Mesophilic co-digestion of dewatered sludge produced in a oxidation-ditch process and wasted fried tofu

Togari, Taketo; Yamamoto-Ikemoto, Ryoko; Nakakihara, Eri; Nakade, Takahiro; Gu, Tingting; Honda, Ryo

doi:10.2208/jscejer.69.iii_597

Cited by 5 publications

(5 citation statements)

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“…In Period I, biogas was generated stably; methane yield of total input substrates was 0.22 L/g-TS, and approximately 0.54 L methane was generated per gram of tofu mixture. This result was close to the methane production potential, 0.55L/g-TS that was obtained in the previous study [14]. Methane fermentation was suggested to be conducted stably without accumulation of VFAs or ammonia inhibition.…”

Section: Operating Performance Of the Co-digestion (Run 2)supporting

confidence: 90%

“…The authors compared the operating performances of the thermophilic digestion and the mesophilic digestion conducted in the previous study [14], and the comparison results are summarized in Table 6. Methane yields of total substrates and tofu mixture, and VS removal rates were calculated in the period with maximum substrate TS.…”

Section: Comparison Of Thermophilic and Mesophilic Digestionmentioning

confidence: 99%

“…A previous study [14] showed that in Ishikawa Prefecture, Japan, there is a large amount of OD sludge and waste fried tofu (a typical organic waste in local town being generated every year) and efficient treatment is needed. Fried tofu contains high amount of protein and oil, as estimated by Li [15] that the theoretical methane production potential of fat and protein are 0.998 L/g and 0.52 L/g, respectively, and thus high methane recovery from fried tofu could be expected.…”

Section: Introductionmentioning

confidence: 99%

“…If the waste fried tofu could be used in a nearby WWTP for co-digesting with sludge, it might be possible to recover methane gas and treat the organic waste effectively. Therefore, in the previous study [14], a co-digestion experiment of OD sludge and waste fried tofu was conducted at mesophilic temperature, and the results showed that the fried tofu addition contributed greatly to the methane gas production. In addition, stable digestions were obtained at substrate concentration of 100 g/L for sludge digestion and 101.5 g/L for co-digestion.…”

Section: Introductionmentioning

confidence: 99%

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Methane Recovery and Microbial Community Analysis of a High Solid Thermophilic Co-digestion of Sewage Sludge and Waste Fried Tofu

Togari

Tsuchiya-Nakakihara

et al. 2016

J. of Wat. & Envir. Tech.

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A continuous high solid co-digestion experiment of dewatered sludge from an oxidation ditch process and waste fried tofu was conducted at 55°C in the present study. Sludge retention time was 10 days, and the mixing ratio of sludge, dry and raw fried tofu was 1:0.39:0.06 (dry weight basis). Total solids (TS) of substrate was increased gradually (30, 50, 70, 100 g/L) in the sludge digestion, while TS was increased and then decreased in the co-digestion (43.5, 72.5, 101.5, 72.5 g/L). In the sludge digestion, performance was stable when the TS was below 70 g/L (organic loading rate (OLR) was 5.9 kg-volatile solids (VS)/(m 3 ·d)), and methane yields of sludge were 0.05-0.08 L/g-TS. In the co-digestion, biogas production significantly increased by the fried tofu addition. When total TS was increased to 101.5 g/L (OLR 8.8 kg-VS/(m 3 ·d)), accumulation of ammonia and volatile fatty acid was observed, inhibition was indicated. Methane fermentation failed to recover when the TS was decreased to 72.5 g/L (OLR 6.3 kg-VS/(m 3 ·d)). Results of the denaturing gradient gel electrophoresis analysis of the microbial community revealed a significant difference in the bacterial community with the fried tofu addition, while no major difference in the archaeal community was recognized.

