Kazumasa KAMACHI*
Yasuhiro HOMMA**
Satoru SUZUMURA**
*
Swing Engineering Corporation
**
Swing AM Corporation
The biological nitrogen removal process is usually adopted for nutrient removal from sewage as the advanced wastewater treatment. Recently, in addition to the conventional dissolved oxygen sensors, ammonia sensors have been utilized more and more to optimize the aeration and decrease the operational cost. In this study, based on the operational data in a full scale sewage treatment plant, where ammonia sensors were used in the anaerobic/nitrification/endogenous-denitrification process, the optimized operational parameters were investigated by the simulation with activated sludge model, and the characteristics of aeration optimization by using ammonia sensors were revealed.
Keywords: Sewage treatment, Nitrification/endogenous-denitrification, Activated sludge model, Ammonia sensor
This paper is a revised edition of papers published in Volume 20, 2nd/3rd Issues 2015 and Volume 21, 2nd/3rd Issues 2016 of the Journal of EICA.
In lakes and enclosed coastal seas, excessive inflow of nutrients such as nitrogen and phosphorus causes eutrophication, the red or blue tides resulted from the proliferation of phytoplankton. Thus, the biological nitrogen removal technologies by the nitrification and denitrification were adopted in the advanced wastewater treatment processes for nutrient removal from sewage. Typical nitrogen removal processes include anoxicaerobic (A/O) process, step-feed multi-stage A/O process, and nitrification/endogenous-denitrification processes, and so on.
In recent years, dinitrogen monoxide (N2O), with a global warming potential (GWP) of 298 times of that of (CO2) 1), has gained increasing attention. N2O emission is estimated to be approximately 10 % (CO2 equivalent) of the total emissions of greenhouse gases (GHG) produced in sewage treatment2), and reduction is desired. N2O emissions are considered relatively small in the treatment processes with the ability of nitrogen removal3); advanced wastewater treatment is required from the viewpoint of reducing the emission of GHG.
The nitrification/endogenous-denitrification process employs denitrification followed nitrification, and uses organic substances adsorbed onto activated sludge or accumulated in cells as hydrogen donors, without external addition of the hydrogen donor required for denitrification. Although the required hydraulic retention time (HRT) is longer than A/O process, this process is applied in some facilities because no pump is needed for the circulation of mixed liquid after nitrification and the nitrogen removal rate is expected to be higher4)-8).
Since significant time and cost are required for the investigation with lab-scale studies or full-scale experiments in real facilities under a variety of operational conditions. Hence, the number of operational conditions feasible to be investigated by the experiments is limited. Furthermore, the investigation cost could be higher since the experiments should be carried out under safe operational conditions. The Activated Sludge Model (ASM) proposed by IWA (International Water Association) describes the biological reactions in activated sludge using numerical formulas 9). Application of ASM enables flexible reproduction of any facility structure and operating conditions and therefore allows prediction and analysis of process behaviors without increasing costs (Table 1). As a result, it is possible to operate without relying solely on the experience and to determine the operational strategies with the smooth communication. In Japan, ASM has been technically evaluated by the Japan Sewage Works Agency for its practical use10). The agency has published a number of reports on the optimization of operating methods to ensure better effluent quality and to save energy and on the application of ASM to the validation of process design for the expansion and rebuilding projects based on the flowrate and water quality of influent11)-13).
The existing representative method of aeration control uses a dissolved oxygen (DO) meter installed in the aeration tank to control aeration so that the specified concentration of DO is maintained. With recent functional improvements in ion electrode type ammonia sensors, that are directly submerged in the aeration tank and capable of continuous measurement14), advancement of nitrification can now be directly detected. The sensors are now increasingly used in sewage treatment processes for aeration control replacing DO meters. Some examples of aeration control using ammonia sensors have been reported, including complete nitrification using an ammonia sensor located near the end of the aerobic tank11), 12), 15), and feed forward control by an ammonia sensor located upstream16).
