Shimotoda, Japan
Shimotoda, Japan

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Hashimoto T.,Japan Sewage Works Agency | Onda K.,Ebara Corporation | Morita T.,Ebara Corporation | Luxmy B.S.,Ebara Corporation | And 3 more authors.
Journal of Environmental Engineering | Year: 2010

This study aimed to investigate the contribution to estrogen removal from the activated sludge of an estrogen-degrading bacterium, Novosphingobium sp. Strain JEM-1, isolated by the writers from the activated sludge. The cell numbers of the Strain JEM-1 were investigated in two full-scale wastewater-treatment plants using real-time PCR. Strain JEM-1 appears to be commonly distributed in the activated sludge. The cell numbers of Strain JEM-1 in the oxidation ditch process were higher than those in the conventional activated sludge (CAS) process, and the effluent concentrations of E1 in the CAS process tended to decrease with increased cell numbers of Strain JEM-1. In a bench-scale experiment to investigate bioaugmentation with Strain JEM-1, there was a significant difference in the effluent concentrations of estrogens between the experimental series and the control series. Linear relationships were observed between cell numbers of Strain JEM-1 and the efficiency of removal of estrogens. These results suggest that Strain JEM-1 contributes to the estrogen removal in the activated sludge. © 2010 ASCE.

Hidaka T.,Public Works Research Institute | Wang F.,Public Works Research Institute | Togari T.,Ishikawa Prefectural Government | Uchida T.,Public Works Research Institute | And 2 more authors.
Bioresource Technology | Year: 2013

In local cities, many small sewage and waste treatment facilities are operated independently. To encourage processing by anaerobic digestion at a centralized sewage treatment plant (STP), high-solid sewage sludge is helpful because it reduces the energy and cost required for transporting the sludge from other STPs. Mesophilic and thermophilic anaerobic digestion of sewage sludge at total solids concentrations (TS) of 7.5% and 10% were evaluated using laboratory-scale continuous reactors. Under the mesophilic condition, sewage sludge of 10% TS was successfully treated. Under the thermophilic condition, sewage sludge of 7.5% TS was not successfully treated when the total ammonia concentration was over 2000. mg. N/L. Batch experiments showed that it takes a few weeks for the methane fermentation activity to recover after being inhibited. The effectiveness of adding easily biodegradable organic matter was confirmed. These results show that high-solid sewage sludge is suitable for small facilities by controlling the operating conditions. © 2013 Elsevier Ltd.

Isaka K.,Hitachi Ltd. | Itokawa H.,Japan Sewage Works Agency | Kimura Y.,Hitachi Ltd. | Noto K.,Hitachi Ltd. | Murakami T.,Japan Sewage Works Agency
Bioresource Technology | Year: 2011

A pilot plant involving a nitritation-anammox process was operated for treating digester supernatant. In the preceding nitritation process, ammonium-oxidizing bacteria were immobilized in gel carriers, and the growth of nitrite-oxidizing bacteria was suppressed by heat-shock treatment. For the following anammox process, in order to maintain the anammox biomass in the reactor, a novel process using anammox bacteria entrapped in gel carriers was also developed. The nitritation performance was stable, and the average nitrogen loading and nitritation rates were 3.0 and 1.7kgNm -3d -1, respectively. In the nitritation process, nitrate production was completely suppressed. For the anammox process, the startup time was about two months. Stable nitrogen removal was achieved, and an average nitrogen conversion rate of 5.0kgNm -3d -1 was obtained. Since the anammox bacteria were entrapped in gel carriers, stable nitrogen removal performance was attained even at an influent suspended solids concentration of 1500mgL -1. © 2011 Elsevier Ltd.

Kimura Y.,Hitachi Ltd. | Itokawa H.,Japan Sewage Works Agency | Noto K.,Hitachi Ltd. | Murakami T.,Japan Sewage Works Agency | Isaka K.,Hitachi Ltd.
Bioresource Technology | Year: 2013

Stable nitrogen removal from the digester supernatant for sludge via the nitritation-anammox process under steady operations of ammonium concentration and flow rate has been often reported. In this study, the effects of four non-steady operations, intentional fluctuations of influent concentration from 890 to 650mg-N/L and hydraulic load of the 10% increase, temporally shutdown for 3-d and maximum capacity of each reactor, were evaluated in the nitritation-anammox process treating digester supernatant for sludge. No serious effects were observed in the anammox reactor because the aeration-control system in the nitritation reactor responded and controlled the nitritation efficiency satisfactorily against intentional fluctuations and temporally shutdown. Finally, the maximum capacity of each reactor was evaluated, and the nitritation rate was found to be 2.3kg-N/m3/d at a DO of 4.0mg/L, and the nitrogen-conversion rate was 9.0kg-N/m3/d. © 2013 Elsevier Ltd.

