• Journal of Korean Society of Environmental Engineers
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• v.30 no.10
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• pp.992-998
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• 2008

Recently, a new concept for nitrogen removal that is simultaneous nitrification and denitrification(SND) has been studied for wastewater treatment process. The DMR(Daiho Microbic Revolution) process that used in this study consists of two suspended anoxic, anaerobic reactors and an aerobic biofilm reactor. The function of aerobic environment and the intensity of air flow rate(2.0, 1.0, 0.5, 0.4, 0.2 L/min) were studied in the biofilm reactor; also SND and nutrient removal efficiencies were investigated. Experimental results indicated that the change in air flow did not affect COD$_{Cr}$ removal significantly. Thus sustained at 93%. The lower the air flow rate, the higher T-N removal efficiency was attained(i.e.80% at 0.2 L/min). SND efficiency was 62, 65, 72 and 78% corresponding to each air flow rate. T-P removal was sensitive to aeration intensity and removal enhanced from 75% to 96% when the air flow rate was changed from 2.0 to 0.5 L/m; however second release occured in the clarifier at 0.2 L/min. Phosphorus content of activated sludge was 5.0%, as P releases and acetate uptake a ratio of 0.75 mg P/ mg HAc.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.659-669
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• 2008

Two sets of four parallel activated sludge reactors (ASRs) maintaining an MLSS of 3000 mg/L were operated to investigate the effect of DO, HRTs and bio-contact media (BCM) packing ratios on the removal efficiency of organic matters and nitrogen. Packing ratios of BCM to BCM-ASR systems 1, 2, 3, and 4 were 0% (suspended growth only), 10%, 15% and 20%, respectively. All systems were operated at an HRT of 4 hr, 6 hr, and 8 hr, respectively; DO concentration was maintained 0.5~1.0 mg/L and 1.5~2.0 mg/L for each HRT condition. In terms of TSS, TCODcr and SCODcr removal efficiency, all systems had a similar level of the removal efficiency under varied HRTs, and DO. But organic removal efficiency of systems with BCM was approximately 3~5% higher than systems without BCM at the same HRT and the DO. About the nitrification efficiency, with high DO (1.5~2.0 mg/L), as HRT (4 hr, 6 hr, 8 hr) or BCM packing ratio increased, the slight increment of nitrification efficiency was observed. However, under the low DO (0.5~1.0 mg/L), increase of BCM packing ratio and HRT resulted in large increase of the nitrification efficiency. At the same HRT and BCM packing ratio, the nitrification efficiency increased greatly with up to 15% as DO increased. When the HRT increased from 4hr to 8hr, the denitrification efficiency slightly increased by 5~10% only, under all DO conditions. Systems with BCM had higher denitrification efficiency, ranged 62.7~91.1% than systems without BCM showed 32.1~65.6%. And the increase in BCM packing ratio from 10% to 20% resulted in about 14~16% denitrification efficiency increment. BCM packing ratio showed great effect on the denitrification. The increase of the DO (from 0.5~1.0 mg/L to 1.5~2.0 mg/L) at the same HRT and BCM packing ratio resulted in slight decrease of denitrification efficiency with up to 7% for systems with BCM. But for systems without BCM, the denitrification efficiency decreased with up to 28%. In all system, the denitrification efficiency had more influence on the TN removal efficiency than nitrification efficiency. So, BCM packing ratio (0%, 10%, 15%, 20%) has greater effect on the TN removal than HRT and DO. The TN removal efficiency increased as packing ratio of BCM increased with up to 45%. As a result, the highest TN removal efficiency was observed 73.7% at the condition showed the highest denitrification efficiency that DO of 0.5~1.0 mg/L, an HRT of 8 hr, and 20% of BCM packing ratio was maintained.

• Journal of Korean Society of Water and Wastewater
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• v.23 no.5
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• pp.527-537
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• 2009

