Sludge Dewatering with Cyclodextrins: a New Cost-effective Approach

Polymers are typically added to flocculate sludge during wastewater treatment. We have found that cyclodextrins (CDs) boost the performance of these polymers by increasing the cake solids and drainage rates of beltor screw-pressed biological or primary sludge. These benefits are obtained at very low CD dosage. CDs also decrease the specific resistance to filtration and increase the capture rate of solids during belt pressing. Results from three different full-scale fields from two paper mills and a municipal wastewater treatment system are discussed. In all cases, a combination of higher cake solids, better drainage, better filtrate clarity and lower polymer use was obtained. The CD application for sludge dewatering is being introduced commercially.