Study On The Biological Aerated Filter For The Livestock Breeding Wastewater Advanced Treatment

With the rapid development of livestock breeding industry, the wastewaterdischarging of which become a more serious pollution day by day, and the researchon wastewater treatment of livestock breeding increasingly develops. Through themethod of experiment, the treatment for livestock breeding wastewater byBiological Aerated Filter was studied in the paper. The main conclusions obtainedas follows:（1）In the condition of suitable temperature,1L/h in flooding velocity,10:1in gas-water ratio,it took28days of continual operation to build a stable biofilm inBAF（Biological Aerated Filter）. The biological film have a stable structure, and themicrobial growth is in a good condition, in which COD and总氮removal ratewere94.3%and38.4%respectively.（2） Through the laboratory study of COD and总氮removal in condision ofdifferent gas-water ratios and different hydraulic retention time, the best reactioncondition for that BAF dispose livestock breeding wastewater is confirmed to begas-water ratio15:1,hydraulic retention time14hours, and the strainaway rate ofthe COD,总氮were95.2%and43.3%respectively.（3） Through theoretical derivation and simulation of experimental datum,it wasfound that the first order reaction kinetics can apply to biological aerated filtersremoving pollutants. Under the best reaction condition, empirical rate equation fordegradation of COD was ρ_A=ρ_A0exp（0.095t+1.2753）, and empirical rate equation fordegradation of ammonia nitrogen was ρ_A=ρ_A0exp（0.095t+1.2753）. （4）BAF have a good dislodge for trace pollutant（e.g. Roxarsone andestrogen）.Roxarsone,s removing most occur in the front60centimeters precoat, andthe trace pollutant in wastewater only have a little effection on the removal ofconventional pollutants.