Carbon microsphere and NH4Cl recovery from a real pharmaceutical intermediate wastewater through wet oxidation

Traditional treatments for pharmaceutical wastewater focus on organic pollutants degradation, resulting in a waste of resources and an increase in carbon emissions. In this study, a novel process was proposed to recover carbon microsphere and NH4Cl from a real pharmaceutical intermediate wastewater meanwhile improving the biodegradability of the treated effluents. The wet oxidation was the core treatment method, at an initial pressure of 1.0 MPa, a reaction temperature and time of 250 °C and 90 min, 14.52 g/L of coke was produced through wet oxidation process, the coke is 59.11 μm in an average particle size, and has a calorific value of 5387 kcal/kg. After filtrating the coke, the COD of the effluent was reduced from 35,432.37 to 8422.708 mg/L and ammonia nitrogen increased from 5908.11 to 17,162.16 mg/L simultaneously. NH4Cl with 35 % purity was separated by Rotary Evaporation in a yield of 11.02 g/L, and the COD of distillate was reduced to 3213.49 mg/L, the BOD5/COD value of distillate increased greatly from 0.098 to 0.91, which makes distillate meet the requirement for further biological treatment. Wet Oxidation combined with Rotary Evaporation as a novel process was proposed, the process could make the hazardous pharmaceutical wastewater detoxicated and biodegradable, meanwhile realizing “near-zero emission”. [Display omitted] •The pharmaceutical wastewater is detoxicated and biodegradable by Wet Oxidation.•The “carbon capture” is realized and organic matter coke to carbon microsphere.•Ammonification of organic nitrogen produces ammonia nitrogen to recover NH4Cl.•Achieve “near-zero emission” of pharmaceutical wastewater through wet oxidation.•Significant reduction in organic matter but no carbon emissions.