SOLVIA PneumoSBR is a cyclic biological wastewater treatment plant. Filling, aeration and settling take place in one reactor, and the clarified water is removed not by a mechanical decanter but by the gentle pneumatic displacement of the upper layer.
The plant works in cycles within a single reactor: the effluent is admitted, passes through biological treatment, the activated sludge settles, the upper layer of clarified water is removed, and the excess sludge is drawn off after it. What sets the development apart lies not in the biology of the cycle but in its last stage: the water is not taken from one point but displaced by volume, by a flexible element running along the inner wall of the vessel.
It is meant for compact cyclic treatment works, new and refurbished alike: from a private house or a hotel to a small settlement or a modest production site. Existing SBR plants are converted in the same manner, with the decanting stage moved over to pneumatic displacement; the vessels may be cylindrical or rectangular, and the solution is adapted to different capacities.
A working cycle runs through several stages. During filling and mixing the effluent enters the reactor, the mixed liquor is recirculated and conditions for denitrification are created. Aeration then starts, the microorganisms of the activated sludge oxidise the organic load and nitrification proceeds. At the settling stage the equipment is switched off and the sludge falls to the bottom, after which the treated water is displaced pneumatically and the excess sludge is removed to hold the sludge age.
After settling, two layers stand in the reactor: clarified water above, settled activated sludge below. The task of the decanting stage is to take off the upper layer without lifting the lower one, and the water at the outlet depends on how that is done no less than on the biological process. Decanting arranged badly stirs up the sludge, carries suspended solids over, clouds the discharge and unsettles the quality of treatment, while the decanting devices themselves clog.
In classical SBR plants the clarified water leaves through a floating or a fixed decanter, a telescopic pipe, a pump draw-off or a powered decanting mechanism. Such a device has to stand inside the reactor, travel with the water level, open and close, and take water from the upper layer without catching the sludge. The medium around it is biologically active: sludge, biofilm, foam, fats, suspended solids and a load that varies.
A moving mechanism in such a medium calls for attention as time passes, and service grows harder. Drawing water from one zone creates local turbulence and, in an unlucky regime, lifts the settled sludge, while the exact decanted volume is not always simple to control: it depends on the position of the intake, on the work of the floats and on the local hydraulic conditions. Mechanical parts also complicate the design of the plant.
The place of the decanter is taken by a pneumatic displacing element — a flexible element along the inner side surface of the vessel. Once settling is over, the controller opens the pressure valve, compressed air enters the sealed cavity behind the element, and the element moves smoothly from the wall towards the centre of the reactor, lifting the clarified water to the discharge nozzle.
The element works neither as a pump nor as a decanter: it draws no water through a moving pipe and creates no suction zone, but reduces the working volume of the upper part of the reactor. The water leaves evenly around the perimeter, without abrupt currents and without a moving assembly in the contaminated medium, and the decanted volume is set by the time and the profile of the pressure supply rather than by the position of the intake and the level in the tank.
What matters is not the displacement alone but its rate: if the water rises too fast, the settled sludge is stirred up and the quality of the discharge falls. The rate of the upward flow of clarified water is therefore held below the free settling velocity of the characteristic activated sludge flocs. Decanting in SOLVIA PneumoSBR becomes a controlled hydrodynamic process rather than a consequence of the decanter design and the local hydraulics.
No separate hydraulic system is needed for this. The compressor or blower of an SBR plant is there for the aeration, and the same compressed air may be fed to the displacing element through a receiver and a control valve, while the work of the element is synchronised with the cycle programme by the controller. The air then serves both the biological stage and the controlled decanting, and fewer points of failure are left in the plant.
SOLVIA PneumoSBR is SOLVIA's own technological development in the field of compact SBR plants for the biological treatment of wastewater. The solution brings together cyclic biological treatment, gravity settling and the gentle pneumatic displacement of the treated water with no mechanical decanter in the wastewater zone. The line is being developed as a product platform for local, settlement and industrial treatment works. Structural parameters, control regimes and layout decisions are not disclosed in open materials and are selected for the individual site.
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