A HYDROLYSIS THICKENING FILTRATION PROCESS FOR THE TREATMENT OF WASTEACTIVATED-SLUDGE

A process has been developed for reducing both the mass and volume of waste activated sludge generated by the biological treatment of a phar maceutical wastewater, As a result of the mixture rule the sludge is c lassified as a hazardous waste. Thus, treatment and disposal have trad itionally been very costly. This study focused on optimizing an engine ered hydrolysis operation in terms of solids reduction, environmental impact, practicality and cost. Dewaterability screening studies were a lso conducted in an attempt to transform the residual solids into a re adily filterable material. The resultant hydrolysis/thickening/filtrat ion process begins with room temperature sludge acidification using su lfuric acid. This results in 50 to 60 percent solubilization of suspen ded solids, thus sharply reducing the mass of solids to be handled. Al so, carbon dioxide is liberated during the reaction phase, enabling so lids separation and thickening to occur via flotation. Subnatant hydro lysate can then be recycled to enhance solids solubilization. Once pro perly conditioned with acid and cationic polymer, the residual solids are readily pressure filtered to cake dryness in excess of 50% solids. Results of laboratory studies indicate that the overall process is ca pable of substantially reducing sludge cake production.