Pilot-Scale Testing of a Submerged Anaerobic Electrochemical Membrane Bioreactor

Bilge water is a difficult maritime wastewater stream because its composition changes with vessel activity, fuel handling, cleaning practices, and storage conditions. It can contain emulsified oils, lubricants, detergents, suspended solids, metals, salts, and persistent organic compounds. A treatment process that performs well with a controlled laboratory mixture may respond very differently when exposed to real shipboard wastewater.

Pilot-scale testing provides the bridge between laboratory research and reliable operation in a port, shipyard, or onboard setting. For ElectroSAnMBR, the central challenge is to demonstrate how a submerged anaerobic electrochemical membrane bioreactor performs when biological conversion, electrochemical reactions, and membrane separation operate as one treatment system.

The approach is relevant to Australia, where major ports such as Sydney, Melbourne, Brisbane, Fremantle, and Port Hedland handle diverse commercial and industrial vessels. Remote export terminals may have limited wastewater infrastructure, while coastal communities have strong incentives to prevent hydrocarbon discharges near sensitive marine environments, including the Great Barrier Reef and temperate estuaries.

A robust pilot must therefore measure more than pollutant removal. It should establish energy demand, membrane stability, sludge production, operational resilience, safety, maintenance requirements, and compliance potential under conditions that reflect Australian maritime logistics and local water-quality expectations.

From Laboratory Research to Pilot Evidence

A submerged anaerobic electrochemical membrane bioreactor combines an anaerobic biological reactor with submerged membranes and electrically assisted treatment. Anaerobic microorganisms break down biodegradable organic matter without continuous aeration, reducing the energy normally associated with oxygen transfer. Electrodes can support oxidation, reduction, microbial activity, or the transformation of compounds that are difficult to remove biologically.

At pilot scale, the objective is to test how these mechanisms interact over sustained operation. Hydraulic retention time, sludge age, membrane flux, electrical current, electrode spacing, mixing, temperature, and organic loading should be varied within a controlled test plan. The project’s European research context and Horizon 2020 support provide a framework for examining this integrated process as an environmental engineering technology rather than as a simple filtration unit.

The need for this integration is explained in traditional treatment limits, particularly where oil-water separation, chemical dosing, biological treatment, and polishing steps are operated as disconnected stages. Pilot work can show whether electrochemical assistance reduces those limitations while keeping the system compact enough for maritime applications.

Designing a Realistic Bilge Water Feed

Synthetic wastewater is useful for repeatable experiments, but a pilot should progressively incorporate authentic bilge water or carefully characterised blends. Samples may differ according to vessel type, engine-room activities, detergent use, tank cleaning, and the time wastewater has spent in storage. Salinity, pH, temperature, oil concentration, chemical oxygen demand, toxicity, and suspended solids should be recorded for every batch.

A staged feed strategy can protect the bioreactor while revealing its limits. Initial operation with a representative synthetic mixture allows operators to confirm membrane integrity and electrical controls. Increasing proportions of real bilge water can then be introduced as the anaerobic community adapts. Short-term shock-load tests should assess the effects of sudden oil, solvent, detergent, or salt increases without treating those events as normal operating conditions.

Australian deployment conditions deserve specific attention. Wastewater from vessels arriving at Port Botany or the Port of Melbourne may be handled through established reception systems, while facilities supporting mining and bulk exports in Western Australia may face longer supply chains and fewer specialist technicians. A pilot design that can tolerate variable feed quality, intermittent delivery, and limited laboratory access will have greater practical value.

Managing Membranes, Electrodes, and Biology

Membrane fouling is one of the main technical risks. Oil droplets, biological solids, colloids, and precipitated minerals can form a resistant layer on the membrane surface, increasing transmembrane pressure and reducing permeate flow. Submerged operation can simplify tank layout, yet it still requires effective gas scouring, relaxation cycles, cleaning procedures, and control of solids concentration.