This report discusses optimized conditions for aeration control using an ammonia sensor in the nitrification-endogenous denitrification process, together with the simulation with ASM.
| Application | Utilization example of ASM | Conventional method | Utilization effect of ASM |
| Design support | ・Comparative study of treatment method and flow (advanced treatment in existing facilities, study of step inflow ratio, etc.) ・Prediction of treated water quality with changes in inflow water volume and quality (facility construction, rebuilding and renewal plans, study of high concentration inflow, etc.) |
・Capacity calculation based on design specifications excessively relying on experience ↓ ・Design with sufficient margins (not necessarily optimal for each facility) |
・Capable of quantitative evaluation taking into account conditions unique to each facility ↓ ・Optimization of design specifications ・Effective use of existing facilities |
| ・Evaluation of treatment process with a few application examples | ・Verification using experiments and real facilities ↓ ・Exorbitant time requirements and costs for study ・Study cases are limited. |
Capable of simulation under various conditions ↓ ・Reduction in time and cost for study ・Diversification of choices |
|
| Operation management support | ・Optimization of operation conditions ・Responses to abnormal cases such as deterioration of processed water quality ・Study of processed water quality for energy savies in operation |
We conducted a field investigation using the second system at the Kakamigahara Purify Center that treats sewage flowing in through a separate sewer system from the Kiso River and Nagara River basins (covering 4 cities and 6 towns) on the right bank of the Kiso River (Figure 1) The second system is capable of treating an average daily flowrate of 7333 m3 per tank and a maximum daily flowrate of 9000 m3 per tank with a nominal volume of 5482 m3 per tank. The system is designed for the anaerobic-anoxic-aerobic process (A2O process). The system partially uses the anaerobicaerobic-anoxic-aerobic process (AOAO process: anaerobic-nitrification/endogenous denitrification process) where the circulation of mixed liquid after nitrification is stopped.
The biological reaction tank in the target facility is divided into 8 segments and in each segment water is mixed by the submerged stirrer. In the A2O process reaction tank (system 2-B tank 2-7), there are an anaerobic segment for biological removal of phosphorus, an anoxic segment for denitrification, and an aerobic segment for removal of BOD and nitrification in order. In the AOAO process reaction tank (system 2-A tank 2-1, system 2-B tank 2-5), there are an anaerobic segment for biological removal of phosphorus, an aerobic segment for removal of BOD and nitrification, an anoxic segment for endogenous denitrification, and an aerobic segment for nitrification of residual ammonia in order (Table 2). Here, ‘capacity’ indicates the actually available capacity of the tank taking into account structures in the tank. The treated water from each system is discharged after the addition of the inorganic coagulant (PAC) to coagulate residual phosphorus and remove by sand filtration.
DO meters are used for aeration control in the Tank 2-1 and Tank 2-7 and ammonia meters with ion electrode type sensors are used in the Tank 2-5 (Figure 2). Aeration is controlled by the adjustment of working time of airflow control valve based on the differences between the measured values and the set values of the sensors. The airflow control valves are located in the water inlet of each tank, and aeration rate for aeration tanks is constant and fixed.
| Tank | Capacity | Target System | System 2-A | System 2-B | |
| Tank 2-1 | Tank 2-5 | Tank 2-7 | |||
| Treatment Method | AOAO | AOAO | A2O | ||
| Aeration Control | DO Meter | Ammonia sensor | DO Meter | ||
| Nitrification Liquid Circulation | None | None | No.8→No.3 | ||
| No.1 | 397 m3 | Anaerobic | Anaerobic | Anaerobic | |
| No.2 | 582 m3 | Anaerobic | Anaerobic | Anaerobic | |
| No.3 | 582 m3 | Aerobic | Anaerobic | Anoxic | |
| No.4 | 582 m3 | Aerobic | Aerobic | Anoxic | |
| No.5 | 556 m3 | Anoxic | Aerobic | Aerobic | |
| No.6 | 635 m3 | Anoxic | Anoxic | Aerobic | |
| No.7 | 688 m3 | Anoxic | Anoxic | Aerobic | |
| No.8 | 688 m3 | Aerobic | Aerobic | Aerobic | |
| Total | 4710 m3 | ||||
Fig. 1 View of target facility
Fig. 2 Ammonia sensor
We used the IWA activated sludge model, ASM2d, available in the commercial software to perform the simulation. We simulated the real facility to prepare a process model consisting of eight complete mixing biological reaction tanks and one final sedimentation tank (Figure 3). Since NO3-N concentration decreased in the final sedimentation tank due to denitrification, we set up a virtual anoxic tank in the sludge returning line to reflect this denitrification process. The used software employs the KLa model using the overall volumetric oxygen transfer coefficient (KLa) for the oxygen transfer, and represents aeration amount as the correlation to KLa.
