The physiological and biochemical mechanism of nitrate-nitrogen removal by water hyacinth from agriculture eutrophic wastewater

The parameters affecting the nitrogen removal process by the immobilized bacteria in the anoxic-oxic process have been studied by investigating two bench scale Runs A and B. The hollow polypropylene pellets have been dosed into the anoxic reactor in Run A and into the oxic reactors of both Runs up to 24% of volume. Run B was operated with no pellets in the anoxic reactor as a control. The maximum nitrification rate of 0.4 kg NH4-N/m3d was achieved in sufficient DO (6.5 mg/l) at 15°C in the reactor with both activated sludge and immobilized micro-organisms. The volumetric nitrification rate was found to be greatly dependent on bulk oxygen concentration especially when the DO was maintained below 4 mg/l. A mathematical model developed successfully simulated the experimental results showing the variation of nitrification rate with DO. In the case of denitrification, the contribution of immobilized bacteria was prominent when lesser concentration of MLSS was present in the activated sludge in the combined immobilized and activated sludge system. The presence of immobilized bacteria in the anoxic reactor will be effective when higher nitrate nitrogen loadings are expected and the maintenance of higher MLSS than 2 g/l in an activated sludge facility is not feasible.

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Nitrogen removal from water containing high nitrate nitrogen in a paddy field (wetland)

Water Science & Technology ◽

10.2166/wst.2003.0576 ◽

2003 ◽

Vol 48 (10) ◽

pp. 209-216 ◽

Cited By ~ 13

Author(s):

H. Nakasone ◽

H. Kuroda ◽

T. Kato ◽

T. Tabuchi

Keyword(s):

Ground Water ◽

River Water ◽

Green Tea ◽

Nitrogen Removal ◽

Nitrate Nitrogen ◽

Nitrogen Concentration ◽

Spring Water ◽

Paddy Fields ◽

High Nitrogen ◽

High Nitrogen Concentration

Nowadays, it has become very common to find in Japan that nitrate nitrogen concentrations are very high in spring water and in well water where the land use of a watershed is agricultural. We have often observed around 50 mg/L of nitrate nitrogen in the spring water where we live. Crops produced in those fields are mainly vegetables such as celery, cabbage, lettuce, carrots, and so on. Green tea is also popular in Japan. In order to produce good quality green tea, farmers apply a great amount of nitrogen fertilizer. This amount can reach up to 1,000 kg/ha in some areas, although the average application amounts to 628 kg/ha in Japan. As a result, ground water that is rich in nitrate flows into the river, which results in a high nitrogen concentration in river water and ground water. Further, this causes a low pH in river water in some tributary rivers in Japan, though this kind of case is very rare. We knew from field tests that if water contained a high nitrogen concentration and was introduced into paddy fields, high nitrogen removal would be performed. This paper presents the outline and results of a system on how to remove nitrogen using paddy fields (wetlands). Further, this paper presents the evaluated results of the removal quantity at the watershed level.

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Nitrate uptake using mesoporous silica embedded with zero-valent palladium nanoparticles

RSC Advances ◽

10.1039/c4ra16531d ◽

2015 ◽

Vol 5 (26) ◽

pp. 20557-20561 ◽

Cited By ~ 3

Author(s):

Chee Ling Tong ◽

Ela Eroglu ◽

Xiaofei Duan ◽

Robert N. Lamb ◽

Kevin Jarrett ◽

...

Keyword(s):

Mesoporous Silica ◽

Nitrogen Removal ◽

Palladium Nanoparticles ◽

Nitrate Uptake ◽

Nitrate Nitrogen

In situ reduction of palladium(ii) acetylacetonate during the synthesis of SBA-15 mesoporous silica affords material impregnated with palladium nanoparticles, with the material being effective for nitrate-nitrogen removal.

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Study of Reed Aqueous Extract’s Allelopathy on Alligator Weed

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.518-523.5363 ◽

2012 ◽

Vol 518-523 ◽

pp. 5363-5365

Author(s):

Guo Fu He ◽

Juan Li ◽

Wei Liu ◽

Jing Li Du

Keyword(s):

Aqueous Extract ◽

Photosynthetic Pigment ◽

Root Activity ◽

Biochemical Mechanism ◽

Alligator Weed ◽

Water Culture ◽

Extract Concentration ◽

Pigment Contents ◽

Mda Content ◽

Physiological And Biochemical

In order to ascertain the allelopathy of Reed on Alligator Weed, the water culture experiments were performed to investigate the effects of aqueous extract on the growth, physiological and biochemical mechanism in Alligator Weed. The results showed that aqueous extract of Reed inhibited the growth of Alligator Weed, and the inhibition became stronger as the concentration of the extract increased. Some results from physiological and biochemical mechanism of treated Alligator Weed indicated that with the increase of extract concentration, photosynthetic pigment contents, root activity and CAT activity decreased, while P and MDA contents increased; N content decreased first and then up to normal. The results showed that aqueous extract of Reed inhibited the photosynthesis, CAT activities of Alligator Weed but increased the MDA content of Alligator Weed.

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