• Journal of Korean Society on Water Environment
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• v.36 no.4
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• pp.322-331
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• 2020

By introducing chemically enhanced primary treatment (CEPT) in the first stage of sewage treatment, organic matter in sewage can be effectively recovered. Because CEPT sludge contains a high biodegradable organic matter in volatile solids (VS), it is feasible to convert the collected CEPT sludge into energy through anaerobic digestion. This study examined the properties and biochemical methane potential (BMP) of the CEPT sludge obtained from a sewage treatment plant located in an ocean area. The CEPT sludge contains a VS content of 37,597 mg/L, which is higher than that of excessive sludge (ES), i.e., 33,352 mg-VS/L. In the methane generation reaction, the lag period was as short as 1 to 2 days. The BMP for the CEPT sludge was 0.57 ㎥-CH₄/kg-VS_removed which is better than that of ES, i.e., 0.36 ㎥-CH₄/kg-VS_removed. Unfortunately, the CEPT sludge showed a high salinity as 0.56~0.75% probably due to the saline sewage. Due to the salinity, repeated BMP testing in a sequencing batch reactor showed significantly low methane production rates and BMPs. Also, the ES showed a strongly reduced BMP when the salinity was adjusted from 0.20 to 0.70% by NaCl. The ES mixture with higher CEPT content showed a better BMP, which is suitable for co-digestion. Besides, anaerobic digestion for 100% CEPT sludge can be a considerable option instead of co-digestion.

• Journal of Korean Society on Water Environment
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• v.24 no.1
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• pp.30-35
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• 2008

In this study, we investigated the nitrification/denitrification rate and classification of output nitrogen of a sequencing batch reactor (SBR) system with the variation of COD loads ; COD loads of 0.3, 0.4, 0.6, 0.7, 0.8, 1.0 and $1.2kgCOD/m^3{\cdot}d$ were tested to determine the optimum conditions for the operation of the SBR and increase its nitrogen removal efficiency. As the COD loads increased, the nitrification rate at aerobic(I) period and the denitrification rate at anoxic(I) period were decreased. With the variation of COD loads, the amounts of nitrogen removed in the clarified water effluent were 63.9, 54.2, 34.7, 22.5, 13.7, 12.5 and 26.5 mg/cycle, respectively. The amounts of nitrogen removed during the sludge waste process were 19.5, 26.6, 41.0, 47.3, 58.1, 72.4 and 88.1 mg/cycle, respectively. The amounts of nitrogen removed by denitrification were 66.8, 69.3, 68.9, 56.5, 39.5, 7.3 and 0.0 mg/cycle, respectively, indicating that COD load more than $0.7kgCOD/m^3{\cdot}d$ decreases the amounts of denitrified nitrogen. The nitrogen mass balances were calculated as the percentages of nitrogen removed in the clarified water effluent or by denitrification and sludge waste processing in each cycle of SBR operation and were 99.0, 98.5, 95.4, 82.1, 73.0, 60.5 and 74.8% for COD loads of 0.3, 0.4, 0.6, 0.7, 0.8, 1.0 and $1.2kgCOD/m^3{\cdot}d$, respectively.

• Journal of Environmental Health Sciences
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• v.31 no.4 s.85
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• pp.340-348
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• 2005

Laboratory scale experiments were conducted to compare the performance of two types of sequencing batch reactor(SBR) systems, anoxic-oxic-anoxic-oxic $((AO)_2)$ SBR and anoxic-oxic-anoxic $(A_2O)$ SBR on the biological nitrogen and phosphorus removal. Also, the profiles of DO and pH in reactors were used to monitor the biological nutrient removal in two SBRs. The break point in the pH and DO curves at the oxic period coincided with the end of nitrifying activity at about 1 h 30 min in oxic phase, and the change in pH appears to be related to nitrate concentration. The TOC removal efficiency in $A_2O$ SBR was higher than that in $(AO)_2$ SBR. The denitrification was completed at the influent period. The 2nd non-aeration and aeration periods were not necessary for the nitrogen and phosphorus removal because of the low influent TOC concentration in this study. The release and uptake of phosphorus in $AO_2$ SBR was much higher than that in $(AO)_2SBR.$ In order to uptake more phosphorus, the 1st aeration period in $A_2O$ SBR should be prolonged.