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Section: Operating Performance Of the Co-digestion (Run 2)supporting

confidence: 90%

Section: Comparison Of Thermophilic and Mesophilic Digestionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Methane Recovery and Microbial Community Analysis of a High Solid Thermophilic Co-digestion of Sewage Sludge and Waste Fried Tofu

Togari

Tsuchiya-Nakakihara

et al. 2016

J. of Wat. & Envir. Tech.

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“…There was no major difference in the carbon content between the OD sludge and the raw sludge, but the nitrogen content in the OD sludge was higher than that in the raw sludge. Togari et al [8] reported that the biogas production potential of OD sludge was almost the same as that of excess sludge produced in the conventional activated sludge process.…”

Section: Batch Experimentsmentioning

confidence: 95%

Effects of Microwave Pretreatment of Dewatered Sludge from an Oxidation-Ditch Process on the Biogas Yield in Mesophilic Anaerobic Digestion

Togari

Yamamoto-Ikemoto

Ono

et al. 2016

J. of Wat. & Envir. Tech.

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Microwave pretreatment was applied to highly concentrated dewatered sludge produced from an oxidation ditch process (OD sludge) to improve its degradation and biogas production in mesophilic anaerobic digestion. In a batch experiment using methane fermentation, the biogas production potential of OD sludge was increased after microwave irradiation. The increase in the biogas potential depended on the irradiation period and the temperature. Continuous digestion of the pretreated OD sludge was carried out in mesophilic conditions using a laboratory-scale digester at 25 days of hydraulic retention time (HRT). Although the biogas yield in the control digester was 0.12 NL/g-total solids (TS), that fed with OD sludge pretreated with max 100 W of irradiation at 80°C for 60 min was 0.15 NL/g-TS. Subsequently, dewatered OD sludge was pretreated by a novel continuous microwave irradiation device at 400 W for 20 min and fed into a pilot-scale co-digester with six kinds of waste biomass. The biogas yield of the reactor was increased from 0.25 NL/g-TS to 0.28 NL/g-TS. Assuming that the biogas yield of each co-digesting biomass was constant, the biogas yield of the OD sludge was estimated to increase by 42%.

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Improvement of dewatering characteristics by co-digestion of rice straw with sewage sludge

Yamamoto-Ikemoto

Tsuchiya-Nakakihara

et al. 2016

Environmental Technology

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A continuous mesophilic co-digestion of sewage sludge and softened rice straw was conducted and the dewatering characteristics of digested sludge were evaluated by a dewatering experiment using a belt press. The digestion was operated with solid retention time (SRT) of 25 days, and the feeding ratio of sludge to rice straw was 1:0.5 (total solids base). After 129 days of stable operation, the properties of digested sludge were analysed; then five kinds of cationic coagulants were tested to select the optimal coagulants for dewatering, and two coagulants were selected and used in the dewatering experiment because of lower doses and lower moisture of sludge cakes. Sludge property analysis showed that by the addition of rice straw, the fibrous materials in the digested sludge increased remarkably and the normalized capillary suction time (CST) decreased significantly, indicating that the dewatering properties was improved. The results of dewatering experiment showed that by the addition of rice straw, specific filtration rate of digested sludge increased by 81.2% and 174.6%, respectively; water content of dewatered sludge cakes decreased by 8.2% and 13.4%, respectively. The dewaterability of digested sludge was suggested to be improved due to rice straw addition.

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Mesophilic co-digestion of dewatered sludge produced in a oxidation-ditch process and wasted fried tofu

Cited by 5 publications

References 0 publications

Methane Recovery and Microbial Community Analysis of a High Solid Thermophilic Co-digestion of Sewage Sludge and Waste Fried Tofu

Methane Recovery and Microbial Community Analysis of a High Solid Thermophilic Co-digestion of Sewage Sludge and Waste Fried Tofu

Effects of Microwave Pretreatment of Dewatered Sludge from an Oxidation-Ditch Process on the Biogas Yield in Mesophilic Anaerobic Digestion

Improvement of dewatering characteristics by co-digestion of rice straw with sewage sludge

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