• Journal of Korean Society of Environmental Engineers
• /
• v.35 no.5
• /
• pp.301-306
• /
• 2013

This research was conducted to investigate whether sequential anoxic/aerobic biofilm reactors and microfilteration (MF) membrane system can be used as a direct treatment for the removal of perchlorate and nitrate in groundwater. The biofilm process consisted of an anoxic first stage to remove perchlorate and nitrate and aerobic second stage to remove remaining acetate used as a carbon source for dissimilatory reduction of perchlorate and nitrate. In final stage, hollow fiber MF membrane was used to remove turbidity. In this research, perchlorate was reduced from the influent concentration of 102 ${\mu}/L$ to below the IC detection level (5 ${\mu}/L$) and nitrate was reduced from 61.8 mg/L (14 mg/L $NO_3$-N) to 4.4 mg/L (1 mg/L $NO_3$-N). Acetate used as a carbon source was consumed from 179 mg/L $CH_3COO-$ to 117 and 11 mg/L $CH_3COO^-$ in effluents from anoxic and aerobic biofilm reactors, respectively. Turbidity was reduced from 3.0 NTU to 1.5, 0.3, and 0.2 NTU in effluents from anoxic/aerobic biofilm reactors and MF membrane, respectively. It is expected that the sequential anoxic/aerobic biofilm reactors and MF membrane system can efficiently remove perchlorate and nitrate in surface water or groundwater.

• Membrane Journal
• /
• v.12 no.2
• /
• pp.67-74
• /
• 2002

Submerged membrane bioreactor(SMBR) and reverse osmosis(R/O) systems treated dye wastewater for reusing of industrial water. The permeate fluxes of SMBR at 20-25 cmHg of lab. test and field test were 10 LMH($1/m^2$.hr) all test. Removal efficiencies of CODcr, $COD_{Mn}$ and T-N were 93%, 90% and 60% in the SMBR, respectively The advanced treatment of combined process(SMBR+R/0) was accomplished for increasing the removal efficiency of non-biodegradable materials and T-N. Therefore, the removal efficiency of T-N obtained in 80% above, then nitrogen concentration was under 15 mg/L. The combined process(SMBR+R/0) was suitable to reuse of the dye wastewater.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.11 no.1
• /
• pp.189-196
• /
• 1991

The objective of this study was to investigate the effect of temperature on microbial characteristics and treatment efficiency in aerated submerged biofilm process. From the results of the research, conclusions were derived as following: 1. Biofilm density, attached biomass and biofilm thickness were $30-42mg/cm^3$, $1.2-2.7mg/cm^2$ and $380-690{\mu}m$, respectively. These were greatly affected by the variation of temperature ($5-20^{\circ}C$) and packing ratio(45-90%). 2. The ratio of suspended biomass to the total biomass in the reactor was in the range of 10 to 50 % in accordance with the variation of temperature and packing ratio. Therefore, the portion of suspended biomass cannot be neglected. 3. BOD removal efficiency increased as either temperature or biomass(suspended and attached) concentration increased. 4. The aerated submerged biofilm process appeared to be less affected by temperature variation and the estimated temperature correction coefficient of the Van't Hoff-Arrhenenius equation was 1.042.

• Journal of Korean Society of Environmental Engineers
• /
• v.35 no.1
• /
• pp.57-63
• /
• 2013

A combined process consisted of a biofilm reactor and a continuously stirred-tank reactor (CSTR) was investigated for highly loaded ammonium wastewater treatment via nitrite accumulation. To enhance ammonium oxidizing bacteria over nitrite oxidizing bacteria on the surface of carriers, the biofilm reactor was operated at temperature of $35^{\circ}C$ for more than three months but the influent ammonium (500 mg-N/L) was partially oxidized to nitrite (240 mg-N/L). As pH was increased from 7.5 to 8.0, nitrite accumulation was fully achieved due to the inhibition of nitrite oxidizing bacteria under high free ammonia concentration. The biofilm reactor performance was severely deteriorated at the hydraulic retention time of 12 hr, at which incomplete nitrification of ammonia was observed. Various solubilization methods were applied to sewage sludge for enhancing its biodegradability and the combined method, alkaline followed by ultrasonic, gave the highest solubilization efficiency (58%); the solubilized solution was used as the external carbon source for denitrification reaction in CSTR. FISH analysis showed that the dominant microorganisms on the carriers were ammonium oxidizing bacteria such as Nitrosomonas spp. and Nitrospirar spp. but low amounts of nitrite oxidizing bacteria as Nitrobacter spp. was also detected.

• Proceedings of the Membrane Society of Korea Conference
• /
• 2001.11a
• /
• pp.135-138
• /
• 2001

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.7 no.3
• /
• pp.45-53
• /
• 1987

The purpose of this research was to study the kinetics of a packed bed aerobic biofilm process. Experiments were carried out by feeding an aerated packed bed reactor with a synthetic wastewater. The reactor packed with glass beads as media had a nominal hydraulic detention time of 5 hours. The flow pattern in the reactor was determined by a tracer test using a NaCl solution to be a completely-mixed type. The results of the research showed that the F/M ratio in the reactor was almost constant since the the biomass increased due to the growth of biofilm as the volumetric organic loading increased. It was also proved theoretically and experimentally that packed bed aerobic biofilm process could be analyzed by the kinetics of completely-mixed activated sludge process with sludge recycle.

