The invention relates to a method for the precipitation of arsenic and heavy metals from acidic, in particular sulphuric acid, process water (12), containing both arsenic and heavy metals, comprising a precipitation method phase (II) with a sulphide precipitation stage (C) in which arsenic and at least one primary heavy metal are precipitated together, wherein a sulphide precipitating agent (16) is added to the process water (12) such that arsenic is precipitated as arsenic sulphide and the at least one primary heavy metal is precipitated as metal sulphide. The sulphide precipitation stage (C) comprises a first sulphide precipitation step (C.1) in which a sulphide precipitating agent is added to the process water (12) in a first sulphide precipitation reactor (14), whereby an intermediate fluid (22) is generated still containing arsenic or still containing arsenic and the primary heavy metal. The intermediate fluid (22) is transferred into a second sulphide precipitation reactor (30) after the first sulphide precipitation step (C.1). The sulphide precipitation stage (C) comprises a second sulphide precipitation step (C.2) in which a sulphide precipitating agent is added to the intermediate fluid (22) in the second precipitation reactor, whereby a residual fluid (32) is generated which is substantially free from arsenic.

A method of treating process water of a flotation plant is disclosed. The flotation plant comprises a mineral flotation line and a process water circuit for treating underflow and/or overflow of the flotation line. The process water circuit comprises a gravitational solid-liquid separator for dewatering underflow and/or overflow of the mineral flotation line to separate sediment from supernatant comprising at least water and unrecovered fine particles comprising valuable material; and a recover water tank for collecting process water. According to the method, prior to leading supernatant from the gravitational solid-liquid separator into the recover water tank, it is subjected to cleaning flotation, in which at least 90% of the flotation gas bubbles have a size from 0.2 to 250 μm, in a cleaning flotation unit. An arrangement for treating process water of a flotation plant, and its use are also disclosed.

A three-dimensional electrode-ozone oxidation-electrocatalytic membrane coupled wastewater treatment device, including a circulating fluidized bed reactor. The circulating fluidized bed reactor includes a funnel-shaped internal, a truncated cone, a fiber ball filter, a gas-liquid distribution plate, an inner cylinder, an intermediate cylinder and an outer cylinder. The inner cylinder, the intermediate cylinder and the outer cylinder are coaxial. The inner cylinder is an electrocatalytic membrane assembly; the intermediate cylinder is a gas diffusion electrode; and the outer cylinder is a stainless-steel mesh. A particle electrode is filled between the intermediate cylinder and the outer cylinder, and between the intermediate cylinder and the inner cylinder. The intermediate cylinder is connected to a negative electrode. The inner cylinder and the outer cylinder are connected to a positive electrode. A wastewater treatment method using the device is also provided herein.

The present invention provides for a method for separating starch from processing solutions containing starch containing plants or roots such as potatoes, sweet potatoes, wheat, corn, tapioca, yams, cassaya, sago, rice, pea, broad bean, horse bean, sorghum, konjac, rye, buckwheat and barley to provide commercially acceptable starch while reducing disposal of solid or liquid waste matter into landfills or water treatment facilities.

A system for treatment of a polluted effluent, includes an outer chamber configured to treat the polluted effluent in mixture with a purification slurry including particles of one or more catalysts and/or organoclays, or a mixture thereof. The outer chamber includes (i) a stirring unit consisting of an engine and a stirrer, configured to mix the polluted effluent and the purification slurry to prevent the particles from sinking without causing a turbulence, (ii) a membrane located at the top of the outer chamber through which a treated effluent passes, while preventing the particles of one or more catalysts and/or organoclays from exiting the outer chamber together with the treated effluent, (iii) a membrane cleaning system configured to remove and collect the particles of one or more catalysts and/or organoclays accumulated on the membrane, and re-introducing the particles back to the bottom of the outer chamber.

A dryer system includes an electrodialytic regenerator that comprises a first channel that dilutes a first stream of liquid desiccant and a second channel that concentrates a second stream of the liquid desiccant. An air-liquid interface is in fluid communication with the second stream of the liquid desiccant and an input air stream and exposes the second stream of the liquid desiccant to the input air stream. The absorption of the water from the input air stream creates a dehumidified air stream. The system includes a heat transfer element in thermal communication with the air-liquid interface. The heat transfer element carries latent heat generated from the absorption of the water from the input air stream. The system includes a drying chamber coupled to receive the dehumidified air stream and the heat.

A process for converting ammonium (NH.sub.4.sup.+) of a mainstream of a wastewater plant to dinitrogen gas (N.sub.2), including the consecutive steps of i.) removing biodegradable carbon compounds in the mainstream, ii.) converting ammonium (NH.sub.4.sup.+) in the mainstream to nitrite (NO.sub.2.sup.−) in an aerated biological process containing ammonium oxidizing bacteria (AOB) in a nitration vessel (133a-133d); and iii.) denitrifying the resulting stream from step ii.) to dinitrogen gas in an anammox vessel (200). Growth of nitrite oxidizing bacteria (NOB) in step ii.) is prevented by periodically subjecting the bacteria in said nitration vessel (133a-133d) to water suppressing growth of nitrite oxidizing bacteria (NOB).

A process for treating sour water includes combining the sour water with an alkali or alkaline metal hydroxide to produce a sour water mixture, the sour water comprising sulfides, passing an electric current through the sour water mixture, where passing the electric current through the sour water mixture causes at least a portion of the sulfides to react to produce a treated sour water comprising sulfates and having a pH of 7.1 to 9.8, saturating the at least a portion of the sulfates in an aqueous sulfate solution, and separating at least a portion of saturated sulfates from a saturated aqueous sulfate solution.

A process is described for treating water, in particular for obtaining ultrapure water, in which a decationized water stream is passed at least through a first strong base anion exchange bed and a second strong base anion exchange bed, which is arranged downstream, in particular directly downstream, of the first strong base anion exchange bed. Furthermore, a water treatment system and a counter-current ion exchange unit for carrying out such a process are described.

A liquid filter article, including: a housing having an inlet, an outlet, and an adsorbent bed there between, the bed comprising: a first stage having a first adsorbent, the first adsorbent including an activated carbon honeycomb infused with a plurality of zero valent iron nanoparticles (“Fe-AC”); and a second stage having a second adsorbent, the second adsorbent being selected from iron oxide particles supported on activated carbon honeycomb (“FEOX-AC”), iron oxide particles supported on activated alumina honeycomb (“FeOX-AA”), or a combination thereof, wherein the first stage is in fluid communication with the second stage. Also disclosed is a method of using the liquid filter article to remediate heavy metals in water.