Fig. 3 Process model
We used the result of the field investigation for the fractionation data of primary effluent and influent flowrate, and employed adjusted parameters17). We set the capacity of the virtual anoxic tank at 200 m3 to match the NO3-N concentration in the returned sludge denitrified in the final sedimentation tank, and set the return rate from the aerobic tank into the anaerobic tank at 20 % of the influent flow rate of the anaerobic tank17). We fractionated organic substances in the primary effluent using the physicochemical flocculation filtration method18).
We used inorganic nitrogen (NH4-N, NH4-N＋NO3-N) in the Tank No. 8 to evaluate the simulation results. In section [2], we totaled KLa in the tanks to check the increase and decrease of aeration due to changes in flow. We set the standard solution of NH4-N at 1.0 mg/L or lower.
[1] Optimal set value of NH4-N based on water-temperature
We simulated the process flow in the real facility (Process Flow 1 in Table 3) to examine the content of NH4-N and NO3-N in the Tank No. 8 against the set value of NH4-N for the ammonia sensor, as well as the sum of KLa in the tanks. Water-temperatures were set at 25.5 °C, 22.0 °C, and 18.0 °C, respectively in the three water-temperature periods (high, medium, and low). We set the concentration of MLSS in the biological reaction tank at 1 800 mg/L, 2 000 mg/L, and 2 300 mg/L respectively, according to the representative operating conditions in the real facility (Table 4). The flowrate of returned sludge was set at 50 % of the influent flowrate for all water-temperature periods according to the operating conditions in the real facility. The discharge amount of excess sludge was adjusted as appropriate value under each simulation condition to ensure the MLSS concentration in the Tank No. 8 to be kept at the specified value. To ensure the NH4-N concentration in the Tank No. 5 to be kept at the specified value, air was supplied to obtain KLa in the Tank No. 4 and Tank No. 5 in a ratio of 10 : 4. We ensured that the concentration of DO was 1.0 mg/L in the Tank No. 8. We used the steady calculation result in 100-day operation with the step of 0.05 day under average inflow conditions for each simulation condition.
[2] Examination of process flow in low water-temperature period
We examined changes in the process flow in order to improve the effluent quality in the low watertemperature period (Table 3). We used the same conditions as those in section [1] for Process Flow 1. In Process Flow 2, we examined possible increases in the number of aerobic tanks to concurrently accelerate nitrification and denitrification in the aerobic tank, in Process Flow 3, we examined possible increases in the number of endogenous denitrification tanks to accelerate endogenous denitrification. In Process Flow 2, we set the ratio of KLa in the Tank No. 3, Tank No. 4 and Tank No. 5 at 10 : 5 : 4, in Process Flow 3, we set the ratio in the Tank No. 3 and Tank No. 4 at 10 : 4. The other conditions were set to be the same as those in section [1].
