During my time at university, I always showed much enthusiasm for traditional industrial chemistry. However, in my first job I came to realize that the further exploitation of raw materials in chemical processes without consideration for natural cycles is not sustainable. In contradistinction to my first work, most tasks in environmental research are placed at the junction between humans and nature. And in environmental research, there is always a good chance that the most economic solution is in compliance with nature and therefore stabilizes the ecological system.
Currently, I am working at the Umweltforschungszentrum Halle-Leipzig (UFZ, Centre for Environmental Research). The UFZ was established in 1991 and is exclusively devoted to environmental research. It currently employs a total of about 650 staff members. Founded in response to the severe pollution prevailing in central Germany, the UFZ has already become an acknowledged center of expertise in the remediation and renaturation of contaminated landscapes, as well as in the preservation of natural landscapes.
My current phytoremediation project focuses on the task of germ reduction in municipal sewage. Using sewer water for irrigation is economically and ecologically of great interest in developing countries where water resources are limited. However, there is a risk that pathogenic microorganisms present in the sludge might contaminate food and groundwater. For example, diarrheal diseases, spread mainly by contaminated water or food, kill nearly three million young children every year. Infectious diseases are the world's leading cause of death, killing at least 17 million people every year.
It is already acknowledged that planted soil filters enable the effective removal of pathogens from wastewater--they are known to be even more efficient than traditional wastewater treatment methods. According to the current state of research, the processes of pathogen removal in planted soil filters are due to physical, chemical, and biological effects:
Adsorption, filtration, and sedimentation in the rooted soil matrix increase the retention time of germs in the planted filter body beyond their average lifetime. Other specific conditions, such as the concentration of dissolved oxygen in the pore water of the filter body, reduce the ability of pathogens to survive in planted soil filters. Competition between nonautochtonous (in this case pathogenic) and autochtonous bacterial populations (typical soil microorganisms) as they pass through a planted soil filter diminishes the survivability of pathogenic bacteria. Protozoa that "eat" bacteria also reduce the germ concentration in the treated wastewater.
However, the processes of pathogen removal are by no means fully understood. In particular, the interactions in the rhizosphere and the role of the filter in pathogen removal under different climatic and other operating conditions need to be better understood. This lack of understanding hampers the optimal technical realization of planted soil filters. A third aspect is the advantages farmers could have using this technology in comparison with the traditional irrigation with untreated wastewater.
Therefore, in a project funded by both the UFZ and the German Ministry of Education and Research, the UFZ built a pilot-scale research plant in Langenreichenbach (Saxony, Germany). With German and Mexican partners (University of Halle, Umweltschutz-Nord GmbH, and the Universities of Mexico City and Merida), one more plant is being built in Mexico using the same design. Another pilot-plant is planned for construction in Mexico (on the Yucatán Peninsula) by Ökotec Ltd. (Germany).
Comparing the operation of plants at various locations that differ in climate and germ contamination is both of technological and scientific interest. The goal of research is to ascertain the technological, chemical, and biological parameters that affect pathogen removal in planted soil filters, so that the newly gained knowledge can be used for technological development in both industrialized and developing countries.
Using the tools of molecular biology, another task that lies ahead in this research field is to clarify the principles of pathogen removal in planted soil filters. To assess the efficacy of the pilot plant, the colony-forming units of different indicator organisms as well as the quantity of pathogenic organisms in the untreated and treated wastewater have to be determined.
One of the project's advantages is our general knowledge that these systems are reducing pathogens. The natural pathway of human excrement--including the reduction of pathogens--is through the soil. Even the cycling of soil from nonfertility to fertility results from the death of organic matter. Thus in our research project, an artificial system is more or less linked into natural cycles.
At the UFZ, an interdisciplinary team of biologists, chemists, engineers, and economists works together in the field of phytoremediation. Typical for such a joint project of technology transfer is the linkage between basic and applied researches and between laboratory to pilot scales.
If you are interested in joining this project or in other work taking place at the UFZ, go here!