• Journal of Microbiology and Biotechnology
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• v.22 no.7
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• pp.1005-1014
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• 2012

The understanding of the relationship between ammonia-oxidizing bacteria (AOB) communities in activated sludge and the operational treatment parameters supports the control of the treatment of ammonia-rich wastewater. The modifications of treatment parameters by alteration of the number and length of aerobic and anaerobic stages in the sequencing batch reactor (SBR) working cycle may influence the efficiency of ammonium oxidation and induce changes in the AOB community. Therefore, in the research, the impact of an SBR cycle mode with alternating aeration/mixing conditions (7 h/1 h vs. 4 h/5.5 h) and volumetric exchange rate (n) on AOB abundance and diversity in activated sludge during the treatment of anaerobic sludge digester supernatant at limited oxygen concentration in the aeration stage (0.7 mg $O_2/l$) was assessed. AOB diversity expressed by the Shannon-Wiener index (H') was determined by the cycle mode. At aeration/mixing stage lengths of 7 h/1 h, H' averaged $2.48{\pm}0.17$, while at 4 h/5.5 h it was $2.35{\pm}0.16$. At the given mode, AOB diversity decreased with increasing n. The cycle mode did not affect AOB abundance; however, a higher AOB abundance in activated sludge was promoted by decreasing the volumetric exchange rate. The sequences clustering with Nitrosospira sp. NpAV revealed the uniqueness of the AOB community and the simultaneously lower ability of adaptation of Nitrosospira sp. to the operational parameters applied in comparison with Nitrosomonas sp.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.6
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• pp.535-550
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• 2018

Total organic carbon (TOC) will replace chemical oxygen demand ($COD_{Mn}$) as an effluent water quality standard in public sewage treatment works (PSTWs) from 2021 in Korea. To ensure effective control of TOC in the effluent, investigation was carried out into TOC levels and sewage treatment operation factors in five target PSTWs using anaerobic-anoxic-aerobic ($A_2O$) processes, media, membrane, and sequencing batch reactor (SBR) technologies. TOC removal efficiencies appeared to be 93-96% on average. As a fraction of TOC, biodegradable dissolved organic carbon (BDOC) was reduced from 64% in the influent to 9% in the effluent in these PSTWs. During the investigation, biological treatment processes were applied flexibly for operation factors such as HRT, SRT, MLSS, F/M ratios and BOD volume loads, based on the influent characteristics and design conditions. As a result, we suggest efficient operating conditions in PSTWs by evaluating relationships between TOC removal and operation factors.

• Advances in environmental research
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• v.9 no.4
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• pp.233-249
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• 2020

To date, there is no central wastewater (WW) treatment plant in Erbil city, Kurdistan region, Iraq. Therefore, raw WW disposes to the environment and sometimes it used directly for irrigation in some areas of Erbil city. Disposal of the untreated WW to the natural environment and using for irrigation it causes problems for the people and the environment. The aims of the current work were to study the characteristics, design of primary and different secondary treatment units and reusing of produced WW. Raw WW samples from Ashty city-Erbil city were collected and analyzed for twenty three quality parameters such as Total Suspended Solids (TSS), total dissolved solids, total volatile and non-volatile solids, total acidity, total alkalinity, total hardness, five-day Biochemical Oxygen Demand (BOD5), Chemical Oxygen Demand (COD), biodegradability ratio (BOD5/COD), turbidity, etc. Results revealed that some parameters such as BOD5 and TSS were exceeded the standards for disposal of WW. Design and calculations for primary and secondary treatment (biological treatment) processes were presented. Primary treatment units such as screening, grit chamber, and flow equalization tank were designed and detailed calculation were illustrated. While, Conventional Activated Sludge (CAS), Sequencing Batch Reactor (SBR) and Moving Bed Biofilm Reactors (MBBR) were applied for the biological treatment of WW. Results revealed that MBBR was the best and economic technique for the biological treatment of WW. Treated WW is suitable for reusing and there is no restriction on use for irrigation of green areas inside Ashty city campus.

• The Journal of the Korea Contents Association
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• v.6 no.10
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• pp.34-40
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• 2006

