Faculty Profiles - Masanobu Takashima

Papers - Masanobu Takashima

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Performance improvement and decolorization in the high-solid thermophilic anaerobic digestion of thermally pretreated sewage sludge Reviewed International journal

M. Takashima and J. Yaguchi

Water and Environment Journal 2022.7

This laboratory-scale study attempted performance improvement and decolorization in the high-solid thermophilic anaerobic digestion of thermally pretreated sewage sludge, as it tends to be disturbed by ammonia inhibition and color generation. Sewage sludge was adjusted to 7−8% total solids (TS), and pretreated at 150oC for 1 hour. The digesters were operated at 55oC and 20 days hydraulic retention time. An addition of powdered activated carbon (approximately 2% of the feed TS) significantly contributed to the removal of propionate, and reduced the color in digested sludge by about 27%. Microbial analysis detected less abundance of bacterial Synergistia and archaeal Methanosarcina, and implied more hydrogenotrophic methanogenesis with the activated carbon addition. Conditioning with ferric chloride for dewatering digested sludge mitigated the color of dewatered liquor by about 67%. Therefore, these methods were demonstrated to be effective and partly overcome the above-mentioned problems.

Fundamental Study on Wastewater Treatment Technology with Resource Recovery

Masanobu TAKASHIMA

( 51 ) 7 - 12 2021.9

A fundamental study was conducted on the municipal wastewater treatment technology with resource recovery. Here, organic particles in wastewater were separated with sieves, and nitrogen and phosphorus were recovered as ammonia and orthophosphate, respectively, by adsorption. The sieving of wastewater revealed that the particle size of 22 μm or larger consists of 92% of suspended solids. The maximum adsorption capacity was 17 mg-N/g-adsorbent for the ammonia-zeolite system, and 0.89 mg-P/g-adsorbent for the phosphate-water treatment sludge system. A column experiment showed that the linear velocity of 0.1 m/h or less is recommended for continuous operation. Better adsorbents and experimental conditions should be further investigated for efficient nutrient recovery.

High-solids thermophilic anaerobic digestion of sewage sludge: effect of ammonia concentration Reviewed

M. Takashima and J. Yaguchi

Journal of Material Cycles and Waste Management 23 205 - 213 2021

High-solids thermophilic anaerobic digestion fed with sewage sludge of 7?8% and 9?10% total solids was investigated at the hydraulic retention time of 20 days in this lab-scale study. The anaerobic digester fed with 7?8% sewage sludge was successfully operated, resulting in volatile solids (VS) destruction of 57.8% and methane production of 0.327 L/gVS (at standard temperature and pressure). When fed with 9?10% sewage sludge, the control digester was upset after about 80 days of operation. Total ammonia nitrogen (TAN) of 2,500 mgN/L or more caused inhibition to anaerobic microorganisms. Another digester combined with weekly-batch ammonia stripping of digested sludge in a side-stream configuration (80oC, 2 hours, initial pH of 9 with NaOH and return ratio of 70%), was maintained at the average TAN of 1,720 mgN/L, and was able to continue without ammonia inhibition. TAN was a better indicator on inhibition of ammonia than free ammonia nitrogen (FAN). Microbial analysis revealed poor microbial diversity of digested sludge, that is, Class Clostridia for Bacteria and Geneus Methanothermobacter and Methanosarcina for Archaea were predominated. In conclusion, high-solids thermophilic anaerobic digestion can accommodate the influent sewage sludge up to 10%, as far as TAN is properly controlled in digester.

High-Solid Anaerobic Digestion of Sewage Sludge Incorporating Pre-digestion Ammonia Stripping of Waste Activated Sludge

M. Takashima, J. Yaguchi, N. Nakao

8th IWA-ASPIRE Conference and Exhibition, Hong Kong 2019.10

This study investigated high-solid anaerobic digestion fed with sewage sludge of appro. 15% total solids (TS). Thermal pre-treatment and ammonia stripping of the waste activated sludge (WAS) portion was incorporated for ammonia removal and recovery. The laboratory anaerobic digester with an efficient volume of 2.0 L was operated at the hydraulic retention time of 30 days and loading rate of 4.0 g VS/L-d, achieving VS destruction of 60% and gas production of 0.50 NL/g VS. After thermal pre-treatment of 130 oC and 1 hour, the stripping device was operated batchwise at 80 oC and initial pH of 9 for 3 hours, recovering 18% of the WAS nitrogen as ammonia. The results indicated that the high-solid digestion is feasible, as the pre-digestion ammonia stripping can maintain total ammonia at appro. 3,000 mgN/L in digester. Improved ammonia production and removal during pre-treatment is needed for less inhibition and more recovery of ammonia.

