Energy efficient aeration of wastewaters from the pulp and paper industry

摘要

More than 50% of the electrical power needed to treat pulp and paper industry effluents is usednfor aeration in biological treatment stages. A large share of the oxygen that passes through thenwastewater is not consumed and will be found in the off-gas. Energy can be saved by aeratingnunder conditions where the oxygen transfer is most efficient, for example at low concentrationsnof dissolved oxygen Consider the sludge as an energy source; electricity can be saved by avoidingnsludge reduction through prolonged aeration. High oxygen transfer efficiency can be retainednby using the oxygen consumption of biosolids. Quantified savings in the form of needed volumesnof air while still achieving sufficient COD reduction are presented. The tests have been madenin a bubble column with pulp mill process water and sludge from a biological treatment plant.nThese were supplemented with case studies at three pulp and paper mills.