UV Photolytic Mechanism ofN-Nitrosodimethylamine in Water:  Roles of Dissolved Oxygen and Solution pH

2005 ◽  
Vol 39 (24) ◽  
pp. 9702-9709 ◽  
Author(s):  
Changha Lee ◽  
Wonyong Choi ◽  
Jeyong Yoon
Keyword(s):  
Dissolved Oxygen ◽  
Solution Ph

scholarly journals Removal of Manganese(II) from Acid Mine Wastewater: A Review of the Challenges and Opportunities with Special Emphasis on Mn-Oxidizing Bacteria and Microalgae

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2493 ◽  
Author(s):  
Yongchao Li ◽  
Zheng Xu ◽  
Hongqing Ma ◽  
Andrew S. Hursthouse
Keyword(s):  
Dissolved Oxygen ◽  
Mine Drainage ◽  
Enzymatic Catalysis ◽  
Microbial Oxidation ◽  
Solution Ph ◽  
Chemical Reagents ◽  
Synergistic Interactions ◽  
Challenges And Opportunities ◽  
Mine Wastewater ◽  
Neutral Conditions

Many global mining activities release large amounts of acidic mine drainage with high levels of manganese (Mn) having potentially detrimental effects on the environment. This review provides a comprehensive assessment of the main implications and challenges of Mn(II) removal from mine drainage. We first present the sources of contamination from mineral processing, as well as the adverse effects of Mn on mining ecosystems. Then the comparison of several techniques to remove Mn(II) from wastewater, as well as an assessment of the challenges associated with precipitation, adsorption, and oxidation/filtration are provided. We also critically analyze remediation options with special emphasis on Mn-oxidizing bacteria (MnOB) and microalgae. Recent literature demonstrates that MnOB can efficiently oxidize dissolved Mn(II) to Mn(III, IV) through enzymatic catalysis. Microalgae can also accelerate Mn(II) oxidation through indirect oxidation by increasing solution pH and dissolved oxygen production during its growth. Microbial oxidation and the removal of Mn(II) have been effective in treating artificial wastewater and groundwater under neutral conditions with adequate oxygen. Compared to physicochemical techniques, the bioremediation of manganese mine drainage without the addition of chemical reagents is relatively inexpensive. However, wastewater from manganese mines is acidic and has low-levels of dissolved oxygen, which inhibit the oxidizing ability of MnOB. We propose an alternative treatment for manganese mine drainage that focuses on the synergistic interactions of Mn in wastewater with co-immobilized MnOB/microalgae.

scholarly journals (303) Challenges of Organic Hydroponic Production of Strawberries (Fragaria ×ananassa)

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1010E-1011 ◽  
Author(s):  
Brandon Jewell ◽  
Chieri Kubota
Keyword(s):  
Dissolved Oxygen ◽  
Nutrient Solution ◽  
Nitrate Nitrogen ◽  
Ammonium Nitrogen ◽  
Nitrifying Bacteria ◽  
Oxygen Level ◽  
Coconut Fiber ◽  
Solution Ph ◽  
Organic Nutrient

Feasible protocols for organic hydroponic production of strawberry are necessary and this study compares the yield and fruit quality of organic and conventional inorganic hydroponic production. Some issues identified with organic hydroponic strawberry production are: 1) dominant ammonium nitrogen form; 2) solution alkalinity; and 3) dissolved oxygen level of nutrient solution. Eighty bare-rooted `Diamante' plantlets were planted in coconut fiber pots with a mixture of coconut coir (30%) and perlite (70%) and grown in a modified nutrient film technique system inside a polycarbonate greenhouse. The organic nutrient solution contains mostly ammonium nitrogen and little nitrate nitrogen. To enhance colonization and activities of nitrifying bacteria, coconut fiber mats were placed in the organic nutrient solution reservoir. A similar system was also introduced for stock solution pre-conditioning where nitrification and pH stabilization were achieved before application to the strawberry plantlets. The organic nutrient solution prior to pre-conditioning had only 1.53 mg·L-1 nitrate nitrogen, although the nitrate nitrogen level increased to 63.2 mg·L-1 after pre-conditioning. The organic nutrient solution pH was 4.5 initially, 8.5 after 24 hours of pre-conditioning, and finally, shifted to and stabilized at 5.7–5.9 after 3 days. Dissolved oxygen level is critical for both nitrifying bacteria activities and plantlet root growth; therefore, oxygen enrichment was achieved by constantly aerating the nutrient solution in the reservoir, which raised the oxygen level from 2.5 to 7.4 mg·L-1. Comparisons of yield and quality of strawberry fruits between organic and inorganic nutrient solutions will be presented and further improvements of hydroponic systems will be discussed.

scholarly journals Electrolysis-assisted UV/sulfite oxidation for water treatment with automatic adjustments of solution pH and dissolved oxygen