Enhanced phosphate release from anaerobically digested sludge through sulfate reduction Reviewed

M. Takashima

Waste and Biomass Valorization 10 ( 11 ) 3419 - 3425 2019.10

This study was conducted to demonstrate enhanced phosphate release in mesophilic anaerobic digestion of sewage sludge in relation to sulfate reduction. Sulfate was added as sulfuric acid to influent sewage sludge at the three levels, 0, 461 and 922 mg-S/L (0, 14.4 and 28.8 mmol/L, respectively). The sewage sludge used was one without artificial modification for 70 days, and then chemically pre-precipitated one artificially prepared by adding 4 g/L (17.9 mmol/L) of FePO4・4H2O for 77 days (Influent total phosphorus of 302 and 855 mg/L, respectively). The anaerobic digesters were operated at 35 oC and 20 days hydraulic retention time. The phosphate concentration in digested sludge at the final stage reached 7.3, 89 and 112 mg/L for the sewage sludge without artificial modification, and 114, 258 and 461 mg/L for the chemically pre-precipitated sewage sludge, at the three levels of sulfate addition respectively. The phosphate concentration was almost proportional to the sulfate concentration added, indicating that the introduction of sulfate to anaerobic digestion can enhance phosphate release. The enhanced phosphate release was attributable to sulfate reduction to sulfide and subsequent release of phosphate from ferric or ferrous phosphate. In addition to the above mechanism involving sulfate reduction, phosphate release was estimated to occur from ferric phosphate along with iron reduction. A possible disadvantage of involving sulfate reduction is that part of the methane is lost due to the consumption of methane precursors.

High-solid Thermophilic Anaerobic Digestion with Ammonia and Phosphate Recovery

M. Takashima, J. Yaguchi

3rd IWA Resource Recovery Conference, Venice, Italy 2019.9

This study investigated high-solid thermophilic anaerobic digestion fed with sewage sludge of 9?10% total solids. Ammonia stripping in a side-stream configuration and selective adsorption by porous iron hydroxide were introduced to digested sludge, respectively, for ammonia and phosphate recovery. The laboratory anaerobic digester performed well at the hydraulic retention time of 20 days and loading rate of 3.96 gVS/L-d, showing VS destruction of 57.8% and gas production of 0.522 NL/gVS. The stripping device was operated batchwise at 70oC and initial pH of appro. 9.0 for 2 hours, recovering 20.7% of influent nitrogen as ammonia and keeping total ammonia at 1,760 mgN/L in digester. Also, 54.6% of influent phosphorus was recovered as phosphate by the selective adsorption, when conducted at the pH of 4?5 for 24 hours. The lower pH was advantageous for saving the amount of cationic polymer added and improving the dewatering characteristics of digested sludge.

Super-high Solids Anaerobic Digestion of Sewage Sludge? Effects of Solids Content and Ammonia Stripping

M. Takashima, N. Nakao

IWA World Water Congress and Exhibition, 16-21 Sept, 2018, Tokyo 2018.9

This study evaluated super-high solids anaerobic digestion fed with sewage sludge of 10?20% total solids (TS). At 15% TS or higher, ammonia stripping in a side-stream or pre-digestion configuration was combined for ammonia removal and recovery. Laboratory anaerobic digesters performed well at the hydraulic retention time (HRT) of 20?30 days and loading rate of 4.0?5.2 gVS/L-d, and showed approximate VS destruction of >50% and gas production of 0.5 NL/gVS. The stripping device was operated batchwise at the temperature of 80oC and initial pH of 9 for 2?3 hours, showing average ammonia recovery of 6.6?16.8 mgN from g influent TS. The results indicated that methane production is possible up to the influent TS of about 20%, and the side-stream configuration is superior for ammonia recovery. High viscosity and deteriorated dewaterability of digested sludge pose a problem for operation, transport and further processing.

Effects of thermal pretreatment and trace metal supplementation on high-rate thermophilic anaerobic digestion of municipal sludge Reviewed

M. Takashima

J. Env. Eng., ASCE 2018.2

High-solids anaerobic digestion of sewage sludge and ammonia removal/recovery by stripping

M. Takashima, N. Nakao

The 15th IWA World Conference on Anaerobic Digestion, Beijing, China 2017.10

Super-high solids municipal anaerobic digestion combined with ammonia stripping

M. Takashima, N. Nakao

The 2nd International Resource Recovery Conference, New York, USA 2017.8

Treatment of eutrophic lake water and phosphorus recovery by reusing alum sludge and/or wood Reviewed

M. Takashima, S. Nakamura, M. Takano and R. Ikemoto

J. Water Reuse Desalinaion 5 ( 4 ) 446 - 453 2015.12

Phosphorus recovery from sewage sludge incinerated ash through iron phosphate

M. Takashima

1st IWA Resource Recovery Conference, Ghent, Belgium, 30 Aug.-2 Sep. 2015.8

Treatment of eutrophic lake water and phosphorus recovery by reusing alum sludge and/or wood

