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.

The invention relates to a method and an assembly for recovering magnesium ammonium phosphate from slurry supplied to a reaction container (10) in which an aerobic milieu that is alkaline as a result of CO.sub.2-stripping is present and in which the slurry is guided in a circuit with the aid of ventilation. Cationic magnesium, such as magnesium chloride, is added to the slurry, and magnesium ammonium phosphate crystals which are crystallized out of the slurry are removed via a removal device (30) provided in the base region of the reaction container. The slurry is supplied from the first reaction container (10) to a second reaction container (12) via a first line (14), wherein an anaerobic milieu is set in the second reaction container in order to redissolve the phosphate, and MAP crystals crystallized in the second reaction container are supplied to the first reaction container.

A membraneless electrochemical device comprises a fluid feed stream input to the membraneless electrochemical cell, a first electrode, and a second electrode. The first electrode comprises a first redox-active material configured to have a proton-coupled oxidation reaction with a first portion of the fluid feed stream, and the second electrode comprises a second redox-active material configured to have a proton-coupled reduction reaction with a second portion of the fluid feed stream. The first portion and the second portion of the fluid feed stream are separated. A first effluent stream comprises the first portion and has a first pH, and a second effluent stream comprises the second portion and has a second pH, different from the first pH.

Methods and systems for removal of ions from aqueous fluids are provided. In certain embodiments, the present disclosure provides a method of removing one or more oxyanions from an aqueous fluid, including the steps of contacting an aqueous fluid containing oxyanions with an aluminum metal whereby aluminum ions are released from the aluminum metal into the aqueous fluid, wherein the one or more oxyanions in the aqueous fluid react with the aluminum ions to form one or more ettringites; controlling a rate of release of the aluminum ions from the aluminum metal; and removing at least a portion of precipitated ettringites from the aqueous fluid.

The invention discloses a biological desulfurizer for removing organic sulfur in fracturing flowback fluid and application thereof. The biological desulfurizer includes a compound with a triazine structure formed by modifying chitosan with aldehydes and inorganic salts. The triazine structure has a good removal effect on hydrogen sulfide and organic sulfur such as mercaptan and sulfide. The biological desulfurizer of the invention has a sulfur capacity of up to 250 g/kg and a desulfurization efficiency of over 95% in 15 min. It can effectively remove the stink of sulfur-containing working water, improve the working environment of the well site, and reduce the impact of sulfur compounds on the atmospheric environment during the development of oil and gas fields.

A method for treating phosphate-containing wastewater, such as phosphogypsum pond water. The method includes the steps of: (a) adding a first cation to the wastewater to precipitate fluorosilicate from the wastewater; (b) adding a second cation to the wastewater to precipitate fluoride from the wastewater; (c) raising the pH of the wastewater to precipitate the second cation from the wastewater; (d) removing residual silica from the wastewater; and (e) precipitating phosphate from the wastewater. The precipitated fluorosilicate may be sodium fluorosilicate. The precipitated phosphate may be struvite.

Filters comprising a Chlorella ellipsoidea by-product (lipid-free biomass) for aquaculture wastewater treatments and methods for removing ammonia, phosphorous, and organic matter from aquaculture wastewater using such filters. The filters have multiple layers of a compressed Chlorella ellipsoidea lipid free biomass by-product of Chlorella ellipsoidea biodiesel production, wherein each of the multiple layers is separately changeable.

The invention relates to methods of production of a silica concentrate from geothermal fluids. More particularly, although not exclusively, the invention relates to the production of a colloidal silica concentrate, colloidal silica or precipitated silica from high temperature geothermal fluids by ultrafiltration to produce size-specific silica colloids and step-wise concentration of silica to avoid precipitation or gelling.

A combined logic control circuit and a sewage treatment system are provided. The combined logic control circuit includes: at least one signal input component, a control component and at least one signal output component; each signal input component transmits at least one path of first communication signal in a photoelectric isolated manner and converts the first communication signal into a second communication signal; the control component generates at least one path of first control signal according to the at least one path of second communication signal; and each signal output component processes one path of the first control signal to control at least one external electrical device, thereby implementing a particular circuit function; and the power switch component provides power supply to the various circuit components in a photoelectric isolated manner.

A method for using produced water (PW), for example, for use in a fracturing fluid. The method includes performing ultrafiltration on the PW to form filtered PW, filtering seawater (SW) to form filtered SW, and blending the filtered PW with the filtered SW to form an aqueous blend.