| Process Flow 1 | Process Flow 2 | Process Flow 3 | |
| Tank No. 1 | Anaerobic | Anaerobic | Anaerobic |
| Tank No. 2 | Anaerobic | Anaerobic | Anaerobic |
| Tank No. 3 | Anaerobic | Aerobic | Aerobic |
| Tank No. 4 | Aerobic | Aerobic | Aerobic※ |
| Tank No. 5 | Aerobic※ | Aerobic※ | Anoxic |
| Tank No. 6 | Anoxic | Anoxic | Anoxic |
| Tank No. 7 | Anoxic | Anoxic | Anoxic |
| Tank No. 8 | Aerobic | Aerobic | Aerobic |
Set position of the ammonia sensor
| WaterTemperature ℃ | MLSS mg/L |
SRT d |
NH4-N［No.5］ mg/L |
|
| High Water-Temperature Period | 25.5 | 1800 | 15～18 | 2～8 |
| Medium Water-Temperature Period | 22.0 | 2000 | 18～24 | 2～8 |
| Low Water-Temperature Period | 18.0 | 2300 | 20～24 | 2～8 |
Based on the results of the 2.2.3 [2] examination, we increased the number of endogenous denitrification tanks from two to three in June 2015 (Process Flow 1 to Process Flow 2). We analyzed the quality (NH4-N and NO3-Nconcentration) of treated water in the final sedimentation tank every month from April 2014 to May 2015 before the change.
Table 5 shows the operating conditions and average water quality of influent in each water-temperature period during the investigation17). The flowrate of influent was the highest in the high water-temperature period, and the flowrates of returned sludge and excess sludge discharge were the same in the high and low water-temperature periods, but were lower in the medium water-temperature period. Aeration was almost consistent throughout the high, medium, and low water-temperature periods.
| Investigation Period | High Water-Temperature Period | Medium Water-Temperature Period | Low Water-Temperature Period | ||
| 2011/9/13-9/14 | 2012/10/31-11/1 | 2012/2/22-2/23 | |||
| Inflow Water Quality | Water-Temperature (Inflow Water)
|
℃ | 26.3 | 23.7 | 17.3 |
| BOD | mg/L | 82 | 94 | 122 | |
| CODCr | mg/L | 171 | 198 | 218 | |
| NH4-N | mg/L | 14.2 | 18.2 | 19.4 | |
| PO4-P | mg/L | 1.5 | 1.6 | 1.4 | |
| Operation Conditions | Inflow Water Volume | m3 / (day, tank) | 8645 | 7340 | 7185 |
| Returned Sludge Volum | m3 / (day, tank) | 3279 | 1797 | 3310 | |
| Excess Activated Sludge Extraction | m3 / (day, tank) | 60 | 44 | 60 | |
| Aeration | m3 / (day, tank) | 23276 | 23584 | 22874 | |
| MLSS | mg/L | 1960 | 1670 | 3050 | |
| HRT | hr | 13.1 | 15.4 | 15.7 | |
| SRT | d | 20.8 | 20.7 | 31.7 | |
Figure 4 shows the relative proportions of water quality, aeration flowrate, and circulating water flowrate in the anaerobic tank (Tank No. 8) in the A2O and AOAO processes. In any water-temperature period, nitrification was almost complete and the concentration of NH4-N was less than 0.2 mg/L. The concentration of NO3-N in the AOAO process was 0.1 - 1.9 mg/L less than that in the A2O process, while the concentration of PO4-P was 0.1 - 0.4 mg/L more than that in the A2O process. The aeration flowrate was 21 - 29 % and the circulating water flowrate was 100 % in the AOAO process less than that in the A2O process. The Effluent water quality in the AOAO process was similar to that in the A2O process, with reduced the aeration flowrate, and no operation of circulation pump.
Fig. 4 Comparison between A2O and AOAO methods <sup>19)<sup>
To obtain the change in water quality over time, we performed dynamic simulation by using the raw water data from the field investigation conducted on July 17th and 18th, 2014, the operational conditions of Process Flow 1 under the high water-temperature period, and the setting of 4 mg/L for NH4-N concentration in the Tank No. 5. We allotted the flowrate and quality of influent every hour, and when water quality data were not available, interpolated them from the analyzed values. The dynamic simulation covered calculations for 30 days with the time step of 0.05 day.
