Inhibition of nitrate and the accumulated denitrification intermediate (nitrite) on perchlorate bioreduction

2014 ◽  
Vol 49 (4) ◽  
pp. 346-353 ◽  
Author(s):  
Rui Wang ◽  
Liang Chen ◽  
Fei Liu ◽  
Hong H. Chen ◽  
Jia W. Zhang ◽  
...  
Keyword(s):  
Reduction Rate ◽  
Environmentally Friendly ◽  
Critical Factor ◽  
Efficient Technology ◽  
Treatment Technology ◽  
Batch Type ◽  
Perchlorate Reduction ◽  
Negative Effect ◽  
Lag Period ◽  
Denitrification Process

Bioreduction of perchlorate and nitrate by perchlorate-reducing microorganisms (PRMs) is an environmentally friendly, economic, and efficient technology to treat mixed plumes composed of these substances. The influence of perchlorate, nitrate, and denitrification intermediates on PRM activity is a critical factor, which may affect the efficiency of treatment technology. This study investigated the inhibition of nitrate and the intermediate (nitrite) accumulated during the denitrification process on perchlorate bioreduction via a batch-type experiment. From the experiment, it was found that perchlorate had no effect on the denitrification process and that the reduction rate of perchlorate could be improved when NO3−-N/ClO4− ≤1.2. However, a negative effect of nitrate on perchlorate reduction was observed when NO3−-N/ClO4− >1.2 with an accumulation of 18.0 mg NO2−-N /L. This negative effect increased with the concentration of nitrate. Moreover, nitrite from the denitrification process had a similar negative effect on perchlorate reduction. Bioreduction of perchlorate was not started until nitrite was totally reduced, and a 2–13 day lag period was observed for perchlorate reduction after nitrite depletion.

Evaluation of nitrate and perchlorate reduction using sulfur-based autotrophic and mixotrophic denitrifying processes

2015 ◽  
Vol 16 (1) ◽  
pp. 208-218 ◽  
Author(s):  
Deniz Uçar ◽  
Emine Ubay Çokgör ◽  
Erkan Şahinkaya
Keyword(s):  
Nitrate Reduction ◽  
Elemental Sulfur ◽  
Reduction Rate ◽  
Sulfate Concentration ◽  
Biological Reduction ◽  
Perchlorate Reduction ◽  
Guideline Value ◽  
Reduction Efficiency ◽  
Drinking Water Guideline ◽  
Denitrification Process

The biological reduction of nitrate and perchlorate was comparatively evaluated in autotrophic and mixotrophic bioreactors using elemental sulfur and/or methanol as the energy source. The mixotrophic reactor was supplemented with methanol at CH3OH/NO3−-N ratio of 1 or 1.4. The mixotrophic reactor completely reduced perchlorate in the feed up to 1,000 μg l−1. The autotrophic reactor also showed high perchlorate reduction performance and decreased perchlorate from 1,000 μg l−1 to around 33 μg l−1. Complete reduction of 25 mg NO3−-N l−1 was achieved in both reactors, corresponding to a maximum nitrate reduction rate of 300 mg NO3−-N l−1d−1 and 400 mg NO3−-N l−1d−1 in the autotrophic and mixotrophic processes, respectively. Autotrophic denitrification caused an increase of effluent sulfate concentration, which may exceed the drinking water guideline value of 250 mg l−1. In the mixotrophic denitrification process, the effluent sulfate concentration was controlled by adjusting the C/N ratio in the influent. Mixotrophic denitrification was stimulated by 25 mg l−1 methanol addition and 53% of influent nitrate was reduced by the heterotrophic process, which decreased the effluent sulfate concentration to half of the autotrophic counterpart. Therefore, the mixotrophic process may be preferred over the autotrophic process when effluent sulfate concentration is of concern and a higher perchlorate reduction efficiency is desired.

Selenium Uptake by a Coal Mine Wetland Sediment

2003 ◽  
Vol 38 (3) ◽  
pp. 483-497 ◽  
Author(s):  
Susan A. Baldwin ◽  
Al Henry Hodaly
Keyword(s):  
Growth Medium ◽  
Coal Mine ◽  
Mine Waste ◽  
Reduction Rate ◽  
Plant Debris ◽  
Bacteria Growth ◽  
Sulfate Reducing ◽  
Selenium Uptake ◽  
Negative Effect ◽  
Reducing Bacteria

