본 연구는 응집제 자동투입장치를 탈수기 전단에 장착하여 농축슬러지의 플록상태에 따른 고분자 응집제 주입량을 다르게 함으로써 탈수케이크의 함수율 저감 및 응집제 사용량 절감, 탈수여액의 수질개선 등 탈수특성에 미치는 영향을 평가하는데 그 목적이 있다. 응집제 자동투입장치를 B시 S하수처리장의 벨트프레스 전단에 적용한 결과 고속회전 및 응집제 분사를 통한 균일한 플록이 형성됨에 따라 기존 시스템 대비 탈수케이크 함수율 및 응집제 주입율 저감효과를 나타내었다. S하수처리장 농축슬러지(TS; Thickened sludge)에 대한 여름철, 가을철 및 겨울철의 기존 시스템 대비 응집제 자동투입장치의 최적 운전조건은 탈수케이크의 함수율 기준으로 판단해 볼 때 각각 DS-P(14%), DS-P(13%) 및 DS-P(12%)로, 이때의 탈수케이크 저감율은 25.3%, 30.7% 및 13.3%를, 고분자 응집제(P; Polymer) 저감율은 17.6%, 16.7% 및 20.0%를 각각 나타내었다. 응집제 자동투입장치의 회전속도와 유입 농축슬러지량 대비 고분자 응집제 주입율과의 상관관계를 평가한 결과 회전속도를 900~1,200 rpm의 범위 내에서 운전시 플록형성이 양호하게 나타났다.

본 연구는 하수슬러지의 플록상태를 파악할 수 있는 응집제 자동투입장치를 탈수기 전단에 장착하여 하수슬러지(소화슬러지, 농축슬러지) 플록상태에 따른 고분자 응집제 주입량을 다르게 함으로써 탈수케이크의 함수율 저감 및 응집제 사용량 절감, 탈수여액의 수질개선 등을 평가하는데 그 목적이 있다. 응집제 자동투입장치를 B시 N하수처리장 소화슬러지 및 S하수처리장 농축슬러지에 적용한 결과 고속회전 및 응집제 분사를 통한 균일한 플록이 형성됨에 따라 탈수케이크 함수율 및 응집제 주입율 저감효과를 나타내었다. 하수슬러지의 탈수실험 결과 소화슬러지에 대한 고분자 응집제의 적정주입율은 12%로 나타났으며, 이때의 비저항계수(SRF)는 1.11×1011 m/kg으로 나타났다. 또한, 농축슬러지에 대한 고분자 응집제의 적정주입율은 16%로 나타났으며, 이때의 비저항계수(SRF)는 1.68×1011 m/kg으로 나타났다. 또한 응집제 자동투입장치의 회전속도와 유입 하수슬러지량 대비 고분자 응집제 주입율과의 상관관계를 평가한 결과 회전속도를 900~1,200 rpm의 범위 내에서 운전시 플록형성이 양호하게 나타났다. 기존 시스템 대비 응집제 자동투입장치의 경제성 평가 결과 N하수처리장 및 S하수처리장의 경우 각각 연간 263,542,490원 및 42,174,700원으로 산출되었으며, 시설투자비 회수기간은 각각 2.3년 및 7.1년으로 나타났다. 따라서, 하수처리장 탈수기 전단에 응집제 자동투입장치를 적용함으로써 함수율 및 약품주입량 저감 뿐만 아니라 중앙제어실을 통한 실시간 모니터링이 가능하므로 인력감축 유도 및 공정자동화에도 기여할 수 있을 것으로 판단된다.