Figure 5 shows the calculated and measured values of NH4-N and NH4-N ＋ NO3-N in each tank at 17 : 00 and 13 : 00. At both time the behavior of NH4-N and NH4-N＋ NO3-N was consistent and endogenous denitrification under anoxic conditions was well simulated. The maximum error of prediction for the NH4-N concentration was 0.9 mg/L in the Tank No. 8, with the measured and calculated values of 0.2 mg/L and 1.1 mg/L, respectively at 17 : 00, and 0.6 mg/L and 0.7 mg/L, respectively at 13 : 00. Similarly, the maximum error for NH4-N＋NO3-N was also 0.9 mg/L, with the measured and calculated values of 5.8 mg/L and 5.9 mg/L, respectively at 17 : 00, and 5.1 mg/L and 4.2 mg/L, respectively at 13 : 00. These errors were in the acceptable range, since the average values of influent were used during the simulation.
Fig. 5 Comparison between measured and calculated values
Figure 6 shows the relationship between the measured values by the ammonia sensors and by the lab analysis with the samples taken at the time of sensor inspection (monthly).For the inspection of ammonia sensors, the manufacturer’s standard ammonia solution diluted with the effluent of wastewater treatment plant (target NH4-N concentration: 10 mg/L) and the actual water samples were used.The values measured by the ammonia sensor tended to be slightly lower than the actual concentration obtained by the lab analysis, but the good linearity was obtained with the high correlation coefficient.
Fig. 6 Comparison between measured value by ammonia meter and analyzed value
[1] Optimal set value of NH4-N concentration under different water-temperature
Figure 7 and Table 6 show water quality in the Tank No. 8 for each set value of NH4-N in the Tank No. 5. In all water-temperature periods, NH4-N in the Tank No. 8 increased with the increase in its set value in the Tank No. 5, the NH4-N set value in the Tank No. 5 had a range for the minimum concentration of NH4-N＋NO3-N in the Tank No. 8. In the Tank No. 8, while change in NH4-N＋NO3-N value near its minimum was relatively small, the optimal set values of NH4-N in the Tank No. 5 were 4 mg/L, 5 mg/L, and 6 mg/L in the high, medium, and low water-temperature periods respectively. At the optimal set values, NH4-N ＋ NO3-N values in the Tank No. 8 were 4.9 mg/L, 6.8 mg/L, and 8.1 mg/L, respectively.
It’s supposed that the optimal set values of NH4-N in the Tank No. 5 existed because excessive nitrification consumed organic substances required for endogenous denitrification. This suggests that control of nitrification in the aerobic tank can reduce decomposition of organic substances, thereby accelerating endogenous denitrification in the anoxic tank.
It was found that optimal set values of NH4-N were different under the different water-temperature and the optimal values in the Tank No. 5 was lower under the higher water-temperatures. This may be because high water-temperature accelerated denitrification in the anoxic tank together with the advancement of nitrification in the aerobic tank.
[2] Water quality in each tank
Figures 8 - 10 show water quality in the optimal conditions in each water-temperature period. In all the water-temperature conditions, we verified 3.4 - 3.6 mg/L reduction in NO3-N due to endogenous denitrification in the anoxic Tank No. 6 and Tank No. 7.
The low DO level of less than 0.5 mg/L in the aerobic Tank No. 4 and No. 5 concurrently advanced nitrification and denitrification with notable reduction in NH4-N＋NO3-N. In the Tank No. 4 and Tank No. 5, reduced NH4-N＋NO3-N were 4.3 mg/L, 3.8 mg/L, and 1.1 mg/L respectively, in the high, medium, and low -temperature periods, revealing that denitrification was more active in the aerobic tank at higher watertemperatures.
This may be because an appropriate residual amount of NH4-N controlled by the ammonia sensor reduced the DO level in the aerobic tank, concurrently advancing nitrification and denitrification.
