Assessing and minimizing the leakage of powdered activated carbon from wastewater treatment processes for micropollutant removal

  • Bewertung und Minimierung von Pulveraktivkohle-Schlupf aus Abwasserreinigungsverfahren zur Elimination von Mikroverunreinigungen

Krahnstöver, Therese; Weßling, Matthias (Thesis advisor); Pinnekamp, Johannes (Thesis advisor); Wintgens, Thomas Josef (Thesis advisor)

Aachen (2019, 2020)
Dissertation / PhD Thesis

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2019


To prevent the emission of potentially harmful anthropogenic micropollutants into rivers and lakes, an increasing number of wastewater treatment plants is currently being equipped with advanced water treatment processes. When applying micropollutant adsorption onto powdered activated carbon (PAC), an efficient separation of PAC particles is crucial to prevent PAC leakage into the receiving water body. In this thesis, the separation of PAC in advanced wastewater treatment processes is studied. In the frame of a detailed literature research, the state of the art in solids separation in PAC processes is determined and practical recommendations are made. As a basis for further studies, a thermogravimetric method for sensitive and quantitative detection of low PAC concentrations in wastewater samples is developed. By successively heating solid samples under nitrogen and oxygen atmospheres, it allows for the quantification of PAC in mixed solid samples. Using this method, the PAC separation in a large-scale deep bed filter is examined. The focus is on the dynamic behavior of solids retention, headloss and micropollutant separation efficiency in the course of a filtration cycle. The experiments show a very good solids retention and it is found that PAC in particular is separated more efficiently than other solids. To minimize the load of PAC particles sized <10 µm in the influent to filtration processes, laboratory experiments were performed to study and optimize the flocculation of PAC after adding iron salt as a coagulant. The results show that, when operating PAC plants, it is essential to put a focus not only on effective adsorption, but also on adequate solids separation. Thus, the thesis at hand may give helpful advice on optimum PAC separation to process developers, plant designers and operators.