Immobilization of activated sludge by PVA–boric acid method

Abstract A new method (polyvinyl alcohol–boric acid method) for an inexpensive and effective immobilization of activated sludge was developed. Using activated sludge immobilized by this PVA–boric acid method, synthetic waste‐water was treated at a high loading rate of 0.5–2.35 kg TOC/m 3 day. Total organic carbon and total nitrogen were removed at efficiencies of 93 and 30–40%, respectively. The kinetic constants Y and b for this immobilized activated‐sludge process were determined to be 0.594g mixed liquor suspended solids (MLSS)/g TOC and 0.0219 day −1 , respectively. The cost calculation of chemicals required for the immobilization of activated sludge by this PVA–boric acid method was proved to be extremely inexpensive for the immobilization of activated sludge.