Research On Treatment Of Ammonia-nitrogen In Anaerobically Digested Swine Wastewater By Air Stripping With Organic Composite Denitrification Reagent

The digested wastewater has high ammonia nitrogen and low carbon to nitrogen ratio, so the effect of the aerobic treatment was poor. To address this issue, this research utilized the technique which joint organic composite denitrification agent and air-stripping as the pre-treatment of the the aerobic treatment. An organic composite denitrification agent which was prepared in the laboratory was the key of the study.Based on the degradation of traditional air-stripping, this dissertation focused on the performance of organic composite denitrification agent Y in the treatment of ammonia nitrogen in the digested swine wastewater, the process conditions, and the mechanism of it. The main conclusions drawn in this study are as follows:(1) The experimental research of traditional air-stripping indicated that:high pH and temperature and high cost was required, and the ammonia removal rate still needs improved. Considering the treatment effect, energy consumption, the optimum pH value is 10.00 to 12.00, reaction time is 72h, per unit time (per hour) gas-liquid ratio is 240:1-360:1,and the water temperature is 20?40?.Under the conditions that pH value is 10.50, temperature is 20?, per unit time(per hour)gas-liquid ratio is 240:1, and reaction time is 72 hours, the removal rate of ammonia-nitrogen is up to 95.69%.(2) The experimental research of organic composite denitrification agent/air-stripping indicated that:adding denitrification reagent can really increase removal rate, and the best dosage of the denitrification agent is 6 mg/L. Considering the treatment effect, energy consumption, the optimum pH value is 10.00 to 11.00, blow-off time time is 24h-48h, per unit time (per hour) gas-liquid ratio is 240:1,and the water temperature is 20?40?.(3) The experimental research of comparison of organic composite denitrification agent/air-stripping and traditional air-stripping shows that:The impact of each factor on the ammonia removal of both methods is completely consistent.The nitrogen removal efficiency increases when the water level is reduced,or Something deposited were removalled, or any one of these rest factors is increased such as pH, temperature, initial concentration of ammonia nitrogen, air-liquid ratio in unit time(per hour) and blow-off time;Under the same conditions,the removal rate the removal speed of ammonia nitrogen by organic composite denitrification agent/air-stripping are higher than that by the traditional air-stripping,and less trating time is required. Especially when the temperature is 14.8?-30?, pH is 7.00-11.00, the difference was larger and organic composite denitrification agent/air-stripping show the most obvious advantages. But its greatest value lies in the following situations:in summer (when the temperature is above 20?), good removal effect of ammonia nitrogen can be achieved with no pH or a little of pH needs adjusted,and no temperature needs controlled,but a small amount of (6 mg/L) organic composite denitrification agentY be used. Under the conditions that pH value is 7.56, temperature is 20?, per unit time (per hour) gas-liquid ratio is 240:1, and the blow-off time is 72 hours, the removal rate of ammonia-nitrogen is up to 91.29%;when pH value is 9.00, temperature is 20?, only treat 48 hours, the removal rate of ammonia-nitrogen can be up to 91.22%.However, during the cold season the pH must be adjusted to 11.00 at least, for example, when the temperature T=13.5?, even pH is adjustedto 9.00-10.00, the ultimate effect of organic composite denitrification agent/air-stripping is as poor as traditional air-stripping instead of much better.(4) The result of mechanism analysis turns out that:Organic composite denitrification agent Y mainly Promote the free ammonia remove from liquid to gas in some effective ways. It is unlikely to convert NH4+-N to NO2--N, NO3--N, organic nitrogen,or other forms of nitrogen.as the organic composite denitrification agent/air-stripping significantly restricted by the influencing factors of free ammonia percentage, it is unlikely to promote ammonia nitrogen transforms from ammonium ions form to free ammonia molecules form also.