반류수 MLE공정에서 고형물 부하율 기반 일차슬러지 제어기술 개발

장신요(Shinyo Chang),신풍식(Pung Shik Shin),박현(Hyeon Park),정연구(Yeon-Koo Jeong) 대한환경공학회 2020 대한환경공학회지 Vol.42 No.12

목적: 반류수를 대상으로 고형물 부하율을 측정하여 일차슬러지 제거, 재순환, 투입에 대한 제어기술을 개발하여 처리용량 증가 및 공정성능 향상을 달성하고자 하였다. 방법: 파일럿 플랜트는 실플랜트와 유사하게 일차침전지+MLE공정으로 제작하였고, 유입 고형물 부하율을 기반으로 슬러지 인발량을 제어할 수 있도록 구성하였다. 상태점 분석으로 일차슬러지에 대한 제거 하부배출속도, 전체 하부배출속도를 결정하였다. 수동인발, 자동인발, 자동인발+재순환, 자동인발+투입 방식으로 구분하여 운전하였다. 일차슬러지 제어기술에 대한 성능평가 항목은 일차, 이차침전지의 SS 제거효율과 일차슬러지 농도로 하였다. 재순환 및 투입에 의한 생물반응조 성능향상은 암모니성질소, 총무기질소(TIN), 인산염인 제거효율과 SNR, SDNR을 통해서 판단하였다. 재순환으로 변화된 아세트산 농도와 미생물 군집특성을 비교하여 성능향상 원인을 분석하였다. 결과 및 토의: 유입 반류수 SS 모니터링 평균값은 2.2 (0.7 ~ 6.3) g/L로 일차침전지는 고농도 SS와 변동에 대응한 처리가 필요하였다. 실제 침강속도에 기반한 상태점 분석이 정밀하게 일차슬러지 제거, 재순환, 투입에 대한 안정적인 운전 가능여부와 구체적인 설계 및 운영기준을 제시할 수 있는 것으로 나타났다. 유입 고형물 부하율 변화에 따라서 하부배출속도를 제어하는 자동인발은 고농도 슬러지를 안정적으로 인발할 수 있으며, SS 제거효율도 안정적으로 유지할 수 있었다. 슬러지 재순환 운전에서도 안정적 운전이 가능하며 실플랜트에서 일차침전지 처리용량을 2배 이상 증가할 수 있는 것으로 나타났다. 일차슬러지 재순환으로 생물반응조 TIN 제거효율은 24.2 ~ 52.3% 향상되었고 인산염인 제거효율은 최대 20.1% 향상되었다. 일차슬러지 투입으로 생물반응조 TIN 제거효율이 32.6% 향상되었다. 아세트산을 포함한 휘발성 유기산이 생성되고 제거효율이 향상된 것은 재순환에 의해 일차슬러지와 접촉하였고 발효 미생물 주요 종 비율이 2.0% 존재하였기 때문으로 판단된다. 유입 반류수에는 질소, 인 처리미생물 주요 종이 26.4% 존재하여, 일차슬러지 투입으로 미생물 공급이 이루어져서 제거효율을 향상시켰다고 판단된다. 결론: 반류수를 대상으로 고형물 부하율을 측정하여 일차슬러지 제거, 재순환, 투입을 제어하는 기술은 일차침전지 처리용량을 증가시킬 수 있고 생물반응조의 질소, 인 제거효율을 향상시키는 것으로 사료된다. Objectives : By measuring the solids loading rate for the sidestream, it was intended to achieve increased treatment capacity and improved process performance by developing control technologies for primary sludge removal, recirculation, and input. Methods : The pilot plant was manufactured by the primary clarifier + MLE process similar to the full-scale plant and was configured to control the amount of sludge withdrawal based on the inflow solids loading rate. The state point analysis was used to determine removal underflow withdrawal rate and the total underflow withdrawal rate for the primary sludge. The operation was divided into manual withdrawal, automatic withdrawal, automatic withdrawal + recirculation, and automatic withdrawal + input methods. The performance evaluation items for primary sludge control technology were primary sludge concentration and SS removal efficiency for primary and secondary clarifiers. The improvement in the performance of the bioreactor