[3] Comparison between DO meter and ammonia sensor
Figure 11 shows the relationship between the set values of NH4-N and values of DO in the Tank No. 5 in each water-temperature period. With the optimal set value of NH4-N, DO was at the low level of 0.1 - 0.3 mg/L in the Tank No. 5. As an example, DO was 0.1 - 0.18 mg/ L in the Tank No. 5 in the medium water-temperature period, when NH4-N was 4 - 6 mg/L. We calculated the maximum measurement error according to the specification of the sensor, it was ± 0.45 mg/L (± 5 % of the measured value plus ± 0.2 mg/L) at the optimal setting of the NH4-N value in the medium water-temperature period. We determined that this value was well accepted in the optimal range shown in Figure 7. Then, we examined DO meters. The DO value was 0.13 mg/L, corresponding to the optimum set value of NH4-N of 5 mg/L and the measurement error of the DO meter is 0.13 ± 0.2 mg/L (± 1 % of its measurement range of 20 mg/L). When this range was converted into the NH4-N set value in Figure 11, the error range was 2.5 – 8.0 mg/L or more. Thus, we presume that DO meters were not as capable as ammonia sensors at accurately controlling this process due to their wider error range, giving ammonia sensors the advantage in aeration control.
In the real facility, however, aeration variations were larger in the ammonia sensor control system than in the DO meter control system. This may be because aeration control by ammonia sensors was affected by the biological nitrification and there was the delay for the reflection of aeration on NH4-N than the control by DO meters. The aeration variation caused by the fluctuation of influent water quality was difficult to be stable and reflected by the NH4-N concentration because of above delay. The adjustment of control parameter to decrease the aeration variation should be one of research topic in the future.
Fig. 7 NH4-N set values and inorganic nitrogen in Tank No. 8
| Water-Temperature ℃ |
MLSS mg/L |
Tank No. 5 NH4-N |
Tank No. 8
NH4-N + NO3-N
Calculation Resultmg/L |
||
| Set Value mg/L |
Optimal Value mg/L |
||||
| High Water-Temperature Period | 25.5 | 1800 | 2～8 | 4 | 4.9 |
| Medium Water-Temperature Period | 22 | 2000 | 2～8 | 5 | 6.8 |
| Low Water-Temperature Period | 18 | 2300 | 2～8 | 6 | 8.1 |
Fig. 8 Behavior of DO and inorganic nitrogen in the high water-temperature period
Fig. 9 Behavior of DO and inorganic nitrogen in the medium water-temperature period
Fig. 10 Behavior of DO and inorganic nitrogen in the low water-temperature period
Fig. 11 Relationship between NH<sub>4</sub>-N set value and DO in the Tank No. 5
Figure 12 shows the water quality in the Tank No. 8 and the sum of KLa in all tanks at each setting of the NH4-N value in each process flow.
Both in the current Process Flow 1 (with two aeration tanks) or in Process Flow 2 (with three aeration tanks), there was little change in both NH4-N and NH4-N ＋ NO3-N concentration in the Tank No. 8. However, in Process Flow 3, in which the number of endogenous denitrification tanks increased from two to three, the NH4-N set value of 5 mg/L was optimal and the NH4-N ＋ NO3-N concentration dropped to 7.2 mg/L. This maybe be caused by the enrichment of endogenous denitrification in the anoxic tank with the increased retention time.
Furthermore, almost no difference was found in the sum of KLa under the different process flow (Table 7).
Fig. 12 Simulation result of inorganic nitrogen due to change in process flow20)
| Water-Temperature ℃ |
MLSS mg/L |
Tank No. 5 NH4-N |
Tank No. 8 NH4-N＋NO3-N Calculation Result mg/L |
Sum of KLa 1/d |
||
| Set Value mg/L |
Optimal Value mg/L |
|||||
| Process Flow 1 | 18.0 | 2300 | 2～8 | 6 | 8.1 | 238 |
| Process Flow 2 | 18.0 | 2300 | 2～8 | 6 | 7.8 | 239 |
| Process Flow 3 | 18.0 | 2300 | 2～8 | 5 | 7.2 | 240 |
Figure 13 shows the NH4-N ＋ NO3-N concentration in the effluent from the final sedimentation tank in 2014 and 2015. After the change from Process Flow 1 to Process Flow 2 (anoxic tanks increased from two to three), NH4-N＋NO3-N increased for some periods, then decreased by 1.0 mg/L on average in and after October. We cannot simply compare the analysis results of water sampled in spots in the morning and the simulation results using the average inflow water quality, but can presume that Process Flow 2 is more effective in the low water-temperature period than in other periods.
