Considering the high potential of the widely-used halogenated hydrocarbons on the global warming and ozone depletion, the development of effective thermal destruction methods of these compounds are quite urgent and indispensible. As part of the research efforts of this area, the destruction of CCl4 and flame characteristics have been investigated numerically by the co-firing CCl4 with CH4 in an industrial LNG-fired combustor as a function of molar ratio of the CCl4 to CH4 using a commercial code of STAR-CCM+. Considering a broad range of Damkohler number associated with the process of intensive CHCs (Chlorinated hydrocarbons) combustion with auxiliary fuel together with the inhibition reaction especially near flammability limits, a proper combustion modeling of CCl4 thermal destruction is quite desirable. In this study, however, after careful review of the literature about the flame characteristics of halogenated hydrocarbon together with the previous study about the modeling of the CCl4 flame based on the data of burning velocity, the eddy breakup turbulent combustion model was employed since it is quite reasonably assumed that chain branching reaction looks dominant in most flame region over the halogenated inhibition effect in strong turbulent reacting flows. One of the most useful results based on this study is that; without any incorporation of flame inhibition effect, the length of co-fired flame increases steadily as the ratio of CCl4 to CH4 (R) increases from 0.0, 0.1, 0.2 to 0.5, and 1.0 together with the increase of the maximum flame and exit gas temperature. The reason of the increase of the flame length with the increase of flame temperature can be explained by the presence of the additional CCl4 fuel with low heating value. Further a detailed discussion has been made on the thermal destruction of CCl4 together with the Cl2 concentration by Deacon reaction.
Continuous deodorization of malodorous sulfur compounds by Thiobacillus neapolitanus R-10 immobilized onto a polypropylene pellet was studied using a column reactor at 30℃. The maximum amounts of immobilized cells was 5.3 g/ℓ polypropylene with 5 × 7.5㎜ in pellet size, and the amounts of immobilized cells in the higher part of the column was as twice as in the lower part. The optimum pH and temperature for removal of dimethyl sulfide were 6.0 and 30℃, respectively. When 5-20 ㎕/ℓ of hydrogen sulfide and methylmercaptan were employed 98% of removal efficiency were achieved. In contrast, lower concentrations of dimethyl sulfide and dimethyldisulfide should be supplied to meet satisfactory deodorization efficiency. The immobilized cell column was successfully operated for the deodorization of mixture of sulfur compounds over 15 days without significant loss of initial activity achieving high efficiency.
Thiobacillus neapolitanus R-10 isolated from sludge of night soil, showed an oxidizing activity on several malodorous sulfur compounds. The microbe successfully utilized hydrogen sulfide(H_2S), methy mercaptan(MM), dimethyl sulfide(DMS) and dimethyldisulfide(DMDS) during the batch culture reaction, of which H_2S was rather rapidly oxidized. To examine the ability for removal of malodorous sulfur compounds, various concentrations of sulfide substrates were supplemented separately to basal medium and their responses were investigated. As the concentration of sulfide was increased, growth was accelerated within three days of cultivation. 2.5mM was the most favorable substrate concentration of sulfide added for all cases tested. However, when the concentration of sulfur compounds were raised over 4mM, they behaved as a growth inhibitor.