Frequently Asked Questions

A membrane bioreactor (MBR) works by combining biological treatment processes with membrane filtration. Wastewater first undergoes biological treatment, where microorganisms break down organic matter. Then, the treated water passes through fine membranes that separate solids, bacteria, and other impurities, leaving clean water for reuse or discharge. MBR systems are efficient, compact, and ideal for high-quality water treatment needs.

Biological waste water treatment is a process that uses microorganisms to remove contaminants from waste water. This type of treatment is widely used in marine, offshore , municipal and industrial waste water treatment plants to purify water before it is discharged into the environment.

The process of biological waste water treatment typically involves several stages. The process of biological waste water treatment involves macerating the waste water, using microorganisms to break down organic matter, and clarifying the treated water.

Biological waste water treatment is an effective, efficient, low-cost, and environmentally friendly way to remove contaminants from waste water.

For more information on the process of biological waste water treatment, check out our blog post on the importance of biological waste water treatment.

Because it is 100% biological and offers actual activated sludge treatment with no need for consumables.  It provides TCO savings.

This is compared to the use of chemical-based units, which is harmful to the environment and has the additional disadvantage of handling logistics/replenishment of chemicals even for disinfection. Additionally, sludge handling also requires flocculation/chemical binding.

Because the other alternative is electrolytic, which is a heavy power consumer and contributes to a negative environmental impact from the diesel electrical power generated for it. Additionally, sludge requires flocculation / chemical binding. G&O Membrane units are biological treatment as well.

Grey water comes from sinks, showers, and laundry – typically low in pathogens.
Black water comes from toilets, containing faecal matter and a high organic load.
Both types must be treated before discharge; G&O bioreactors treat them together or separately, as required.

Learn more about the importance of grey water and black water treatment here

G&O bioreactors also reduce nutrients (phosphorus, nitrogen) and retain microplastics. Oil and grease can be separated upstream (e.g., from galley drains). Membrane systems enhance polishing and protect marine ecosystems from eutrophication and contamination.

Black water treatment typically involves different selections of treatment philosophy, including the use of physical, chemical, and biological processes to remove solids, organic matter, and pathogens from the wastewater.

We at G&O Bioreactors believe that the best, most efficient and eco-friendly way to treat waste water is through biological means. After treatment, the water can then be disinfected and discharged into the environment, or it can be further treated to produce reclaimed water for non-potable uses.

Yes, any biological treatment process will inevitably generate sludge as a natural by-product. Some manufacturers claim their systems produce no sludge build-up, but this is not accurate. Sludge formation is an inherent aspect of biological wastewater treatment, and its management is essential. G&O Bioreactors are designed to minimise sludge accumulation while ensuring compliance with discharge regulations. Sludge can be dewatered, stored in dedicated tanks, or disposed of at reception facilities in accordance with applicable maritime regulations. A proper sludge management policy should be in place on board to ensure efficient and compliant operations.

The primary residue from the biological treatment process is sludge, which contains high levels of coliform bacteria and organic matter. Due to its composition, sludge must be managed appropriately in line with maritime environmental regulations. Common handling methods include dewatering, onboard storage in designated sludge tanks, or disposal at reception facilities. Any discharge must comply with international and local regulations to prevent environmental contamination.

It is 100% biological and hence considered a light sludge.

Compared to chemically & electrolytically based units, which generate inorganic and flocculated sludge, G&O Membrane units offer a higher concentration of sludge output.

Chemically based units produce far the highest due to their chemical binding/flocculation. This sludge requires handling and is troublesome to get discharged. Biological units as those from G&O Bioreactors, generally generate the least sludge.

Chemically based units produce the highest due to their chemical binding/flocculation. On average calculation this is 25–30L/day. This sludge requires handling, is bulky and troublesome to get discharged. Discharge is often restricted due to chemical residues, and port reception facilities are required—leading to extra costs and logistical challenges.

Yes, if you intend to treat both grey water and black water together, a mixing tank is required. G&O Bioreactors are designed with an integrated mixing tank as standard for the combined treatment of black and grey water. However, in some installations, the mixing function can be incorporated into the vessel’s structural tanks instead of using a separate mixing tank. The best approach depends on the specific vessel layout and operational requirements.

G&O Bioreactors are sized according to ISO guidelines unless specific technical requirements from the client indicate otherwise. For specialised applications, we conduct load assessments based on organic and hydraulic factors. These calculations are validated in consultation with the client to ensure optimal system performance. Considerations such as crew size, waste composition, and operational patterns are taken into account when determining the appropriate system capacity.

Compared to other biological units, only using chemicals for disinfection, it is comparable in size. However, full biological treatment requires more space than the harmful chemical treatment units. This can be foreseen and solved during the engineering design phase of the installation.

Additionally, G&O offers to separate the process stages if the footprint is limited. Even integration in structural tanks of vessel is possible.

The unit requires good attention during the starting up phase and the running period.

After this, only fine-tuning of the process is required.

A biological process is sensitive in the early stage, and avoiding cleaning agents with chlorine and other aggressors to biological processes is important throughout the lifetime of the unit.

This is why the G&O biological includes a matrix on which the active sludge can thrive and sustain even during an imbalance of the biological process. Compared i.e to electrolytical units that require very frequent replacement of electrodes and high power demands.

Yes, as type approval is the access to the market, the G&O unit is type approved accordingly.G&O Membrane units offer treatment, including those for special areas like the Baltic Sea and other locations that are protected by local rules & regulations.

Yes, both G&O units offer nitrification. Chemical units do not offer this, and electrolytic types only provide limited nitrification.

1. To protect human health by removing harmful contaminants and reducing the risk of waterborne illnesses. 

2. To protect life below water by reducing negative impacts on marine ecosystems

3. To conserve water resources by treating waste water for reuse
To comply with regulations to avoid fines and legal action
It’s important to properly manage waste water treatment systems to ensure effectiveness, efficiency, and environmental responsibility.