Development of a charge-regulated activated carbon technology for removal of ionizable organic chemicals from water and wastewater

PI: Derick Brown

Co-PI(s): John Fox

University: Lehigh University

Industry partner: Calgon Carbon

Chemicals of emerging concern (CECs) are environmental contaminants that can cause adverse health effects and come from a range of sources including medicines, personal care products, pesticides, cleaning products, and industrial chemicals. CECs are routinely found in municipal and industrial wastewaters and in sources of water for drinking water plants. Sorption, such as with activated carbon, is considered the most feasible removal method for CECs due to its low cost and ease of implementation within water and wastewater treatment plants. However, the majority of CECs are ionizable organic chemicals (IOCs) and exhibit a pH-dependent charge in water. This can make them difficult to remove via sorption without requiring large and problematic changes in the pH at water and wastewater treatment plants. Our proposed project addresses this issue by localizing the requisite pH change immediately adjacent to the activated carbon surface, without requiring pH adjustment of the bulk water. This is done by controlling a surface physiochemical process termed the Charge-Regulation Effect, with the purpose of altering the local pH during the natural adhesion of bacteria at the carbon surface. This charge-regulated pH shift that occurs during bacterial adhesion is a function of the acid/base characteristics of the bacterial and carbon surfaces, and by controlling the activated carbon surface properties, this pH shift will be used to enhance IOC sorption. This approach naturally and passively alters the local pH and enhances IOC sorption, without requiring alteration of the bulk water pH via chemical addition and operator control. This project will enable Lehigh University and Calgon Carbon to work together to develop a predictive capability for the selection and modification of activated carbons to enhance IOC sorption. This will enable the removal of IOCs at water and wastewater treatment facilities, putting Pennsylvania researchers and industry at the forefront of CEC treatment.