It has been confirmed that vented gases from swine manure compositing operations contain biodegradable ammonia and amines as main odorous compounds. The thesis focuses on the odor-removal performance from the gases by sparging them into an activated sludge aeration liquor in which the odorous compounds can be absorbed and biodegraded. An acrylic column (0.20 m i.d.¡Ñ1.2 mH) was used as the activated sludge aeration tank and a wooden case (1.0 mL¡Ñ0.6 mW¡Ñ0.6 mH) as a swine manure compositing tank. Seed sludge for the odor removal experiments was obtained from a swinery wastewater plant located at southern Taiwan. Both swine manure from the swinery and a pre-fermented composite sample obtained from a compositing plant located at East-southern Ping-Dong County were used for the odorous gas generation. Experiments were conducted at mixed liquor suspended solid (MLSS) concentrations of 2,250-2,750 mg/L, liquid pH of 6.4-6.6, and aeration intensities of 0.1-0.5 m3/m3.min. Results show that the experimental removal efficiencies for both ammonia and amines with, respectively, 18-50 and 180-250 ppm in the influent gas were greater than 80% with aerated activated sludge liquid depths of greater than 0.60 m within the tested aeration intensities. Keeping the activated sludge at around 25oC favored the biodegradation of the absorbed ammonia and amines and resulted in the removal of the compounds to around 85-95%. Temperatures of lower than 15oC shifted the removal to as low as 50-60% because of the limitations in both the biological growth and activity. Results from the study confirm that the activated sludge bioscrubbing approach should be applicable to odor control for the compositing plants.

This dissertation consists of two parts on the treatment of hydrogen sulfide and odorants in gases emitted from rubber processing industry. In the first part, we study performance of removal hydrogen sulfide with bioscrubber. An activated sludge aeration tank (W ¡Ñ L ¡Ñ H = 0.40 ¡Ñ 0.40 ¡Ñ 3.00 m) with a 2 mm-orifice air sparger was used to treat gaseous hydrogen sulfide (H2S). The investigation tested the operational stability as well as how the removal ability of H2S was affected by influent H2S concentration (C0 = 50-900 ppm), aeration intensity (Q/V = 0.083-0.50 m3 m-3 min-1), liquid depth (H = 0.5-3.0 m), and mixed-liquor suspended solids concentration (MLSS = 970-2,800 mg L-1). Experimental results indicate that H2S removal efficiencies of 96% and over 98% were obtained with H = 0.5 m and H > 1.0 m in the cited operation conditions, respectively. Experimental results also indicate no sludge bulking problem occurred with total sulfide loadings of 0.047-0.148 kg S kg-1 MLSS d-1. The second part aimed at the removal of odorous compounds in gases emitted from rubber processing industries. Simulated odorous gas for test was prepared by mixing fresh air and an odorous gas drawn from an oven in which a sample of rubber powder was kept either at 160¢XC (for a thermal plastic rubber) or 200¢XC (for a thermal setting rubber). The prepared odorous gas was then premixed with a definite amount of ozone-enriched air and introduced into a contact system. The contact system consists of two sieve-plate columns connected in series and each column has four 1-L chambers. Depending on with or without introducing circulating scrubbing water into the columns, the oxidation reaction could be either wet or dry one. Results indicate the wet oxidation got better performances than the dry one. The former got 97 and over 90% removal of VOCs (volatile organic compounds) and odorous intensity removal, respectively, with the operation conditions of initial ozone concentration 4.0 ppm, THC (total hydrocarbon) concentrations 6.5¡V10.3 ppm (methane equivalent), oxidation temperature 37.3¢XC, gas empty bed retention time (EBRT) 12 s, and liquid/gas rate ratio 0.01 m3/m3. With conditions similar to those cited above, odor concentration (dilutions to the threshold, D/T) in the test gas could be reduced from 1,738¡V3,090 to 31¡V98 with EBRTs of 11.4¡V14.5 s. Activated carbon is effective for both physical and chemical removals of residual VOCs, odorous compounds, and ozone in the effluent gas from the ozonation system. Economical analysis indicates that around US$ 0.16 is required for treating 1,000 m3 of the tested foul gas by the proposed ozonation process.