by recirculation and input was judged through the removal efficiency of ammonium nitrogen, TIN (Total Inorganic Nitrogen) and phosphate phosphorus, SNR (Specific Nitrification Rate), and SDNR (Specific Denitrification Rate). The cause of the performance improvement was analyzed by comparing the acetic acid concentration changed by recirculation and the microbial community characteristics. Results and Discussion : The average value of SS monitoring of the sidestream influent was 2.2 (0.7 ~ 6.3) g/L and the primary clarifier needed treatment in response to high concentration SS and fluctuations. It is judged that the state point analysis based on the actual settling rate can accurately suggest whether the stable operation of primary sludge removal, recirculation, and input is the possible and specific design and operation standards. The automatic withdrawal that controls the underflow withdrawal rate according to the change of the inflow solids loading rate could stably draw out the high-concentration sludge and maintain the SS removal efficiency. It is believed that stable operation is possible even in the sludge recirculation operation, and the treatment capacity of the primary clarifier can be increased more than two times in a full-scale plant. By recirculation of the primary sludge, the TIN removal efficiency in the bioreactor was improved by 24.2 ~ 52.3%, and the phosphate phosphorus removal efficiency was improved by up to 20.1%. The TIN removal efficiency in the bioreactor was improved by 32.6% by the input of primary sludge. VFAs (Volatile Fatty Acids) including acetic acid was produced and the removal efficiency was improved because it was in contact with primary sludge by recirculation and the ratio of major fermentation microorganisms was present at 2.0%. It is determined that 26.4% of the main species of microorganisms treated with nitrogen and phosphorus exist in the sidestream inflow and the removal efficiency was improved by supplying microorganisms through the input of primary sludge. Conclusions : Technology that controls primary sludge removal, recirculation, and input by measuring the solids loading rate for the sidestream is believed to increase the treatment capacity of the primary clarifier and improve the nitrogen and phosphorus removal efficiency of the bioreactor.