Fig. 13 Measurement of inorganic nitrogen due to change in process flow
Based on the results of the field investigation in the Kakamigahara Purify Center, we examined optimized conditions for aeration control using an ammonia sensor in the anaerobic nitrification-endogenous denitrification process, together with the simulation with ASM. The results are summarized below.
[Optimal set value of NH4-N under different watertemperature]
When NH4-N ＋ NO3-N were minimized in the Tank No. 8, the optimal set values of NH4-N in the Tank No. 5 existed and it was 4 mg/L, 5 mg/L, and 6 mg/L in the high, medium, and low water-temperature periods, respectively.
In any water-temperature, NH4-N ＋ NO3-N decreased in the Tank No. 4 and Tank No. 5. This may have occurred because the low DO level (0.5 mg/L or less) accelerated nitrification and denitrification concurrently.
[Comparison between DO meter and ammonia sensor]
With the optimal set value of NH4-N, DO was at the low level of 0.1 - 0.3 mg/L in the Tank No. 5. We presume that DO meters were not capable of controlling the process as accurately as ammonia sensors due to their wider error range, giving ammonia sensors the advantage in aeration control.
[Process flow in low water-temperature period]
In Process Flow 3, in which the number of endogenous denitrification tanks increased from two to three, the NH4-N optimal set value was 5 mg/L and the NH4-N＋ NO3-N value dropped to 7.2 mg/L. Almost no difference was found in the sum of KLa under different process flow.
With the increase from two anoxic tanks to three, NH4-N＋NO3-N in the Tank No. 8 decreased by 1.0 mg/L on average in and after October.
We would like to express our gratitude to Gifu Sewerage Public Corporation and the people involved for the considerable support given to this investigation.
1) Enforcement Order of the Law Concerning the Promotion of the Measures to Cope with Global Warming (Cabinet Order No.143 of April 7, 1999).
2) Committee for the Measures to Prevent Global Climate Change for Sewage Works: The Guidance to Develop the Action Plan to Prevent Global Climate Change for Sewage Works, March 2009, p37.
3) Ministry of the Environment Committee for the Greenhouse Gas Emissions Estimation Methods: Study on the calculation of the volume of greenhouse gas emission, improvement in the estimation method in the field of waste, March 2013, p3.
4) Katsumi MORIYAMA, Kazuaki SATO, Yoshinobu HARADA, and Takeyuki KITAMURA: A Study on Nitrificationdenitrification Process Using Endogenous Respiration for Denitrification, Proceedings of Environmental and Sanitary Engineering Research, Vol.24, pp.65-73 (1988).
5) Kiyoshi MIYAZAKI, Shigenobu MUROSAKI, and Kumiko INO: Nitrogen removal improvement test using recycled, step flowing-in type two-stage nitrification and endogenous denitrification, Proceedings of the 38th Japan Annual Technical Conference on Sewerage, pp.466-468 (2001).
6) Akio KISHIKAWA, Toshio FUKUHARA, and Mitsuki OHTSU: Endogenous Denitrification Operation Using Existing Activate Sludge Plant, Journal of Japan Sewage Works Association, Vol.44, No.534, pp.105-112 (2007).
7) Toshihiko SAKAMOTO, Toshio TERASAWA, Aiko BYODO, and Takae MIYOSHI: Comparison between A2O process and AOAO process, Proceedings of the 47th Japan Annual Technical Conference on Sewerage, pp.170-172 (2010).
8) Takaki NISHIZAWA, Yukimasa MORIMOTO, Takayuki TANIGUCHI, Satoru SUZUMURA, and Narikazu ASAI: Study on operation conditions for AOAO process, Proceedings of the 52nd Japan Annual Technical Conference on Sewerage, pp.772-774 (2015).
