• Journal of Korean Society of Water and Wastewater
• /
• v.29 no.2
• /
• pp.203-209
• /
• 2015

The purpose of this study is to estimate the applicability of a stable anaerobic digester using a separator membrane to the preprocessing thickening process. The results of the experiments showed about a 47.16% weight loss rate for the sludge under anaerobic condition, and about 41.17% under intermittent aeration condition. The concentrations of rejection water were $SCOD_{Cr}$ 25 mg/L, T-N 16.6 mg/L, and T-P 1.4 mg/L on the average under the intermittent aeration condition, which were lower than the concentrations of rejection water under an anaerobic condition. As for the factors affecting the reduction of the flux, correlation analyses of TTF, MLSS, $SCOD_{Cr}$, and $EPS_{Protein}$, $EPS_{Polysacchride}$ resulted in -0.97, -0.95, -0.84 and -0.86, -0.95, respectively, which showed that TTF had the highest correlation to the reduction of the flux. In addition, it was concluded that MLSS, $SCOD_{Cr}$ and $EPS_{Protein}$, $EPS_{Polysacchride}$ also have close correlations. The results are considered to show that, in the case of the process using a tubular membrane in the preprocessing process of an anaerobic digester, an intermittent aeration condition of the thickener considering the contamination of the membrane and load of rejection water is appropriate for the stable preprocessing process.

• Journal of Korean Society of Water and Wastewater
• /
• v.25 no.4
• /
• pp.565-572
• /
• 2011

The effects of chemical pretreatments on the excess sludge production in the membrane-coupled bioreactor were investigated. In addition, their effects on membrane fouling were also evaluated. Two membrane bioreactors were operated. In one reactor, a part of the mixed liquor was t reated with NaOH and ozone gas consecutively and was returned to the reactor. T he f lowrate of the chemical pretreatment stream was 1.5% of the influent flowrate. During the 200days of operation, the MLSS level in the bioreactor with mixed liquor pretreatment was maintained relatively constant at the range of 8,000 ~ 10,000$mg/{\ell}$ while it increased steadily up to 26,000 $mg/{\ell}$ in the absence of the pretreatment. Each reactor was equipped with two laboratory membrane modules where the flux for each module was 20, and 30 ${\ell}/m^2{\cdot}h$, respectively. With pretreatment, almost constant transmembrane pressure(TMP) was observed throughout the operation at the flux of 20 ${\ell}/m^2{\cdot}h$. Without pretreatment the membrane module at the same flux could also be operated at relatively stable condition. However, as the MLSS increases up to 25,000 $mg/{\ell}$, a fast TMP increase was observed. In conclusion, a complete control of excess sludge production in the membrane-coupled bioreactor was possible without significant deterioration of the treated water quality. In addition, it was shown that stable operation in terms of TMP is possible with sludge pretreatment and recirculation.

• Journal of Wetlands Research
• /
• v.18 no.3
• /
• pp.244-249
• /
• 2016

Anaerobic digester supernatant including high concentrations of nitrogen is recycled to water treatment line and make pollutant load increase in municipal wastewater treatment plant(MWTP). To treat nitrogen in anaerobic digester supernatant is suggested the method of MWTP retrofit. In this study, the lab scale reactor was operated about 200 days using supernatant of anaerobic digester. The results could draw operation condition that ammonium nitrogen removal efficiency more than 90% and nitrite conversion efficiency over 70%. Correlation between operation efficiency and operation factors was analyzed based on the operation results. Ammonium nitrogen remove efficiency and nitrite conversion efficiency were related to solid retention time (SRT), ammonium nitrogen load and ammonium nitrogen loading per unit mixed liquer suspended solid (MLSS). Results of this study can be used effective data on nitritation of supernatant of anaerobic digester, and be expected to increase availability of nitritation.

• Membrane Journal
• /
• v.16 no.3
• /
• pp.188-195
• /
• 2006

The purpose of this study was to investigate the effect of an intermittent aeration mode to reduce the membrane fouling in a submerged membrane process using the specifically devised module (YEF 750D-2). The fluid velocity on the module increased with increasing the supplied air volume, and decreased with the increment of MLSS in the biological reactor. The reduction rate of the fluid velocity was found to be $3\times10^{-4}m{\cdot}min/sec{\cdot}L$ per 1,000 mg MLSS/L increased. In the operation of the intermittent aeration, the intermitted stop of the aeration provoked the formation of a cake layer on the gel layer which was previously formed during the aeration, resulting in the highly increased TMP level. However, the TMP level could be significantly lowered by the subsequent backwashing and aeration that effectively removed the cake along with the gel layer on the membrane surface. In this study, the optimum condition for the intermittent aeration was determined to be aeration for 20 sec and pause for 20 sec.

• Membrane Journal
• /
• v.15 no.1
• /
• pp.70-83
• /
• 2005

By supplying air intermittently in various mode, the effects of oxic/anoxic time ratio and air scrubbing in aeration condition on the membrane flux and permeability were investigated. When suction pump stops, vacuum pressure remains inside the suction pump. Therefore, the effect of remaining vacuum pressure in the suction pump on fouling of membrane was investigated. The effect of EPS (Extra cellular Polymeric Substance) which is generated due to the long SRT and high concentration of MLSS and the dose of coagulant on the membrane were also investigated. The suitable oxic/anoxic time ratio for the best removal efficiency of organic matter and nitrogenous matter was 40 minutes (Oxic) : 20 minutes (Anoxic). At this time ratio, alum was dosed into the aeration tank. The result of dosing alum was that the concentration of alum solution might affect nitrification and denitrification. To remove 1 mg/L of phosphorus in MBR process, it needs 0.75 mg/L of alum solution.

