) metals and demonstrate stability over a pH range of 2-14. The sorbent compositions are useful for the separation of metals from aqueous solutions. The cationic heavy metals are captured by the co-existing amine groups (NH.sub.2, NH, N) from the polymeric network while additional metal capture capacity is derived from the introduction of a secondary silane linker.

One or more embodiments relate to a method of separating a target contaminant from an aqueous source by contacting a polyamine network-based sorbent with the aqueous source; and capturing and separating the target contaminant from the aqueous source.