Japanese Journal of Water Treatment Biology

ORIGINALS

Potential of a combined nitritation/anammox process using fixed-bed reactors for nitrogen removal from reject water in a municipal wastewater treatment plant

KEITA TAKAKI, MASAHIKO OKUDA, HIROKI ITOKAWA, HITOSHI NAKAZAWA, KENJI ...

Article type: ORIGINALS
2012 Volume 48 Issue 1 Pages 1-11
Published: 2012
Released on J-STAGE: March 10, 2018

DOIhttps://doi.org/10.2521/jswtb.48.1

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Using anammox as a novel biological process for nitrogen removal from wastewater containing high concentrations of ammonium has attracted much attention. This study focuses on the potential for removing nitrogen from reject water in a municipal wastewater treatment plant using a combined nitritation/anammox process with fixed-bed reactors. In a bench-scale plant that was fed reject water, the nitrite conversion efficiency was above 80% for about 210 days during the nitritation operation. Nitrate production was negligible during this period. We found that the NO₂--N/NH₄⁺-N ratio of the anammox reactor influent could be maintained easily by controlling the flow rate of bypass wastewater according to the nitritation performance. For the anammox reactor, significant nitrogen removal was observed immediately after the start-up and a maximum nitrogen removal rate of 2.9 kgN·m-³·d-¹ was obtained 80 days after start-up. When the influent ammonium concentration was fluctuated intentionally during the experimental operation, the performance of the combined nitritation/anammox process was almost constant and the average nitrogen removal efficiency was 81%.

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Assimilation of Carbon, Nitrogen and Phosphorus by Mud-Skipper Periophthalmus argentilineatus in the Iriomote Island Udara River

JUNICHI UENO, HIROYOSHI KOHNO, OSAMU NISHIMURA, KENSHI KIMURA

Article type: ORIGINALS
2012 Volume 48 Issue 1 Pages 13-21
Published: 2012
Released on J-STAGE: March 10, 2018

DOIhttps://doi.org/10.2521/jswtb.48.13

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Distribution records and ecological studies of mangrove animals were investigated in the tidal flat and mangrove. However, few studies have assessed the influence of these animals on the surrounding environment. For clarifying the effect of mangrove animals on material balance, we examined the resource amount of the mudskipper Periophthalmus argentilineatus and its amount of assimilation of C,N,P. The mudskipper, P. argentilineatus inhabits the intertidal zone and is active on tidal flat surfaces during low tides. Between 2004 and 2007, we found that the population level of this species collected at the Udara River Estuary, Iriomote Island, increased each year. Juvenile fish represented 78－87% of the total captured fish. It is suggested that our investigation conspired at juvenile fish's land life shift time. Efficiency of the amount food of mudskipper were approximately 2.3－6.5%, which was noticeably lower than that of the other fish species. Fish's assimilation of C,N,P in 3 years that study area is 33~833gC, 8~215gN, 2~43gP, we suspected that this was related to the population growth. The C,N,P assimilation by P.argentilineatus were comparatively low, suggesting high energy expenditure by this species because it lives in a tropical area.

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Highly-efﬁcient Anaerobic Digestion of Refractory Organic Waste Using Subcritical Water Hydrolysis as Pretreatment Process

TOMONAO MIYASHIRO, QINGHONG WANG, YINGNAN YANG, KAZUYA SHIMIZU, NORIO ...

Article type: ORIGINALS
2012 Volume 48 Issue 1 Pages 23-27
Published: 2012
Released on J-STAGE: March 10, 2018

DOIhttps://doi.org/10.2521/jswtb.48.23

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In this study, subcritical water hydrolysis was developed to treat refractory organic waste as a pretreatment process for high-efficiency anaerobic digestion. Sewage sludge and cyanobacteria as representative refractory waste were used. Different treatment temperatures were investigated and methane fermentation from the two pretreated wastes by subcritical water hydrolysis were carried out. The results showed that the optimum treatment temperature is 180°C. 0.8 g/l of formic acid, 8.6 g/l acetic acid, 9.9 g/l propionic acid and 0.6 g/l butyric acid were produced from sewage sludge and 405.8 μg/l of microcystin in cyanobacteria was completely removed in the pretreatment process at 180°C. The cumulative methane production was 43.2 ml and 54 ml from pretreated sewage sludge and cyanobacteria, respectively. Both of them were much higher than those produced from untreated one. Therefore, efficient anaerobic digestion of refractory organic waste using subcritical water hydrolysis as pretreatment process could be achieved.

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