회전원판공정과 화학침전공정 조합을 이용한 유기물과 질소*인의 동시제거

박종안,허준무,손부순 한국환경보건학회 1998 한국환경보건학회지 Vol.24 No.1

회전원판공정(rotating biological contactorRBC)과 화학적 처리공정을 결합한 처리시스템을 이용하여 도시하수내 포함된 유기물과 영양염류를 제거할 경우에 수리학적 부하 (hydraulic loading)와 처리수 반송율 (recirculation rate)의 시스템 처리효율에 미치는 영향을 알아보고자 하였다. 각각의 수리학적 부하 0.031, 0.0535 및 0.076 $m^3/m^2/d에서 반송율을 100%, 200%, 300%로 변화시켰고, 질산화에 필요한 알카리도의 보충 및 화학적 처리를 위하여 lime(CaCO$_3$)을 가하여 유입수의 pH를 10.4-11.0으로 유지시켰다. 실험결과 수리학적 부하 0.0535 $m^3/m^2/d에서 BOD, COD의 제거효율이 가장 높게 나타났으며, 질산화 효율 및 질소 제거효율에서는 수리학작 부하 0.035 $m^3/m^2/d, 반송율 300%에서 가장 높았으며, 반송율별에서는 수리학적 부하를 고려할 때 300% 반송하는 것이 가장 높은 유기물 제거효율을 보였다. 반송율과 수리학적 부하를 증가시킬 경우에 발생되는 슬러지내 유기물 함량은 점점 증가하였고, 수리학적 부하 0.076 $m^3/m^2/d, 반송율 300%일 경우에는 유기물 함량이 47%로 매우 높았다. 이는 부하증가에 따른 미생물 성장의 증가와 더불어 수리학적 부하 증가에 따른 전단력의 증가가 영향을 미쳤기 때문이다. 인을 제거하기 위하여 pH를 10.4-11.0으로 유지시킨 경우에 인을 90%이상 제거할 수 있었으며, 유출수내 평균 SS농도는 40 mg/l를 상회하였다. Laboratory-scale experiments were conducted using a three-stage rotating biological contactor unit followed by lime precipitation and sedimentation with effluent recycle to the first stage. The purpose of this study was to evaluate the effects of hydraulic loadings of 0.031-0.076 $m^3/m^2/d and recycle ratio of 1 to 3 on the simultaneous removal of organics and nutrients from domestic wastewater. Lime was added to maintain pH of 10.4-11.0 in the coagulation-flocculation reactor. Results showed that the highest nitrogen removal rate of 70.5% occurred at the lower hydraulic loading of 0.031 $m^3/m^2/d at a recirculation rate of 300%, and similarly, highest nitrification occurred at the same hydraulic loading and recycle ratio. Concentration of ammonia nitrogen in the effluent was less than 1 mg/l at the same operating conditions for higher nitrogen removal. Whereas, high BOD and COD removal was observed at hydraulic loading rate of 0.054 $m^3/m^2/d, and high removal of organic matter was evident from the consistent low COD and BOD value. Results obtained from the operating condition of higher loading rate, 300% of recycle rate showed the highest removals. Increasing in recycle rate and hydraulic loading rate increased the volatile solids fraction of the sludges generated to the extent of 47% at 0.076 $m^3/m^2/d hydraulic loading and 300% recirculation rate. Since pH in the flocculator was maintained at the pH of 10.4-11.0, above 90% removal of phosphorus was obtained. Average concentration of suspended solids was always maintained over 40 mg/l in the effluent. Therefore an RBC unit operating at a hydraulic loading near 0.031 $m^3/m^2/d with a recycle rate of 300% is a viable and feasible alternate conditions to produce an effluent with relative low organic matter and phosphorus, provided that there is a neutralization unit to control the pH and SS of the effluent.

해수 조건에서 총암모니아성 질소 부하량과 수리학적 공기 부하량에 따른 유동상 여과조의 질산화 성능 평가

이재건 ( Jaegeon Lee ),이영훈 ( Younghun Lee ),박정환 ( Jeonghwan Park ) 한국수산과학회 2023 한국수산과학회지 Vol.56 No.6

The purpose of this study was to assess the efficiency of nitrification based on ammonia loading rates and hydraulic air-loading rates in a moving bed bioreactor (MBBR) under seawater conditions. The goal was to provide foundational data for the design of these bio reactors. At an ammonia loading rate of 0.2 g TAN·m^-2 surface area·day^-1, the influent TAN concentration was determined to be 1.76±0.33 mg·L^-1, which is below the safe concentration for fish survival (2 mg·L^-1). Considering operational aspects, the optimal ammonia-loading rate was derived. Subsequently, experi-mental results for nitrification efficiency at the optimal ammonia-loading rate revealed that the optimum hydraulic air-loading rate was 1.8 L·air·m^-2 surface area·min^-1. This condition resulted in the lowest concentrations of TAN and NO₂-N in the influent water, thus establishing the optimal hydraulic air-loading rate. A regression equation was derived for the ammonia-removal rate (Y) based on the ammonia-loading rate (x) and expressed as a 0.5-order equa-tion (Y=ax^0.5+b). Specifically, for TAN concentrations of 0-6 mg·L^-1, the regression equation Y=0.1683x0.5-0.13628, was established.

