In this study, GC-MS linked with an automatic thermal desorber was used to quantitatively analyze the odorous and volatile compounds in the gas emitted from a sewage sludge drying facility. In addition, the removal characteristics of these compounds were investigated by using a pilot-scale packed bed wet scrubber. A quantitative analysis for 58 odorous and volatile compounds in the gas was successfully achieved with GC-MS and GC-FPD. The a quantitative analysis revealed the major odorous compounds were hydrogen sulfide and acetaldehyde. In addition, D-type siloxane compounds such as octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6), were quantitatively measured. The concentrations of siloxane compounds measured in the gas were in the range of 4.54- 7.36 ppmv, higher than those in landfill gas. The average removal efficiency of the odorous and volatile compounds in a wet scrubber was 67.37%. D4, D5, and D6, which are hydrophobic compounds, were also removed by as much as 50.68%, 44.56%, and 70.26%, respectively.

The aim of this paper is to compare the characteristics of the T-P removal from synthesized municipal wastewater by electro-coagulation using cylindrical Al and Fe electrode as anode. For this purpose, a concentric circle type electrolysis reactor was used and the operating conditions for T-P removal from synthesized wastewater are as follows; potential 10 V, electrolyte 0.03% NaCl, initial T-P concentration 1.0 ~ 6.0 mg/L and flow rate 1.0 ~ 5.0 L/min. From the experimental results, T-P concentration of treated wastewater was decreased to less than 0.2 mg/L enough to discharge standard and Al electrode showed performance than Fe electrode for T-P removal by electro-coagulation. Optimal conditions for T-P removal to less than 0.15 mg/L which is 75% of discharge standard for large scale municipal wastewater plant (capacity higher than 500 m3/day) were obtained as follows; flow rate 2.503 L/min, and 2.337 L/min, HRT 1.059 min, 1.134 min, for Al and Fe electrode, respectively. Consumed mass of Al and Fe were of 3.76 times and 8.90 times respectively, were obtained to removed T-P at optimal conditions with potential 10 V, and 0.03% NaCl as electrolyte.

기-액 흡수반응에서 기체의 흡수효율은 흡수탑 내에서 가스의 체류시간과 흡수속도에 크게 기인된다. 이에 따라 선행연구자들은 기-액 반응에서 기체의 흡수율을 증진시키고자 흡수장치개발에 초점을 맞추어왔다. 지금까지 개발되어 이용되고 있는 흡수장치로는 packed tower, spray tower, bubble column, agitated vessel 등 여러 종류가 있으며, Bohner 등에 의하여 jet loop reactor가 개발되었다. Jet loop reactor는 draft tube 내부에 설치된 이유체 노즐에서 기체와 액체가 분사될 때 생성되는 액체제트에 의해 미세한 기포가 형성되어 기-액간의 접촉 면적이 넓어지고 난류강도가 증진된다. 또한, draft tube 내부를 하향류로 흐르던 유체가 annular space를 통해 상향류로 올라간 후, 기-액 흐름의 일부가 draft tube 내부로 재순환되어 기포의 체류시간이 증가하게 된다. 이러한 특징에 의하여 jet loop reactor는 타 반응기에 비하여 기-액간의 물질전달율이 높게 나타난다. 최근 jet loop reactor 내부에 설치된 two-fluid nozzle의 구조를 개선하여 가스와 액체가 nozzle tip에서 분사될 때 draft tube 내부와 외부에서 swirling flow가 형성되는 two-fluid swirling nozzle(TSN)이 개발되었다. Two-fluid swirling nozzle이 부착된 jet loop reactor는 기존의 two-fluid nozzle이 부착된 jet loop reactor에 비하여 기포크기가 미세해지며, 기포와 액체가 draft tube와 annular space를 통과할 때 난류강도가 증가하여, 기-액간 물질전달속도가 더욱 증진될 것으로 예상된다. 본 연구에서는 two-fluid swirling nozzle(TSN)이 부착된 jet loop reactor와 기존의 two-fluid conventional nozzle(TCN)이 부착된 jet loop reactor에서 CO₂를 흡수제거하는 과정에서 두 nozzle간의 성능을 비교평가하고자 하였다. 성능평가는 일정 조업조건에서 알칼리용액의 pH가 10.1에서 7.0까지 중화되는 시간과 순간 CO₂ 이용율과 총괄 CO₂ 이용율을 측정하여 비교하였다. 그 결과 동일한 액체 순환유량 조건에서 TCN을 장착했을 때에 비하여 TSN을 장착했을 때가 전체적으로 더 짧은 중화시간을 나타내며, 순간 CO₂ 이용율은 TSN을 장착한 경우가 TCN을 장착한 경우에 비하여 높게 나타났으며, 알칼리 용액의 pH가 높을수록 순간 CO₂이용율도 높아지는 경향을 보였다. 또한, Jet loop reactor에서 초기 pH 10.1인 알칼리 용액을 pH 7로 중화하는데 이용된 총괄 CO₂이용율은 TSN과 TCN을 사용했을 때 모두 97 % 이상이었으며, 동일한 액체 순환유량에서 TSN을 장착하였을 경우가 TCN을 장착하였을 경우에 비하여 높은 총괄 CO₂이용율을 보였다.

This paper presents the results of the electrochemical treatment of chemical oxygen demand(COD) and total nitrogen(T-N) compounds in the wastewater generated from flue gas desulfurization process by using a lab-scale electrolyzer. With the increase in the applied current from 0.6 Ah/L to 1.2 Ah/L, the COD removal efficiency rapidly increases from 74.5% to 96%, and the T-N removal efficiency slightly increases from 37.2% to 44.9%. Therefore, it is expected that an electrochemical treatment technique will be able to decrease the amount of chemicals used for reducing the COD and T-N in wastewater of the desulfurization process compared to the conventional chemical treatment technique.