| This study carried out a series of experiments about Erhai lake basin pilot scale biological gas engineering undertaken by Yunnan Shunfeng Erhai lake environmental protection technology co.,LTD,aimed to provide reference for the anaerobic digestion process parameters and operation and management of the project.Using batch fermentation device and a home-made new type of CSTR to explore the influence of temperature,concentration and hydraulic retention time on biogas production with cow dung from Erhai lake basin as raw material;to study the influences of dosage of digested slurry back to the fermentation process at the same time.Adopting ammonia stripping method to reduce the ammonia nitrogen content in the digested slurry to lay a foundation of maintaining a long-term stable operation of biogas fermentation engineering.The results are as follows:?In batch type biogas fermentation experiment,the temperature gradient?30,35,38,and 40??and fermentation TS concentration gradient?4%,6%,8%and 10%?were set.When the temperature was 30?,the specific biogas production under 4%,6%,8%and 10%was 0.430,0.506,0.504 and 0.464 m3/kg VS,respectively.When the temperature was 35?,the specific biogas production under 4%,6%,8%and 10%was 0.484,0.574,0.553 and 0.522 m3/kg VS,respectively.When the temperature was38?,the specific biogas production under 4%,6%,8%and 10%was 0.393,0.497,0.491 and 0.513 m3/kg VS,respectively.When the temperature was 40?,the specific biogas production under 4%,6%,8%and 10%was 0.328,0.462,0.489and 0.502m3/kg VS,respectively.At the same time,all the fermentation of concentration of 4%,6%,8%and 10%obtained the maximum specific biogas production rate at 35?.?In the test of new CSTR reactor for the treatment of cow dung,when the fermentation temperature was 30?,the volumetric biogas production rate of the fermentation conditions for HRT=24d and TS=6%,HRT=20d and TS=5%,HRT=16d and TS=4%were 0.641,0.646,0.614 m3/?m3·d?respectively;the specific biogas production rate was 0.322,0.310.0.306 m3/kg.When the fermentation temperature was 35?,the volumetric biogas production rate of the fermentation conditions for HRT=24d and TS=6%,HRT=20d and TS=5%,HRT=16d and TS=4%were 0.744,0.756,0.706 m3/?m3·d?respectively;the specific biogas production rate was 0.389,0.356.0.332 m3/kg.Moreover,new type of CSTR obtained the highest volumetric biogas production rate 0.756 m3/?m3·d?in the temperature of 35?,TS of 5%,HRT of 20d and got the highest specific biogas production rate 0.389 m3/kg VS in the temperature of 35?,TS of 6%,HRT of 24d.?The increasing of recirculation volume?from 0.55L/d to 0.75,1.05 L/d?did not bring about an obvious inhibition for semi-continuous anaerobic digestion of cow dung during a year of digested slurry reflowing.?4?In the trial of ammonia stripping,the volume of digested slurry of 1.0,1.5,2.0 L,blowing rate of 2.0,4.0 L/min,blowing time 211 h were applied.The ammonia nitrogen in 1.0 L digested slurry was removed by 50%more after being blown for 11 h?4.0 L/min?at room temperature with the use of homemade aeration device.This rate was effective to lower NH4-N concentration in the digested slurry for reflowing. |
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