호흡량에 따른 사람의 기도 내 유동 특성에 관한 수치 해석적 연구

성건혁(K.H. Sung),노경철(K.C. Ro),유홍선(H.S. Ryou) 한국전산유체공학회 2012 한국전산유체공학회 학술대회논문집 Vol.2012 No.5

The inspiratory rate of a human is changed with the amount of the workload. The flow field is affected by the inspiratory flow rate. In the flow filed, the wall shear stress is important to predict the inflammation or a injury in airway wall. In addition, the turbulence intensity and secondary flow affect the deposition pattern of particle which is important for the drug-aerosol targeting. Thus the analysis of the flow characteristic in a human airway is important. The purpose of this study is to investigate the effects of the inspiratory flow rate on the flow characteristics in a human airway. The tubular airway is consistent with the oral cavity, pharynx, larynx and trachea. The constant inspiratory flow rate is used at each case of human states regarding the workload. By the effect of geometric airway changes, transition to turbulent airflow after the larynx can occur with relaminarization further downstream. Consequently, the low Reynolds number k-ω turbulence model is used for analysis with flow regime. As the inspiratory flow rate is larger, the wall shear stress and the turbulence intensity increase in airway. On the other hand, the area of recirculation zone is smaller.

단계유입과 내부순환을 이용한 저농도 하수의 질소처리효율 향상을 위한 연구

추태호(Choo, Tai-Ho),김태기(Kim, Tae-Ki),옥치율(Ok, Chi-Youl) 한국산학기술학회 2010 한국산학기술학회논문지 Vol.11 No.2

본 연구에서는 저농도로 유입되어 정상적인 운영이 되지 않고, 질소제거가 어려운 소규모 하수처리시설의 문제점을 해결하기 위하여 5Stage로 구성된 하수고도처리 공정의 저농도 유입성상에서 최적의 단계유입비와 내부순 환비를 결정하기 위해 Lab-Scale 모형실험장치를 제작하여 실험하였다. 저농도의 유입조건에서 효율적인 고도처리를 위해 내부순환과 단계유입이 공정성능에 미치는 영향을 평가한 결과는 다음과 같다. 첫째, 분석항목별 처리효율은 BOD 90.0%, COD 87.8%, T-N 71.0%, T-P 75.3%로 나타났으며, T-N은 단계유입에 따라 처리효율의 변동이 있는 것으로 나타났다. 둘째, 혐기조로 유입되는 단계유입비 70, 60, 50%에서는 각각 73, 80, 78%로 나타나 최적의 단계 유입비 범위로 판단되었다. 셋째, 질소제거를 위해 내부순환을 할 경우 내부순환을 하지않는 경우보다 질소 제거효 율이 증가됨을 알 수 있었고, 내부순환비가 150%이상에서는 더 이상 처리효율에 영향을 미치지 못하는 것으로 나타 났다. 이는 다량의 순환으로 인해 무산소조에 DO의 유입으로 인한 것으로 판단된다. 따라서 내부순환비는 50~150% 가 적정한 것으로 판단되었다. This study was investigated to complement nitrogen removal of low concentration influent municipal sewage. The following are the results of the effect of Internal Recircularion and Step Feed rates on Treatment efficiency at a BOD low concentration influent municipal sewage. Up to 90.0% of BOD, 87.8% of COD, 71.0% of T-N, 75.3% of T-P were removed on average at a low concentration influent. Whereas BOD and T-P were removed without any relations to Step Feed rates, T-N was influenced. Nitrogen removal efficiencies in 80% of Step Feed rates was 65%, which was caused by the lack of Carbon Source for denitrification. Nitrogen removal efficiency in 40% of Step Feed rates was 58%, which means it was not removed but dischared. Consequently, the efficiency was 73%, 80%, and 78% in 70%, 60% and 50% of Step Feed rates, which was concluded as the best range of Step Feed rates. Nitrogen removal efficiency increased under the condition of Internal Recircularion. At over 150% of Internal Recircularion rate, the efficiencies were not affected any more. It is believed that lots of Recircularion caused inflow of DO to anoxic tank. Therefore, the most appropriate Internal Recircularion rate can be concluded as 50~150%.

