Petroleum Refineries

Petroleum refineries generate wastewater continuously across process units, cooling systems, tank farms, desalting operations, equipment cleaning and spill containment areas. Unlike intermittent industrial sites, refineries produce sustained hydraulic loads alongside effluent that shifts in chemistry with crude slate changes, unit start-ups and shutdowns, and process upsets.

That combination of continuous volume and variable composition is what makes petroleum refinery wastewater treatment one of the more demanding industrial treatment problems. Systems have to remain stable under constant load while tolerating contaminant profiles that change without warning.

Australia’s two remaining operating refineries, located in Brisbane (~109,000 bbl/day) and Geelong (120,000 bbl/day), each operate under site-specific environmental licences with defined discharge limits for hydrocarbons, suspended solids, chemical oxygen demand, sulphides, phenols, ammonia and metals. In Queensland, petroleum refining requires an Environmental Authority under ERA 37 of the Environmental Protection Act 1994. In Victoria, the Environment Protection Act 2017 requires an Operating Licence for oil or gas refining. Former refining sites at Kurnell, Kwinana, Altona, Bulwer Island and Clyde now operate as import terminals under converted licence conditions. Still, many retain active wastewater treatment infrastructure for stormwater and residual contamination management.

Refinery effluent is not a single stream. It is the combined output of crude distillation, cracking and upgrading processes, heat exchange and cooling, desalting, tank drainage and routine maintenance across a large, interconnected facility. The result is wastewater that contains free, emulsified and dissolved hydrocarbons, suspended solids, sulphides, phenols, ammonia and residual chemical additives from refining and cleaning processes.

The contaminant load is process-unit-specific. Crude desalting contributes free oil and suspended solids. Fluid catalytic cracking (FCC) adds cyanide and phenol. Alkylation and polymerisation generate spent caustic. Sour water strippers concentrate hydrogen sulphide and ammonia. Published data from IPIECA, Concawe and peer-reviewed literature converge on the following typical raw refinery wastewater concentrations before treatment:

• Oil and grease / TPH: 20 to 3,000 mg/L (up to 10,000 mg/L during upset events)
• COD: 300 to 1,500 mg/L
• BOD₅: 100 to 400 mg/L
• Total suspended solids: 30 to 300 mg/L
• Phenols (total): 20 to 200 mg/L (spent caustic streams up to 7,000 mg/L)
• Sulphides: 5 to 100 mg/L in combined effluent (raw sour water 1,000 to 10,000 mg/L pre-stripping)
• Ammonia-N: 5 to 100 mg/L post-stripping (raw sour water feed 1,000 to 8,000 mg/L)
• BTEX total: 1 to 100 mg/L
• pH: 6.0 to 9.0 (spent caustic streams 11 to 13)

Free oils are the most straightforward fraction to remove. Emulsified hydrocarbons, stabilised by chemical treatment agents and process chemistry, require additional conditioning before separation is achievable. Dissolved hydrocarbons, including BTEX compounds, phenols and sulphides, are not removed by physical separation at all and require biological or chemical treatment downstream.

Hydraulic and contaminant loads fluctuate with crude slate changes (typically every 3 to 10 days), throughput rates, unit start-ups and shutdowns, and process upsets including desalter rag-layer releases and tank-farm stormwater surges. Treatment systems cannot be designed for average conditions alone. They need to maintain separation efficiency and biological performance across the full range of operating conditions, including upset events that can shift influent quality significantly within a short time frame.

Refinery effluent contains three distinct hydrocarbon fractions, and each requires a different treatment mechanism. Free oils are removed by physical separation. Emulsified oils require chemical conditioning and flotation before they can be separated. Dissolved hydrocarbons, including phenols, sulphides and BTEX compounds, need biological or chemical treatment and cannot be removed by physical separation at all. The staging is determined by that chemistry. Each stage has to be in place before the next one can function.

