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호기조에 고정상 담체를 충진한 A<sup>2</sup>/O공정에서 무산소조 체류시간 변화가 유기물질 및 질소 제거에 미치는 영향
황규대,한봉석,Whang, Gye-Dae,Han, Bong-Seok 한국물환경학회 2007 한국물환경학회지 Vol.23 No.4
Four parallel $A^2/O$ systems maintaining an MLSS of 3,000 mg/L were operated to investigate the effects of varying an HRT of anoxic reactors and packing Bio contact media (BCM, fixed beds) in aerobic reactors on organic matter removal and nitrification/denitrification efficiencies. All systems were operated under conditions that the external recycle ratio was kept 0.5 Q while the internal recycle ratio was changed 1.0 Q to 1.5 Q with that $NH_4-N$ concentration of feed was increased to 40 mg/L by adding $NH_4Cl$. In terms of TSS and TCODcr removal efficiency, both systems with BCM and a system without BCM, respectively, had a similar level of the removal efficiency under varied HRTs of anoxic reactors (0.6 hr, 1.3 hr, 2 hr, 2 hr; control, without BC M) showing that varying an HRT of anoxic reactors did not affect the removal efficiency. While SCODcr removal efficiency of systems with BCM was improved approximately 4~5% at the same HRT of anoxic reactor, the removal efficiency of system with BCM was slightly decreased by reducing an HRT of anoxic reactor. The nitrification efficiency for both systems with BCM and a system without BCM was above 94% showing that packing BCM in aerobic reactors and varying an HRT of anoxic reactors did not affect the efficiency significantly despite of increasing $NH_4-N$ concentration of feed. The denitrification efficiency increased from 81.4% to 85.4% at system with BCM while the efficiency decreased when a shorter HRT of anoxic reactors was kept. The excellent effluent quality for $NO_3-N$ concentration was observed although the $NO_3-N$ concentration increased in anoxic reactors that $NH_4-N$ concentration of feed sufficiently converted into nitrate through nitrification. As a result, packing 20% BCM to an aerobic reactor with HRT of 1.3 hr of anoxic reactor in $A^2/O$ system can achieve a similar level of nitrogen removal efficiency in $A^2/O$ system which the aerobic reactor had no BCM and HRT of 2 hr for anoxic reactor is maintained.
축산폐수 전처리를 위한 암모니아 탈기공정의 운전조건이 암모니아 제거에 미치는 영향
황규대,조영무,Whang, Gye-Dae,Cho, Young-Moo 한국물환경학회 2004 한국물환경학회지 Vol.32 No.2
Lab-scale experiments have been carried out to investigate ammonia stripping with a modified spray tower for removing ammonia nitrogen from swine wastewater. The operating conditions such as initial pH, temperature, air flow, hole size of distributor determining the diameter of water drops, and influent solids concentration were closely examined focusing on removal efficiency of ammonia. As a result of the experiment, in order to achieve high rate of ammonia removal by the air stripping system, the air flow rate must be supplied at high rate with sufficiently high initial pH, temperature. The optimum operating condition to meet the residual ammonia concentration of 300 mg/L was the initial pH of 11.0 at $35^{\circ}C$ with the air flow rate of 20 L/min. It also showed that the smaller hole size is, the higher removal rate of ammonia is expected. However, when used a small sized distributor (2 mm), the flooding problem at the upper column occurred due to clogging of the hole. With regard to the influent solids concentration, it was showed that the lower concentration of solids, the higher removal rate of ammonia. The removal of particulate materials in influent led to improve the removal efficiency of ammonia, rather than to control the operating condition including initial pH, temperature, and air flow. The empirical correlation between KLa and operating parameters would be driven as, $K_{La}=(0.0003T-0.0047){\cdot}G^{0.3926}{\cdot}L^{-0.5169}{\cdot}C^{-0. 1849}$. The calculated $K_{La}$ from proposed formula can be used effectively to estimate the optimum reaction time and to calculate the volume of modified spray tower system.