Abstract Sediment from a wetland receiving runoff from a coal mine waste dump in the Elk River Valley of southeast British Columbia was assessed for potential selenium uptake. Selenite [SeO32-, Se(IV)] was found to adsorb to the washed sediment at pH 7 to 8, whereas no selenate [SeO42-, Se(VI)] was adsorbed, in the concentration range of 8 to 225 μg L-1 Se as selenite or selenate. Sulfate- and selenate-reducing bacterial activity was detected in the sediment. In the presence of sulfate-reducing bacteria growth medium, Se as selenate was reduced from 619(±53) μg L-1 to 15(±0.7) μg L-1, and in the presence of selenate-reducing bacteria growth medium, Se as selenate was reduced from 364(±66) mg L-1 to 22(±10) mg L-1. Semi-continuous microcosms containing sediment overlaid with selenate (500 μg L-1 Se) and sulfate (0.9 g L-1) containing water were amended with plant debris from the site or nutrients (lactate and fertilizer). Potential selenate reduction rate (0.76 h-1) was highest in the unamended microcosms. Amendment with plant debris from the site had a negative effect on selenate reduction rate in the short term (after one hour) and a positive effect on Se removal in the long term (after one week). This study suggests that wetland sediments at the mine site may be important sinks for Se.

Optimal operations for groundwater denitrification of drinking water using heterotrophic biological denitrification process

2006 ◽  
Vol 6 (2) ◽  
pp. 125-130
Author(s):  
C.-H. Hung ◽  
K.-H. Tsai ◽  
Y.-K. Su ◽  
C.-M. Liang ◽  
M.-H. Su ◽  
...  
Keyword(s):  
Drinking Water ◽  
Removal Efficiency ◽  
Nitrate Removal ◽  
Drinking Water Treatment ◽  
Nitrate Content ◽  
Source Water ◽  
Nitrogen Gas ◽  
Negative Effect ◽  
Denitrification Process ◽  
Heterotrophic Denitrification

Due to the extensive application of artificial nitrogen-based fertilizers on land, groundwater from the central part of Taiwan faces problems of increasing concentrations of nitrate, which were measured to be well above 30 mg/L all year round. For meeting the 10 mg/L nitrate standard, optimal operations for a heterotrophic denitrification pilot plant designed for drinking water treatment was investigated. Ethanol and phosphate were added for bacteria growing on anthracite to convert nitrate to nitrogen gas. Results showed that presence of high dissolved oxygen (around 4 mg/L) in the source water did not have a significantly negative effect on nitrogen removal. When operated under a C/N ratio of 1.88, which was recommended in the literature, nitrate removal efficiency was measured to be around 70%, sometimes up to 90%. However, the reactor often underwent severe clogging problems. When operated under C/N ratio of 1.0, denitrification efficiency decreased significantly to 30%. Finally, when operated under C/N ratio of 1.5, the nitrate content of the influent was almost completely reduced at the first one-third part of the bioreactor with an overall removal efficiency of 89–91%. Another advantage for operating with a C/N ratio of 1.5 is that only one-third of the biosolids was produced compared to a C/N value of 1.88.

Microbial Perchlorate Reduction in Groundwater with Different Electron Donors

2013 ◽  
Vol 295-298 ◽  
pp. 1402-1407
Author(s):  
Rui Wang ◽  
Ming Chen ◽  
Jia Wen Zhang ◽  
Fei Liu ◽  
Hong Han Chen
Keyword(s):  
Removal Efficiency ◽  
Electron Donor ◽  
Electron Acceptor ◽  
Reduction Rate ◽  
Electron Donors ◽  
Monod Equation ◽  
Hydrogen Addition ◽  
Perchlorate Reduction ◽  
Perchlorate Removal

Effects of different electron donors (acetate and hydrogen), acetate and perchlorate concentrations on microbial perchlorate reduction in groundwater were studied. The results showed that acetate and hydrogen addition as an electron donor can significantly improve perchlorate removal efficiency while a longer period was observed for hydrogen (15 d) than for acetate (8 d). The optical ratio of electron donor (acetate)-to-electron acceptor (perchlorate) was approximately 1.65 mg COD mg perchlorate-1. The highest specific reduction rate of perchlorate was achieved at the acetate-to-perchlorate ratio of 3.80 mg COD mg perchlorate-1. The perchlorate reduction rates corresponded well to the theoretical values calculated by the Monod equation and the parameters of Ks and Vm were determined to be 15.6 mg L-1 and 0.26 d-1, respectively.

