Treatment of a Wastewater from Military Explosives and Propellants Production Industry By Physicochemical Processes

摘要

Laboratory and pilot-plant studies were conducted to investigate the effectiveness of various physical-chemical processes for the separation of nitrocellulose (i.e., cellulose nitrate) from a military wastewater. Special emphasis was placed on in-line filtration (i.e., contact coagulation-filtration), pre-coat filtration and conventional multimedia filtration. In-line filtration involves adding a cationic polyelectrolyte (Cat-Floc) and the military wastewater directly to the filter simultaneously. In pre-coat filtration, the filter media is coated with cationic polyelectrolyte prior to the filtration of the wastewater. It was found that neither in-line filtration nor pre-coat filtration was effective for separating nitrocellulose fine particles from the wastewater. Conventional treatment system uses mixing, flocculation and settling in separate reactor(s) followed by filtration of the settler's supernatant. Another treatment method involving centrifugation was also investigated. Although direct centrifugation of the raw nitrocellulose-manufacturing wastewater could not reduce any turbidity, the combination of chemical coagulation (using cationic polyelectrolyte as coagulant and appropriate material as coagulant aid) and centrifugation could achieve more than 98% of turbidity removal.