Assessment of a hybrid technology for liquid fuel dimethyl aminoethyl azide wastewater treatment

Dimethyl aminoethyl azide (DMAZ) is a liquid fuel in the space industry. Although this fuel is non-carcinogenic, its wastewater suffers from some hazardous pollutants, such as sodium azide (NaN3). A hybrid process of coagulation–flocculation and chemical reaction with nitrous acid was applied for the wastewater treatment. The Taguchi method was used for the process optimization. Coagulant concentration, rapid mixing intensity, duration time, CAMP number and settlement time were found to be effective parameters for the efficiency of the former process. Turbidity and total suspended solids (TSS) of the wastewater were used to track the removal efficiency in the first stage. The complete removal efficiency was achieved. In the latter process, NaN3 was removed using a reaction with nitrous acid. pH of the wastewater was optimized as the controlling factor in the second process. Biochemical oxygen demand (BOD), chemical oxygen demand (COD) and NaN3 removals of 98.9, 98.2 and 96.3% were obtained under the optimum conditions, respectively. As a result, a reduction of 91.9% in turbidity, 98.5% in TSS, 98.5% in BOD, 98.1% in COD and 96.7% in NaN3 concentration were observed in the output of the wastewater.