Laboratory reduction rate and current efficiency studies of batch type electrolytic reduction of U(VI) in a sulfate system

1986 ◽  
Vol 17 (1) ◽  
pp. 69-76 ◽  
Author(s):  
Hiroshi Majima ◽  
Yasuhiro Awakura ◽  
Koji Sato ◽  
Shuichiro Hirono
Keyword(s):  
Current Efficiency ◽  
Reduction Rate ◽  
Electrolytic Reduction ◽  
Batch Type

Preliminary Research on Design Method of Sustainable & Open Residence

2012 ◽  
Vol 204-208 ◽  
pp. 3547-3552
Author(s):  
Zheng Tan ◽  
Ai Feng Wang
Keyword(s):  
Natural Environment ◽  
Family Life ◽  
Architectural Design ◽  
Design Method ◽  
Residential Building ◽  
Environmentally Friendly ◽  
Critical Factor ◽  
Building Design ◽  
Residential Design ◽  
Preliminary Research

The residential building is a critical factor to reflect the relations between human and natural environment, and it is required that the residential design is more flexible, healthier and more environmentally friendly and is capable of fully responding to the demands and changes in family life and harmonizing with the environment, as the time goes on and progresses, the concept of “Sustainable & Open Residence” (SOR) has been promoted and applied by many countries, also attracted considerable attentions in the process of the China's Housing Industrialization. The paper discusses how to achieve such the “Sustainability” and “Open” in residential design based on the author’s understanding on SOR under the current conditions in China, a architect should take the initiative to adopt a number of architectural design method to achieve the sustainability and open in residential building design.

Study on Harmless Technology of Waste Oil-Based Drilling Fluid

2012 ◽  
Vol 524-527 ◽  
pp. 1581-1586
Author(s):  
Ping Quan Wang ◽  
Zhi Wei Qian ◽  
Yang Bai ◽  
Zai Jun Li ◽  
Shuang Meng
Keyword(s):  
Solid Waste ◽  
Ph Value ◽  
Drilling Fluid ◽  
Pollution Index ◽  
Drilling Fluids ◽  
Waste Oil ◽  
Treatment Technology ◽  
Base Oil ◽  
Leaching Toxicity ◽  
Negative Effect

Oil-based drilling fluids are essential for challenging drilling operations. However oil-based drilling fluid after using for the well site and the surrounding environment also poses a serious negative effect. Therefore, for studying on harmless technology of waste oil-based drilling fluid in this paper. Base on the tradition treatment technology for waste oil-based drilling fluid, by the preferred for treatment chemicals, improved the experimental methods and conditions, achieved some research results. Added 8.5g/L xylene/ispropanol complex demulsifier under the 50°C, pH value of 4 conditions to breaking the waste oil-based drilling fluid, the remove base oil rate is 84%, the moisture content is less than 1%, reached the "Twelfth Five-Year" major projects of national requirements' indicators; added 11ml/100g breaker SW-B, 10g/100g lime and 30g/100g cement to system for curing the waste drilling fluid, the solidified strength of the cured than 0.5MPa; Determined to leaching toxicity of solid waste, the pollution index of leaching toxicity of solid waste meeting National Integrated wastewater discharge standard (GB8978-1996).

The Uranium Biosorption by Chlorella Pyrenoidosa and its Physiological Responses to Uranium

2012 ◽  
Vol 610-613 ◽  
pp. 40-43
Author(s):  
Jia Sun ◽  
Guo Ping Yu ◽  
Yue Li
Keyword(s):  
Normal Level ◽  
Physiological Responses ◽  
Chlorella Pyrenoidosa ◽  
Future Application ◽  
Good Prospect ◽  
Low Concentration ◽  
Negative Effect ◽  
Lag Period ◽  
Positive Effect ◽  
Uranium Biosorption

The effect of uranium at various concentration on the growth of Chlorella pyrenoidosa and the resistance of Chlorella pyrenoidosa to uranium were investigated in this paper. The results showed that the content of O2- and the activity of CAT arose when the concentration of uranium varied at the range of 0.1 to 1.0 mg/L. Uranium had no negative effect on the growth of Chlorella pyrenoidosa at the concentration of 0.1 to 0.5 mg/L, however, had positive effect to some extent. And the rise of the content of O2- and the activity of CAT was followed by rapidly returning to the normal level. The uranium at the concentration of 1.0 mg/L prolonged the lag period of the growth of Chlorella pyrenoidosa. The growth of Chlorella pyrenoidosa arose negatively, the content of O2- also arose to an unreturnable level and the activity of CAT was lower than CK when the concentration of uraniumm varied at the range of 5.0 to 10.0 mg/L. The uranium biosorption rate by Chlorella pyrenoidosa reached to the highest value of 70.43%when concentration of uraniumm was 0.5 mg/L. Chlorella pyrenoidosa is resistant to uranium of low concentration（≤1.0mg/L）and its biosorption rate is rather high, which indicated good prospect in its future application.

