A wastewater treatment system including an aeration unit, a contact tank, a dissolved air flotation unit, and a biological treatment unit is disclosed. A method of retrofitting a wastewater treatment system by providing an aeration unit and fluidly connecting the aeration unit to the wastewater treatment system is also disclosed. A method of treating wastewater including aerating wastewater with oxygen, combining the aerated wastewater with activated sludge, floating biosolids from the activated wastewater, and biologically treating the effluent is also disclosed. The method optionally includes combining the floated biosolids with the aerated wastewater and/or activated wastewater. A method of facilitating treatment of high solids content wastewater is also disclosed.

The present invention discloses a method for producing a nutritional microbial solids product while simultaneously producing clean water for multiples uses. The microbial solids product represents a form of single cell protein (SCP) that finds application most typically in formulated animal feeds, but may also be used in food, fertilizer, or soil amendment products. The treated water product can be used directly or polished further for subsequent industrial or agricultural use, including aquaculture and irrigation. The process described utilizes low-value by-products of industrial production for biochemical conversion into SCP. The by-products most suitable to this approach have high organic content that otherwise makes them difficult to dispose of responsibly via traditional methods such as biological wastewater treatment.

A method for nitrate removal from drinking water. The method includes adapting a sludge including hydrogenotrophic denitrifiers (HTDs) by dominating the HTDs in the sludge, cultivating a microalgae biomass, forming a microalgae-HTD biomass by cultivating a mixture of the adapted sludge and the cultivated microalgae biomass, nucleating a plurality of microalgae-HTD granules by cultivating the formed microalgae-HTD biomass in a sequencing batch (SB) mood with a constant HRT, growing the plurality of microalgae-HTD granules by cultivating the nucleated plurality of microalgae-HTD granules in an up flow (UF) mood with a reducing HRT, and continuous nitrate removal from nitrate-contaminated water with a minimum HRT over the grown plurality of microalgae-HTD granules.

Exemplary embodiments describe apparatuses and related processes for improving mixing and sheer in a fixed film reactor. One process can include recycling at least a portion of a biogas product through at least one sparger below a fixed film zone in the fixed film reactor at conditions sufficient for mixing and sheering the film from an internal structure within the fixed film zone. Often, a cross-sectional area of the fixed film zone fills at least about 90% of a cross-sectional area of the fixed film reactor.

A reactor for the biological treatment of wastewater, includes a chamber capable of containing a mixture of wastewater and sludge comprising various levels, each level being defined by a sludge concentration and/or density; means for determining a minimum level and a maximum level of sludge extraction in the chamber, comprising: measurement means capable of measuring the sludge concentration and/or density at various levels of a mixture of wastewater and sludge; selection means capable of selecting a maximum sludge concentration and/or density value and a minimum sludge concentration and/or density value; deduction means capable of deducing a minimum extraction level corresponding to the maximum concentration value selected and a maximum extraction level corresponding to the minimum concentration value selected; extraction means capable of extracting sludge at variable levels between the minimum extraction level and the maximum extraction level.

A process for the treatment of wastewater is disclosed, which comprises (a) contacting the wastewater with fast settling sludge from step (c) in an anaerobic zone, obtaining a mixture of wastewater and sludge; (b) subjecting the mixture from step (a) and slow settling sludge from step (c) to an aerobic zone, obtaining a water and sludge mixture; (c) subjecting a first part of the mixture from step (b) to a sludge selection step, wherein sludge is selected based on settling velocity and a first portion containing slow settling sludge and a second portion containing fast settling sludge are collected, wherein average settling velocity of the fast settling sludge is greater than that of the slow settling sludge, and wherein the first portion is returned to step (b) and the second portion is returned to step (a); and (d) separating sludge from a second part of the mixture from step (b).

Provided herein are methods for removing mercury contaminant from an aqueous solution, the methods including: providing an aqueous solution, the aqueous solution being contaminated with at least trace amounts of an oxidized mercury species; culturing a photoheterotrophic or fermentative heterotrophic bacteria in the aqueous solution under anaerobic conditions in which the bacteria reduce the oxidized mercury species to elemental mercury (Hg.sup.0), wherein the bacteria comprises one or more bacteria of the order Clostridiales; and removing the elemental mercury from the aqueous solution. Also provided are bioreactors for removing mercury contaminant from an aqueous solution, as well as uses of photoheterotrophic or fermentative heterotrophic bacteria, wherein the bacteria comprises one or more bacteria of the order Clostridiales, for removing mercury contaminant from an aqueous solution.

The invention pertains to a method (200, 300, 400) of at least partly removing at least one micropollutant from wastewater (104) comprising carbogenous compounds and at least one micropollutant. The method comprising the steps of: (a) dividing the wastewater (104) into a main stream (105) and a side stream (106); (b) treating main stream (105) with bacteria to reduce the content of carbogenous compounds to provide depleted wastewater (107) comprising at least one micropollutant; (c) treating the depleted wastewater (107) with a second portion of microorganisms (162), having the ability of degrading the at least one micropollutant, to, at least partly, remove the at least one micropollutant thereby providing treated water (170), wherein the second portion of microorganisms (162) have been enriched by feeding the side stream (106) to it before using the second portion of microorganisms (162) in treating the depleted wastewater (107); and (d) feeding a first portion of microorganisms (161), having the ability of degrading the at least one micropollutant, with the side stream (106), to enrich them for subsequent use in treating the depleted wastewater (107) to at least partly remove the at least one micropollutant.

The invention pertains to a method for the purification of substrate-containing wastewater in a continuous flow-through aerobic biologically activated sludge reactor B, wherein at least part of biological sludge 6 is conditioned in a selector S under anaerobic or anoxic conditions with at least part of the substrate-containing, to-be-purified wastewater 2, optionally after a pre-treatment step VB of the supplied wastewater 1, such that at least 20 wt % of the sludge in the selector S has a residence time in the selector which is at least 20% greater than the hydraulic residence time of the sludge/water mixture in the selector, after which the thus conditioned sludge/water mixture 3, optionally after an additional anaerobic or anoxic contact step, is fed to the aerobic purification reactor B and subjected to aerobic treatment B, wherein the treated wastewater 4 after aerobic treatment is optionally separated from the sludge by settling NB, flotation or mechanical separation, and wherein (at least a portion of) the sludge separated from the aerobically treated wastewater is returned to the selector as return sludge 6.

Methods of removing dioxane and optionally one or more CAHs such as 1,1-DCE, cis-1,2-DCE, trans-1,2-DCE, 1,2-DCA, 1,1-DCA, VC, and TCE from a liquid medium contaminated therewith include applying a feedstream of propane to the liquid medium in the presence of at least one propanotrophic bacteria strain selected from Azoarcus sp. DD4 (DD4) and Mycobacterium sp. DT1 (DT1). Propane, 1-propanol and/or 1-butanol may be employed as substrates in the bioaugmentation of the propanotrophic bacteria strain.