Due to the rapid increase on economical growth and individual income in Taiwan, restaurants are getting popular and expanded significantly in the recent years. However, the smoke emitted from those restaurants is frequently argued or accused by the residents living nearby. Although EPA in Taiwan has noted the issues of randomly emitting smoke by restaurants to intensify air pollution and initiated a new law which will be implemented beginning from October to regulate the necessity of equipping hardware facilities for the abatement of smoke emission by those commercial kitchens, most restaurants conventionally use rather simple facility, such as blocking plate and filter, to screen the smoke. Thus, air pollution by the emission by kitchen smoke can not be neglected. This research will focus on the design of lab-scale and field-scale treatment system to deal with kitchen smoke using advanced oxidation technologies. The information obtained form the lab-scale facility will be referred and applied on the design of filed-scale system.
According to the experimental results, varying gas-liquid ratios from 0.6 to 1.5 m3/L will not obviously affect the treatment efficiency. The removal of odor and total hydrocarbon (THC) by water scrubbing process are 25 % and 47~50%, respectively. The addition of using goethite catalyst with water scrubbing will improve the removal of odor and THC up to 45% and 50~58%. Using ozone-based advanced oxidation processes (AOPs) plus goethite catalysts and water scrubbing would result in better removal of odor and THC. The co-addition of hydrogen peroxide with AOPs could achieve the best treatment efficiency by 82% odor removal and 77% THC abatement. In addition, organic matters in the circulation water would be oxidized by hydroxyl radicals generated by the AOPs and the TOC concentration could be properly reduced. Based on this advantage, the use of circulation water will be prolonged effectively. For the control of PAHs in the smoke, only small quantities of naphthalene were detected by heating cooking oil without adding any food materials. Therefore, the addition of food materials in the cooking oil was simulated and more THC and PAHs were quantitatively measured. Nevertheless, the use of lab-scale treatment system equipped with water scrubbing, goethite catalyst, hydrogen peroxide, and ozone would obtain the removal efficiency of 68~75% for PAHs, 80% for odor components, and 73~78% for THC. Based on the promising results from the lab-scale treatment system, a field –scale system for the control of emitted smoke from kitchens was fabricated and applied on two selected restaurants, one was oriental cuisine and the other was western cuisine, closed to Feng Chia University. 80% of odor and THC removal and 70% of PAHs abatement were obtained. Thus, the efficacy of cooking smoke treatment system using either lab-scale or field-scale will maintain stably and equally.
According to this research, four ranges of gas flowrate can be classified as: less than 5, 20~30, 50~60, and 150~180 cubic meter per day. Water scrubbing plus goethite catalyst and hydrogen peroxide can be applied for the gas flowrate less than 30 CMM and the annual cost is less than forty thousand dollar calculated for 5-year operational period. If gas flowrate emitted from commercial kitchen is greater than 50 CMM, ozone would be suggested to combine those treatment processes mentioned above and the annual cost will be increase up to one hundred fifty thousand dollar depending on the selection of facilities required. To sum up, the outcome of this research has provided another useful alternative for the treatment of wasted cooking gas from kitchens. The most credible benefit using this technology is the emission control of gaseous components in the cooking wasted gas. If this new-developing treatment facility can be commercially applied in the future, the relief of adverse impact of restaurant wasted gas on our living environment could be expected.