In this study, the treatment of organic matters and nutrients like Nitrogen and Phosphorus with sequencing batch reactors (SBR) was conducted. The following conclusions can be summarized from the study. The influent BOD concentration was varied 19.6 to 40.0mg/L and the effluent was 3.0 to 14.8mg/L. The variations of BOD removal efficiency during the experimental period was $47.9{\sim}88.4%$ and the average was 80.8%. The average removal efficiency was stabilized with the passage of time. Also the COD concentration was flowed into as $12.2{\sim}32.0mg/L$ and the effluent concentration was varied 3.3 to 18.6 mg/L, and then the average COD removal efficiency was 57.3%(minimun 19.2% and maximum 78.6%). But fortunately, the COD removal efficiency was also stabilized as 70.2% after 79days. In the case of T-N, the influent concentration range was $7.53{\sim}14.99mg/L$ and the effluent concentration was 6.59mg/L(the average removal efficiency was 40.3%) until the first experiment time 79days. But after normalizing the system, it was 4.44mg/L (the average removal efficiency was 56.4%). Also the influent T-P concentration was varied from 0.77 to 1.91mg/L and the effluent concentration was $0.26{\sim}1.53mg/L$. The removal efficiency was varied from 5.3 to 71.7%. considerably, therefore the average removal efficiency was 42.6%. The reason was concluded that the sludge wasn't discharged for increasing MLSS concentration.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.1
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• pp.7-14
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• 2006

In this study, nitrogen removal characteristics of SBR3 process, which is two-sludge system of sequencing batch reactor(SBR) type, were investigated, with comparison of those of SBR1 process, which is conventional SBR process, and SBR2 process, which was designed to enhance denitrification efficiency through step-feeding of wastewater, using domestic wastewater. SBR3 process of two-sludge type can perform external nitrification, on which nitrification occurs in separated reactor, and enhanced denitrification using biosorbed organics. In the results with domestic wastewater, T-N removal efficiency of SBR3 process was better than those of SBR1 and SBR2 processes. It was observed that bigger difference of T-N removal efficiency between SBR3 process and SBR1 & SBR2 processes was showed at low C/N ratio than that at high C/N ratio resulting from more efficient use of organics by biosorption mechanism in denitrification of SBR3 process than those of SBR1 and SBR2 processes. In addition, T-N removal efficiency of SBR3 process according to influent T-N loading rate was better than those of SBR1 and SBR2, even though influent T-N loading rate of SBR3 process was higher than that of SBR1 and SBR2 process resulting from operation of SBR3 process in short hydraulic retention time(HRT) by external nitrification.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.3
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• pp.234-240
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• 2010

The effectiveness of adding powdered zeolite and granular activated carbon (GAC) before starvation into biological reactor for recovering its performances was investigated. Two types of carrier addition in Sequencing Batch Reactor (SBR) system for non-saline and saline wastewater were evaluated after starvation periods. During the experiment, settleablity (SVI), floc size, fractal dimension, $COD_{Mn}$, T-N, T-P removal efficiencies and recovery time were monitored. When the wastewater feeding was resumed after starvation period for 5days, the SVI increased at the beginning of resumption and then decreased with time in both types. And the larger the floc size and fractal dimension of floc, the more increased removal efficiency for $COD_{Mn}$, T-N and T-P was also. Its performance recovery was strongly correlated with floc size and fractal dimension of activated sludge. After resuming the wastewater feeding, the SVI, floc size, fractal dimension, $COD_{Mn}$, T-N, T-P removal efficiency of SBR with carrier improved and reached its initial value faster compared to those of SBR without carrier.

• Journal of Korean Society on Water Environment
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• v.39 no.1
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• pp.61-75
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• 2023

Denitrifying bacteria convert nitrate to nitrogen gas using an external carbon source as an electron donor. The external carbon source affects the denitrification performance and bacterial community structure. Although methanol is a cheap and effective external carbon source, the addition of diverse carbon sources may improve the total nitrogen removal rate and biomass characteristics, such as settleability. In this study, denitrifying reactions were performed using solely methanol and mixed carbon sources of methanol, glucose, and acetate in a sequencing batch reactor. The denitrifying reactor using methanol resulted in a total nitrogen removal rate of 0.39 ± 0.025 kg-N/m³-day while the suspended biomass transformed into dark brown granules. Methyloversatilis discipulorum had the highest predominance at 43.84%. The individual denitrifying biomasses, which were separately enriched with methanol, glucose, and acetate, showed the same total nitrogen removal performance of 0.39 ± 0.016 kg-N/m³-day. However, the addition of mixed carbon sources showed an improved total nitrogen removal rate of 0.42 ± 0.043 kg-N/m³-day, with the domination of Candidatus Saccaribacteria at 25.61%. The denitrifying granules turned pale yellow color. Influent COD/NO₃^--N ratios of 3.5, 5, and 7.5 exhibited COD/NO₃^--N consumptions of 4.3 ± 0.4, 4.4 ± 0.8, and 5.2 ± 0.7, and the consistent predominance of Candidatus Saccharibacteria.