ElectroSAnMBR

From bench to bilge: the ElectroSAnMBR project's path to demonstration

The ElectroSAnMBR initiative sits at the intersection of electrochemistry, anaerobic digestion, and membrane filtration, three disciplines that rarely share the same reactor. The team has spent several years building a submerged anaerobic electrochemical membrane bioreactor capable of stripping hydrocarbons, surfactants, and dissolved organics from oily bilge water. By combining an applied voltage with microbial breakdown and a tight physical barrier, the system aims to deliver cleaner effluent than conventional oil-water separators, particularly in sensitive waters such as the Great Barrier Reef Marine Park.

Bilge water remains a stubborn problem along the Australian coast, where patrol vessels, trawlers, and commercial tankers routinely move between terminals in Sydney, Melbourne, and Fremantle. Even small ships produce hundreds of litres of contaminated water each voyage, and the holding-and-discharge approach struggles to keep pace with tightening International Maritime Organisation rules. Funded under Horizon 2020, the researchers recognised that the same biological processes used for municipal sewage could, with an electrical nudge, tackle hydrocarbons far more aggressively than microbes alone.

What follows is a walk-through of the work packages guiding the project from bench chemistry to a transportable demonstration unit. The aim is to show how each technical layer feeds the next, where Australian collaborators fit, and what kind of techno-economic picture is emerging as the technology moves toward commercial use.

Work packages that frame the research

The project is organised into six work packages that move from fundamental science toward field-ready engineering, each with its own lead institution, deliverables, and review milestones.

Package two sets the chemical baseline, identifying oils, fuels, coolants, and cleaning agents typically found in bilge tanks. Without that fingerprint, downstream optimisation would be guesswork. Packages three and four run in parallel, with electrochemists adjusting voltages and electrode geometries while microbiologists track how mixed anaerobic consortia respond to the resulting hydrogen and electron flux. Package five stitches outputs together inside a single reactor housing and tests the integrated rig on real bilge water rather than synthetic stand-ins.

Electrolysis meets anaerobic digestion

Putting an anode and cathode inside the same tank as methanogenic archaea sounds risky, because electrolysis can generate reactive oxygen species and pH swings that unsettle microbial life. The researchers biased the cell toward low-voltage, low-current conditions, where hydrogen evolution at the cathode becomes a useful electron donor rather than a stressor. The microbes, in turn, consume volatile fatty acids before they escape into the effluent stream.

Materials choice has been a major focus, with stainless steel meshes, mixed-metal oxide coatings, and boron-doped diamond electrodes benchmarked for durability and catalytic activity. Early results suggest a hybrid mesh with periodic polarity reversal keeps scale and biofilm accumulation in check without the maintenance burden of more exotic coatings. Cheaper materials often mean a few percentage points lower current efficiency, and the team has been upfront about that trade-off. For Australian readers watching the marine sector decarbonise, the implications are tangible. Aboard a Royal Australian Navy auxiliary vessel, every cubic metre processed onboard rather than stored for shoreside disposal cuts bunker fuel use and frees up tankage, and the biogas stream can be flared or redirected to a small boiler. Word from local industry is fair dinkum keen to see the rig perform under Australian conditions.

Membrane bioreactor engineering

Membrane fouling is the perennial headache of any membrane bioreactor, and the ElectroSAnMBR configuration adds extra complexity because oil droplets, surfactants, and biological flocs all converge on the membrane surface. Package four addresses this through submerged hollow-fibre modules, controlled backwashing cycles, and the electrochemical self-cleaning effect produced by the electrodes themselves.

Aeration is kept deliberately gentle since the system runs anaerobically, so air scouring is limited. Instead, the team leans on periodic relaxation phases and localised gas evolution at the cathode to provide just enough turbulence to disrupt cake formation. Early results indicate that flux decline rates are competitive with aerobic MBRs running on friendlier feed streams. The team is also documenting how citric acid rinses, sodium hydroxide soaks, and oxidative cleans affect membrane longevity, with each option carrying its own footprint on operating cost and downtime.

From synthetic feed to real bilge water

The leap from synthetic surrogate feeds to authentic bilge water is rarely graceful. Real bilge water carries emulsified cutting oils, hydraulic fluids, and trace metals that laboratory recipes rarely mimic in the right proportions. The first time the rig was challenged with ship-supplied samples, foaming events had to be brought under control with antifoam dosing and tuned hydraulic residence time.

Characterisation work has been treated as a living document, with each new batch adding another data point. Conversations are progressing with Australian partners who could supply comparative samples from vessels operating out of Brisbane and the Port of Kembla. Local input matters because fuel sulphur content, bilge pump cycling, and onboard chemical inventories vary by region. The team has tested the system across temperature windows typical of cold North Sea routes and warmer Australian coastal runs, since microbial activity and oil viscosity shift noticeably between them.

Scaling toward a demonstration reactor

The demonstration phase, anchored in WP5, moves from laboratory cells of a few litres to a skid-mounted unit sized for a corner of a working engine room. The goal is not full-scale commercialisation but proof that the integrated package can survive real operating conditions and maintenance routines.

A detailed walk-through of this transition is laid out in the project's techno-economic analysis for commercial vessels. That study compares the integrated rig against conventional oil-water separators and activated sludge units on capital outlay, footprint, energy draw, and discharge quality, and it is one of the most useful documents for any fleet operator weighing retrofit options. Siting the demonstration reactor involves logistics as much as science, with a consistent feed supply, an effluent pathway that satisfies local environmental rules, and enough instrumentation to capture long-tail data. Discussions have included potential tie-ups with Australian marine research hubs, where university teams often co-locate with port authorities and can offer both analytical depth and practical access.

Outcomes, funding, and next steps

Horizon 2020 funding has allowed the project to commit to long experimental campaigns that would be difficult under shorter commercial contracts, and that continuity is starting to show in the data. Multi-month continuous runs are now possible, membrane autopsies can be scheduled on a meaningful cadence, and the microbial community can be tracked across seasons rather than weeks.

Looking forward, the consortium is preparing the technical case for a pre-commercial pilot, ideally sited at a harbour where a willing operator can host the rig for an extended sea-trial. Key milestones on that path include:

For shipowners, port authorities, and environmental regulators in Australia, the work offers a credible route toward tighter bilge water compliance without the heavy footprint of shoreside reception facilities. The submerged anaerobic electrochemical membrane bioreactor is steadily becoming a system that engineers can specify, crews can operate, and investors can underwrite.

Engineers and policy makers keen to dig into the numbers behind the demonstration rig, including its cost trajectory and payback horizon under Australian operating conditions, can read the project's techno-economic analysis for commercial vessels on the project site and reach out to the consortium about pilot collaboration opportunities.