9) Henze, M., Gujer, W., Mino, T., and van Loosdrecht: Activated sludge model ASM1, ASM2, ASM2d and ASM3, IWA scientific and technical reports No.9, IWA Publishing, London (2000).
10) Japan Sewage Works Agency: Report on technical evaluation of practical use of activated sludge model (2006).
11) Takumi OBARA, Nobuyuki ASHIKAGA, Makoto YAMANAKA, and Katsuya YAMAMOTO (Toshiba Corporation): Applications of Process Simulation Technology for Biological Wastewater Treatment Process - Determination of Ammonium, Journal of EICA, Vol.9, No.2/3, pp.42-46 (2004).
12) Hiroyuki NAGATSUKA, Kazuhiro ENDO, and Tomonori OKAMURA: Development of Control System with Ammonia and Dissolved-Oxygen Concentration for Aeration Tank, Journal of EICA, Vol.17, No.2/3, pp.31-38 (2012).
13) Japan Institute of Wastewater Engineering and Technology: Activated sludge model user manual (2010).
14) Tatsuoki MUROGA, Akio ISHII, Yuichi ITO and Hiroaki MURAKAMI: Development of Ammonia Nitrogen Meter for Aeration Tank, Journal of EICA, Vol.19，No.2/3，pp.140-141 (2014).
15) Ichiro YAMANOI, Yoshiki NISHIDA, and Tsuyoshi TAKEMOTO: Development of high efficiency nitrification control system utilizing ammonia sensors, Proceedings of the 51st Japan Annual Technical Conference on Sewerage, pp.598-600 (2014).
16) Tomoya NAKAMURA, Yoichi HAMAMOTO, Nobuko OSHITA, Toshikazu HASHIMOTO, and Hiroki ITOKAWA: Demonstration of air flow control system using ammonia and nitric acid continuous measuring instrument at sewage treatment plant, Proceedings of the 51st Japan Annual Technical Conference on Sewerage, pp.907-909 (2014).
17) Kazumasa KAMACHI, Yasuhiro HOMMA, and Satoru SUZUMURA: Optimal Aeration Control of Nitrification and Endogenous Denitrification Process with Ammonia Sensor, Using the Activated Sludge Model, Journal of EICA, Vol.20, No.2/3, pp.3-10 (2015).
18) Mamais. D., D. Jenkins and P. Pitt: A rapid physical-chemical method for the determination of readily biological soluble COD in municipal waste-water. Water Res., Vol.27, No.1 pp.195-197 (1993).
19) Kazumasa KAMACHI, Yasuhiro HONMA, Satoru SUZUMURA, Katsuaki KOBAYASHI, and Koji TSUBOUCHI: Applications of nitrification-endogenous denitrification process and study on operation conditions based on activated sludge model, Proceedings of the 51st Japan Annual Technical Conference on Sewerage, pp.874-876 (2014).
20) Kazumasa KAMACHI, Yasuhiro HOMMA, and Satoru SUZUMURA: Optimization of Nitrification-Endogenous Denitrification Process Using an Ammonium Sensor, Journal of EICA, Vol.21, No.2/3, pp.13-17 (2016).
Under the Scenes of our Lives High-pressure pump - Role and Application -
50% capacity boiler feed pump(BFP）playing an active role in a 1 000 MW thermal power plant
Large-capacity, Ultrahigh-efficiency, High-pressure Pumps for Seawater RO Desalination Delivered to Carlsbad Desalination Plant in the U.S.
Streamlines in crossover passage and velocity distributions at inlet of the second-stage impeller (Left:original,Right:optimized)
Discussion Meeting Symposium Ebara research system - Cooperation between research and business to create a new future -
Discussion Meeting (Mr. HIYAMA, Mr. SOBUKAWA, Mr. GOTO）
Under the Scenes of our Lives Standard Pumps - Essential Part of our Everyday Lives -
Examples of standard pumps
Inquiry about Ebara Engineering Review
Inquiry Form