The Ozone Treatment for Nitrogen Removal from Liquid Wastes at High Salinity: Full-Scale Optimization and Economical Aspect

The study involved the optimization of the flow scheme of a full-scale platform for industrial liquid wastes. Non-hazardous liquid wastes from natural gas extraction (spent brine) represent 26% of the total influent wastes. For elevated salinity this waste is strongly inhibitory for traditional biological processes. The implementation of the treatment solution is represented by advanced oxidation with ozone in a separate line to remove the ammonia nitrogen with the direct transformation in nitrogen gas. The ratio of bromides/nitrogen greater than 0.4 was evaluated as being the determining factor to activate the process. Ammonia, without the formation of secondary nitrogen compounds, decreases up to 21 mgL^?1 dosing 300 mgO₃ L^?1 and equal to 0 mgL^?1 at maximum ozone. In addition, the catalytic effect of bromides determines a reduction of nitrate to final concentrations of 5 mgL^?1. Any carcinogenic compounds, such as bromates, or residual stripped ammonia were not noted. The economical evaluation was reported.