| Electrolytic manganese industry can produce large amount of high concentration ammonia wastewater, including manganese slag leachate produced in the repository which is beyond 500 mg/L. Ammonium nitrogen as a nutrient to aquatic plants contributes to eutrophication, which is a big threat to the aquatic ecosystem and human health. The technology was introduced to treat ammonia- containing wastewater in the paper, including the laboratory simulation of wastewater as well as the manganese slag leachate. The purpose of the experiment was found a new denitrification way to treat manganese slag leachate that was economical and efficient. It can provide theoretical reference for industrial processing of electrolytic manganese industry. The following results were achieved based on experiment research and theoretical analysis:?1? Based on the characteristics of high concentration ammonia in manganese slag leachate, a new denitrogenation technology, vacuum stripping, was adopted and a set of vacuum denitrification reactor?VDR? was designed in this study.?2? The VDR's reaction parameters were optimized by response surface methodology?RSM?, and the effects of p H, vacuum degree and time to NH4+-N removal efficiency were explored. Results confirmed that the effect of different parameters showing: vacuum degree>p H>time. And the optimal conditions of vacuum stripping were p H 9.25, vacuum degree 0.10 MPa and time 51.58 min. Under the reaction conditions, the predicted value of NH4+-N removal efficiency was 53.86%.?3? When other ions existed in wastewater, different ion had different effect on NH4+-N removal. The result showed that Mn2+, Ca2+ and Al3+ had an inhibitory effect and the inhibitory effect of Mn2+ was maximum. While Mg2+, SO42-, Cl- and NO3- had little or no effect on NH4+-N removal.?4? The study of NH4+-N removal in manganese slag leachate by vacuum stripping showed that the removal efficiency was approached to 42.62% on the conditions of p H 9.25, vacuum degree 0.10 MPa and time 52±1 min.?5? The paper deduced the deal model of vacuum stripping for ammonia nitrogen wastewater from the classical mass-transfer theory. The model of NH4+-N removal efficiency was described as follows:???And the reactor was improved and optimized through the theoretical calculation. |
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