Removal of High and Low Levels of Ammonium from Industrial Wastewaters

摘要

Over 2×10^11 kilograms of ammonia are produced globally per year by the Haber-Bosch process which combines molecular hydrogen and nitrogen to synthesize ammonia. Most is used for fertilizer and agriculture while the remaining is used for other purposes including industrial processes and explosives. Explosives used in the mining industry are commonly ammonium nitrate (43)-based. Excess ammonia and nitrate which can be dissolve into mine runoff water during blasting. Ammonia in mine and mineral wastewater can range from 20-110 mg/L. Ammonia is also present in several types of industrial wastewater such as caustic soda solutions used in the oil re-refining industry for removal of sulfur compounds from hydrocarbon streams. These waste streams are known as sulfidic caustic solution (SCS) or spent caustic.This thesis concerns the treatment of ammonia in two distinct types of industrial wastewaters in order to meet specific discharge criteria. The first industrial wastewater is a low ammonia concentration WWTP effluent (2 – 6 mg/L TAN as N) from a gold mine in Alaska. The other is an extremely high (6000+ mg/L TAN as N) concentration sulfidic caustic solution from oil re-refining. It was hypothesized that that for the low concentration of ammonia mine water, which had low turbidity and relatively simple water chemistry, advanced separation technologies such as ion-exchange, zeolite and membrane filtration, and electrocoagulation would work well compared to alternative treatment options. For the highly complex matrix oil refining caustic solution, it was expected that a straightforward commonly used ammonia removal technology, such as breakpoint chlorination would work very well.Laboratory column and batch testing using ion-exchange adsorption and chloramination were performed using actual waters contaminated with ammonia. For the low level mine water, several ion-exchange resins and zeolites were tested and compared based on the amount of water that could be treated per unit volume of resin. For the high concentration ammonia water linear regression relationships were determined which model the removal of ammonia as a function of the applied chlorine dose.For the mine water with low levels ammonia it was found that the number of bed volumes in which ammonia was removed with BRZ increased with increasing EBCT and decreasing potassium concentration. It was also found that temperature of a 5 °C did not significantly impact the removal. For removal of ammonia from SCS solution, applied chlorine doses needed to remove ammonia were measured between 2.54 and 2.01 [Cl₂]/[N]. In conclusion the results obtained from this investigation and implications described can be used to assist in the design of systems to remove of ammonia from wastewaters of similar characteristics.