| The rapid development of livestock can meet people’s living needs and provide great convenience,the same time, it is urgent to eliminate the pollution of odor caused by the livestock.As Biological method has the advantages of simple equipment, low operating cost, easy controling conditions,high removal rate etc,it becomes a hot research spot at home and abroad at prevent.In this paper, NH3 and H2S as major environmental contaminants from many stock farms the biological removals of has been investigated in a self-made bio-filter with membrane ceramsite、multi-faceted hollow balls and Pall ring. The better method of biological filter start-up、the effect of various experiment conditions on biological removal of NH3 and H2S also have been discussed and the removal kinetics of NH3 and H2S and the mechanism of biological degradation NH3 and H2S gas have been analysed. The conclusions are as follows:(1)In this experiment, NH3 and H2S have been selected as the research objects, the value of total nitrogen conversion rate and bivalent sulfur conversion rate are regarded as biotrickling filter microbial degradation NH3 and H2S targets, which can show more accurately the biological growth status compared with the removal rate as biodegradation NH3 and H2S index.(2)The suitable reactor startup conditions for microbial degradation of the NH3 and H2S are:the spray amount 60 ml/min, temperature 25 ℃, air input 0.2 m3/h, the initial pH value 7.0, imports of NH3 200 mg/m3, H2S 70 mg/m3(the mass ratio is 2 to 3),through biofilm hanging in packing and direct inleting air simultaneously,after 11 days the reactor has started succesfully, NH3 and H2S removal rate are all above 95%,the total nitrogen conversion rate and divalent sulfur conversion rate are also above 90%.At temperature 25 ℃, the NH3 and H2S removal rate are all above 95%,the total nitrogen conversion rate and divalent sulfur conversion rate reach to 68% and 100% respectively, compared with other temperature,25 ℃ is adopt to two kinds of microbial degradation of ammonia and hydrogen sulfide.At the spray amount 60 ml/min, the NH3 and H2S removal rate all reach to 100%, the total nitrogen conversion rate and divalent sulfur conversion rate are 80% and 100% separately.Two kinds of deodorization microorganisms’growth status in the whole system is best.At air input 0.2 m3/h, the NH3 and H2S removal rate are stable at 99.5%, the total nitrogen conversion rate and divalent sulfur conversion rate all reach to 100%.When the initial pH value 7.0, the NH3 and H2S removal rate are stable at 98.5% and 100% respectively, the total nitrogen conversion rate and divalent sulfur conversion rate reach to 95% and 100% separately.(3)At the inlet concentration of NH3 200 mg/m3, the effect of various inlet H2S concentration on NH3 removal rate has been discussed. The results show that ammonia nitrogen conversion rate、nitrate nitrogen conversion rate and the total nitrogen conversion rate all have been decreased with the increase of inlet concentration of H2S.When the inlet concentration of H2S at 70mg/m3, NH3 removal rate maintained at 98% to 99.5% at most time, the value of total nitrogen conversion rate has been above 95%.At the same condition, under the inlet concentration of H2S 70 mg/m3, H2S removal rate and bivalent sulfur conversion rate have been investigated at the inlet concentration of NH3 200 mg/m3、300 mg/m3、400 mg/m3. The experimental results demonstrate that H2S removal rate have been decreased with the increase of inlet concentration of NH3,but it maintains more than 96.5%, bivalent sulfur conversion rate is also above 98.5%.At the inlet concentration of H2S 500 mg/m3 and NH3 600 mg/m3, the ability of biological filter removal odor has been investigated. The experimental results demonstrate that the outlet of NH3 removal rate keep up to 99%, H2S removal rate is above 98%, bivalent sulfur conversion rate reaches 100% quickly and the value of total nitrogen conversion rate also can get 60%.(4) When stopping inputting the NH3、H2S and spraying the nutrient solution to reactor for 10 days, the bio-filter has been restarted in order to observe the removal effect, one days later the removal rate of NH3 and H2S has resumed to 100% and 99% respectively, the value of total nitrogen conversion rate has resumed from 25% to 100% during 4 days and the bivalent sulfur conversion rate has resumed to 100% only one day later.(5) In this paper, the enzyme reaction kinetics equation is used to analyze the apparent degeneration of NH3 and H2S, through the linear regression, the parameters of equation is obtained, for H2S the Ks is 2394.167 mg/m3, Vm is 16666.667 g(H2S)/m3.d, R2=0.99497;for NH3 the Ksis 344.99655 mg/m3,Vmis 3333.3 g(NH3)/m3.d, R2=0.9946.The actual value of NH3 and H2S degrading amount per day at unit reactor volume is lower than theoretical Vm value, it can be explained that there is big promotion space for the microbial degradation NH3 and H2S ability in reactor.(6)In this paper, the biological membrane growth kinetics and protein growth kinetics have been discussed,through the linear regression, the parameters of equation is obtained,the parameters of the upper biofilm is Ks=27128.5846 mg/d, Mmax is 4.625 d-1, R2=0.9383, the protein parameters of the upper biofilm is Ks=154170.509 mg/d, Mmax is 46.08295 d-1, R2=0.9114。The mechanism of degradation NH3 and H2S in biological filter have alse been investigated in this paper, thus it could provide the theoretical foundation for industrialization. Due to the experimental limit, the removal kinetics and degradating mechanism are a primary discussion in the paper. There are many works to do in order to understand the degradating NH3 and H2S mechanism in the future. |
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