Ovivo deployable membrane bioreactor (MBR) wastewater treatment system

The Ovivo deployable membrane bioreactor (MBR) wastewater treatment system is contained within a standard 20-foot shipping container which allows for easy transport from site to site. The unit is suitable for applications such as: mining sites, construction sites, hotels and resorts, boat marinas, sports and leisure venues, caravan parks, sewer mining and black water treatment.

It provides solids-liquid separation, producing a high-quality, fully disinfected effluent which can be used for non-potable re-use applications.

This plant uses a flat sheet membrane system to produce an effluent that is suitable for discharge to the most sensitive receiving waters. The process employs simple flat sheet membrane panels housed in stainless steel cases and aerated by a coarse bubble diffuser system. A series of these membranes are submerged within an activated sludge treatment tank.

An advantage of this design is that the membrane panels are securely retained and cannot touch or abrade each other, while the cases also act as a flume to ensure effective tank mixing and even distribution of the biomass.

The membrane panels, manufactured with a pore size of 0.08 microns, in operation become covered by a dynamic layer of protein and cellular material. This further enhances the performance effectiveness of the filtration process by providing an effective pore size of less than 0.01 microns.

The raw sewage generally only requires screening (to 3 mm in 2d) and de-gritting prior to entering the membrane bioreactor tank. The process requires no primary or secondary settlement stages and no additional tertiary treatment or UV stages to achieve quality typically better than 5:5:5 mg/L BOD: Suspended Solids: Ammonia.

Advantages include: it does not remove the solids by settlement, therefore the biomass can operate at very high levels of MLSS, generally in the order of 12,000 mg/L; and this high concentration enables a low-tank volume and a long sludge age to be used, which reduces sludge production and allows a small footprint.

The maximum hydraulic flow determines the required number of membrane units. Each membrane unit may contain membrane panels housed within a rectangular case, together with an integral aeration system in the bottom section of the unit. Treated effluent is removed from the membrane units using rotary lobe pumps.

The membrane air diffuser typically allows 3-6% uptake of available oxygen at 3.3 to 3.5 m water depth, dependent on temperature and initial dissolved oxygen levels. Higher uptake rates will be found at lower temperatures and where the influent is initially anoxic.

Aeration is continuous at all times when permeate is flowing through the membrane units. During periods of low influent flow when the permeate flow stops, the aeration blowers can be cut out and will re-start automatically upon permeate flow resuming.