Tank cleaning and sludge treatment in a fully closed system

A joint project

Recently, a team of specialists from BUCHEN UmweltService (Region West) and FILTRATEC found themselves facing an interesting challenge. They were asked to clean an oil containing tank that was connected to a wastewater treatment facility. Their task was to clean a fixed-roof tank of an oil refinery. The task involved the removal, treatment and disposal of approximately 280 m³ compressed sludge. The sludge contained a variety of substances including sand, rust and plastics. Furthermore, the sludge released hydrogen sulphide, carbon monoxide and volatile hydrocarbons. As a result, the flashpoint was below 30°C and thus highly flammable.

The challenge was to carry out the work in a fully closed system under ATEX conditions. Thus no pollutants could be released which would have exceeded the workplace limits or led to unpleasant odour development.

The technology

BUCHEN deployed a fully closed high-pressure cleaning unit to dilute and remove the sludge deposits. By using jet equipment that can be regulated and controlled from outside the tank, the operators were able to pinpoint the material that had to be removed without entering the tank themselves.

FILTRATEC were on site with a wide range of equipment to remove and detoxify the material as well as to separate the sludge with a gas-tight, 3-phase decanter. The entire sludge treatment process was performed using a fully closed system that met all ATEX conditions. The cleaning of the exhaust air was also integrated into the treatment process by FILTRATEC. For the explosion protection the tank was inerted with nitrogen.

To ensure the work was completed as quickly as possible, it was carried out in 24/7 operation. The project – including the subsequent final cleaning tasks – was finished successfully in a fraction of the time that would have been needed in the past when conventional cleaning systems were used. FILTRATEC and BUCHEN were therefore, able to hand over the cleaned tank to the client having fulfilled all requirements. Advantages created through this process: the short completion time, the high standards regarding health, safety and environment, the cost savings achieved through operating with fewer staff compared to conventional methods and the reduced volume of waste that had to be disposed of, thanks to the efficient sludge separation technology.