Method and installation for controlled microbiome shift for biomass densification in a biological treatment of a raw influent

An installation for controlled biomass densification in a biological treatment of a raw influent, said installation comprising:

• a biological tank containing free suspended biomass having a first inlet, a second inlet and a first outlet, the biological tank being configured to be fed at the first inlet with at least a part of the raw influent and return activated sludge (RAS) to produce a mixture of treated water and activated sludge (AS) recovered at the first outlet;
• a separation unit, having a first inlet, a first outlet and second outlet, the separation unit being configured to be fed at the first inlet with the activated sludge (AS) and to produce an effluent recovered at the first outlet and a return activated sludge (RAS) recovered at the second outlet;
• an extracting device configured to extract at least part of the return activated sludge (RAS) and/or part of the activated sludge (AS) as a first source of a waste activated sludge (WAS);
• an external gravity-based selector having a first inlet, a first outlet and a second outlet, the external gravity-based selector being configured to be fed at the first inlet by at least part of the return activated sludge (RAS) and/or part of the activated sludge (AS) and to generate an overflow at the first outlet forming a second source of the waste activated sludge (WAS) from which waste activated sludge (WAS) is extracted and an underflow comprising a first part of dense biomass aggregates recovered at the second outlet;
• a dense biomass aggregate production and/or sustaining unit having a first inlet, optionally a second inlet, a optionally third inlet, and a first outlet, the dense biomass aggregate production and/or sustaining unit tank being configured to be fed at the first inlet with at least a part of the raw influent and optionally at the second inlet with the underflow and to form a second part of dense biomass aggregates;
• the biological tank being further configured to be fed at the second inlet with the produced second part of dense biomass aggregates of the production and/or sustaining unit and optionally with at least part of the first part of dense biomass aggregates of the underflow, thereby obtaining a densified biomass;
• a controller of the amount of the raw influent fed to the dense biomass aggregate production and/or sustaining unit and/or a controller of the amount of the waste activated sludge (WAS) extracted from the first source of the waste activated sludge (WAS) and/or from the second source of the waste activated sludge (WAS).

A method for controlled biomass densification in a biological treatment of an influent, comprising:

• a step of feeding a biological tank containing free suspended biomass with the influent through a first inlet of the biological tank and subjecting the influent to a biological treatment of free suspended biomass, thereby producing a biomass comprising activated sludge (AS);
• a step of separation and/or clarification of the activated sludge (AS), thereby producing an effluent and a return activated sludge (RAS);
• a step of extracting at least part of the return activated sludge (RAS) and/or part of the activated sludge (AS), the return activated sludge (RAS) and/or the activated sludge (AS) forming a source of a waste activated sludge (WAS);
• a step of producing and/or sustaining dense biomass aggregates by a dense biomass aggregates generating process, with at least part of the influent;
• a step of feeding the biological tank with the dense biomass aggregates through a second inlet of the biological tank and subjecting the dense biomass aggregates to the biological treatment with retention of a biomass-fraction with a higher solids retention time (SRT), which results in the accumulation of organisms with biological nutrient removal activity;
• the method being carried out so as to maintain a densified biomass having:
• a dSVI between 35 and 100 ml/g, and/or
• more than 10% of particles with a particle size of between 100 μm and 1000 μm, and/or
• a dSVI30/dSVI10 ratio comprised between 70% and 95%.