Treatment of Waste Solutions Containing High Concentrations of Ammonia Using the Physico-Chemical Method

• Main Authors: Hou,WeiNi, 侯瑋妮
• Other Authors: Cheng,WenPo
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/67117281860316763089

碩士 === 國立聯合大學 === 環境與安全衛生工程學系碩士班 === 102 === This study adopts two chemical treatment procedures to explore the impact factors related to the treatment of waste solutions containing high concentrations of ammonia. In addition to forming ammonium alum through the reaction between aluminum sulfate and the high concentrations of ammonia in the waste solution, it also seeks for methods of preparing ammonium alum by utilizing water treatment sludge and waste solutions with high concentrations of ammonia. This study explores the impacts of different operating conditions on the crystallized amount of ammonium alum, including ammonium/aluminum molar ratio, removal of residual acid and aluminum ion, removal of concentration of ammonia in waste solution, impacts of rotational speed of mixer and time of mixing of ammonium alum; besides, it reckons the theoretical crystallization of ammonium alum based on the changes of ammonia concentration before and after the reaction, then calculates the ratio between the theoretical and actual crystallization, so as to obtain the recovery rate of ammonium alum crystal, which is served as the basis of efficiency evaluation. The results show that the reasonable crystallization conditions of ammonium alum include the ammonium/aluminum molar ratio of about 1.2, sulfuric acid of 100mL, and sludge volume of 300g/L, whereby the removal rate of ammonium ion is up to 69% and the recovery rate of ammonium alum crystal is up to 93%. Moreover, the mixing time and speed also will affect the recovery rate of ammonium alum crystal, in which the recommended mixing time is 5-30 minutes, and the recommended mixing speed is based on the velocity gradient (G) at about 100. The ammonium alum crystal recovered by filtering and settling for crystallization after mixing is quite lower than that obtained by directly crystallizing in sludge solution after mixing. In addition, the rise of crystal temperature will also reduce the crystallization rate of ammonium alum, however, in terms of the sludge solution after filtering, the research results indicate that a second mixing still can remove the ammonium ion. Moreover, a small amount of aluminum sulfate is added in the sludge, which can facilitate the removal of ammonium ion significantly, so as to reduce the treatment costs effectively. Moreover, this study also conducts a preliminary research on the treatment of ammonia-containing waste solution by methods of diaphragm electrolysis and electro dialysis. The results show that the chlorine generated through electrolysis with a two-slot electrode can remarkably conduct the oxygenolysis for the ammonium ion in the waste solution. However, the three-slot electro dialysis can noticeably dialyze the ammonium ion in the waste solution to the negative slot and then recover the ammonium solution through gasification; relatively, it can also dialyze the chlorine ion in waste solution into the positive slot, so as to produce chlorine by electrolytic oxidation.