Biomedical subjects

Youming Tan

Publications and source records attributed to Youming Tan.

4 recordsLinked to original sources

PubMed2004

[Development of coated electrode of immobilized denitrifying bacteria and bio-electrochemical denitrifying reactor].

OBJECTIVE: A coated electrode of immobilized denitrifying bacteria was developed to study the feasibility of electrochemical denitrification. METHODS: The coated electrode of denitrifying bacteria was made by batch cultivation and PVA immobilization using activated carbon fiber (ACF). The coated ACF electrode was used as cathode, while graphite as anode in bioelectrochemical reactor. RESULTS: After having been acclimated in two stages, mixotrophic and autotrophic denitrification stages, the denitrifying bacteria could use hydrogen as electron donor to reduce nitrate. When the initial nitrate concentration was 30.7mg NO3- -N/L, the denitrification rate was 38.4% at an applied electric current of 10mA and a hydraulic retention time of 12 hours. CONCLUSION: With great surface area and a rough surface, it was very easy to develop a biofilm on ACF. The membrane of PVA gel could adhere to the surface of ACF firmly. After having been acclimated, the denitrifying bacteria could use hydrogen generated by the electrolysis of water to be treated as electron donor to reduce nitrate.

Ammonia↗

PubMed2004

[Factors affecting denitrification by denitrificans coated electrode].

OBJECTIVE: To optimize the efficiency of coated electrode denitrifying reactor. METHODS: Synthetic groundwater was treated by coated electrode denitrifying reactor submitted to different operational parameters, such as electric current intensity (CI), oxidation reduction potential (ORP), hydraulic retention time (HRT) and temperature. RESULTS: Denitrification efficiencies of the reactor was found to be related with the applied electric current. The denitrification efficiency was 57.3% with a HRT of 12 hours and the optimum applied electric current intensity was 15 mA. Nitrate removal rate of the reactor was calculated to be 34.4 g NO3(-)-N/m3 x d. Denitrification efficiencies were also found to be related to HRT. The average denitrification velocity was 0.183 mg NO3(-)-N/h within 12 hours. The denitrification rates increased when the temperature of synthetic water raised from 5-35 degrees C. After the electrodes had been connected to the power supply for 1 hour, the concentration of dissolved oxygen (DO) and ORP decreased sharply to 1.08 mg/L and -40 mV, respectively. CONCLUSION: An adaptable reduction environment could be set up in the reactor for autotrophic denitrification shortly after the bio-electrochemical reaction began. The optimum electrode potential and current density were 2.5 V and 0.083 mA/cm2 . As the bio-electrochemical reaction went on, the pH volume decreased sharply, and nitrite accumulation was found corresponsively, which leads to the inhibition of denitrification. HRT should be controlled within 12 hours. Anode oxidation reaction could offer inorganic carbon sources for autotrophic denitrifying bacteria, but might lead to pH increase, should be paid attention in the practical operation.

Bioreactors↗

PubMed2003

[Study on denitrification using different carbon sources].

In this study, bench scale tests were conducted to study the potentials of immobilized denitrifier to reduce nitrate in the presence of 4 different carbon sources: glucose, cane sugar, methanol and acetic acid. The results showed that the carbon sources can be used by the immobilized bacteria as exogenous carbon sources. While using methanol, the average denitrifying velocity was lower than the others. Dissimilatory reduction to ammonium was not significant and accounted for less than 5% of reduced nitrate. By a 6-hour hydraulic residence time, the denitrification rates were higher than 96%. The nitrate enriched water of S lake was also treated by the immobilized denitrifier to study the character of denitrification, especially on the using of natural carbon sources as electron donotor. The results showed that more than 90% of the nitrate in the water could be reduced by the immobilized bacteria, and more than 20% of the natural carbon sources in the water could be used by the immobilized cells.

Acetic Acid↗

PubMed2002

[Study on the denitrification of drinking water with upflow anaerobic sludge blanket reactor].

The characteristics of denitrification was investigated with a pilot scale upflow anaerobic sludge blanket (UASB) reactor at room temperature. The results showed that when brewery waste degrading sludge was used as seed, the starting process was completed within 7 weeks, with hydraulic residence time shortened from 11.1 h to 4.7 h, COD/N/P = 200/5/1 and influent NO3-(-)N concentration increased from 5 mg/L to 100 mg/L. After the process starting, the most probable number [n(MPN)] of denitrifying bacteria was 60 folds and the maximum velocity of CH4 produced was 10 folds higher than before. The removal efficiency of No3-(-)N was 99%, C/N ratio and pH value were investigated as effect factors. When C/N > = or 1.0, the NO3(-)-N removal efficiencies were not different from those of C/N < 1.0 groups significantly. The pH value could meet the discharge standards.

Nitrates↗