Effect of DTPA and EDTA on activated sludge reactors treating bleached kraft mill effluent

This study alerts paper mills to the progressive effects of chelants such as DTPA and EDTA have on activated sludge biomass by sequestering metals needed for metabolism and promoting structural stability in the capsule and cell wall. Effects range from dissolution of capsular material, through decreased substrate uptakes rates and ultimately decreased system performance. Chelants are not present in high enough concentrations in most conventional kraft mills, however, the combination of increasing application of peroxide and trends towards reducing water consumption may result in increased chelant concentrations in wastewaters being treated by biological systems. This is true for mills with very low water use, TFC bleached kraft mills, and mechanical pulp mill that brighten using H2O2.