Chen X.,Ehime University | Fujiwara T.,Kochi University | Nakamachi K.,Maezawa Industries Inc. | Kawaguchi Y.,Japan Sewage Works Agency | And 2 more authors.
Desalination | Year: 2012

A novel pilot-scale oxidation ditch (OD) system with an anaerobic tank and dual dissolved oxygen (DO) control technology was used to treat raw domestic wastewater during 310. days of operation. Three intensive sampling sessions indicated that the dual DO control technology could create stable aerobic and anoxic zones along the main ditch, even with large influent fluctuations. Dramatic total nitrogen (TN), total COD, and total phosphorus removal efficiencies were achieved within ranges of 78-90%, 83-91%, and 69-82%, respectively. June nitrogen balance results revealed that 60% of influent TN was denitrified and that 92% denitrification occurred in the main OD, demonstrating the advantage of the dual DO controls. In addition, COD balance values showed that 67% of the mineralized COD was due to denitrification, and aerobic oxidation was minimized. With lower influent BOD/N ratios of 4.0-4.7, significant TN removal performances were obtained in this OD system. Maximizing COD for denitrification and minimizing aerobic degradation suggest that this novel OD system shows promise for highly effective sewage treatment with effective COD consumption. © 2011.

Fujita M.,Ibaraki University | Tsuji K.,Japan Sewage Works Agency | Akashi A.,Kobe Steel
Water Science and Technology | Year: 2010

The cell numbers of ammonia-oxidising bacteria (AOBs), Nitrospira and Nitrobacter in activated sludge used to treat wastewater from a thermal power plant in Japan were examined for nine months using a real-time PCR quantification technique. AOB cell numbers ranged 2.8 × 10 10-2.3 × 10 11 cell/L. The amoA clone analysis showed that the only Nitrosomonas halophila was responsible for ammonia oxidation over the period. Nitrospira were in the range of 2.6 × 10 9-2.4 × 10 10 cell/L and Nitrobacter were less than 1% as common as Nitrospira. Meanwhile, maximum nitrification rates, maximum ammonia- and nitrite-oxidation rates obtained from aerobic batch tests, ranged 0.5-1.3 mmol-N/L h and 1.0-2.5 mmol-N/L h, respectively. No clear correlations were observed between the cell numbers of AOBs or Nitrospira and their maximum rates, because the maximum cell-specific ammonia- and nitrite-oxidation rates varied remarkably over the ranges of 1.1-11.9 and 2.4-21.6 fmol-N/cell h, respectively. To explore the factors controlling maximum cell-specific nitrification rates, the relationship to influent nitrogen loads per AOB or Nitrospira cell numbers was investigated. Fairly good correlations were obtained. Considering the effluent ammonia and nitrite concentrations were zero and only Nitrosomonas halophila had a role in ammonia oxidation over the period, we conclude that the amount of nitrogen oxidised per AOB or Nitrospira cell numbers likely controls maximum cell-specific ammonia- or nitrite-oxidation rates, respectively. © IWA Publishing 2010.

Shinya F.,METAWATER Co. | Tsuboi H.,METAWATER Co. | Miyata A.,METAWATER Co. | Shimada M.,Japan Sewage Works Agency | Yamashita H.,Japan National Institute for Land and Infrastructure Management
Water Practice and Technology | Year: 2015

This study discusses efforts being made to realize energy self-sufficiency in a sewage treatment plant, and to achieve both energy conservation with low-load water treatment based on thorough, intensive solid-liquid separation and 'energy production' by using sludge treatment capable of converting recovered biomass into energy with maximum efficiency. Intensive solid-liquid separation resulted in higher suspended solids and Biological Oxygen Demand (BOD) removal rates than those achieved with conventional primary settling tanks. Using thermophilic digestion of raw sludge, recovered by intensive solid-liquid separation, and garbage as substrates, the Volatile Solids (VS) decomposition rate was 70% and generated digestion gas was 759 Nm3/t-loaded VS on average under conditions of Hydraulic Retention Time (HRT) 5 days and a VS load of 6.0 kg-VS/m3/day. The generated digestion gas was totally used to generate power with phosphoric acid fuel cells. © IWA Publishing 2015.

