Treatment Of Concentrated Ammonia Wastewater By Stripping-absorption Combined Process

Ammonia nitrogen is one of the main contaminant lead to eutrophication and bad water quality. Especially concentrated ammonia nitrogen wastewater, if discharged directly into water would cause great harm to the water environment. At the same time, more strict rules and regulations are set out to restrict the discharge of ammonia. The purpose of this study is to look for more economical and effective technology to treat concentrated ammonia nitrogen wastewate. In this study, the treatment of concentrated ammonia nitrogen wastewater by air stripping-adsorption combined process was investigated, using air stripping in the multi-faceted ball packed tower as the pretreatment method, and adsorption by new ammonia adsorbent Amar-01 as the deep treatment method.A large-scale air stripping packed tower equipment was designed and made. Using concentrated ammonia nitrogen wastewater from a vanadium smelting as the experimental feed solution, factors affecting absorption mass transfer efficiency such as air flow rate, temperature, pH value of the wastewater etc. are investigated, and the stripping mass transfer coefficient KLWas obtained. It was found that within the scope of the experiment conditions, the best KL= 0.0072 m/h. And the experimental results show that the best stripping conditions:waste water pH 11.5, absorption solution pH 0.25-0.5, the stripping waste water circulation flow 6.0m3/h, absorption solution circulation flow 6.0m3/h.In order to build up a calculation mode for the design of the air stripping packed tower, the ammonia absorption rate equation in the packed tower is deduced, and overall mass transfer coefficient of ammonia in the experimental stripping tower KX＝0.7209 KmoL/h·m2 was obtained. Then based on the KX, the relationship of the packed tower size with treatment flow rate and ammonia removal rate of wastewater was simulated.Based on the previous study results, the deep treatment of ammonia nitrogen waste water by multistage mobile bed adsorption was investigated, using Amar-01 as a adsorbent. After comparing various operation modes of mobile bed adsoption mode and mobile bed desoption mode, a suitable mobile bed process for the treatment of ammonia wastewater was obtained.Using the air stripping—multistage adsorption combined process, a pilot plant with treatment capacity of 30m3/d ammonia wastewater was designed. The results show that the concentration of ammonia nitrogen wastewater decreased from about 13g/L down to below 15mg/L after treatment by the air stripping - adsorption combined process.