In this study, the treatment of livestock wastewater using an aerobic granular sludge based sequencing batch reactor was investigated. The reactor operation was carried out by general injection and split injection methods. The average removal efficiency of organic matter after the adaptation period was 71.5 and 87.4%, respectively. Some untreated organic matter was attributed to recalcitrant organic matter. The average removal efficiency of total nitrogen was 65.6 and 88.4%, respectively. These results indicate that the denitrification reaction by split injection was carried out smoothly. As for the solids, the ratio of aerobic granular sludge/mixed liquor suspended solid can be determined as the main factor of the process operation, and the ratio increased gradually and finally reached 86.0%. Correspondingly, the sludge volume index (SVI) was also improved, reaching 54 mL/g at the end of operation, and it is believed that the application of a short settling time contributed to the improvement of settleability.

The purpose of this study was to evaluate the operational characteristics of wastewater treatment using Sequencing Batch Reactor (SBR) with Aerobic Granular Sludge (AGS) separator in the pilot plant. Pilot plant experiments were conducted using SBR with AGS separator and pollution removal efficiencies were evaluated based on the operational condition and surface properties of AGS. The results of the operation on water quality of the effluent showed that the average concentration of total organic carbon, suspended solids, nitrogen, and phosphorus was 6.89 mg/L, 7.33 mg/L, 7.33 mg/L, and 0.2 mg/L, respectively. All these concentrations complied the effluent standard in Korea. The concentration of mixed liquor suspended solid (MLSS) fluctuated, but the AGS/MLSS ratio was constant at 86.5±1.3%. Although the AGS/MLSS ratio was constant, sludge volume index improved. These results suggested that the particle discharged fine sludge and increased the AGS praticle size in the AGS. Optical microscopy revealed the presence of dense AGS at the end of the operation, and particles of > 0.6 mm were found. Compared to those of belt-type AGS separator, the required area and power consumption of the hydrocyclone-type AGS separator were reduced by 27.5% and 83.8%, respectively.

In this study, the effect on the stability of Aerobic Granular Sludge (AGS) caused by an AGS separator was investigated. The AGS separator was a hydrocyclone. The main factors of the AGS separator were filter pore size (0.125∼0.600 mm), conical-to-cylindrical ratio (1.5∼3.0), and operating time (1∼20 min). The AGS/mixed liquor suspended solid (MLSS) ratio gradually increased to 0.500 mm (AGS/MLSS: 84.3±3.0%). AGS was best separated at the conical-to-cylindrical ratio of 2.5 (AGS/MLSS: 84.7±3.3%). As the operating time increased, the AGS separation performance also tended to increase. The shortest AGS separator run time, but the highest AGS separation performance was 10 min (87.0±2.5%). AGS stability was evaluated by operating the selected AGS separator and sequencing batch reactor. The average removal efficiencies of TOC, TCODCr, SS, TN, and TP were 95.7%, 96.9%, 93.0%, 89.0%, and 96.2%, respectively, which met the effluent standards in Korea. In addition, the AGS/MLSS ratio tended to remain constant, and the sludge volume index demonstrated a tendency to decrease from 140 mL/g to 70 mL/g. During the operation, the particles of AGS in optical microscope observations gradually increased.

In this study, the effect on the stability of Aerobic Granular Sludge (AGS) with different Carbon/Nitrogen (C/N) ratios was investigated. The C/N ratios were controlled to 10.0, 7.5, 5.0, and 2.5 using the sequencing batch reactor, and the results showed that the removal efficiency of organic matter and total nitrogen decreased simultaneously with the decrease of C/N ratio. The removal efficiency of organic matter and total nitrogen at C/N ratio of 2.5 was 70.7% and 52.3% respectively. In addition, the AGS/mixed liquor suspended solids (MLSS) ratio showed a tendency to decrease from 85.7% to 73.7%, while the sludge volume index showed a tendency to increase from 82 mL/g to 102 mL/g as the C/N ratio decreased. At the same time, the apparent deviation of polysaccharide (PS) content in extracellular polymeric substances was observed, and polysaccharides/protein (PS/PN) ratio decreased from 0.62 to 0.31 as the C/N ratio decreased. Optical microscope observations showed that the reduction in C/N ratio caused the growth of filamentous bacteria and significantly affected the stability of AGS.

