No description available.

No description available.

Thesis (M.S.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains vii, 32 p. : ill. Includes abstract. Includes bibliographical references (p. 32).

Thesis (M.S.)--University of Michigan, 1985.

Thesis (M.S.)--University of Michigan, 1985.

Thesis (M. D. S.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 50-62). Also available in print.

published_or_final_version / Endodontics / Master / Master of Dental Surgery

This study armed to develop a chemical scrubbing process to eliminate odorous VOCs (volatile organic compounds) in gases emitted from hot-melted coal tar used in bamboo antiseptic processing. Major VOCs are mono-aromatic hydrocarbons (MAHs), polycyclic aromatic hydrocarbons (PAHs), phenol and ammonia. A pilot scrubber with a recycling scrubbing liquid tank and with an acrylic column of 0.10 m in length, 0.10 m in width, and 0.58 m in height, packed with 1¡¦¡¦ diameter plastic packings to a height of 0.38 m will be used for the scrubbing test of the emitted gas. Aqueous solutions of sodium hypochlorite (NaOCl), hydrogen peroxide (H2O2), detergent, and the Fenton¡¦s reagent (hydrogen peroxide with ferrous chloride) will be used as oxidants for the VOCs. Results indicated that with operation conditions of VOCs 20-30 ppm (as methane), an empty bed retention time (EBRT) of around 28.5 s in the packed section, and a sodium hypochlorite concentration of 450 mg Cl2/L with pH of 6, around 45.3-50.3% of the VOCs in the influent gas could be removed at a L/G (liquid to gas flow rate ratio) of 0.295 m3/m3. A test indicated that the overall odor(expressed as the dilution to threshold D/T value) removal was around 97.6% and the D/T were 1303 and 30.9, respectively, for the influent, and scrubber effluent. Using double packed towers to deal with coal tar odorous, result from the test indicated that 70-75 and 94.4% of VOCs and odorous intensity in the influent gas could be removed, respectively, with the operation of an initial sodium hypochlorite concentration of 450 mg Cl2/L with pH of 6, combined with a hydrogen peroxide concentration of 4000 mg/L with pH of 9 , VOCs (methane equivalent) concentrations of 20-30 ppm, gas flow rate of 8 NL/min, and a liquid/gas rate ratio of 0.295 m3/m3. At running 300 minutes can smell much odor than beginning. Baesd on the results from the pilot study, a full-scale plant with waste gas flow rate 200 m3/min was proposed. It was estimated that the cost is around NT$ 20.9 and 52.2 for treating 1,000 m3 of the emitted gases, respectively, for sodium hypochlorite, and sodium hypochlorite combined with hydrogen peroxide. Efforts should be made by decreasing the cost by other alternative technologies.

Almost all dyestuffs used for textile processing impose heavy colors on effluents such that they can¡¦t meet effluent regulations. Sodium hypochlorite (NaOCl) has long been used for effluent decoloration by most textile plants. However, despite by the operators¡¦ experience, there is still no scientific method for controlling the dosing rate of sodium hypochlorite. An insufficient dosage may result in an aesthetically and legally unacceptable effluent. Whereas an excessive one may lead to the formation of chlorine-containing organic compounds which are harmful to the aquatic life and may limit the water utilization. It is necessary to develop a control technique for chlorination decoloration of textile wastewaters. In this study, secondary effluent samples from a textile wastewater plant and synthetic wastewater samples prepared by two azo-type dyestuffs were used for chlorination decoloration tests in a batch reactor with a residual chlorine indicator. Experimental results indicate that the most economic and effective reaction conditions for decoloration of the test wastewaters were pH = 4 and residual chlorine = 14 mg/L. In the conditions, wastewaters with true color intensity = 1,200 ADMI could be reduced to values less than 400 ADMI within 60 min. Results also confirm that on-line monitoring of residual chlorine concentration in the reacting liquid can be used to achieve a better control of chlorine addition. Experimental data also indicate that the color removal rate (-dC/dt) was linearly proportional to the color intensity (C) and free hypochlorous acid (HOCl) concentration.

This study armed at the development of an adequate process for the odor control of a gas vented from a plant for treating olefin-resin manufacturing wastewater.The gas contains various aromatic and olefin compounds, such as toluene, £\-methyl styrene, vinyl toluene, styrene, naphthalene, dicyclopentadiene, and indene.Primary tests showed that these odorous compounds could not be effectively eliminated by a biotrickling filter packed with fern chips.Instead, these compounds can easily be removed or eliminated by using sodium hypochlorite as an oxidant and followed by sodium thiosulfate as a reductant for removing the residual chlorine odor. Results indicate that by scrubbing the gas with sodium hypochlorite solution with an effective residual chlorine of 40-60 mg/L, pH of 7.9-9.8, and oxidation-reduction potential (ORP) of 500-760 mV, concentration of volatile organic compounds (VOCs) in the test gas could be removed from 250 ppm (expressed as methane) to 23 ppm.Trace olefin and chlorine odors in the oxidized gas could further be removed by scrubbing it with an aqueous solution of 270 mg/L Na2S2O3.The overall VOC removal was around 92%.