SOLVIA VertaMABR is a vertical bioreactor for the deep biological treatment of wastewater. An anaerobic denitrification zone, a membrane-aerobic zone with a bubbleless oxygen supply and a biofiltration polishing zone sit one above another in a single vessel, and the flow passes them from the bottom upwards.
SOLVIA VertaMABR gathers into one vertical vessel three stages that the familiar schemes spread over separate structures: an anaerobic denitrification zone at the bottom, a membrane-aerobic zone with gas-permeable membranes in the middle, and biofiltration polishing at the top. The flow moves upwards and passes them in sequence, and a separate secondary clarifier is not needed in the basic logic of the solution. The patent materials describe the same division by height.
It is meant for local, village, off-grid and small industrial treatment works rated from 1 to 500 m³/day, where deep biological treatment is required on a limited plot and at a moderate energy demand. The same apparatus serves sites of different capacity, from a small local plant to village treatment works, and stays modular: the plot takes one vertical vessel instead of a horizontal row of tanks.
The vertical layout here is not the shape of a tank but the order of the processes. The wastewater enters the lower part of the vessel, where the conditions for denitrification are held, rises into the membrane-aerobic zone, where nitrification and the oxidation of organics take place, and leaves through the biofiltration zone at the top. The treated water is drawn off above, and all three stages end up in one apparatus rather than in a horizontal row of separate tanks.
In the lower zone the nitrates returned from above are reduced to molecular nitrogen, while the activated sludge is kept in suspension by a mixer with an adjustable rotation speed. There is no separate secondary clarifier in the basic logic of the solution, and the suspended solids and the fine particles of sludge are retained by the biofiltration media above — the abstract explains the compactness by exactly these three stages in one vessel.
The middle zone holds cassettes of gas-permeable membranes. Air is fed inside the membranes at a low pressure, the oxygen passes through the wall and enters the cryogel biocatalytic coating formed on the outer surface from a macroporous PVA cryogel with immobilised micro-organisms. It does not leave into the water as bubbles, no bubbling arises in the volume of the zone, and the abstract states oxygen utilisation as a benchmark of 90–95 %.
The pollutants approach the coating from the outside, from the liquid phase, the oxygen from the inside, through the membrane, and the micro-organisms work within the cryogel, where the two flows meet; this arrangement is named diffusive bubbleless counter-diffusion aeration. What sets it apart from MABR reactors with a spontaneously growing biofilm is that the coating is formed beforehand, and the description of the development puts the start-up period at 24–48 hours instead of 3–6 weeks.
Nitrification of ammonium nitrogen proceeds in the membrane-aerobic zone, and the nitrate-bearing water from its upper part returns down the nitrate recycle pipeline into the anaerobic zone. The recycle ratio is adjustable within 100–400 % of the raw wastewater flow, so total nitrogen removal is governed not by the geometry of the reactor alone but also by an automatic change of the recycle — which matters on sites with a variable load.
Dissolved oxygen and pH sensors are brought onto a programmable logic controller, which adjusts the air flow into the membranes, the nitrate recycle ratio and the mixing regime of the anaerobic zone. Monitoring and remote data transmission over GSM/Wi-Fi are provided as well: the development is intended, among other things, for remote sites, villages and small production facilities, where a permanent operator may be absent.
The upper zone holds media of foam beads retained by a metal mesh, and it works in two directions at once. It holds back the suspended solids and the fine particles of activated sludge, while an attached biofilm develops on the surface of the media and further oxidises the residual organic load. The claim of the invention describes this zone as placed in the upper part of the vessel.
Many MABR systems keep the membrane-aerated zone as the main biological stage and do not build a separate biofiltration polishing step into the vessel. In a calculated and experimental example at 10 m³/day the BOD reduction came to 97 %, the COD reduction to 94 %, the nitrification of ammonium nitrogen to 92 %, total nitrogen removal to 88 % at a recycle of 250 %, the suspended solids at the outlet to 4.2 mg/l, the specific energy demand for aeration to 0.10 kWh/m³ and the start-up to the working regime to 36 hours. These are the results of one particular execution, not a guarantee for any site.
SOLVIA VertaMABR is SOLVIA's own technological development in the field of compact deep biological wastewater treatment; the technology holds patent protection in Russia. The solution brings together a vertical vessel, an anaerobic zone, a membrane-aerobic zone with gas-permeable membranes, a cryogel coating with immobilised biomass, a biofiltration zone, an adjustable nitrate recycle, DO and pH sensors, a controller and remote monitoring. The structural parameters, the composition of the cryogel coating, the control regimes, the arrangement of the membrane cassettes and the automation settings are selected for the individual site and are not disclosed in full in open materials.
In an MBR the membrane separates the treated water from the activated sludge, calls for cleaning and protection from fouling, and usually works with intensive aeration. Here the gas-permeable membranes do not filter the water: their duty is the bubbleless supply of oxygen straight to the biocatalytic layer, while the retention of solids is left to the biofiltration media above.
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