This study evaluated the biosorption properties of calcium ion using Aerobic Granular Sludge (AGS). A sequencing batch reactor was used to induce the production of Extracellular Polymeric Substances (EPS) through salinity injection, and the calcium ion adsorption efficiency was analyzed by a batch test. The EPS contents showed significant changes (104-136 mg/g MLVSS) at different salinity concentrations. The calcium ion adsorption efficiency was highest for AGS collected at 5.0% salinity, and it was confirmed that the biosorption efficiency of AGS was increased owing to the increase in EPS content. The results of the Freundlich isotherms showed that the ion binding strength (1/n) was 0.3941-0.7242 and the adsorption capacity (Kf) was 2.4082-3.3312. The specific surface area and the pore size of the AGS were 586.1 m2/g and 0.7547 nm, respectively, which were not significantly different from each other. It was confirmed that the influence of biological properties, such as EPS content, was relatively large among the factors affecting calcium ion adsorption.

The purpose of this study was to evaluate the effects of different Hydraulic Retention Times (HRTs) on the contaminant removal efficiency using Aerobic Granular Sludge (AGS). A laboratory-scale experiment was performed using a sequencing batch reactor, and the Chemical Oxygen Demand (COD), nitrogen, orthophosphate removal efficiency, AGS/MLSS ratio, and precipitability in accordance with the HRT were evaluated. As a result, the COD removal efficiency was not significantly different with the reduction in HRT, and at a HRT of 6 h, the removal rate was slightly increased owing to the increase in organic loading rate. The nitrogen removal efficiency was improved by injection of influent division at a HRT of 6 h. As the HRT decreased, the MLSS and AGS tended to increase, and the sludge volume index finally decreased to 50 mL/g. In addition, the size of the AGS gradually increased to about 1.0 mm. Therefore, the control of HRT provides favorable conditions for the stable formation of AGS, and is expected to improve the contaminant removal efficiency with the selection of a proper operation strategy.

The purpose of this study was to evaluate the effect of high-salinity wastewater on the microbial activity of Aerobic Granule Sludge (AGS). Laboratory-scale experiments were performed using a sequencing batch reactor, and the Chemical Oxygen Demand (COD), nitrogen removal efficiency, sludge precipitability, and microbial activity were evaluated under various salinity injection. The COD removal efficiency was found to decrease gradually to 3.0% salinity injection, and it tended to recover slightly from 4.0%. The specific nitrification rate was 0.043 0.139 mg NH4 +-N/mg MLVSS·day. The specific denitrification rate was 0.069 0.108 mg NO3 --N/mg MLVSS·day. The sludge volume index (SVI30) ultimately decreased to 46 mL/g. The specific oxygen uptake rate decreased from an initial value 120.3 to a final value 70.7 mg O2/g MLVSS·hr. Therefore, salinity injection affects the activity of AGS, causing degradation of the COD and nitrogen removal efficiency. It can be used as an indicator to objectively determine the effect of salinity on microbial activity.

The purpose of this study is to biological treatment of high salinity wastewater using Aerobic Granular Sludge (AGS). In laboratory scale’s experiments research was performed using a sequencing batch reactor, and evaluation of the denitrification reaction in accordance with the injection condition of salinity concentration, surface properties of microorganisms, and sludge precipitability was performed. The results showed that the salinity concentration increased up to 1.5%, and there was no significant difference in the nitrogen removal efficiency; however, it showed a tendency to decrease gradually from 2.0% onward. The specific denitrification rate (SDNR) was 0.052 0.134 mg NO3 --N/mg MLVSS (mixed liquor volatile suspended solid)·day. The MLVSS/MLSS (mixed liquor suspended solid) ratio decreased to 76.2%, and sludge volume index (SVI30) was finally lowered to 57 mL/g. Using an optical microscope, it was also observed that the initial size of the sludge was 0.2 mm, and finally it was formed to 0.8-1.0 mm. Therefore, salinity injection provides favorable conditions for the formation of an AGS, and it was possible to maintain stable granular sludge during long-term operation of the biological treatment system.

The purpose of this study was to confirm the applicability of aerobic granular sludge (AGS) in the advanced sewage treatment process. Simulated influent was used in the operation of a laboratory scale reactor. The operation time of one cycle was 4 h and the reactor was operated for six cycles per day. The volume exchange ratio was 50%. The influent was injected in divisions of 25% to increase the removal efficiency of nitrogen in every cycle. As a result, the removal efficiencies of CODCr and TN in this reactor were 98.2% and 76.7% respectively. During the operation period, the AGS/MLVSS concentration ratio increased from 70.0% to 86.7%, and the average SVI30 was 67 mL/g. The SNR and SDNR were 0.073 0.161 kg NH4 +-N/kg MLVSS/day and 0.071 0.196 kg NO3 --N/kg MLVSS/day respectively. These values were higher or similar to those reported in other studies. The operation time of the process using AGS is shorter than that of the conventional activated sludge process. Hence, this process can replace the activated sludge process.