Frequently Asked Questions
Learn more about Bioreactors, and the work that they do on marine vessels.
On this page you will find answers to some of the most asked questions that we receive regarding bioreactors and the work they do on marine vessels.
What is a membrane Bioreactor and how does it work?
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.
What is biological waste water treatment?
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.
What is the process of biological waste water treatment?
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.
Why use biological waste water treatment?
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.
Why should I choose a G&O biological sewage treatment unit?
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.
What is grey and black waste water?
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
What else can be removed in the treatment process?
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.
How do you treat black water waste?
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.
Is any sludge generated in the unit – and how should it be handled?
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.
What residues originate from the process?
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.
What is the composition of sludge from a G&O Biological unit?
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.
Which treatment unit produces the most sludge (dry solids)?
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.
Which treatment unit produces the most wet 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.
Is the organic reduction (BOD5) in G&O biological treatment better or worse than the alternative?
G&O Biological units offer the highest reduction (BOD5) in organic treatment.
Chemically based treatment units offer the lowest. G&O Membrane units offer by far the highest reduction in Coliforms.
How does the G&O biological unit perform in the reduction of suspended solids?
It performs equally compared to electrolytic and chemically based units. A G&O membrane unit typically delivers close to 100% reduction in suspended solids and operates with a controlled sludge level to protect the membrane.
How does the G&O biological unit perform on the reduction of Coliforms (E-coli)?
It performs equally compared to electrolytical and chemically based units however, G&O units do not require harmful chemicals for the disinfection stage.
G&O units utilize Ultraviolet disinfection, which is 100% chemical-free solution. G&O Membrane units offer by far the highest reduction in Coliforms.
How is the fecal coliform control of a G&O unit?
It is controlled using Ultraviolet disinfection.
Compared to the use of chemical units that rely on harmful chemicals such as Chlorine and additional media to regulate the chlorine in the effluents, G&O Membrane units offer a natural barrier to retain 99,9% of the fecal coliforms.
Is a mixing tank required?
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.
How does G&O determine the sizing of equipment?
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.
How is the installation footprint of G&O units compared to others?
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.
Does the G&O unit require heavy operational attention and maintenance?
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.
Does the G&O unit comply with IMO MEPC.227(64)?
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.
Does the G&O unit provide a nitrification stage, which is vital for the release of nitrogen, which otherwise serves as a nutrient and oxygen depletion in the waters when released?
Yes, both G&O units offer nitrification. Chemical units do not offer this, and electrolytic types only provide limited nitrification.
Why is it important to treat waste water before it is released back into the ecosystem?
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.
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