Details

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Oil refineries and gas processing plants generate wastewater from various unit operations. The sources of petrochemical wastewater are diverse and can originate from oilfield production, crude oil refinery plants, the olefin process plants, refrigeration, and energy unities. This wastewater typically contains hydrocarbons (HC), volatile organic compounds (VOCs), heavy metals, and other contaminants associated with petroleum refining.

The produced water that returns to the surface as wastewater during oil and gas production contains hydrocarbon from the deposit as well as naturally occurring toxic substance like arsenic and radium, salts, heavy metals, and chemical additives injected into the well to facilitate extraction. Proper management or treatment is needed for reuse, discharge, or final disposal to minimize their impact on the environment. Due to the complexity of the wastewater composition, petrochemical wastewater requires combination of different treatment methods. At some unique cases, the treatment requires multistage chemical or biological treatment based on the incoming composition loading and the treated water quality.

For the pretreatment, Tilted Plate Interceptor (TPI) or Corrugated Plate Interceptor (CPI) is used as oil-water separator before it passes down to further treatment such as chemical treatment and biological treatment. TPI and CPI use mechanical mechanisms to separate the oil from the water via gravity force. With the tilted and corrugated plate in the system, it increases the efficient surface area where it allows the O&G to float on the surface. The floating O&G will be skimmed via oil skimmer and collected separately for disposal. 

Following treatment with TSS and heavy metal removal, coagulation-flocculation process is required. Due to the various heavy metal presence in the wastewater, an optimum pH must be obtained based on the metal precipitation graph. Global Tankcom team is experts in conducting jar tests to determine the suitable metal precipitator, coagulant, and flocculant. A sedimentation process is required to remove the flocs and colloidal that have formed in coagulation and flocculation processes. In petrochemical wastewater, the metal flocs (Barium, Boron, Aluminium, Iron, Lead, Zinc, Copper, Nickel, Chromium, Cadmium, Mercury, etc) are considered heavier than other industries hence, Lamella clarifier is most suitable for heavier metal flocs to get sedimented and cost-effective compared to DAF and sedimentation tank. The working mechanism for Lamella clarifier is easier and operator-friendly, also it is safer especially at brownfield. The inclined plates increase the solid settlement rate or Solid Loading Rate (SLR) as the surface is high compared to conventional sedimentation tank.  

Once the Oil & Gas (O&G), Total Suspended Solids (TSS), heavy metal and most of the toxic constituents have been removed, the wastewater can be treated in the biological process if the organic loading is still high and exceeded the discharge limit. Some cases, after the chemical treatment, the wastewater can be discharged or proceed to reclamation process with less/no organic loading. In biological treatment, aeration methods are widely used with Membrane Bio Reactor (MBR) to increase the performance of the biological system. The activated sludge process or aeration is accomplished by pumping the air into a tank and promotes the growth of microorganisms in the wastewater. The aerobic microorganism consumes on pollutants (organic loading) to survive and concurrently reduces the organic loading in the stream.


As a final stage, polishing system is essential for achieving the stringent discharge quality as stated in DOE. In polishing system, activated carbon filtration and sand filtration is provided to enhance organic matter, odour removal as well as suspended solid removal, respectively.