Increased control and efficiency over the wastewater purification can be achieved through creating conditions that allow the operator to selectively prioritize the digestive function of microorganism in the activated sludge. The gas-dispersion return sludge is created using pure oxygen or oxygen containing trace amounts of ozone as a reactive gas, which is blended with return sludge to create a mixture of gas and liquid, which is passed through an atomizer or a cavitation pump to instantly render the reactive gas to an ultra-fine bubble state. At least a portion of the ultra-fine bubbles dissolve within the gas-dispersion return sludge, activating the dormant microorganisms. Due to a complete or an almost complete absence of biodegradable material in the gas-dispersion return sludge, the microorganism prioritize their digestive function, and when exposed to biodegradable pollutants present in wastewater, digest the pollutants using biochemical pathways different from the ones used in nature.

An object of the present invention is to provide a method for producing PHA, which is capable of suppressing the cost of overall production equipment including a waste water treatment process in production of PHA using microorganisms. Provided is a method including: a production step of purifying or molding polyhydroxyalkanoic acid biosynthesized in bacterial cells of a microorganism; a discharge step of discharging waste water containing nitrogen-containing impurities from the production step; and a nitrogen removal step of biologically treating the waste water to remove the nitrogen-containing impurities from the waste water. In the method, the residual ratio of the polyhydroxyalkanoic acid in the production step is 99% by weight or less, and the waste water that is biologically treated in the nitrogen removal step contains the polyhydroxyalkanoic acid in addition to the nitrogen-containing impurities.

An aerobic biological treatment apparatus includes a reaction tank (tank body), a water permeation plate horizontally installed in a lower part of the reaction tank, a large-diameter particle layer formed on an upper side of the water permeation plate, a small-diameter particle layer formed on an upper side of the large-diameter particle layer, an oxygen dissolution membrane module disposed on an upper side of the small-diameter particle layer, a receiving chamber formed on a lower side of the water permeation plate, a raw water dispersion pipe supplying raw water into the receiving chamber, a diffuser pipe installed to perform gas diffusion in the receiving chamber and the like. A condensed water drainage pipe branches from an exhaust pipe from the oxygen dissolution membrane module, and a valve is provided.

An aerobic biological treatment apparatus includes a reaction tank (tank body), a water permeation plate horizontally installed in a lower part of the reaction tank, a large-diameter particle layer formed on an upper side of the water permeation plate, a small-diameter particle layer formed on an upper side of the large-diameter particle layer, an oxygen dissolution membrane module disposed on an upper side of the small-diameter particle layer, a receiving chamber formed on a lower side of the water permeation plate, a raw water dispersion pipe supplying raw water into the receiving chamber, a diffuser pipe installed to perform gas diffusion in the receiving chamber and the like. A condensed water drainage pipe branches from an exhaust pipe from the oxygen dissolution membrane module, and a valve is provided.

Provided is a wastewater treatment system. The wastewater treatment system includes an equalization (EQ) tank which receives contaminated wastewater having a high nutrient content from a plant, a dissolved air flotation (DAF) system and an on-site oxygen generation system which provides gas phase oxygen to the wastewater treated in the equalization (EQ) tank and/or the dissolved air flotation (DAF) system. The dissolved air flotation system includes at least one air dissolved air flotation vessel which may house an aerator grid assembly having a perforated lateral diffuser and optionally, a primary aerator assembly.

Provided is a wastewater treatment system. The wastewater treatment system includes an equalization (EQ) tank which receives contaminated wastewater having a high nutrient content from a plant, a dissolved air flotation (DAF) system and an on-site oxygen generation system which provides gas phase oxygen to the wastewater treated in the equalization (EQ) tank and/or the dissolved air flotation (DAF) system. The dissolved air flotation system includes at least one air dissolved air flotation vessel which may house an aerator grid assembly having a perforated lateral diffuser and optionally, a primary aerator assembly.

The invention relates to water regeneration in a fish breeding complex combining closed and flow-through water supply systems. A module of a biological filter in a water regeneration system comprises a reservoir, an aerator, a channel for sludge accumulation and discharge and a reservoir bottom sloped in direction of the water movement and, with the water surface, forming a diffuser providing for circulation of water and filler in the biological filter. Fish breeding complex comprises fish breeding pools and a water regeneration system comprising a mud settler-denitrificator, a device for water lifting and aeration, a biological filter, degassing and disinfection units. Each fish breeding pool comprises water oxygenation and disinfection systems, dosage units, water discharge systems and insoluble residues collecting and discharge systems. In the water flow-through mode, water regeneration system is switched off and water supply from an outside source and wastewater discharge are switched on.

A method for treating wastewater containing organic contaminants is disclosed. Wastewater containing organic contaminants is fed into an outer pipe of a pipe-in-pipe assembly, wherein the outer pipe concentrically surrounds an inner pipe. Oxygen is fed into the inner pipe which is rotatably mounted and is provided with openings, thereby to provide different sizes of oxygen bubbles to the outer pipe. The oxygen is dispersed into an annular portion between the outer pipe and the inner pipe thereby contacting the wastewater with oxygen; and the thus treated wastewater is collected. The inner pipe may be a tunable membrane material, and the outer pipe may have a biocatalyst material present on its inner surface.

A method for treating wastewater containing organic contaminants is disclosed. Wastewater containing organic contaminants is fed into an outer pipe of a pipe-in-pipe assembly, wherein the outer pipe concentrically surrounds an inner pipe. Oxygen is fed into the inner pipe which is rotatably mounted and is provided with openings, thereby to provide different sizes of oxygen bubbles to the outer pipe. The oxygen is dispersed into an annular portion between the outer pipe and the inner pipe thereby contacting the wastewater with oxygen; and the thus treated wastewater is collected. The inner pipe may be a tunable membrane material, and the outer pipe may have a biocatalyst material present on its inner surface.

Disclosed is a method for managing the operation of an apparatus for injecting oxygen into a purification basin. The oxygen notably being used by the biomass present in the purification basin to consume the pollution present in an effluent feedstock contained in the basin. The method comprises varying a rotational speed of the shaft by using a frequency variator, wherein an applied variation in speed is between plus 15% and minus 15% of the nominal speed of the shaft.