The Turkmenbashi refinery, located on the Krasnovodsk Gulf of the Caspian Sea, is one of Turkmenistan’s two oil-processing facilities.
In late 2013 London-listed PetroGas LLP was selected by Turkmenbashi Complex of Oil Refineries as the EPC contractor for a vast rehabilitation program, including the reconstruction of water supply, petrochemical plants, and the construction of a modern wastewater treatment plant. For the latter, PetroGas appointed Cannon Artes.
The effluent treatment plant has an overall capacity of over 1,000 m3/h, among the world’s largest industrial wastewater treatments (WWT), arranged on four wastewater treatment trains, a mobile sludge dehydration unit, and a sanitary water treatment system.
While PetroGas took care of the land clearing, execution of civic works, mechanical installation, electrical and instrumental wiring and cabling, automation of the entire system, and the site services, our team focused on the technological portion of the project.
We provided the overall process design and the detailed engineering of all units, with pre-fabricating the critical equipment in our factory in Oliveto, Italy.
To meet the stringent limitations on the concentration of various chemical species in the treater water outlet and enable effective water reuse, each train was designed to incorporate an oil separation section, a biological oxidation section, and a tertiary treatment.
Oil separation features Coalescing Plates Interceptors (CPI) and Dissolved Air Flotation (DAF). The biological section features the state-of-the-art Membrane Bioreactor (MBR) technology, guaranteeing efficient oxidation of the organic substrate with a quantitative separation of all suspended solids, bacteria, and viruses as only an ultrafiltration membrane can do.
The tertiary treatment, which is in most cases useless downstream of an MBR unit since all solids and bacteria are removed there, is targeted to the selective removal of those organic molecules that are difficult to be biologically oxidized. Therefore, an Advanced Oxidation Process (AOP) with hydrogen peroxide injection, a specifically developed catalyzer, and an adsorption unit was implemented. This aids in the removal of residual aromatics and toxic compounds down to parts per billion levels.
The supplied solution
The Effluent Water Treatment plant is divided into two systems: system one treats 900 m3/h of low salinity industrial water to be recycled and reused in the cooling system, while system two has a capacity of 300 m3/h of high salinity wastewater for discharge into the Caspian Sea.
Each system ensures correct flexibility with a 2 x 50% train solution.
Performance guarantees are reached by treating the incoming water streams with a three-step treatment design:
- Mechanical Treatment with Corrugated Plate Interceptor and Dissolved Air Flotation unit technologies for enhanced Oil & Suspended Solids removal;
- Biological Treatment with denitrification, oxidation, and an MBR system, including all the chemical dosing skids to significantly remove COD, BOD and Ammonia
- Tertiary Treatment by Activated Carbon filtration necessary to guarantee the low concentration required for water reuse.
As a further solution for higher demanding performance for removal of phenols down to ppbs level, system two was implemented, a dedicated Advanced Oxidation treatment with dedicated dosages of H2O2 and liquid catalyzer.
Aside from the main Effluent Water Treatment Plant completing the wastewater complex, our team supplied a Domestic Water Treatment composed mainly of an MBR system (25 m3/h of treated water) and the Mobile Sludge Treatment unit (15 m3/h of treated sludge).