포기조에 충진된 고정상 담체가 A<sup>2</sup>/O공정에서 질소제거에 미치는 영향
황규대,배성현,Whang, Gye-Dae,Bae, Sung-Hyun 한국물환경학회 2006 한국물환경학회지 Vol.22 No.6
Activated sludge reactors maintaining an MLSS of 3,000 mg/L and packed Bio Contact Media (BCM fixed beds) was studied in lab-scale to determine the optimal packing ratio and an HRT of aerobic reactor in terms of organic removal, nitrification, denitrification efficiencies. At all HRTs of 3 hr, 5 hr, 7 hr respectively, reactors without BCM, control reactors, had the lowest TCODcr removal efficiency about 74.6%, and reactors with the BCM packing ratios of 10%, 15%, 20% had a greater TCODcr removal efficiency above 81.4%. As HRT decreased, the TCODcr removal efficiency decreased also in all reactors. However, a better utilization of TCODcr even at a higher organic loading was observed in reactors with BCM. The nitrification efficiency at all reactors was greater than 94%, and reactor with 20% packing of BCM had the highest nitrification efficiency at 97.9% while the TKN loading increased at $0.085mgTKN/m^3{\ast}day$ as HRT decreased, In terms of denitrification efficiency, the reactor without BCM ranged from 11.6% to 13.7%, and the reactors with BCM ranged from 28.3% to 63.4% which suggests that the more BCM is packed in the reactors, the higher the denitrification efficiency is achieved. Two parallel $A^2/O$ systems maintaining an MLSS of 3,000 mg/L were operated to investigate the effect of BCM packing ratio of 20% on organic removal, nitrification, denitrification efficiencies. Packing with BCM in system of aerobic reactor affected the SCODcr removal efficiency that increased from 73% to 78%. The nitrification efficiency for both systems with or without BCM was greater than 95%. The denitrification efficiency of systems with BCM and without BCM was 85.8% and 81.8%, respectively which appears that the denitrification efficiency was increased slightly by packing BCM. Compared denitrification efficiency in $A^2/O$ system to previous experimental study with activated sludge reactors operates with the same HRT $A^2/O$ system showed only 29% greater denitrification efficiency. It suggests that $A^2/O$ system with BCM can achieve a similar level of denitrification efficiency when the HRT of anoxic reactor is decreased to some extent.
분뇨의 감압증발법 처리과정에서 발생한 응축수의 생물학적 처리에 관한 연구
황규대,정원식,김복현 ( Gye Dae Whang,Won Sick Chung,Bok Hyun Kim ) 한국물환경학회 1996 한국물환경학회지 Vol.12 No.1
Depressurizing evaporation process was developed for the treatment of night soil. It is a compact treatment process, and can be built in a small area without malodor generation. However it produces condensate which contain high concentration of organic material and ammonia nitrogen. This study was performed to determine the optimum treatment conditions for the activated sludge and rotating biological contactor process, which were selected as secondary treatment unit for condensate. Six bench scale activated sludge units and rotating biological reactors were operated. Three units received undiluted wastewater and the remaining three units received wastewater diluted with tap water. The dilution ratio was 1 : 1. Test results indicated that the activated sludge unit which received diluted wastewater and was operated 12hours of HRT and l0days of SRT produced the best quality of effluent. The SCOD and NH₃-N removal efficiency were 95% and 18%, respectively. The kinetic coefficients, yield coefficient(Y), and decay coefficient(Kd), were 0.251㎎MLSS/㎎COD and 0.121day ¹, respectively. For RBC process, the unit received diluted wastewater and was operated with hydraulic loading of 30 liter per day produced the best quality of effluent. The SCOD and NH₃-N removal were 90% and 38%, respectively.
돈분을 이용한 혐기성 유기산 발효공정의 운전인자에 관한 연구
황규대(Gye Dae Whang),김민호(Min Ho Kim),김도연(Do Yeon Kim) 한국물환경학회 1999 한국물환경학회지 Vol.15 No.4
Bench scale fermenter fed with swine waste was operated to study the effects of fermentation temperature, initial VSS concentration and pH on the acids production rate. The experiment was carried out by varied mixture ratio of 1%, 5%, 10%, 20% and operating temperature of 15℃, 25℃, 35℃ and 45℃. It was determined that the VSS decay rate function is approximately first order with respect to the remaining VSS concentration. The VSS decay rate constant increased with temperature and temperature coefficient θ was estimated to be 1.027. Higher total volatile fatty acids(TVFAs) production rate was observed at higher solid concentration and temperature. The yield of TVFAs(as COD) ranged from 0.0603 to 0.8828g/gVSS destroyed. The TVFAs yields increased with temperature, but decreased with initial VSS concentration. Although the yield of TVFAs decreased with initial VSS concentration, the higher ratio of gSCOD produced per gVSS destroyed was observed. With in a pH range from 5 to 10, slightly higher TVAFs yields were observed at higher initial pH value but the effect of pH was negligible. Because fermented swine waste has relatively low nitrogen and phosphorous content and relatively high TVFAs, it can be used as a substitute for external carbon source in biological nutrient removal process.