Key Laboratory of Northwest Water Resources

Key Laboratory of Northwest Water Resources

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Su J.F.,Xi'an University of Architecture and Technology | Su J.F.,Key Laboratory of Northwest Water Resources | Lian T.T.,Xi'an University of Architecture and Technology | Huang T.L.,Xi'an University of Architecture and Technology | And 5 more authors.
Ecological Engineering | Year: 2017

Harmful algal blooms (HABs) could be deemed hazardous materials in aquatic environments. In this study, we investigated aerobic denitrification and algicidal effects of the Raoultella sp. R11. Based on PCR amplification, the denitrification genes napA was detected. A response surface methodology (RSM) analysis demonstrated that the maximum nitrate removal ratio was 96.06%, and optimal conditions occurred for inoculum of 13.02% (v/v), initial pH of 6.65, C/N ratio of 7.59 and temperature of 27.08 °C based on a ridge analysis. When the Microcystis aeruginosa flour as carbon and nitrogen source for denitrification in aerobic conditions, the NO3 −-N and TOC removal ratios were 72.36% and 85.56%, respectively. Additionly, the denitrification rate was 0.0123 mg L−1 h−1. Furthermore, the infrared spectrogram and SEM images showed the M. aeruginosa cell structure was destroyed, indicating that R11 could use algal death for denitrification. Therefore, Raoultella sp. R11 played a crucial role for simultaneous denitrification and algicidal effects in wastewater treatment. © 2017 Elsevier B.V.

Wei H.,Key Laboratory of Northwest Water Resources | Li J.,Key Laboratory of Northwest Water Resources | Shi H.-X.,Gas Technology Institute | Li K.-B.,Northwest University, China
2011 International Conference on Electric Technology and Civil Engineering, ICETCE 2011 - Proceedings | Year: 2011

The effect of ultrasonic on the oil-containing wastewater's flocculation by PAM and PAC as flocculatants were studied. The results indicated that PAM and PAC showed effective flocculating effect on the removal of oil and CODcr from the simulated wastewater, and the experimental optimum conditions for PAM were, dosage 2.0mg/L, pH unbuffered, reaction time 2.0min, precipitation 30min, the removal efficiency of COD and oil achieved 50.03% and 43.3%, respectively. The removal efficiency of COD and oil achieved 43.2% and 37.8% for PAC at the same conditions except the dosage of PAC was 80mg/L. Ultrasonic can degrade the wastewater obviously, and the degradation efficiency increased with the increasing of ultrasonic power and reaction time, removal efficiency of COD and oil were 48.9% and 44.6% under the condition of power 150W, reaction time of 90min. Ultrasonic/ flocculation experiment indicated that ultrasonic enhanced the flocculation effect of PAM and PAC on oil-containing wastewater, the removal efficiency of COD and oil were above 60% under ultrasonic power of 135W, reaction time of 30min, pH unbuffered at the same flocculation conditions above mentioned. However, Ultrasonic and floccalation had no obvious synergy effects on oil-containing wastewater. Then the experimental schemes of first ultrasonic, then flocculation and first flocculation, then ultrasonic were adopted to degrade oil-containning wastewater furtherly, the results showed the effect of ultrasonic and flocculation were correlated with wastewater's concentration to a great degrees. © 2011 IEEE.

Dang Y.,Northwest University, China | Li K.-B.,Northwest University, China | Luo Q.,Northwest University, China | Wei H.,Key Laboratory of Northwest Water Resources | Guo H.-S.,Second Plant of Operation Management Company
2011 International Conference on Electric Information and Control Engineering, ICEICE 2011 - Proceedings | Year: 2011

A low cost agricultural waste buckwheat hull after extracted natural pigment was used as bisorobent for removal of a cationic dye methylene blue from aqueous solution. The sorbent was characterized by FTIR, scanning electron microscopy (SEM), and potentiometric mass titration. The results showed that buckwheat hull is porous material with functional groups such as hydroxyl and carboxyl, and the pHzcp the initial dye concentration of 100 mg/L. At the optimized condition the maximum removal was found to be 99.54%, which is found to be at pH 4.12. The kinetics of adsorption of methylene blue onto buckwheat hull at five different initial concentrations was determined by batch experiments. The obtained data were analyzed by pseudo-first-order, pseudo-second-order, and intraparticle diffusion equations. Sorption processes were found to follow pseudo-second order kinetics. Intraparticle diffusion was found to take part in sorption processes but it could not be accepted as the primary rate determining step. Response surface methodology based on Box-Behnken design was used to further evaluate the effects of important parameters, namely, pH, initial dye concentration and temperature on the percentage removal of dye. A quadratic model for predicting the optimum point was established. The optimum conditions for removal of dye from water were found to be as follows: adsorbent concentration of 0.3 g per 50 mL of dye solution, pH 6.0, temperature of 40 C, and was in good agreement with the experimental value. This study further implies that buckwheat hull is a promising sorbent for removal of dye from water. © 2011 IEEE.

Wei H.,Key Laboratory of Northwest Water Resources | Yang H.,Key Laboratory of Northwest Water Resources | Zhao L.,Key Laboratory of Northwest Water Resources | Li K.-B.,Northwest University, China | Yu X.-L.,Key Laboratory of Northwest Water Resources
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2014

The intensification of levofloxacin degradation in ultrasonic/H2O2/fly ash combined system was studied. The experimental parameters such as fly ash adding amount, H2O2 concentration, pH value and levofloxacin initial concentration on degradation efficiency were evaluated. The results indicated that when compared with single sonolysis, H2O2 oxidation, ultrasonic/H2O2 and fly ash/H2O2 binary systems, levofloxacin degradation was markedly promoted in ultrasonic/H2O2/fly ash ternary system. Levofloxacin degradation in ultrasonic/H2O2/fly ash system followed apparent first-order kinetics. The removal efficiency for 20 mg/L levofloxacin under fly ash adding amount of 1.5 g/L, H2O2 concentration of 15.0 mmol/L, pH 7.16, and ultrasonic power of 325 W could achieve 99.12% within 160 min treatment, whereas TOC removal only attained 17.37%. Fluorescence probe analysis indicated that the combination of ultrasonic/H2O2/fly ash enhanced the heterogeneous Fenton-like reaction on fly ash surface. HPLC/MS/MS analysis revealed that three intermediates were generated, which derived from demethylation of the piperazinyl ring, the transformation of the quinolone moiety through the loss of C2 and attack of quinolone moiety by ·OH.

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