Biomedical subjects

Qifang Luo

Publications and source records attributed to Qifang Luo.

8 recordsLinked to original sources

PubMed2004

[Screening and characterization of dominant bacteria for the degradation of endocrine disruptor di-n-butyl phthalate].

OBJECTIVE: In order to screen the dominant bacteria for degrading endocrine disruptor di-n-butyl phthalate (DBP). METHODS: The activated sludge was acclimated by DBP as sole carbon source. DBP concentration was increased progressively. 5 strains were isolated from the sludge by the plane-table after 10 weeks, 1 strain of which grew and degraded DBP well. RESULTS: By orthogonal test, it was indicated that the appropriate degradation conditions of DBP for this best strain were degradation time 32 h, DBP concentration 200 mg/L, rate of shaking incubator 100 r/min, pH 7.0, temperature 30 degrees C. The degraded rate of DBP is more than 95% under above conditions. CONCLUSION: The bacterium was identified as Pseudomonas.

Bacteria↗

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↗

PubMed2003

[Study on biodegraded characteristics of endocrine disruptor di-n-butyl phthalate].

The biodegraded Characteristics of di-n-butyl Phthalate (DBP), endocrine disruptor were studied. The activated sludge was acclimated using DBP as the only carbon in the culture medium. DBP concentration was increased progressively from 0.05 g/L to 0.5 g/L. The degradation tests were carried out on the constant temperature table using the acclimated sludge at different PH, temperature, DBP concentration and hydraulic residence time. The results showed that DBP could be rapidly degraded-nearly 90% in 48 hours. The appropriate condition for DBP degradation was pH 6.0-8.0, temperature 25 degrees C-35 degrees C, DBP concentration no more than 300 mg/L, and hydraulic residence time 12 h-24 h. The form of biodegradation of DBP can be described as the first-order reaction model.

Biodegradation, Environmental↗

PubMed2002

[Distribution and role of denitrifying, nitrifying, nitrosation and ammonifying bacteria in east lake].

The most probable number (MPN) method was employed to determine the distribution and role of four nitrogen cycle bacteria, including ammonifying bacteria, denitrifying bacteria, nitrosobacteria and nitrobacteria, in East Lake, Wuhan. The results showed that the n(MPN) of nitrosobacteria in water was most in rainy season and least in dry season, while the number in common season between them. The n(MPN) of water nitrobacteria in rainy season was less than in the other two seasons. The n(MPN) of water ammonifying and denitrifying bacteria were most in common season, least in dry season. The n(MPN) of nitrosobacteria in sediment in rainy season was more than that in other seasons. The n(MPN) of sediment nitrobacteria was most in dry season while denitrifying bacteria was more in dry season than in other seasons. The n(MPN) of ammonifying bacteria had no difference among three seasons. Compared with water phase, the n(MPN) of nitrosobacteria in sediment phase was more in rainy and dry season (p < 0.01), while nitrobacteria's number was prevailing in water phase during common and rainy season while denitrifying bacteria's was prevailing only in common season(p < 0.01). The ammonifying bacteria had no difference in water and sediment. The results demonstrated that the difference in distribution of four nitrogen cycle bacteria in two phase and three season played a significant role in nitrogen removal, which promoted ammoniation, nitrification, nitrosification and denitrification in lake. The study also found that the lg[n(MPN)] of denitrifying and ammonifying bacteria in water and sediment had significant correlation with the catching gas volume(p < 0.001). Furthermore, different season had different gas volume (p < 0.01), which showed that ammoniation and denitrification could convert organic nitrogen and nitrate into gas nitrogen(NH3, N2O, N2) and also varied greatly with different season.

Ammonia↗

PubMed2002

[Variations and transformations of nitrogen pollutants in source and tap water of D-lake].

Ammonia, nitrite and nitrate pollutions and variations in source water and tap water of D-Lake are investigated. The removal effects of nitrogen in routine proceeding of water production and the transformations of the different forms of nitrogen in natural condition with simulated test are studied at the same time. The results show that the nitrogen pollutions in source and tap water of D-waterworks are higher than T-waterworks', although both waterworks have same resource. Compared with D-waterworks, the nitrogen pollutions of source and tap water in Z-waterworks are lower than D-waterworks' and they have different variation and distribution. The forms of nitrogen could be partly transformed during the routine production, but the total percentage of nitrogen removal efficiency is not significant (just about 20%). The simulate test shows that NH4+(-)N could change into NO2-(-)N, while No2-(-)N into NO3-(-)N, which is partly transformed into nitrogen gas by microorganism and majority of which are remained in tap water by form of NO3-(-)N.

Ammonia↗

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↗