scholarly journals Eco-environmentally friendly operational regulation: an effective strategy to diminish the TDG supersaturation of reservoirs

2013 ◽  
Vol 10 (11) ◽  
pp. 14355-14390 ◽  
Author(s):  
J. J. Feng ◽  
R. Li ◽  
R. F. Liang ◽  
X. Shen
Keyword(s):  
Environmentally Friendly ◽  
Discharge Pattern ◽  
Dimensional Model ◽  
Dissolved Gas ◽  
Power Station ◽  
Power Stations ◽  
Regulation Scheme ◽  
Negative Effect ◽  
Gas Bubble Disease ◽  
Natural Rivers

Abstract. The presence of elevated total dissolved gas (TDG) downstream of a spillway may result in an increased incidence of gas bubble disease in fish. Supersaturated TDG is transported and dissipated more slowly in reservoirs than in natural rivers because of a higher water depth and lower turbulence and endangers fish. This paper presents the operational regulations concerning the mitigation of the TDG supersaturation impact on fish in the Bala Reservoir on the Zumuzu River. The paper includes the joint operations of the upstream and downstream power stations. A laterally averaged two-dimensional model is employed to simulate the TDG transportation and dissipation in the Bala Reservoir in addition to the hydrodynamics and water temperature. According to a comparison of the simulation results of different operational scenarios, this paper suggests a regulation scheme. With respect to the upstream power station, the adoption of an interval-discharge pattern instead of a continuous-discharge pattern is recommended to minimize the negative effect on the reservoir caused by supersaturated TDG. With respect to the downstream power station, the adoption of a surface tunnel rather than a bottom tunnel is recommended as a release structure. This paper is a reference for the eco-environmentally friendly operation of large and deep reservoirs.

scholarly journals Effect of Potassium Chlorate on the Treatment of Domestic Sewage by Achieving Shortcut Nitrification in Constructed Rapid Infiltration System

2018 ◽  
Author(s):  
Qinglin Fang ◽  
Wenlai Xu ◽  
Zhijiao Yan ◽  
Lei Qian
Keyword(s):  
Nitrogen Removal ◽  
Accumulation Rate ◽  
Carbon Sources ◽  
Potassium Chlorate ◽  
Nitrite Accumulation ◽  
Ammonia Oxidizing Bacteria ◽  
Treatment Technology ◽  
Obvious Effect ◽  
Removal Method ◽  
Denitrification Process

Constructed rapid infiltration system (CRI) is a new type of sewage biofilm treatment technology, but due to its anaerobic zone lacks of the carbon sources and the condition for nitrate retention, its nitrogen removal perfomance is very poor; However, shortcut nitrification-denitrification process presents distinctive advantages, as it saves oxygen, requires less organic matter and needs less time for denitrification compared to conventional nitrogen removal method. Thus, if the shortcut nitrification-denitrification process could be applied to CRI system properly, the simpler, more economic and efficient nitrogen removal method will be obtained. But, as its reaction process shows that the first and the most important step of achieving shortcut nitrification-denitrification is to achieve shortcut nitrification. Thus, in this study, we explored the feasibility to achieve shortcut nitrification, which produces nitrite as the dominant nitrogen species in effluent, by addition of potassium chlorate (KClO3) to the influent. In an experimental CRI model system, the effects on nitrogen removal, nitrate inhibition and nitrite accumulation were studied, and the advantages of achieving shortcut nitrification-denitrification were also analysed. The results showed that shortcut nitrification was successfully achieved and maintained in a CRI system by adding 5 mM KClO3 to the influent at a constant pH of 8.4. Under these conditions nitrite accumulation rate was increased, while a lower concentration of 3 mM KClO3 had no obvious effect. The addition of 5 mM KClO3 in influent presumably allowed sufficient activity of ammonia-oxidizing bacteria (AOB) but inhibited nitrite-oxidizing bacteria (NOB) strongly enough to result in a maximum nitrite accumulation rate of up to over 80%. As a result, nitrite became the dominant nitrogen product in the effluent. Moreover, if the shortcut denitrification will be achieved in the subsequent research, it could save 60.27 mg carbon source (CH3OH) consumption when treatment of per liter sewage in CRI system compared with full denitrification process.

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