Performance Of Biological Removing Hydrogen Sulfide In Intermittent State

Odor pollution from industry processing and disposal of wastewater was paidmore and more attention with the enhancing of urbanization and the rapiddevelopment of modern industry. How to effectively resolve the pollution of theenvironment and obtain the optimum treatment technology for odor pollution hasbeen one of the hot issues concerned in the field of environmental protection.Biofiltration has been recognized as a most promising technology for the purificationof odor gaseous pollutants because of simplicity of processes and equipments, lessinvestments, lower operation cost, facility of operate and control, high removalefficiency and limited negative environmental effects.Most previous work about biological removal of odor was reported with lowconcentration waste gas under low gas velocity, viz. empty bed residedce time （EBRT）at room temperature. For the waste gas of high load under high gas velocity was little,also for the research at low temperature, which has been proven to have badprocessing effect, weak shock resistance and unstable in the long term run.In this work, the biofilter packed with the mixtures of chicken manure andpolyethylene （PE） were employed to remove hydrogen sulfide （H₂S） waste gas withhigh load and high gas velocity under low temperature in a long term run. Theexperiment was carried out in intermittent mode, which was a simulation practicalapplication. The removal efficiencies of H₂S were investigated at various gas velocityand inlet load; The performance of the biofilter was obtained with high load and highgas velocity was experimentally analyzed; The biological removal of H₂S in abiofilter was investigated under low temperature; The nutrients, SO₄^2-, S, pH,moisture content, pressure drop, and microbial quantities of change in packingmaterials were measured; The kinetics of removaling H₂S with high inlet load and gasvelocity was evaluated.The following main conclusions were obtained:（1） H₂S with high inlet load and gas velocity under low temperature was successfully removed in a three-section biofilter.Under the condition of temperature from9℃to16.5℃, H₂S removal efficiencyexceed95%with inlet concentration of50³000mg·m^-3and EBRT of13s, theelimination capacity reached776g·m^-3·h^-1. The reactor has not received maximumcapability of the H₂S removal.（2） A good performance of the biofilter was obtained with high inlet load underhigh gas velocity.At EBRT of13s, H₂S removal efficiency in a three-section biofilter achieved65%with inlet concentration of50³000mg·m^-3, and the elimination capacity528g·m^-3·h^-1was obtained. The reactor has not received maximum capability of thebiofiter.At EBRT of5s, H₂S removal efficiency in a one-section biofilter exceed94%with inlet concentration of50³000mg·m^-3, and the elimination capacity reached2043g·m^-3·h^-1. The reactor also has a higher potential of the H₂S removal.（3） The kinetics of removaling H₂S with high inlet load and high gas velocity（EBRT of10s,6.7s and5s） was evaluated based on the Michaelis-Menten model.The calculated value of experimental and the predicted showed their correlativity wasgood. Two kinetic parameters were K_s with a value of550mg·m^-3, V_m with a value of6.8×10⁴g·m^-3·d^-1, and the correlation R²with a value of0.9872.（4） The method of artificial spray has been used to keep humidity, when themoisture content in packing media was dropped. The stable removal efficiency couldbe maintained with the moisture content ranges from30%to60%.（5） During H₂S biofiltration, the pH value of packing material dropped, thelowest value was5.77, the acidification did not occur, and the removal efficiency hasnot been changed obviously with the reducing of pH value. The Desulfotomaculumhas a good adaptability to the pH value of packing material.（6） H₂S was degraded to SO₄^2-and S during biofiltration. The content of SO₄^2-was accumulated with the removaling process and the maximum content of SO₄^2-inthe1stsection biofilter was3.593mg·g^-1dry packing medial.（7） The Nitrogen nutrients were sufficient and the blocking and compression ofpacking material did not occur during the long term run of biofilter. （8） During H₂S biofiltration, microorganism in packing materials has a goodadaptability to high load pollutant. The bacteria in the biofilter are more than fungusand actinomycetes.In conclusion, H₂S with high inlet load and high gas velocity in intermittentmode under low temperature were successfully eliminated in a biofilter packed withthe mixtures of chicken manure and polyethylene （PE）. The results showed that thebiofilter has high removal efficiency, stable performance and higher potential of theH₂S removal in the long term run.