• Membrane Journal
• /
• v.12 no.1
• /
• pp.21-27
• /
• 2002

The formation of soluble microbial products(SMP) and molecular weight distribution on loading rate were observed in batch-type culture medium, which phenol was fed as a substrate. The molecular weight destribution was obtained by using 30K, 100K dalton and $0.45{\mu}$ membrane filters. When the phenol concentrationas a substrate was 120, 230 and 440 mg/L , the specific substrate utilization rate(q) showed 0.639, 1.281 and 1.744 mgTOC/mgMLSS/day, respectively. The endogenous biomass decay rate constant($K_d$) at each substrate concentration was 0.00536, 0.0661 and 0.0749($day^1$), respectively. The $SMP_e$ product rate constant($k_{SMP}_ e$) showed 0.006, 0.0058 and 0.0057($day^1$), respectively. The initial influent substrate during the course of time degraded and produced $SMP_s$. The $SMP_s$ was converted to the $SMP_{nd}$ and endogenous phase converted to the $SMP_e$ ingredients. The molecula weight distribution on loading rate was converted to a higher MW during the course of time.

• Membrane Journal
• /
• v.29 no.4
• /
• pp.216-222
• /
• 2019

In this study, permeation experiments were conducted using naturally circulating spherical beads, backwashable plate membrane and the air supplied from the bottom of the MBR. The activated sludge solution was maintained at 8,000 mg/L of MLSS and compared transmembrane pressure (TMP) with respect to FR (filtration and relaxation), FR/BW (filtration and relaxation/backwashing), SFCO (sinusoidal filtration continuous operation) and SFCO/BW (sinusoidal filtration continuous operation/backwashing). As the backwashing flux decreased from 47 to $14L/m^2{\cdot}hr$, the TMP increased generally, but the TMP of FR system increased significantly comparing with SFCO. In addition, the backwashing method reduced more TMP comparing to the cleaning method using spherical beads, and it was confirmed that the operation method using the spherical beads and the backwashing simultaneously is more effective than each method.

• Membrane Journal
• /
• v.32 no.6
• /
• pp.465-474
• /
• 2022

The suction pressure was measured with respect to operational time by the backwashable flat sheet membrane module in membrane bioreactor (MBR). The membrane module having the nominal pore size of 0.2 ㎛ and the effective membrane area of 128cm² was submerged in MLSS 8,000 mg/L active sludge aqueous solution. The suction pressure was observed with respect to permeation flux and the quorum quenching (QQ) treatment. The effects of FR and SFCO operation methods were compared and analyzed in the experimental groups: vacant bead (VB), BH4 and DKY-1 beads. The suction pressure reduction was the most effective for the permeation flux 40 L/m² ⋅h with the injection of DKY-1 QQ beads. Also, the suction pressure reduction by the backwashing method was more than twice for using DKY-1 QQ beads.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.1B
• /
• pp.119-124
• /
• 2006

The purpose of this study was the comparison of pollutants removal and the track study of the nitrogen and phosphorus, the estimation of the nitrification and denitrification rate, and the investigation of the nitrogen mass balance between intermittently aerated membrane bioreactor(IAMBR) and intermittently aerated bioreactor(IABR), thus it verified the validity of the membrane submergence. As a result, it had no difference of organic matter removal, however, IAMBR showed better efficiency than IABR in the nutrients. Also, $NO_3{^-}$-N concentration at the anoxic state in the reactor was lower in IAMBR, and the denitrified nitrogen of IAMBR was 40.9%, that of IABR was 10.7%, thus it found out that the denitrification capability of IAMBR was higher than IABR above fourfold. Therefore, it seems resonable to conclude that the membrane helps to improve the removal of pollutants, because of the high MLSS concentration and the available method of intermittent inflow/outflow.

• Journal of Environmental Science International
• /
• v.11 no.6
• /
• pp.569-576
• /
• 2002

Anaerobic/aerobic reactor system was used to treat a synthetic wastewater with glucose as carbon sources(0.38~2.29 kg COD/m3.day) and Acid Red 14(1.05 "24.00 g Acid Red 141m3.day, color degree of 570 ~ 1710). COD removal efficiency by the anaerobic stage in operation period were above 90 % organic loading rate of 0.38 ~ 2.29 kg COD/m3.day(except, adaptation period) and the removal efficiency of the whole system were above 96 %. The decolorization of the Acid Red 14 was through the alteration of the dye structure(or cleavage of the Azo bond) during the anaerobic treatment. In the A/A system, the anaerobic stage played an essential role in removing both color and COD. In addition it also improves biodegradability of dye f3r further aerobic treatment. After operation, average MLSS concentration of anaerobic sludge reactor, anaerobic fixed-bed reactor and aerobic fixed-bed reactor were 17100mg/L, 20000mg/L, and 10000mg/L, respectively.