Three sets of parallel MBRs (reactor No.1, reactor No.2, reactor No.3) maintaining an MLSS of 4,000 mg/L, 6,000 mg/L and 8,000 mg/L, respectively, were operated to investigate the effect of various HRTs and DO concentration of MBRs on the removal efficiency of organic matters and nitrogen. The HRTs were operated on 4 hr, 6 hr, 8 hr. DO concentrations were ranged 1.5~2.0 mg/L and 0.5~1.0 mg/L respectively on each HRT conditions. MBR was divided into an aerated part and non-aerated part by baffle placed under the water. DO concentrations were controlled by altering the position of baffle. In terms of TSS and CODCr, all systems had a similar level of the removal under varied HRTs and MLSS. TSS removal efficiency was more than 99% and CODCr removal was ranged 94~97% under all conditions. Under the same condition on the HRT and MLSS concentrations, DO concentrations did not affect the organic removal efficiency. On the nitrification efficiency, with high DO concentration, as HRT or MLSS increased, the slight increment of nitrification efficiency was observed. However, under the low DO concentration, increase of MLSS and HRT resulted in larger increase of the nitrification efficiency. At the same HRT and MLSS, the nitrification efficiency increased greatly with up to 16% as DO increased. When the HRT increased from 4hr to 8hr, the denitrification efficiency slightly increased under most of conditions. However, the increase of MLSS resulted in about 19~39% denitrification efficiency increment. MLSS concentrations showed great effect on the denitrification. The increase of the DO concentration at the same HRT and MLSS resulted in decrease of denitrification efficiency with up to 27%. In all systems, the denitrification efficiency had more influence on the TN removal efficiency than nitrification efficiency. So, MLSS concentration has greater effect on the TN removal than HRT and DO. The TN removal efficiency increased as MLSS increased with up to 37%. As a result, the highest TN removal efficiency was observed 79.0% at the condition showed the highest denitrification efficiency that DO of 0.5~1.0 mg/L, an HRT of 8 hr, and 8,000 mg/L of MLSS concentration were maintained.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.3
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• pp.82-92
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• 2013

The Intermittent Aeration MBR systems have the advantage of controlling reaction time by changing aeration period and are one of economic BNR systems since these processes do not require MLSS recirculation that demands capital and operation costs. In this study, two intermittent aeration MBR systems were studied by computer simulation: an intermittent aeration MBR system that had both 1hr/1hr and 4hr/4hr aeration/unaeration periods at intermittent reactor and NEW INTERMITTENT-process that was an energy saving process and certified as a new process by Korean government. Since DO concentration reached only at 0.23mg/L at intermittent reactor when it was aerated, the Intermittent aeration MBR system having 1hr/1hr aeration/unaeration period showed simultaneous nitrification/denitrification and had the highest nitrogen and phosphorus removal efficiencies that were 57% and 55%, respectively. Since this study was based on the constant influent flow and characteristics, more studies are needed to define the operational characteristics of intermittent aeration MBR systems under dynamic influent conditions.

• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.219-230
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• 2018

The present study examined a moving bed biofilm reactor (MBBR) bioreactor on a laboratory scale for simultaneous removal of atrazine, organic carbon, and nutrients from wastewater. The maximum removal efficiency of atrazine, chemical oxygen demand (COD), total phosphorus (TP) and total nitrogen (TN) were 83.57%, 90.36%, 90.74% and 87.93 respectively. Increasing salinity up to 40 g/L NaCl in influent flow could inhibit atrazine biodegradation process strongly in the MBBR reactor.Results showed that MBBR is so suitable process for efficiently biodegrading of atrazine and nitrogen removal process was based on the simultaneous nitrification-denitrification (SND) process.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.63-70
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• 2012

This study was carried out to investigate change in influent concentration of domestic wastewater flowed from a newly constructed separate sewer system (SSS) and biological nutrients removal efficiency of a full scale Air-vent sequential batch reactor (SBR, $600m^3/d$). The average concentration of $BOD_5$, SS, T-N and T-P from SSS were 246.5 mg/L, 231.6 mg/L, 42.974 mg/L, 5.360 mg/L, respectively which corresponds to 2.2times, 1.2times, 1.8times and 2.1times higher than those from the conventional combined sewer system (CSS). The removal efficiency of $BOD_5$, SS, T-N, and T-P for the Air-vent SBR operated with influent from SSS averaged 99.1%, 99.0%, 91.2%, and 93.5%, respectively. Especially the respective nitrogen and phosphorus removal was 15% greater than that of the SBR operated with influent from CSS. Simultaneous nitrification and denitrification (SND) was observed in an aerobic reactor(II) as a result of DO concentration gradient developed along the depth by the Air-vent system. In order to achieve T-N removal greater than 90%, the C/N ratio should be over 6.0 and the difference between $BOD_5$ loading and nitrogen loading rate be over 100 kg/day (0.130 kg $T-N/m^3{\cdot}d$). Even with high influent T-P concentration of 5.360 mg/L from SSS (compared with 2.465 mg/L from CSS) T-P removal achieved 93.5% which was 15.5% higher than that of the SBR with influent from CSS. This is probably due to high influent $BOD_5$ concentration from SSS that could provide soluble carbon source to release phosphorus at anaerobic condition. In order to achieve T-P removal greater than 90%, the difference between $BOD_5$ loading and phosphorus loading rate should be over 100 kg /day (0.130 kg $T-N/m^3{\cdot}d$).