• Proceedings of the Membrane Society of Korea Conference
• /
• 1993.10a
• /
• pp.40-41
• /
• 1993

생물 ㅏ반응기의 생산성을 높이기 위해서는 반응기내의 미생물 농도를 높이는 것이 필요하다. 미생물 농도를 높이기 위한 한 방법으로써 막을 이용한 미생물 재순환에 대한 많은 연구가 수행되어 왔다. 이러한 연구들은 발효조 밖에서 막을 이용하여 미생물을 분리하여 다시 발효조 내로 순환시키는 방법이 주를 이루어 왔으나 이들은 공정이 복잡하고 고분자 합성막을 이용한 경우 고온 멸균의 어려움이 있는등 산업화하는데 여러가지 문제점을 가지고 있었다.

• 한국생물공학회:학술대회논문집
• /
• 2002.04a
• /
• pp.351-354
• /
• 2002

This research discussed about the substrate transport phenomena in anaerobic biofilm. Three anaerobic fixed biofilm reactors were filled with the sludge of anaerobic digestor from Suyoung wastewater treatment plant. After 15 days of biofilm formation periods, suspended solids within the reactors were removed, and each fixed biofilm reactor was supplied with synthetic wastewater of different concentration of 8.00 mgTOC/L, 9.76 mgTOC/L and 18.97 mgTOC/L, respectively. The experimental results in conjunction with substrate transfer phenomena indicated that data - thickness, substrate removal rate. At the low influent substrate concentration(reactor 1 : 8.00 mgTOC/L, reactor 2 : 9.76 mgTOC/L), the rate of substrate utilization($k_v$), effective diffusivity($D_{eff}$) of substrate in biofilm were similar. While $k_v$ and $D_{eff}$ of the high influent substrate concentration(reactor 3 : 18.97 mgTOC/L) were higher than data in the reactors of the low influent substrate concentration.

• Microbiology and Biotechnology Letters
• /
• v.35 no.1
• /
• pp.73-80
• /
• 2007

Biofilm media was equipped in two-compartmented wastewater treatment bioreactor which was separated by porcelain septum. DC 2.0 volt of electric potential was charged to anodic (oxidative) biofilm media (ABM) to induce oxidation potential but not to that of carbon (neutral) biofilm media (CBM) that was used for control test. Biofilm structure, biomass variation, Off variation and wastewater treatment efficiency in the bioreactor equipped with ABM (ABM-bioreactor) and CBM (CBM-bioreactor). Time-coursed variation of biofilm structure forming on surface of ABM and CBM was observed by scanning electron microscopy. The biofilm growing on ABM was dispersed on surface and was not completely covered the media but the biofilm growing on CBM was continuously increased and finally covered the media. The ORP of CBM was decreased to 100 mV, which was reciprocally proportional to the biomass growth. However, the ORP of ABM was about 800 mV, which was maintained during operation for about 60 days. The treatment efficiency of COD in the ABM bioreactor was 2 times higher than those in the CBM bioreactor. From these results, we proposed that electrochemical oxidation potential charged to biofilm media may inhibit formation of biofilm extremely condensed and activate bacterial cell metabolism.

• Journal of Korean Society of Environmental Engineers
• /
• v.29 no.8
• /
• pp.922-929
• /
• 2007

The complete oxidation of ammonia to nitrate is a distinctive two-step process divided into the oxidation of ammonia to nitrite(nitritation) by Nitrosomonas and the oxidation of nitrite to nitrate(nitratation) by Nitrobacter. The nitrogen removal via nitrite accumulation offers several advantages such as saving costs for aeration, saving carbon source and finally reduction of sludge discharge. In this work a suspended bioreactor coupled with membrane filtration(MBR) was used to find the process conditions of nitrite build-up. The MBR enables to reach sufficient nitrifying bacteria in the bioreactor, although the autotrophic bacteria can be easily washed out due to their lower growth rate. The dissolved oxygen concentration $c'_{O2}$ and ammonia concentration $c_{NH3}$ in the reactor were varied and investigated as parameters for nitrite accumulation. As a result the higher ammonia concentration in the reactor is very effective for starting nitrite build-up and the effect was strengthened in combination with lower dissolved oxygen concentration. With lower $c'_{O2}<0.3$ $mgL^{-1}$ $O_2$ and high $c_{NH3}=6.3\sim14.9$ $mgL^{-1}$ $NH_3N$ the 74% of the nitrite accumulation was achieved. Specially, it was found that the nitrite accumulation could occur not only in biofilm reactor as many references showed but also in the membrane bioreactor carried out in this study.