Treatment of wastewater produced during tank cleaning

Cleaning water from tank cleaning occurs in numerous industrial sectors. The logistics sector also plays a crucial role in this. The transport of industrial goods is crucial for a country’s economy. The transport vehicles are heavily soiled after use, which is why they have to undergo tank cleaning. The resulting cleaning water must not be allowed to flow into the environment without treatment.

A company in Germany manufactures railway wagons for national and international use. These include particularly robust tank wagons that transport oil, gas or fuel, among other things. The tank wagons are particularly reliable, which is why they are in use for many years. After each transport, tank cleaning of the tank wagons is particularly important. For this purpose, the company has built a cleaning facility for tank wagons in Oberhausen in southern Germany. Tank cleaning produces cleaning water, the treatment of which is an important part of the process.

Since the tank wagons transport many different oils and gases, the cleaning water from tank cleaning is very heavily contaminated with different components. This results in a very high inert chemical oxygen demand. In addition, the cleaning plant for tank wagons uses different detergents, which further increase the degree of contamination of the cleaning water.

One of the customer’s challenges was the irregular wastewater load that is generated during tank cleaning. The cleaning water accumulates in the cleaning plant for tank wagons exclusively during working hours. No wastewater from tank cleaning is produced in the evening hours, at night and on weekends. The client wanted to remove a large part of the pollution from the cleaning water itself in order to subsequently discharge it into the municipal sewage treatment plant.

The ClearFox® team installed a containerized wastewater treatment plant with a fixed bed biological reactor and lamella clarifier on the site of the cleaning plant for tank wagons. It used an existing on-site pumping basin as a balancing tank. The wastewater from tank cleaning collects in this tank before it flows continuously into the treatment plant.

The biological treatment stage takes place in the fixed bed biological reactor. Microorganisms treat the dissolved substances in the wastewater and convert them into secondary sludge. The lamella clarifier separates this from the treated wastewater and stores it. For this project, the ClearFox® team took over the complete planning, the project planning of the treatment plant, the installation on site and the instruction of the employees. Prior to delivery, the ClearFox® team constructed a concrete foundation to ensure the containerised wastewater treatment plant would stand securely. The installation time of the wastewater treatment plant was limited to one day, as the ClearFox® team pre-assembled it in the main factory in Bayreuth and only installed it on site.