Purpose. The technology allows for water purification to produce high-quality drinking water from highly mineralized water, processing the resulting concentrates and eliminating secondary environmental pollution.
Specifications. Membrane – OPMN-P; working pressure – 1.5 MPa; permeate selection coefficient – 90%. A mixture of ammonium chloride with ammonium hydroxide at their molar ratio of 1:4, respectively, and magnesium chloride at the ionic ratio PO43-:NH4+:Mg2+ = 1:1:2, initial pH of the medium 10.5-11.0 and stirring duration (5- 10) min for the precipitation of phosphates from the resulting concentrates in the form of struvite (the yield of phosphate ions in the sediment is 95.1-97.8%). 66.7-76.0 vol.% of the fractional composition of the sediment is represented by particles (2.5-20) microns.
Application area. Water treatment; treatment of water, industrial and domestic wastewater.
Advantages. The methods provided by the technology for the preliminary preparation of highly mineralized water before desalination will significantly increase the service life of the membranes, as well as carry out water conditioning without the use of additional equipment and reagents.
Technical and economic effect. The proposed technology makes it possible to reduce energy consumption for water production by approximately two times compared to single-stage purification.
Description. The technology involves several stages of water treatment. Preliminary preparation of wastewater with a turbidity of 98.0-176.5 mg/dm3 – sequential filtration through sand with a fraction size of (1-2) mm. Nanofiltration makes it possible to achieve the maximum permissible concentration limit for phosphate discharge into the sewer system when using the OPMN-P membrane with an initial content of phosphate ions of up to 100 and 130 mg/dm3 with a permeate selection coefficient of 90 and 70%, respectively. The technology also provides for the use of a mixture of ammonium chloride with ammonium hydroxide at their molar ratio of 1:4, respectively, and magnesium chloride at the ionic ratio PO43-:NH4+: Mg2+ = 1:1:2, initial pH value of 10.5-11.0 and duration . stirring (5-10) minutes to precipitate phosphates from the resulting concentrates in the form of struvite – a high-quality complex fertilizer. The technology is based on the introduction of the process of dephosphating and defluoridation of waste and natural waters, as well as the maximum reduction in the content of hardness salts and other salts with polycharged ions in sea water to concentrations of phosphate ions below their maximum permissible concentrations for discharge into sewers, fluoride and chloride ions – to Maximum permissible concentrations of drinking water with processing of the resulting concentrates and the exclusion of secondary environmental pollution.