Removal of Microconstituents by Adsorption focusing on the Separation of Powdered Activated Carbon

Due to improved measurement methods microconstituents can be detected in the range of nanograms nowadays. These substances can be found ubiquitously in the aquatic environment. Source of these contaminants are industrial and communal waste water treatment plants (WWTP) and the agricultural sector. By adding 10-20 mg/l of powdered activated carbon (PAC) to the WWTP effluents microconstituents can be eliminated with a high efficiency. Due to small particle sizes in combination with high flow rates the subsequent and necessary PAC separation is a challenging task. The state of art is to use regular sedimentation tanks by adding coagulant and flocculation agents in combination with rapid sand filters. Besides being cost intensive, this method shows other disadvantages. The project team focused on testing five alternative test plants for the separation of PAC with different PAC products, coagulants and polymers. The results of a lamella separator, micro sieve, pile fabric cloth filter and dissolved air flotation have been compared with a regular sedimentation tank. The cloth filter clearly showed the best performance with retention rates of up to and above 95 %.