본 연구는 부산광역시 하수슬러지 처리공정 중 탈수기에 유입되는 배관부에 하수슬러지의 플록상태를 파악할 수 있는 응집제 자동주입장치를 장착하여 하수슬러지 플록상태에 따른 적정 응집제 주입량을 다르게 함으로써 탈수효율 향상 및 응집제 사용량을 감소시키고, 나아가 하수슬러지의 건조효율을 증가시키는데 그 목적이 있다. Pilot-scale 응집제 자동주입장치는 B시 소재 N하수처리장의 원심탈수기 전단에 설치하여 2013년 8월 7일 ~ 16일(10일간)동안 운전하였다. 또한, 응집제 자동투입장치의 설치시 운전상의 문제 발생시에 대비하여 bypass관을 설치하여, 기존 시스템으로 전환이 용이할 수 있도록 설계하였다. 고분자 응집제 주입율은 기존 시스템에서 운영하고 있는 유입슬러지량 대비 고분자 응집제 주입율인 14%를 기준으로 운전을 실시하였으며, 응집제 주입율을 11%에서 9%까지 점차적으로 낮추어 가면서 적정 운전조건을 찾고자 하였다. 응집제 자동투입장치를 원심탈수기 전단에 적용한 결과 고속회전 및 응집제 분사를 통한 균일한 플록이 형성됨에 따라 탈수케이크 함수율 및 응집제 주입율 저감효과를 나타내었다. 기존 시스템 대비 응집제 자동투입장치의 운전조건별(DS-P(11%), DS-P(10%) 및 DS-P(9%)) 탈수케이크의 함수율은 기존 함수율 82.4%에서 각각 80.6(저감량 1.8%), 80.9(저감량 1.5%) 및 81.5%(저감량 0.8%)의 높은 탈수효율을 나타내었다. 또한, 응집제 저감율은 DS-P(11%), DS-P(10%) 및 DS-P(9%)에서 각각 21.4, 28.6 및 35.7%를 나타내었다. 또한, 기존 시스템(DS-P(14%); COD 179.2 mg/L, SS 139.3 mg/L) 대비 응집제 자동투입장치의 운전조건별(DS-P(11%), DS-P(10%) 및 DS-P(9%)) 탈수여액 중 COD 및 SS의 농도는 각각 66.2, 76.4, 81.5 mg/L 및 12.0, 19.3, 55.6 mg/L를 나타내었다. 따라서, 하수처리장 탈수기 전단에 응집제 자동주입장치를 적용함으로써 함수율 및 약품주입량 저감 뿐만 아니라 인력감축 유도 및 중앙제어실을 통한 실시간 모니터링이 가능하므로 공정자동화에도 기여할 수 있을 것으로 판단된다.

Emissions of air pollutants and greenhouse gases (GHGs) from aircraft activities at 11 small-scale airports were investigated using the emissions and dispersion modeling system (EDMS) version 5.1.3 during the two year period of 2009~2010. The number of landing and take-off (LTO) at these airports was dominant for the aircraft type B737, accounting for more than 60% of the total LTOs. Out of the 11 small-scale airports, Gwangju (GJ, RKJJ) airport was the largest emitter of air pollutants and GHGs, whereas Yangyang (YY, RKNY) airport was the smallest emitter. The emissions of NOx and VOCs in 2010 at the 11 airports ranged from 1.9 to 83 ton/y and 0.1 to 17 ton/y, respectively. In 2010, the emissions of CO2 ranged from 394 to 21,217 ton/y. The emissions of most air pollutants (except for NOx and PM10) and GHGs were estimated to be the highest in taxi-out mode. The highest emissions of NOx and PM10 were emitted from climb-out and approach modes, respectively. In addition, the total LTOs at the 11 small-scale airports accounted for the range of 9.3~9.9% of those at four major international airports in Korea. The total emissions of air pollutants and GHGs at the 11 airports ranged from 4.8 to 12% of those at the four major airports.

Ion exchange resin was used to remove silica ion at ultralow concentration. The effects of temperature, type of ion exchange resin and single/mixed-resin systems on removal efficiency were estimated. As temperature increased, the slope of concentration profile became stiff, and the equilibrium concentration was higher. In the single resin system, the removal of silica was continued up to 400 min, but the silica concentration was recovered to initial concentration after 400 min due to the effect of dissolved CO2. In the mixed-resin system it took about 600 min to reach equilibrium. Because of faster cation exchange reaction than anion exchange reaction, the effect of CO2 could be removed. Based on the experimental results carried out in the mixed-resin system, the selectivity coefficients of silica ion for each ion exchange resin were calculated at some specific temperatures. The temperature dependency of the selectivity coefficient was expressed by the equation of Kraus-Raridon type.

The performance of ozone contactor in ozone-BAC advanced water treatment process was evaluated by the degree of decomposition of organic matters. The degree was measured by the analyses of UV254 absorbance and the concentrations of DOC and BDOC for the sand filtered water and the ozone treated water, respectively. In addition, the ozone concentration in the contactor, required for the maximum BDOC concentration, was selected as the optimum concentration, and the appropriate residential time of ozone treated water in a reservoir was recommended based on the residual ozone concentration in the treated water. The following results were obtained from the pilot scale experiments. By ozonation UV254 absorbance was decreased, and BDOC concentration was increased. The change of DOC concentration by ozonation was negligible, but the excess input of ozone resulted in the removal of the small amount of BDOC by complete oxidation. The optimum ozone concentration was 0.58 mg O3/mg DOC. In order to remove residual ozone, 20 minutes of the residential time were enough after ozonation.

