Research on the organic biodegradability of secondary effluent treated by ozonation
Key Laboratory of Beijing for Water Quality Science and Water Environmental Recovery Engineering, Beijing University of Technology, Beijing 100124, China.Huan jing ke xue= Huanjing kexue / [bian ji, Zhongguo ke xue yuan huan jing ke xue wei yuan hui "Huan jing ke xue" bian ji wei yuan hui.] 02/2010; 31(2):363-7.
The secondary effluent of three WWTPs was treated by ozonation to investigate organic biodegradability enhancement. The bulk experimental method was used. Ozone adding dosage was controlled to be 2, 4, 6, 8, 10 mg/L by adjusting the adding time. Results showed, UV254 and SUVA(UV254/DOC)decreased with the increasing of the ozone dosage. When ozone adding dosage was 6 mg/L, UV254 and SUVA decreased about 54.4% and 56.6% respectively; while BOD5/COD, BDOC and BDOC/DOC were improved above 30%, 360% and 360% respectively. It could be concluded that suitable ozonation could improve the biodegradation of the organic substances in the secondary effluent. The organic substance was analyzed by the excitation-emission matrix (EEM) to investigate the variation regularity of organic matter changes of the ozoned and non-ozoned secondary effluent. The main organic substances of the secondary effluent in the plant were aromatic protein like substances and humic substances, ozone could significantly remove these types of organic substance.
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ABSTRACT: In order to improve the water treatment performance of ozone in recirculating aquaculture systems, and enhance its application safety in the field of aquaculture, the O3/UV integration reaction system were designed. The reaction system was mainly composed of ozone addition dissolved area, ultraviolet catalytic reaction area, stay reaction area. The system was 1 250 mm of high, 750 mm in diameter, and the ultraviolet catalytic reaction was 400 mm in diameter. The working principle of system was that using static mixer way to add ozone, which could dissolve wastewater high efficiency and low energy consumption in ozone addition dissolved area. The wastewater with not completely dissolved ozone bottom up entered to ultraviolet catalytic reaction area, which could generate two advantages. On one hand, under the ultraviolet catalysis, the stronger oxidizing of hydroxyl was produced in further reaction, accelerated the rate of degradation of organic matter, and enhanced the effect of disinfection sterilization. On the other hand, it could reduce the residual amount of ozone in cultivation water, which improved the safety of the device. After treating in ultraviolet catalytic reaction area, the wastewater enter into the reaction area, which the main purpose was to keep a certain residence time of wastewater, and to improve the purification effect of degradation of organic matter and the ammonia nitrogen removal. The relationship of the suitable ozone dosage and wastewater treatment capacity in the ozone additive dissolved area, the process parameters about the ratio of ultraviolet radiation dose and the influence factors of wastewater purification and disinfection sterilization were studied through the test method. The experimental results showed that: 1) Under the condition of meeting with a certain water of dissolved ozone concentration, it could improve ozone dissolution rate and utilization rate through using low ozone inlet flow rate and low water flow. When the wastewater flow was 5 m3/h and the ozone dosage was 8.17 g/h, the ozone dissolution rate was 82.7%, the concentration of ozone in wastewater was 1.53 mg/L and the ozone utilization rate was up to 97.7%. 2) It could improve the removal rate of ozone residual quantity in wastewater by means of increasing the number of UV and lamp power. The effect of performance improvements was more obvious through increasing the number of UV lamp. When the UV additive amount was 1 996 MJ/cm2 and the residual ozone concentration of 1.36 mg/L of influent wastewater in this system, the removal rate of residual ozone could be up to 83.82%, which achieved low residual ozone in aquaculture water and ensured the safety of breeding biology. 3) Compared with using ozone separately, the removal rate of UV254, total organic carbon, chemical oxygen demand and water colour of this system were increased to 109.95%, 89.77%, 29.25% and 51.44%, respectively, and the sterilization removal rate could be more than 97%. The integration reaction system had the feature of disinfection sterilization of aquaculture wastewater, degradation of organic matter efficient, removing water colour and increasing dissolved oxygen, which showed a better wastewater treatment performance. ©, 2014, Chinese Society of Agricultural Engineering. All right reserved.
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ABSTRACT: The inactivation characteristics of Escherichia coli and Bacillus subtilis spores, the removal efficiency of dissolved organic carbon(DOC), color, UV254 and fluorescence intensity with ozone were investigated in a practical reuse water in Beijing. The transferred ozone(TOD) was used as ozone consumption dose. Furthermore, the correlation between inactivation characteristics of pathogenic microorganisms and color was analyzed. Results showed that inactivation characteristics of Escherichia coli and Bacillus subtilis spores with ozone were associated with residual ozone concentration(CR) in water. When CR was lower than the detection limit, the inactivation rate of Escherichia coli increased slowly with the increase of TOD. When TOD increased 3 mg/L, the inactivation rate increased 1.5 log. No significant inactivation of Bacillus subtilis spores was observed. When CR was greater than 0, the inactivation rate of Escherichia coli increased much more quikly with the increase of TOD. When TOD increased 3 mg/L, the inactivation rate increased 3 log. The inactivation rate of Bacillus subtilis spores also increased quickly with the increase of TOD. In the ozone disinfection process, no significant changes in DOC were observed. But the removal efficiency of color, UV254 and fluorescence intensity was obvious. When color no longer changed with the increase of TOD, CR in water began to rise quikly and pathogenic microorganisms began to enter into efficient inactivation phase.
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