PubMed | Osaka University and Japan Sewage Works Agency
Type: Journal Article | Journal: Journal of bioscience and bioengineering | Year: 2016

This study investigated changes in the structure and metabolic capabilities of the bacterial community in a full-scale membrane bioreactor (MBR) treating municipal wastewater. Microbial monitoring was also conducted for a parallel-running conventional activated sludge (CAS) process treating the same influent. The mixed-liquor suspended solid concentration in the MBR reached a steady-state on day 73 after the start-up. Then the MBR maintained higher rates of removal of organic compounds and nitrogen than the CAS process did. Terminal restriction fragment length polymorphism analysis revealed that the bacterial community structure in the MBR was similar to that in the CAS process at the start-up, but it became very different from that in the CAS process in the steady state. The bacterial community structure of the MBR continued to change dynamically even after 20 months of the steady-state operation, while that of the CAS process was maintained in a stable condition. By contrast, Biolog assay revealed that the carbon source utilization potential of the MBR resembled that of the CAS process as a whole, although it declined transiently. Overall, the results indicate that the bacterial community of the MBR has flexibility in terms of its phylogenetic structure and metabolic activity to maintain the high wastewater treatment capability.

Zhan J.X.,ET Water Inc | Ikehata M.,ET Water Inc | Mayuzumi M.,ET Water Inc | Koizumi E.,ET Water Inc | And 2 more authors.
Water Science and Technology | Year: 2013

A feedforward-feedback aeration control strategy based on online oxygen requirements (OR) estimation is proposed for oxidation ditch (OD) processes, and it is further developed for intermittent aeration OD processes, which are the most popular type in Japan. For calculating OR, concentrations of influent biochemical oxygen demand (BOD) and total Kjeldahl nitrogen (TKN) are estimated online by the measurement of suspended solids (SS) and sometimes TKN is estimated by NH4-N. Mixed liquor suspended solids (MLSS) and temperature are used to estimate the required oxygen for endogenous respiration. A straightforward parameter named aeration coefficient, Ka, is introduced as the only parameter that can be tuned automatically by feedback control or manually by the operators. Simulation with an activated sludge model was performed in comparison to fixed-interval aeration and satisfying result of OR control strategy was obtained. The OR control strategy has been implemented at seven full-scale OD plants and improvements in nitrogen removal are obtained in all these plants. Among them, the results obtained in Yumoto wastewater treatment plant were presented, in which continuous aeration was applied previously. After implementing intermittent OR control, the total nitrogen concentration was reduced from more than 5 mg/L to under 2 mg/L, and the electricity consumption was reduced by 61.2% for aeration or 21.5% for the whole plant. © IWA Publishing 2013.

Mizuta K.,Japan Sewage Works Agency | Shimada M.,Japan Sewage Works Agency
Water Science and Technology | Year: 2010

Reduction of greenhouse gas (GHG) emissions is one of the most important tasks facing municipal WWTPs. Electric power consumption typically accounts for about 90% of the total energy consumption. This study presents a benchmarking analysis of electric power consumption. The specific power consumption (SPC) ranged from 0.44 to 2.07kWh/m3 for oxidation ditch plants and from 0.30 to 1.89kWh/m3 for conventional activated sludge plants without sludge incineration. Observed differences of the SPC can be attributed to the difference in the scale of plants rather than to different kinds of wastewater treatment processes. It was concluded that economical benefits by centralizing treatment had contributed significantly to the reduction of energy consumption. Further analysis was carried out on the plant that had shown an extremely small SPC value of 0.32kWh/m3. In this WWTP, a large amount of digestion gas was generated by anaerobic digestion. In particular, it was used to generate power using phosphoric acid fuel cells to generate approximately 50% of the energy consumed in the plant. It was calculated that this plant had reduced the overall SPC by 0.17kWh/m3. The effect of power generation using digestion gas demonstrated clearly the advantage of implementing energy recovery schemes. © IWA Publishing 2010.

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