• Journal of Korean Society of Water and Wastewater
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• v.23 no.4
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• pp.439-446
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• 2009

This study was performed to evaluate SND(simultaneous nitrification and denitrification)efficiency, nitrogen removal efficiency and filtration function of non-woven fabric by using submerging MBR packed with granular sulfur covered with non-woven fabric filter. Synthetic wastewater was used as influent wastewater. Concentration of $NH_4{^+}-N$ in influent was maintained about 40 mg/L and the experiment was performed in four phases according to the flow rate. Nitrogen loading rate divided four phases ranging from $0.04 kg\;NH_4{^+}-N/m^3-day$ to $0.16 kg\;NH_4{^+}-N/m^3-day$. As a result, the maximum $NH_4{^+}-N$ removal rate was accomplished at $0.142 kg\;NH_4{^+}-N/m^3-day$ in nitrogen loading of $0.147 kg\;NH_4{^+}-N/m^3-day$. Nitrification efficiency was higher than 95% in all phases. $NO_3{^-}-N$ loading rate was adjusted ranging from $0.22 kg\;NO_3{^-}-N/m^3-day$ to $0.89 kg\;NO_3{^-}-N/m^3-day$. The maximum $NO_3{^-}-N$ removal rate was accomplished up to $0.71 kg\;NO_3{^-}-N/m^3-day$ in $NO_3{^-}-N$ loading of $0.89 kg\;NO_3{^-}-N/m^3-day$. The maximum $NO_3{^-}-N$ removal efficiency was 95% in $NO_3{^-}-N$ loading of $0.22 kg\;NO_3{^-}-N/m^3-day$. T-N removal rate was 90% and concentration of T-N in effluent was 3.7 mg/L in T-N loading rate of $0.039 kg\;NO_3{^-}-N/m^3-day$. In this study, TMP in reactor with and without non-woven fabric filter were observed to define fouling of hollow-fiber membrane module. Reaching time to standard washing pressure(22 cm Hg) of two reactors were 29 days with non-woven fabric But the reactor without non-woven fabric reached standard washing pressure only after 4 days. Accordingly, non-woven fabric was demonstrated the superiority as a filtration ability. With high nitrogen removal rate and decreasing of fouling of membrane, MBR packed with granular sulfur covered with non-woven fabric filter submerging in activated sludge aeration tank can be used as an advanced treatment process.

• Journal of Environmental Science International
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• v.16 no.7
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• pp.813-821
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• 2007

Laboratory scale experiments were conducted to investigate the removal characteristics of nitrogen and phosphorus in two sequencing batch biofilm reactors (SBBRs). SBBR1 had a short first non-aeration period and SBBR2 had a long first non-aeration period. The removal characteristics of nitrogen and phosphorus in each SBBR were precisely observed according to the variation of influent TOC concentration, and the operation control parameters (pH, DO concentration, ORP) in each reactor were measured. In biological nitrogen removal, there was little difference between SBBR1 and SBBR2 and the nitrogen removal efficiencies were very low. The nitrogen and phosphorus removal characteristics in high influent TOC concentration were different from those in low TOC. Nitrogen removals by simultaneous nitrification/denitrification (SND) were occurred in both SBBR1 and SBBR2. The P removal in SBBR1 was superior to that in SBBR2. The second P release was observed in SBBR1 which had long second non-aeration period.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.9
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• pp.939-947
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• 2008

PCR-DGGE method was applied to analyze changes of microbial community in simultaneous nitrification and denitrification (SND) bioreactor with various DO concentrations. In the analysis of eubacterial community, band profiles of DGGE were similar with 2 or 1 mg/L DO concentrations in the reactor. Experimental results led to 16 different bacteria being identified, including 5 dominant strains(3 strains of Uncultured Bacterium, 1 strains of Bacillus, 1 strains of Uncultured Bacteroidetes). DGGE results at 0.5 mg/L DO concentration led to 12 strains being identified, including 7 dominant strains(5 strains of Uncultured Bacterium, 2 strains of Zoogloea sp.). DGGE results at 0.1 mg/L DO concentration led to 11 strains being identified, including 3 dominant strains(1 strains of Uncultured Bacterium, 2 strains of Zoogloea sp.). In DGGE band profiles of $\beta$-AOB($\beta$-Ammonia Oxidizing Bacteria), only one band was observed. This band had 97% similarity with Nitrosomonas sp. done DNB Y20. This band was clearly observed at the 2, 1 and 0.5 mg/L DO concentrations, while the brightness of the band at 0.1 mg/L DO concentration was mostly dimmed. In DGGE band profiles of denitrification process, 5 bands(3 strains of Uncultured organism containing nirS, 2 strains of Uncultured organism containing nirK) were observed. Among those bands, the brightness of one band was gradually increased at the lower DO concentrations. This band has 86% identity with Uncultured organism clone eS1 cd1 nirS gene, partial cds. Based on this result, it could be concluded that Uncultured organism clone eS1 cd1 nirS gene, partial cds is a predominant microorganism in the denitrification process.