Looking for a "Mr. Clean" against chemically contaminated surfaces

Whether as a water-repellent coating on pans and pots, as a water-shedding protection on clothing, or as a foam former in fire extinguishing foams – so-called per- and polyfluorinated chemicals, short PFC, are used in a variety of applications because of their water, dirt, and grease-repellent properties. Due to their chemical structure, however, they are hardly or not at all biodegradable. They do not occur naturally in the environment.

The joint project "Biogenic Polymer Condensates for Use in Groundwater Remediation and Drinking Water Protection" (Biokon) aims to develop effective substances to eliminate these chemicals from water cycles and soils in combination with robust treatment technology. Additionally, the ongoing processes are to be monitored using suitable, yet-to-be-developed models and monitoring tools. The Department of Plant and Safety Engineering at TU Berlin, led by Prof. Dr. Michael Schwarze, is involved in the project. Cooperation partners are the companies Sensatec from Kiel and Geologik from Münster.

Worldwide, PFC concentrations have been detected in nature. They enter the environment through wastewater and PFC-contaminated sludge used as fertilizer on soils, surface waters, and groundwater. So far, efficient environmental remediation methods to eliminate these substances have not been established. Studies by Ruhr University Bochum have shown that some PFC are ingested by humans through drinking water and accumulate in the blood. Based on animal experiments with rats and mice, especially short-chain PFC are suspected of being carcinogenic. However, the transferability of these findings to humans is controversial.

In addition to PFC, the project also focuses on volatile chlorinated hydrocarbons (LCKW) as a second group of pollutants. These solvents were used in large quantities across nearly all industrial sectors until the 1980s. A large portion of the contaminated sites in Germany are polluted with LCKW. Therefore, the elimination of these partially volatile and carcinogenic substances plays a central role in site remediation. Often, the contamination is located beneath buildings or sealed surfaces, making excavation of the contaminated material impossible. The costs of traditional site remediation are generally very high and often very time-consuming.

The Biokon research project is divided into two phases. In the first phase, the goal is to dissolve the pollutants – mainly LCKW – from the soil and make them available in the aqueous phase. In the second phase, PFC contamination will be remediated. Current remediation measures only prevent uncontrolled spread. With the help of specially developed biogenic polymer condensates by the company Biosid Deutschland GmbH, PFC are to be transferred from the unsaturated zone of the soil into the groundwater aquifer. The groundwater is pumped and separated from PFC in a treatment plant. Initially, condensates with appropriate properties are identified and developed in the laboratory. In a pilot test at a PFC-contaminated site – paper sludge was applied as fertilizer on agricultural fields – the developed methods are to be tested.

The scientists involved in the project aim to develop an economically viable remediation method that is tailored to site- and pollutant-specific requirements and considers various condensate, monitoring, and treatment techniques. This is intended to contribute to a sustainable supply of clean groundwater. The users include operators of drinking water treatment plants and their customers, as well as farmers who irrigate their fields with groundwater.

Biokon is funded by the Federal Ministry of Education and Research. It is part of the BMBF funding program "KMU-Innovativ: Resources and Energy Efficiency" within the technology and application area "Sustainable Water Management".