2021 ◽  
Vol 403 ◽  
pp. 126278 ◽  
Author(s):  
Long Chen ◽  
Yunfei Xue ◽  
Tao Luo ◽  
Feng Wu ◽  
Akram N. Alshawabkeh
Keyword(s):  
Water Treatment ◽  
Dissolved Oxygen ◽  
Solution Ph ◽  
Sulfite Oxidation

Influence of Dissolved Oxygen on Trivalent Chromium Removal from Wastewater by GQSS

2012 ◽  
Vol 251 ◽  
pp. 416-420
Author(s):  
Jun Guo Li ◽  
Yan Shi ◽  
Ling Hong Wei
Keyword(s):  
Dissolved Oxygen ◽  
Redox Potential ◽  
Significant Influence ◽  
Steel Slag ◽  
Trivalent Chromium ◽  
Post Treatment ◽  
Chromium Removal ◽  
Lower Content ◽  
Solution Ph ◽  
Gas Quenching

Gas quenching steel slag (GQSS) without any post treatment and modification could be utilized to remove Cr(III) from wastewater. Due to lower content of reductive material in GQSS, it was suggested that dissolved oxygen in solution should be declined slightly to the minimum with libration time, and then increased as the testing centrifuge tubes without lids because of dissolution of oxygen from atmosphere. Dissolved oxygen chromium original have significant influence on redox potential in solution. pH increased with the increasing of libration time because of dissolution of alkaline material in GQSS. But dissolution oxygen has little influence on pH in solution. It was suggested that Cr(III) removal percentage when the solution was sealed from atmosphere was slightly higher than that as the soltuion without seal, which was related with the influence of dissolved oxygen on pH and redox potential in solution.

Removal of Chromium(VI) by Zero Valent Iron: Effects of Environmental Factors

2011 ◽  
Vol 356-360 ◽  
pp. 1093-1096
Author(s):  
Pin Hua Rao ◽  
Wen Qi Zhang ◽  
Jie Zhao ◽  
Xin Yu Dong
Keyword(s):  
Humic Acid ◽  
Environmental Factors ◽  
Dissolved Oxygen ◽  
Removal Efficiency ◽  
Low Ph ◽  
Zero Valent Iron ◽  
Solution Ph ◽  
Adsorption Sites ◽  
Chromium Vi ◽  
Geochemical Factors

The influences of various geochemical factors, such as pH, phosphate, bicarbonate, humic acid, permanganate, and dissolved oxygen, on hexavalent chromium(Cr(VI)) removal by zero-valent iron(Fe0) were investigated in a batch setting. Results showed that low pH environments were favorable to removal of Cr(VI) compared with high pH environments. Phosphate significantly inhibited removal of Cr(VI) possibly due to competition of adsorption sites on corrosion products. Humic acid introduced a marginal influence on Fe0reactivity toward Cr(VI) reduction, whereas bicarbonate enhanced Cr(VI) removal by maintaining the solution pH near neutral. Permanganate cumbered the removal of Cr(VI) due to its competition for electron from oxidation of Fe0. The removal efficiency of Cr(VI) was higher in oxic conditions than that in anoxic conditions.

The Ultrastructure of Monkey Gingival Epithelium

1967 ◽  
Vol 25 ◽  
pp. 16-17
Author(s):  
C.N. Sun
Keyword(s):  
Epithelial Cells ◽  
Macaca Nemestrina ◽  
Stratum Granulosum ◽  
Solution Ph ◽  
Gingival Epithelial Cells ◽  
Stratum Spinosum ◽  
Cell Layers ◽  
Gingival Epithelium ◽  
The Individual ◽  
Different Thickness

The present study demonstrates the ultrastructure of the gingival epithelium of the pig tail monkey (Macaca nemestrina). Specimens were taken from lingual and facial gingival surfaces and fixed in Dalton's chrome osmium solution (pH 7.6) for 1 hr, dehydrated, and then embedded in Epon 812.Tonofibrils are variable in number and structure according to the different region or location of the gingival epithelial cells, the main orientation of which is parallel to the long axis of the cells. The cytoplasm of the basal epithelial cells contains a great number of tonofilaments and numerous mitochondria. The basement membrane is 300 to 400 A thick. In the cells of stratum spinosum, the tonofibrils are densely packed and increased in number (fig. 1 and 3). They seem to take on a somewhat concentric arrangement around the nucleus. The filaments may occur scattered as thin fibrils in the cytoplasm or they may be arranged in bundles of different thickness. The filaments have a diameter about 50 A. In the stratum granulosum, the cells gradually become flatted, the tonofibrils are usually thin, and the individual tonofilaments are clearly distinguishable (fig. 2). The mitochondria and endoplasmic reticulum are seldom seen in these superficial cell layers.

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