The DHT project, a key initiative at the Shiraz refinery, upgrades 26,000 barrels per day of regular gas oil to Euro 5 standard. The project represents a total investment of 183 million euros.

The hydrotreating (DHT) unit removes impurities, particularly sulfur and nitrogen compounds, to bring the gas oil into compliance with the global Euro 5 standard. The unit is also significant for environmental and economic reasons, as the produced gas oil meets international standards (Euro 5) and improves engine efficiency.