Petroleum refineries in Australia operate under site-specific environmental licences issued by state environment protection authorities. These are not general trade waste permits. They are detailed instruments setting defined limits for hydrocarbons, suspended solids, chemical oxygen demand, sulphides, phenols, ammonia and metals, with structured monitoring, reporting and audit requirements.

The regulatory framework differs by state:

NSW: The Protection of the Environment Operations Act 1997 (POEO Act) governs licensing under Chapter 3. Refineries and petroleum terminals hold Environment Protection Licences (EPLs) with site-specific discharge conditions. Section 66(6) requires EPL holders conducting pollution monitoring to publish their data. Ampol’s former Kurnell refinery, now an import terminal, retains EPL 837 with active stormwater and groundwater management conditions.

VIC: The Environment Protection Act 2017 (effective 1 July 2021) requires an Operating Licence (OL) for oil or gas refining, the highest tier in the new permission system. Viva Energy Geelong holds Operating Licence OL000046555 with mandatory Annual Performance Statements published on the EPA Victoria portal. The General Environmental Duty under section 25 imposes a proactive obligation on all duty holders to minimise risks of harm, with aggravated corporate penalties up to $3.3 million.

QLD: The Environmental Protection Act 1994 classifies petroleum refining as Environmentally Relevant Activity (ERA) 37 under Schedule 2 of the Environmental Protection Regulation 2019, requiring a site-specific Environmental Authority (EA). No model conditions exist for ERA 37. Each refinery EA is custom-conditioned based on the facility’s specific operations, discharge points and receiving environment.

WA: The Environmental Protection Act 1986 governs licensing under Part V (Prescribed Premises) administered by DWER. BP Kwinana, which ceased refining in March 2021, retains its DWER licence with wastewater treatment plant capacity of 7.93 ML/day permitting treated discharge to Cockburn Sound.

All Australian refineries are also required to report annual emissions of 93 substances to the National Pollutant Inventory (NPI) under the National Environment Protection (National Pollutant Inventory) Measure 1998, including benzene, toluene, xylenes, ammonia, oil and grease, phenols, sulphides, lead, mercury and PAHs. Receiving water quality is assessed against the ANZG 2018 / ANZECC 2000 Default Guideline Values, which provide the species-protection trigger concentrations that site-specific discharge limits are typically back-calculated from.

Compliance extends beyond meeting discharge numbers. Refineries are subject to structured monitoring and reporting requirements, including routine sampling, performance verification, incident notification and environmental performance audits. Treatment systems need to provide consistent, verifiable performance under continuous operation, with sufficient redundancy and control to manage process variability without breaching licence conditions.

The potential for off-site impact to surface water and groundwater means regulatory scrutiny at refineries is high. Wastewater infrastructure has to support long-term environmental risk management, operational transparency and demonstrable compliance across the operational life of the facility. A treatment system that performs under normal conditions but fails under process upsets is not sufficient.

Baldwin starts by mapping wastewater sources across the facility: process units, utilities, tank farms, cooling systems and drainage networks, to understand hydraulic pathways and contaminant loading across the full operational range. That includes profiling free and emulsified hydrocarbons, suspended solids, sulphides and chemical residues, and evaluating how crude slate changes, operating conditions and process upsets influence influent variability.

From that assessment, Baldwin designs and builds staged treatment systems configured for continuous, high-throughput operation: oil-water separation, dissolved air flotation, clarification, filtration and polishing, chemical treatment, or combinations of these with appropriate equalisation capacity depending on what the facility requires. Every system is Australian-made, with PLC control and local service and parts support nationally.

Baldwin has supplied oil-water separation and DAF systems to petroleum and hydrocarbon processing facilities across Australia.

Ongoing operational support focuses on treatment stability, monitoring performance trends and maintaining compliance with licence and reporting requirements over time.

Talk to Baldwin’s engineering team about your refinery site. Call (02) 4954 0440 or arrange a site assessment.

Reviewed by Baldwin Industrial Systems’ engineering team