수치해석 기법을 이용한 호흡 유량에 따른 사람의 기도 내 유동 특성 연구

성건혁,유홍선,Sung, Kun Hyuk,Ryou, Hong Sun 대한의용생체공학회 2012 의공학회지 Vol.33 No.4

The inspiratory flow rate of a human is changed with the amount of the workload. The flow characteristic is affected by the inspiratory flow rate. In the flow field of airway, the both of turbulence intensity and secondary flow affect the deposition pattern of particles which is important for the drug-aerosol targeting. Thus the analysis of the flow characteristic in a human airway is important. The purpose of this study is to investigate the effects of the inspiratory flow rate on the flow characteristics in a human airway. The tubular airway is consistent with the oral cavity, pharynx, larynx and trachea. The relatively inspiratory flow rate is used at each case of human states regarding the workload. By the effect of geometric airway changes, transition to turbulent airflow after the larynx can occur with relaminarization further downstream. The low Reynolds number k-${\omega}$ turbulence model is used for analysis with flow regime. As the inspiratory flow rate is larger, the turbulence kinetic energy and secondary flow intensity increase in airway. On the other hand, the area of recirculation zone is smaller.

보일러 연료분사량에 따른 배기 배출물 및 성능에 미치는 FGR률의 영향에 관한 연구

배명환(Myung-whan Bae),류지호(Ji-Ho Ryu),정광호(Kwang-ho Jung) 한국자동차공학회 2020 한국 자동차공학회논문집 Vol.28 No.2

The purpose of this study is to collect the data for application to the development of flue gas recirculation(FGR) control systems in order to reduce NOX emissions without deteriorating the fuel economy in a boiler. The effects of FGR rate on boiler exhaust emissions and performance under four kinds of nozzle tip with the different fuel injection amount are experimentally investigated by using an once-through boiler with a FGR system. The experimental boiler efficiency is obtained by the effective output heat method. Meanwhile the calculated boiler efficiency is obtained by the heat loss method. It is found that the equivalence ratio is gently increased as the FGR rate is elevated at the constant fuel injection amount, but the change of equivalence ratio is significant when the fuel injection amount is increased at the same FGR rate. Also, one can conclude that the changes of O₂, CO₂, THC and soot emissions are small, but the changes of NOX and CO emissions are large although the equivalence ratio is increased by elevating the FGR rate at the constant fuel injection amount. And the boiler efficiencies obtained by the experiment and calculation are hardly changed although the FGR rate is elevated at a constant fuel injection amount.

노즐직경 및 유량변화에 따른 수소재순환 이젝터 성능에 관한 수치해석적 연구

박종우(Jong-Woo Park),곽지영(Ji-Young Kwak),전동연(Dong-Yeon Jun),이열(Yeol Lee) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11

The hydrogen recirculation ejector is one of the efficient device to improve the efficiency of the fuel-cell electric vehicles. In the present study, numerical simulations have been performed to understand the detailed flow structure of such highly compressible and complicated flows inside the ejector system. Commercial codes for two-dimensional and three-dimensional models were utilized for various nozzle diameters and primary nozzle flow rates. It was noticed that the hydrogen recirculation rate was increased as the primary nozzle diameter increased for fixed volume flow rates of the primary/secondary nozzles.

COMBUSTION CHARACTERISTICS OF HYDROTREATED VEGETABLE OIL-DIESEL BLENDS UNDER EGR AND LOW TEMPERATURE COMBUSTION CONDITIONS

Sombat Marasri,Pop-Paul Ewphun,Prathan Srichai,Chinda Charoenphonphanich,Preechar Karin,Manida Tongroon,Hidenori Kosaka 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.3