The membrane unit must be evaluated alongside the biological process rather than in isolation. A stable anaerobic community may reduce organic loading to the membrane, while electrochemical reactions can change particle charge, pH, oxidation state, or precipitation behaviour. These changes may improve separation in some conditions and accelerate fouling in others. Research on membrane bioreactor principles helps frame why high-strength bilge water requires close control of solids and surface interactions.

Electrode durability also matters. Electrochemical components may experience corrosion, scaling, passivation, and changes in performance as the feed composition shifts. Pilot monitoring should include voltage, current density, conductivity, electrode condition, energy consumption, and any metal release. The selected materials need to withstand saline wastewater and repeated cleaning without creating a new contamination concern.

Measuring Treatment Performance and Safety

Pilot success should be assessed through a balanced set of indicators. Oil and grease removal remains essential, but it should be reported with chemical oxygen demand, total organic carbon, suspended solids, turbidity, nutrients, salinity, selected metals, and relevant toxicity measurements. Where the feed contains detergents or hydrocarbons, targeted analysis can reveal whether compounds are destroyed, transformed, retained in sludge, or transferred to the permeate.

Operational data should be linked to treatment results. Useful measures include permeate flux, transmembrane pressure, recovery after cleaning, methane production, sludge yield, electrical energy per cubic metre, chemical consumption, downtime, and operator hours. A pilot that achieves high removal while requiring frequent intervention may be unsuitable for a vessel or small port facility.

Safety controls must cover hydrogen, methane, electrical equipment, confined spaces, chemical cleaning agents, and volatile hydrocarbons. Gas monitoring and ventilation are especially important in enclosed maritime environments. The design should also prevent accidental release of untreated wastewater during start-up, maintenance, power loss, or a sudden membrane failure.

Regulatory review should occur early. Australian operators may need to consider the requirements of the Australian Maritime Safety Authority, state environment protection agencies, port authorities, local trade-waste arrangements, and international discharge rules under MARPOL. A pilot does not automatically establish regulatory approval, but it can generate the validated evidence needed for future approvals and operating permits.

Turning Pilot Results into Deployment Decisions

A pilot-scale trial should produce a transparent operating envelope rather than a single headline removal figure. The final report should identify acceptable ranges for oil concentration, salinity, organic loading, temperature, membrane flux, electrical input, and cleaning frequency. It should also state the conditions under which treatment performance declines or the process must be taken offline.

A modular configuration may suit Australian ports better than a permanently fixed installation. Containerised equipment could be tested near a port reception facility, then relocated between coastal sites. For remote operations, automation, remote monitoring, spare-parts planning, and straightforward sampling protocols may be as important as biological performance. Energy integration with shore power or renewable generation could reduce operating costs where grid access is constrained.

The following practices can strengthen a pilot programme:

• Use real bilge water alongside a defined synthetic reference feed.
• Establish baseline performance before increasing organic and oil loading.
• Track membrane fouling, cleaning recovery, and electrode condition continuously.
• Report energy use and operator effort with pollutant removal results.
• Include shock loads, saline conditions, and intermittent operation in the test plan.
• Build in gas detection, spill containment, and automatic shutdown systems.
• Compare treated water quality with Australian port and environmental requirements.

Pilot data should be interpreted through life-cycle and whole-of-system analysis. Reduced aeration may lower energy demand, while electrode replacement, membrane cleaning, sludge handling, and pre-treatment can add costs. Methane recovery may offer a useful energy pathway, but its value depends on gas quality, scale, safety controls, and whether the site can use or export the recovered energy.

A successful demonstration will show how the technology behaves in the working conditions that matter: variable feed chemistry, limited space, changing vessel schedules, saline wastewater, and strict protection of receiving waters. It can then support a defensible decision about a larger demonstration, a port-based treatment unit, or further optimisation before commercial-scale deployment.

Project partners, port operators, shipowners, laboratories, and environmental regulators can contribute by sharing representative wastewater data, hosting controlled trials, and reviewing performance criteria. Engagement through the ElectroSAnMBR research programme can help turn pilot measurements into a practical evidence base for cleaner maritime operations in Australia and beyond.