M. Takashima, S. Nakamura, M. Takano and R. Ikemoto

IWA World Water Congress and Exhibition, Lisbon, Portugal 2014.9

Treatment of eutrophic lake water was investigated, when alum sludge and/or wood were used as the media for lab-scale filtration. Process 1 consisted of Column 1 with wood and Column 2 with alum sludge in series, and Process 2 of Column 3 with alum sludge. The filtration velocity was 0.45 and 0.91 m/d for 49 days each. Alum sludge was excellent at removing and recovering phosphorus, and the filtration combining wood and alum sludge enabled the concomitant removal of nitrogen and phosphorus.

Examination on Alum Sludge for Rapid Phosphorus Adsorption from Municipal Wastewater Effluent

M. Takashima and S. Nakamura

2nd IWA Specialized International Conf. on Ecotechnologies for Wastewater Treatment, Verona, Italy 2014.6

Acidic thermal post-treatment for enhancing anaerobic digestion of sewage sludge Reviewed

M. Takashima and Y. Tanaka

J. Environmental Chemical Engineering 2 773 - 779 2014.4

Acidic thermal post-treatment (ATPT) was examined for treatment conditions in a batch study, and was demonstrated to enhance anaerobic digestion of sewage sludge in a continuous study. Approximately 75% of VSS destruction was achieved in the ATPT process, which was 2-2.5 times more that in the control process, 30-37%. The ATPT process also showed 14-21% more methane production and 22-23% better dewaterability, but formed around 3 times more color, compared to the control process. Sulfuric acid as the acidifying agent caused more release of phosphate from the digested sludge, which enables efficient phosphorus recovery.

Fundamental study on fractional recovery of iron phosphate from acidified incinerated ash solution

M. Takashima

The 3R International Scientific Conf. on Material Cycles and Waste management, Kyoto 2014.3

In this study, fractional recovery of iron phosphate was examined from acidified solutions of wastewater sludge incinerated ash. The incinerated ash showed 79 ? 85% solubilization of phosphorus, when acidified at the pH of 0.8 ? 1.5. Adding ferric chloride (Fe/P molar ratio of 1.1) and adjusting the pH to 1.9 ? 2.1 precipitated relatively pure iron phosphate from the acidified solutions. The metals, Al, Zn and Cu, were present in the precipitates with the content of 1.8 ? 2.0, 0.036 ? 0.046, 0.015 ? 0.017 %DW, respectively. The separation of those metals from ferric phosphate precipitates thus was partly successful, and it is necessary to understand the behavior of metals at such low pH.

Application of alum sludge and aquatic plants for advanced treatment of municipal wastewater

M. Takashima, S. Yasui, S. Nakamura

5th IWA-ASPIRE Conference and Exhibition 2013.9

This study investigated the advanced treatment of municipal wastewater effluent and concomitant nutrient recovery. Three lab-scale filtration columns were prepared, depending on the presence or absence of alum sludge as the media and of an aquatic plant, watercress (Nasturtium officinale), and were operated at the filtration rate of 0.13-0.25 m/d for 252 days. In conclusion, the advanced treatment using alum sludge and watercress was demonstrated to be very effective for polishing wastewater and recovering valuable nutrients.

Effects of thermal pretreatment and trace metals on high-rate thermophilic anaerobic digestion of sewage sludge

M. Takashima, E. Nakakihara, R. Ikemoto

13th World Congress on Anaerobic Digestion 2013.6

This study attempted high-rate thermophilic anaerobic digestion of sewage sludge by applying thermal pretreatment of waste activated sludge (170oC and 1hr) and trace metal addition (0.49 mg-Ni/L and 0.54 mg-Co/L). The thermal pretreatment not only increased VS and VSS destruction by 6% and 9%, respectively, but also improved dewaterability of digested sludge drastically. The trace metal addition showed negligible effect on the overall performance. DGT analyses suggested that 70-88% of soluble Ni and only 5-10% of soluble Co be present in a bioavailable form. Furthermore, the Co content in the influent sewage sludge was suspected to be insufficient nutritionally.

Nutrient export and material recycling using aquatic plants: Lake Kitagata case study Reviewed

M. Takashima, H. Nanbu, K. Kato, C. Kataya, A. Ogawa and T. Ishida

Journal of Material Cycles and Waste Management 14 ( 3 ) 266 - 273 2012.9

Performance of anaerobic membrane bioreactor for sewage sludge at ambient and mesophilic temperature

M. Takashima

Euromembrane 2012 2012.9

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Papers - Masanobu Takashima