Pre-anoxic/Orbal Oxidation Ditch/Rotary Disc Filter Treatment of Mixed Sewage in Industrial Park

The design scale of a sewage treatment plant in the industrial center of a district in Changzhou is 2×10^(4) m^(3)/d. Data analysis, process selection and analysis and main structure design were carried out for the sewage treatment plant to ensure that the effluent quality meets the discharge standards. The operation results after the implementation of the project show that the project can effectively improve the effluent quality of the sewage treatment plant. The removal rates of COD, NH+4, TN and TP are 93.97%, 98.63%, 82.67% and 97.37% respectively, and the effluent quality can be discharged stably up to the standard. Using cost analysis to study the operation of the sewage treatment plant, the results show that the total investment of the sewage treatment plant is 40 million yuan, the electricity cost of this project is 0.426 yuan/m^(3), the pharmaceutical cost is 0.655 yuan/m^(3), and the material replacement fee is 0.323 yuan/m^(3). The direct operating cost is 1.404 yuan/m^(3). This method has good practical guiding significance for the optimization and operation transformation of the same type of sewage treatment plants.

Study on Electrokinetic Remediation of Cadmium-contaminated Soil

In order to improve electrokinetic remediation efficiency of cadmium-contaminated soil,the effects of electric field intensity,remediation time and electrolyte on removal rate of total Cd in Cd-contaminated soil by electrokinetic remediation were studied through the preparation of Cd-contaminated soil and the construction of electrokinetic remediation equipment. The results showed that under the same condition,with the electric field intensity increasing from 2. 5 to 3 V/cm,the total Cd removal rate increased by 10. 62%,and with the increase of the electric field intensity from 3 to 3. 5 V/cm,the removal rate increased by 1. 87%;when the remediation time was prolonged from 72 to 96 h,the removal rate of total Cd increased by 6. 68%,and with the remediation time prolonged from 96 to120 h,the removal rate of total Cd increased by 8. 75%; and with the remediation time prolonged from 120 to 144 h,the removal rate of total Cd only increased by1. 07%. Compared with citric acid as the electrolyte,the acetic acid group improved the remediation efficiency by 12. 14% and the total energy consumption by62. 13%,while the hydrochloric acid group improved the remediation efficiency by 18. 04% and the total energy consumption by 187. 9%. Comprehensively from total Cd removal rate and energy consumption,the remediation effect was the best under the electric field intensity of 3 V/cm and the electrokinetic time of 120 h with acetic acid as the electrolyte,which achieved a total Cd removal rate of 41. 95%.

Experimental Study on In-situ Leaching and Electrokinetic Remediation of Composite Heavy Metal-contaminated Soil

[Objectives] This study was conducted to investigate in-situ leaching and electrokinetic combined remediation of composite heavy metal-contaminated soil.[Methods] Leaching and electrokientic combined remediation was applied to remediate artificially-simulated composite Cd,Cu,Pb,and Zn-contaminated soil.The electrokinentic remediation of the soil was carried out using EDTA and acetic acid as the eluents with electrodes placed on the top and bottom of the soil,to investigate the effects of different types and concentrations of eluents,reaction time and energization methods on the remediation.[Results]Applying electrodynamic force to the leaching remediation process achieved good removal effects of Cd,Cu,Pb,and Zn in the soil.Compared with pure leaching,the leaching and electrokinetic combined remediation saved 23.8% of EDTA consumption.EDTA showed the ability to complex heavy metals better than acetic acid,and after 10 d of reaction,the 0.1 mol/L EDTA achieved very good removal effects on Cd,Cu,Pb,and Zn from the upper and middle layers of the soil column,exhibiting removal rates of 94.4%,93.3%,91.4% and 92.8% in the upper layer and 87.2%,88.2%,83.3% and 84.6%,respectively.Compared with the conventional experiments,the intermittent energization method and the voltage-increasing method improved the removal rates of Cd,Cu,Pb and Zn by 6.3%,6.1%,5.9%and 6%,and 0.6%,0.9%,0.5% and 0.4%,respectively,and saved 46.8% and 10.3% of energy consumption,respectively.[Conclusions]The study provides reference for the remediation of composite heavy metal-contaminated soil.

Study on CeO_2/CuFe_2O_4 Catalytic Ozonation of Resorcinol

In order to improve the catalytic ozonation effect of resorcinol, the spinel CuFe_2O_4 was modified by doped CeO_2, and X-ray diffraction(XRD) and scanning electron microscopy(SEM) were used for characterization analysis. The effects of composite catalyst CeO_2/CuFe_2O_4 dosage, ozone dosage, initial pH and reaction temperature on degradation were studied, and the stability of the catalyst was tested. The results showed that the composite effect of CeO_2/CuFe_2O_4 prepared by combustion method was good, and the catalyst presented a laminated structure, in which 30 wt% CeO_2/CuFe_2O_4 degradation effect was significant. The removal rate of resorcinol using CeO_2/CuFe_2O_4 composite catalyst was higher than that using ozone or CuFe_2O_4 separately by 41.8% and 11.9%, respectively. In a reaction with resorcinol concentration of 100 mg/L, the catalyst dosage of 1.0 g/L, the ozone dosage of 2.5 mg/(L·min), at pH=9, temperature of 20 ℃, for reaction time of 40 min, the resorcinol removal rate was 88.5%. The catalyst CeO_2/CuFe_2O_4 still showed good degradation effect after repeatedly using for 10 times, and the dissolution rate of metal ions was lower than that of CuFe_2O_4.

Discussion on Preparation and Application of BiOIO_(3)-based Composite Materials

BiOIO3 is a layered semiconductor photocatalyst,which has good chemical properties and has attracted wide attention from researchers because of its unique structure.However,pure BiOIO3 has defects such as insufficient response to visible light and easy recombination of photogenerated electrons.Therefore,in recent years,scholars have tried to modify BiOIO3 to expand its light absorption range,reduce the recombination of photogenerated electron-hole pairs and reduce its limitations,thereby improving its visible light catalytic performance.Current researches focus on the improvement of the catalytic activity of photocatalytic materials from morphology control,precious metal deposition,ion doping and construction of heterojunctions.

Electrokinetics-magnetic/alkali Composite-modified Biochar for Remediation of Cd-contaminated soil

[Objectives]This study was conducted to explore the removal performance and mechanism of heavy metal Cd in soil by combining electrokinetic technology and modified biochar.[Methods]The electrokinetics-magnetic/alkali composite-modified biochar method was applied to remediate Cd-contaminated soil.[Results]When remediating the soil for 120 h under electric field strength of 2 V/cm with 0.1 mol/L citric acid as the electrolyte,the current periodically varied with the remediation time.Cd^2+in the soil dissociated and migrated from the soil surface,and the addition of the magnetic/alkali composite-modified biochar in the cathode area affected the hydrolysis balance of heavy metal Cd^2+ions and maintained soil pH in a low range.The exchangeable Cd content at the test sampling points near the cathode area was relatively high,and the organic Cd area was evenly distributed.The average removal rate of Cd in the soil was up to 90.31%.The hexagonal anode device configuration enhanced the electromigration performance and made the soil pH and conductivity change within a certain range,which was beneficial to the migration of Cd2+and improved the removal rate of soil heavy metal Cd.[Conclusions]This study provides a theoretical basis for the treatment of soil heavy metal pollution and the resource utilization of composite-modified biochar.