The filtration tests were made in cell with a low concentrated suspension. The suspension with a concentration of cM=1.14～2.67․10-3 g/g consists of paper paint and water. The particles in the suspension have a particle size x<1㎛. The used depth filters consists of glass fibres, which are coated by polymer. The filtration in depth filters accorded in different mechanism, which were explained by physical models. The model which would be allows to make a promise of the filtration reaction. This filter media allows to get a high filtration time and a good separation rate. The Particle distribution is measured by a photon correlation spectroscopy(PCS). PCS measures particle sizes 0.03 ㎛<d<3 ㎛ in the suspension. The filtered suspension has a very low concentration Co≤5×10-4 g/g of solid in sample. The PCS also informs us about the number of the particles in the suspension. The makes it possible to calculate the concentration of the in sample.

We have been proposed model equation which is able to predict the trihalomethane producing concentration formation, that is one of byproduct, in the water treatment processes. In proposed model, the effects of trihalomethane factors like chlorine contact time, pH, temperature, TOC and UV-254 are considered. The concentration of the trihalomethane produced is proportion to the contact with chlorine, pH of water, temperature of water TOC and UV-254, respectively. This proposed model could be predicted the formed concentration of trihalomethanes by trihalomethane factors.

In this study, sulfate reduction reaction was used to increase the decomposition of organics, which is the most critical factor for the stabilization of a landfill site. Composite of sewage sludge, papers, and incineration ashes was used in the column. The experimental results indicated that out of 10 reactors, the reactors 3, 4, 8, and 9 showed higher organics (i.e., TOC) removal rate than that in the absence of sulfate. The organics removal rates (K) in R3 and R9 were 8.65e-4/d and 3.82e-4/d, respectively. The times to reach 10% of initial concentrations in R3 and R9 was 7.3 and 16.5 years, respectively, showing faster organics decomposition rates in these reactors.

The effect of ozone on the formation and the removal of disinfection byproducts(DBPs) of chlorination process was studied to elucidate the performance of water treatment process. The samples of raw water, prechlorination process, and preozonation process were analyzed quantitatively according to the Standard Methods for the Examination of drinking water. As a result, most of total trihalomethanes(THMs) which were formed in prechlorine treatment process was not removed in the preozonation process. Most of haloacetic acids(HAAs), haloacetonitriles(HANs), and chloral hydrate(CH) was removed in sedimentation and biological activated carbon(BAC) filtration processes. However, DBPs were increased more or less by postchlorine step. In particular, the formation of THMs and HAAs depends on ozone more than chlorine, but, the formation of HANs and CH depends on chlorine more than ozone. The seasonal variation of DBPs concentration for the year needs to be investigated to study the temperature effect because DBPs strongly depend on temperature among various efficient factors.

In this study, it was performed using submerged nonwoven bioreactor(SNBR) for removal of organic matter, nitrogen and phosphate under different aeration intervals(intermittent aeration). We applied the SNBR at the cheap nonwoven fiber module instead of the expensive membrane. The SNBR was mainly made up of an activated sludge reactor and a transverse flow nonwoven module, with an innovative configuration being in application between them. In case of sewage, the aeration conditions experimented consist of continuous aeration and 60min/60min, 120min/60min, 120min/120min of aeration/nonaeration time intervals, respectively. In case of landfill leachate, the intermittent aeration condition was 120min/120min at aeration/nonaeration. Consequently, a high COD removal rate (about 94%) was achieved in sewage and leachate. Although nutrient removal rate was relatively high without any additional chemicals.

Optical microscope, SEM (Scanning Electron Microscopy) and fluorescent microscope were used for qualitative and morphological studies of the attached biomass on PE (polyethylene) substratum under anaerobic condition. It was shown by the observation of optical microscope that the initial attachment of biomass began in crevices of the surface of PE. The shape and structure of the attached biofilm could be observed by SEM photographs, but species of bacteria were and methanogens were not classified. A large number of methanogenic bacteria were identified on the surface of PE substratum by fluorescence under 480nm of radiation. It was estimated that methanogenic bacteria was also related to initial attachment of biomass under anaerobic condition.

The lab-scale anaerobic continuous reactor which was filled with the sludge of anaerobic digestion from Suyoung wastewater treatment plant was operated by feeding of various concentrations and flow rates. This experiment indicated that more than 6,870 mgCOD/L of substrate concentration was required to promote good metabolism and growth of anaerobic biomass. And increasing loading rate slowly was also required in order to treat substrate of higher concentration and higher loading rate. The substrate concentration of about 10,000 mgCOD/L was adequate to generate biogas efficiently. The pH was sharply decreased at the onset of higher loading rate, but the pH was restabilized soon at 8. During the experiment, the amount of the attached biomass was kept constant.