A method of removing barium, calcium, strontium, and magnesium from frac flowback. A sulfate reagent and carbonate reagent are mixed with the frac flowback, causing barium, calcium, strontium, and magnesium to precipitate. The precipitants are crystallized and the resulting frac flowback and crystals are separated into relatively heavy solids and a stream of relatively light solids. The stream of relatively light solids is subjected to a further separation process that produces sludge that is recycled to aid in the crystallization process and a treated effluent which is recycled to the fracking operation or collected and used in another fracking operation.

A process for treating a flue gas desulfurization discharge stream containing dissolved sulfates is presented. Soluble barium compounds, such as barium chloride or barium carbonate are added to the stream in lieu of the traditional two-step lime/carbon dioxide process. The barium compounds cause the sulfate to precipitate as insoluble barium sulfate. The barium sulfate solids settle out of the discharge stream and can be filtered from the process water. The use of soluble barium compounds eliminates the need for subsequent pH adjustment, results in lowering calcium and magnesium concentrations in the discharge stream, and decreases scaling potential in downstream equipment.

The present invention provides a method for treating a copper-containing waste etching solution, which includes: preparing basic copper chloride nanometer seed crystals and synthesizing basic copper chloride mono-crystals; making an acidic waste etching solution subjected to agglomeration reaction with an ammonium-containing solution and slurry containing the basic copper chloride mono-crystals to obtain basic copper chloride crystal particles and copper-removed waste solution; making an alkaline waste etching solution react with sulfuric acid to obtain a copper sulfate mixed solution; and then evaporating, concentrating, cooling and crystallizing the copper sulfate mixed solution obtained by the reaction of the alkaline waste etching solution and the sulfuric acid in sequence to obtain copper sulfate pentahydrate solids. In a case of low investment, the present invention not only can realize the recycling of copper in the copper-containing waste etching solution, but also can obtain various high-value products, and can achieve both environmental and economic benefits.

A multi-stage submerged membrane distillation water treatment apparatus including: a plurality of raw water tanks arranged in multiple stages ranging from a first stage to an n-th stage and storing raw water, the raw water flowing sequentially from the first stage to the n-th stage; membrane distillation (MD) modules submerged in the respective raw water tanks and discharging a portion of the raw water as vapor; heat exchangers submerged in the respective raw water tanks and maintaining the raw water at a predetermined temperature by performing heat exchange between the raw water and vapor supplied from the respective previous-stage MD modules; a vapor generator generating and supplying high-temperature vapor to the first-stage heat exchanger; a condenser condensing vapor supplied by the n-th-stage MD module; and a raw water feeder feeding low-temperature raw water to the first-stage raw water tank via the condenser.

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 hydrate production apparatus according to the present invention comprises: a main body unit having a reaction space in which a hydrate is produced therein; an inlet pipe unit connected to one side of the main body unit so as to introduce, into the reaction space, a host material and a guest material for producing the hydrate; an outlet pipe unit connected to the other side of the main body unit so as to discharge the hydrate produced in the reaction space to the outside; and a pulverizing device unit provided inside the reaction space so as to increase a reaction area for producing the hydrate by pulverizing, into fine-sized particles, an object to be pulverized, which is at least one of the introduced host material and guest material.

The present invention is a process, a method, and system for recovery and concentration of dissolved ammonium bicarbonate from a wastewater containing ammonia (NH3) using gas separation, condensation, and crystallization, each at controlled operating temperatures. The present invention includes 1) removal of ammonia from waste (sludges, semi-solids, and solids and liquids) without the use of chemicals at a temperature of at least 80 degrees Celsius, 2) condensing the gaseous containing ammonia, carbon dioxide and water vapor to remove water vapor concentrating the amount of gaseous ammonia and carbon dioxide, 3) concentrating the ammonia and carbon dioxide in the water by established means, such as concentrating the gas using partial condensation followed by passing the concentrated gas through an absorption column at a temperature of between about 20 and 50 degrees Celsius to form dissolved ammonium carbonate and ammonium bicarbonate, or total condensation followed by dewatering using reverse osmosis, and 4) crystallizing concentrated dissolved ammonium carbonate and ammonium bicarbonate at a temperature of less than about 35 degrees Celsius to form solid ammonium bicarbonate and ammonium carbonate.

An apparatus for the extraction of phosphorus from wastewater that includes a precipitation module and a retention module. The precipitation module includes a crystallization vessel, one or more inlets disposed in a lower region of the precipitation module and at least one outlet disposed in an upper region of the precipitation module. The retention module includes a sedimentation vessel, at least one inlet disposed in an upper region of the retention module and at least one outlet disposed in a lower region of the retention module. At least one outlet of the precipitation module is connected to at least one inlet of the retention module and at least one outlet of the retention module is connected to at least one inlet of the precipitation module. The volume VS of the sedimentation vessel is greater than/equal to 0.6 times the volume VC of the crystallization vessel (VS≧0.6.Math.VC).

The present invention relates to a water treatment method including: a filtration step of feeding water to be treated to a membrane filtration device having loaded therein a porous separation membrane and performing filtration treatment to obtain filtrate; a discharging step of discharging the water to be treated in the membrane filtration device, which has been separated and concentrated by the porous separation membrane; and a cleaning step of cleaning the porous separation membrane by at least one treatment of physical cleaning and chemical cleaning, in which a cycle including a combination of the filtration step, the discharging step and the cleaning step is repeated multiple times, thereby obtaining filtrate. In each cycle, the filtration step and the discharging step are repeated multiple times, and the cleaning step is then carried out.

Unconventional hydrocarbons production from shale and tight-sand formations unlocks vast new energy sources to the nation. However, public perception about excessive potable water use in hydro-fracturing and possible pollution routes in discharging and reusing produced water (flow-back water) promotes state's stringent regulations and opens the door to develop effective produced water treatment methods. This invention is therefore aimed at properly treating produced water to avert health and environmental liabilities and convert economic losses to useful by-products using innovative methods to de-oil, de-scale, and de-salt produced water.