7 results about "Struvite Crystals" patented technology

The invention belongs to the technical field of industrial and agricultural waste recycling, and particularly relates to a method for recycling biogas slurry nutrients by mechanically and chemically activating anaerobic biogas residue biochar. According to the method, magnesium oxide desulfurization residues and oxalic acid are used as grinding aids, and biochar is activated by using a mechanochemical technology, so that the content of water-soluble phosphorus in the biochar is increased, and the water-soluble phosphorus is used as a phosphorus source of an MAP reaction. Meanwhile, Mg < 2 + > in MDWR provides a magnesium source for MAP reaction. The particle size of the activated biochar is reduced, the specific surface area is increased, the activated biochar can be used as a seed crystal to accelerate struvite crystal formation, and the nitrogen and phosphorus adsorption performance is improved by increasing the specific surface area; and finally, synergistically recovering nitrogen and phosphorus nutrients in the biogas slurry through MAP chemical precipitation and physical adsorption of activated biochar. According to the method, the process for recycling the biogas slurry nutrients by using the mechanochemical activated charcoal is obvious in recycling effect. The problem of disposal of two wastes of biogas slurry and biogas residue in an agricultural pig farm is solved, and an innovative process is provided for resource utilization of industrial and agricultural wastes.

This invention discloses a device and its application for the deep treatment of aquaculture wastewater using bipolar membrane-assisted struvite crystallization and synergistic electro-Fenton oxidation. The device is a galvanic cell structure, including a tank, a magnesium negative electrode, and a carbon material positive electrode (dissolved oxygen reduced to produce H₂O₂). A bipolar membrane serves as a separator in the middle of the tank, dividing the galvanic cell into a negative electrode chamber and a positive electrode chamber. Under the potential difference between the magnesium negative electrode and the carbon material positive electrode, the bipolar membrane spontaneously drives water dissociation, producing acids and bases. After the aquaculture wastewater is added to the positive electrode chamber and / or the negative electrode chamber, driven by the self-generated electric field of the galvanic cell, the negative electrode chamber removes nitrogen and phosphorus pollutants from the wastewater through struvite crystallization and recovers the struvite crystals as resource-based fertilizer. The positive electrode chamber performs Fenton oxidation treatment on the wastewater, achieving organic matter degradation and microbial inactivation. This device has a simple structure and is easy to operate. It achieves efficient treatment of aquaculture wastewater using a galvanic cell model and shows broad application prospects in environmental protection technology research and experimental development.

The invention relates to a multifunctional Fe3O4 (at) N-P-HC compound for concerted catalysis and nutrient recovery as well as preparation and application thereof. The preparation method comprises the steps of preparation of the Fe3O4 (at) N-P-HC compound, hydrothermal carbonization reaction of agricultural and forestry wastes, preparation of struvite crystals and preparation of a compound fertilizer. The prepared compound with magnetic FeO as a core and nitrogen and phosphorus doped hydrothermal carbon as a carrier realizes closed-loop circulation of catalysis, fertilizer supply and recovery. The compound fertilizer disclosed by the invention is a brand new two-in-one functional product of a slow release fertilizer and a soil conditioner, a synergistic interaction effect is realized, and the additional value of the product is greatly improved; according to the invention, integrated treatment of waste treatment, resource recovery and product high-value treatment is adopted, so that maximum utilization of resources is realized.

This invention relates to the field of sludge treatment technology, and more particularly to a method for preparing struvite by acid leaching of phosphorus from sludge gasification residue with kaolinite assistance. The method includes the following steps: S1, calcining a mixture of kaolinite and sludge in a certain proportion at 800-1000℃ for a period of time; S2, dissolving the calcined product with an acid solution, separating the solid and liquid, and collecting the phosphorus-containing supernatant; S3, adding a certain amount of magnesium and ammonium sources to the phosphorus-containing supernatant, adjusting the pH to 9.4-10, stirring for a period of time, separating the solid and liquid, washing the filtered solid with deionized water, and drying to obtain struvite crystals. This invention introduces kaolinite before sludge calcination, increasing the phosphorus content in the calcined product, improving the utilization rate of sludge gasification residue, and solidifying heavy metals in the sludge. It avoids a large amount of heavy metals entering the phosphorus-containing supernatant during acid leaching, resulting in a stable and reliable MAP struvite material.

The invention discloses a method and system for recovering phosphorus in phosphorus-containing wastewater, and the method comprises the following steps: (1) adjusting the pH value of the phosphorus-containing wastewater to 8.0-9.0, and then adding ammonium salt, magnesium salt and polyaluminum chloride into the phosphorus-containing wastewater to obtain a magnesium ammonium phosphate precipitate; (2) adding a sodium hydroxide solution into the magnesium ammonium phosphate precipitate to carry out an aluminum ion dissolution reaction, and after the reaction is finished, separating and purifying a reaction product to obtain a high-purity magnesium ammonium phosphate crystal and a sodium metaaluminate solution; and (3) introducing CO2 gas into the sodium metaaluminate solution, neutralizing and regenerating the sodium metaaluminate solution into polyaluminum chloride, and reusing the polyaluminum chloride. According to the method, the operation steps are flexibly adjusted according to different phosphorus concentrations in the phosphorus-containing wastewater, so that the phosphorus removal efficiency is improved, struvite crystals are purified, resource utilization is facilitated, meanwhile, the flocculant polyaluminum chloride can be recycled, and the treatment cost is reduced.

The invention discloses an algae collaborative aquaculture wastewater circulation treatment system and treatment device. The system comprises a culture unit, a circulating power unit, a solid-liquid pretreatment unit, a circulating algae membrane treatment unit, a chemical dosing unit and a recycling unit, and all the units form a closed recycling water path through circulating pipelines. The solid-liquid pretreatment unit separates residual feed from suspended solids and forms a concentrated blowdown stream. The circulating algal membrane treatment unit brings the body of water into contact with the algal membrane interface and introduces the recovery stream into the recovery vessel (3). The recovery container (3) comprises an upper-layer recovery cavity (31) and a lower-layer sedimentation recovery cavity (36) which are vertically overlapped and communicated, and an overflow vertical pipe (33) is arranged between the upper-layer recovery cavity (31) and the lower-layer sedimentation recovery cavity (36); and the dosing unit is used for dosing a magnesium source into the overflow vertical pipe (33), so that struvite crystals are generated, settled and recycled in the lower settling and recycling cavity (36). The recycling unit outputs struvite crystals and algae biomass, and lower-layer supernate flows back to the breeding unit.

The invention provides an aquaculture wastewater phosphorus resource recovery method based on struvite process mediation, relates to the technical field of livestock and poultry breeding waste recycling and sewage treatment, is applied to an aquaculture wastewater phosphorus resource recovery system, and comprises the following steps: roughly filtering biogas slurry, and then feeding the biogas slurry into a microwave ultrasonic coupling reactor for pretreatment; a magnesium source is added into the pretreated biogas slurry, the pH is adjusted to be alkaline, and the adjusted mixed solution sequentially passes through a primary seed crystal generator, a pulse microwave regulation and control device and a secondary crystal growth reactor to generate struvite crystals; carrying out spiral extrusion dehydration, cutting granulation and spraying coating on the slurry containing struvite crystals to obtain coated slow-release fertilizer particles and separated supernate; wherein the supernate is sent to an adsorption column, and secondary recovery of phosphorus resources is carried out through regeneration of an adsorbent. Therefore, efficient recovery of phosphorus resources, deep purification of wastewater and high value of products are realized.