This paper investigates the effects of Hydrotreated vegetable oil (HVO)-diesel blends on combustion characteristics under various ambient oxygen concentrations and ambient temperatures in a constant volume combustion chamber (CVCC). Combustion characteristics were presented in terms of heat release rate, ignition delay and integral heat release. The shadowgraph images of spray combustion were presented for spray development and combustion progress. The experiment was carried out on CVCC under constant injection pressure and energizing time. The synthetic gas with varied oxygen concentrations between three discrete values from 21, 15 and 10 % to simulate EGR on engine conditions. The ambient temperatures were varied at 1100, 900 and 700 K to study the effects of ambient temperatures. Four different fuels were tested: commercial diesel, commercial diesel-HVO blends and HVO with the single-hole injector. The results showed that decreasing ambient oxygen concentration to 10 % resulted in 13.42 % lower heat release rate and 13.89 % lower integral heat release. This also extended ignition delay. Decreasing ambient temperature resulted in longer ignition delay with higher peak heat release rate. Increasing HVO showed 6.43 % shorter ignition delay compare to diesel due to higher cetane number. The shadowgraph images showed that HVO has better evaporation 0.7 to 0.9 ms after injection due to its lower density, viscosity and distillation temperature at T90.

코안다 노즐을 이용한 배기가스 재순환 버너의 연소 유동 특성 및 NOx 저감에 관한 연구

하지수(Ji Soo Ha) 한국가스학회 2017 한국가스학회지 Vol.21 No.3

연소로에서 질소산화물을 저감하기 위하여 여러 가지 방법으로 연구가 진행되어 오고 있는데 그 중에 배기가스를 재순환하여 저감하는 방법이 있다. 본 연구는 배기가스를 재순환하는 방법으로 연소로 외부에 코안다 노즐을 이용하여 배기가스를 재순환 유입하는 방법을 사용하였다. 코안다 노즐을 이용하여 배기가스를 재순환하고 혼합가스는 연소로 접선 방향으로 투입하여 선회유동을 유발하는 특징을 가지는 배기가스 재순환 버너이다. 이러한 버너에서 연소로 내의 선회 유동 특성을 살펴보고 온도와 반응속도 분포를 살펴봄으로써 코안다 노즐을 이용한 재순환 버너의 연소 유동 특성을 규명하였다. 과잉공기계수와 코안다 노즐 간격을 변화하여 배기가스 재순환 유입량 특성을 살펴보았으며 과잉공기계수를 증가하면 재순환 유입량비가 증가하였고 코안다 노즐 간격을 증가하면 코안다 노즐 공기 출구에서 속도가 낮아져서 재순환 유입량이 감소한다는 특성을 알았다. 배기가스 출구에서 평균온도는 코안다 노즐 간격 변화에 거의 무관하며 과잉공기계수 증가에 따라 감소하는 것을 알았다. 이러한 특성으로 배기가스 출구에서 NOx 농도는 과잉공기계수 증가에 따라 현저히 감소하고 코안다 노즐 간격에는 상대적으로 영향이 적은 것으로 나타났다. Various researches have been conducted for the reduction of NOx at the combustion furnace and exhaust gas recirculation method is commonly used technology for NOx reduction. The present research adopted coanda nozzles at the outside pipes of furnace to entrain the exhaust gas for the exhaust gas recirculation and the mixed gas was ejected to the tangential direction to cause the swirl flow in the furnace. The combustion flow characteristics in the exhaust gas recirculation burner with coanda nozzle has been elucidated by analyzing the swirl flow streamlines, temepraure and reaction rate distribution in the furnace. The exhaust gas entrained flow rate has been investigated by changing the excess air factor and coanda nozzle gap and the exhaust gas entrained flow rate increased with the increase of excess air factor and it decreased with the increase of coanda nozzle gap. The mean temperature at the exit plane of exhaust gas decreased with the excess air factor and it was little affected by the increase of coanda nozzle gap. The NOx mass fraction at the exhaust gas exit plane remarkably decreased with the excess air factor and it was also little affected by the increase of coanda nozzle gap.