| NOx is one of the main air pollutants, causing acid rain, being harmful to human health, resulting in the photochemistry smoke and the climate change. Conventional NOx treatment technologies are difficult, complex and expensive. People in the world are making efforts to look for and investigate new mehhods to control NOx pollution. According to the denitrification principles, Bio-trickling filter is used to purify the waste gas contained nitric oxide under anaerobic conditions.The experiment uses NaNO2 as the only nitrogen sources. The activated sludge from waste water plant is domesticated to obtain the denitrification bacteria and then inoculated them to the activitied carbon and the ceramic pellets. The experiment studies the influnce on the removal efficiency of carbon sources, the filter media, the gaseous flow rate, the recycle liquid flow rate, the NO influx concentration, the oxygen concentration and the height of the filter media. And also the dynamic model is built to analyse the NO removal process and is verified by experimental data. By stopping the experiment equipment a piece of time to investigate its recovering function. At the later stage of the experiment, we have pictures of the living things in the filter media. The experimental results show as follows:(1) By comparing methyl alcohol, ethanol and glucose, the methyl alcohol is the best carbon sources of denitrification.(2)Under the condition of NO concentration less than 1200 mg/m3 and recycle liquid flow rate from 0.05 L/min to 0.15 L/min, the recycle liquid flow rate has little effect on the bio-trickling filter performance. (3) Under the condition of NO concentration less than 1200 mg/m3, the gaseous flow rate and the influx gas concentration have remarkable effect on the removal efficiency. When the gaseous flow rate is 0.3 m3/h,the influx gas concentration less than 1200 mg/m3,the removal efficieny of activited carbon filter media is above 90%. When the gaseous flow rate increases to 0.9 m3/h,the influx gas concentration less than 1000 mg/m3,the removal efficieny of activited carbon filter media is about 85%. When the gaseous flow rate is 0.3 m3/h, the influx gas concentration less than 1200 mg/m3, the removal efficieny of ceramic pellet filter media is above 87%. When the gaseous flow rate increases to 0.9 m3/h,the influx gas concentration less than 1000 mg/m3, the removal efficieny of ceramic pellet filter media is about 80%.(4)The height of the filter media has effect on the removal efficiency.The lowest layer of the filter media has the highest removal efficiency ,its removal efficiency is above 50%.With the increase of the filter media height,the total removal efficiency increases.(5)After 11 months running,the resistance of activited carbon is bigger than that of ceramic pellets.But the resistance of the two bio-trickling filter is not big and less than 300 Pa.(6)When the oxygen concentration is less than 4%,the removal efficiency changes a little.However, when the oxygen concentration excesses 4%,the removal efficiency decreases obviously.(7)If the system stops within 16 h,there is no influence on the removal efficiency,and if the system stops within 48 h,the removal efficiency can recover 90% after 1h running.However if the system stops within 360 h, the removal efficiency can only recover 70% after 1 h running.(8)The quantiy and variety of organisms in the activited carbon filter media are more plentiful than that in the ceramic pellets filter media. The main organisms that are observed in the activited carbon filter media are Bacillus,Filamentous bacteria,and Neato,and the main organisms that are observed in the ceramic pellet filter media are Bacillus and Filamentous bacteria.(9)The results of Dynamic analysis show that one-stage biogradation kinetic model coincides with experiment results well.And,the constantξ.α/Q changes along with the inlet concentration Cgi.For the activited carbon filter media,the following equation exists.(ξ·α)/Q = 44561exp(Cgi/2000) for Cg≤1200 mg/m3.For the ceramic pellet filter media,the following equation exists.(ξ·α)/Q = 44721exp(Cgi/2000) for Cg≤1200 mg/m3.The results of the experiment show that it is feasible to use the denitrification bacteria in the bio-filtration filters to remove NO. It also points out the direction that the study will be gone on for the final application.
|
PDF Full Text Request