Advanced Materials Research Vols. 726-731

Abstract: Papermaking wastewater effluent from a biological processing unit was treated by an advanced treatment method-electrochemical oxidation process. The experiments were carried out in an electrochemical reactor using RuO₂\SnO₂ coated on titanium as anode and stainless steel as cathode. The changes of Chemical Oxygen Demand (COD) reduction and other relative parameters have been determined as a function of treatment time and applied current density. The optimum reaction time and current density was 60min and 5mA/cm², respectively. Results indicate that as an advanced treatment method, electrochemical oxidation can treat papermaking wastewater to achieve the standard of effluents effectively.

Abstract: Based on a large number of mine geological environment treatment project experience and theoretical results, the basic principles of mine geological environment management were generalized, they are overall planning, implementation step by step; adjust measures to local conditions, assisting nature; ecological priority, comprehensive treatment; ensuring safety, doing according to its abilities; minimum intervention, landscape harmonious; feasibility in technology, rationality in economy; dynamic design, timely adjust. These principles will help to reasonably determine the treatment targets, and for the right design scheme.

Abstract: Based on the enhanced formation of hydroxyl free radical (OH), Strengthen ozone oxidation can intensify the oxidizing ability and lower reaction selectivity as a kind of the Advanced Oxidation Technologies (AOTs). This paper introduces the research progress of strengthen ozone oxidation technology such as H₂O₂ strengthen, catalytic strengthen, UV strengthen, ultrasound strengthen, hydrodynamic cavitations strengthen et al, and points out the research focus and application prospects of this technology.

Abstract: In this paper, poly(vinylidene fluoride) nanofiber was prepared by an electrospinning method. Graphene oxide sheets was obtained via filtration from graphene oxide aqueous solution which synthesized by Hummers method. By sonication, a homogeneously dispersed and well distributed poly acylic acid and graphene oxide nanosheets solution were obtained, and this can be used to modify the neat poly (vinylidene fluoride) nanofiber membrane for not only increasing the hydrophilic properties but also improving the mechanical properties. The poly(vinylidene fluoride)/graphene oxide composite membrane was characterized by SEM, FT-IR, pore properties and mechanical properties. The composite membrane showed an appropriate pore size, excellent mechanical property comparing with pure poly(vinylidene fluoride) membrane. The results showed the membrane could be feasibly used as a MF membrane.

Abstract: Three columns filled with multi-size combined medium were utilized in the simulative vertical-flow constructed wetland systems to treat wastewater at hydraulic loading rate of 2000-3000 mm/d, that the same kind of media including biological ceramsite, anthracite and zeolite in each column. Comparative analyses were made in treatment performances between multi-size medium and single medium. The results showed that compared with the treatment performances of single medium, the purifying effect had great influence by the multi-size combined medium which were made up of same kind and different size of filter medium. Contrast with the corresponding single medium, the average removal efficiencies of COD_Cr, Total Nitrogen (TN), and Total Phosphorus (TP) were increased obviously which were purified by the multi-size combined medium. Good performances were achieved in terms of removal of BOD₅ and COD_Cr in the column of multi-size combined biological ceramsite medium. The average removal efficiencies of TN were great in the column of multi-size combined zeolite medium. Good performances were also achieved in terms of removal of TP in the column of multi-size combined anthracite medium.

Abstract: The zero-valent iron (Fe⁰) and the activated carbon were used as reaction mediums, the reactivity characteristics and removal effect of hexavalent chromium (Cr (VI)) contaminated ground water using Fe⁰/AC-PRB were investigated. The results showed that AC adsorbed Cr (VI) under the pH conditions of influent, and Cr (VI) was removed. Also, the chromium could be deoxidized by zero-valent iron effectively, when simulated groundwater containing 10mg/L hexavalent chromium was continuously input. During the process, the redox products, Fe³⁺ and Cr³⁺, precipitated on the reaction media without transferring into downstream water. The pH value increased from 7.0 in influent to 8.0 in effluent, and the total iron concentration of effluent was below 0.30mg/L. Chromium was distributed mainly in the form of organic/sulphide fraction and residue fraction when the aquifer was flushed with deionized water, Moreover, bioavailable weak acid extractable fraction was not detected, indicatinga low ecological risk of chromium remained in the aquifer.

Abstract: In this study efficiency of organic matter in municipal wastewater sludge treated by supercritical water is investigated. Influences of main reaction parameters, including temperature (380~500°C), pressure (23-30 MPa), residence time (1-10 min), oxidant dose (100%-200%), were evaluated. Orthogonal Array design was applied in order to consider each parameters impact on COD removal. Study results indicate that 97.89% of COD in the sludge sample can be removed in 10min at 500°C, 30MPa and 200% H₂O₂ oxidant excess dose. Temperature, pressure, resident time are main factors to affect the reaction, while oxidant dose has a little effect on removal of COD in municipal wastewater sludge. The conclusion is the organic matter in municipal wastewater sludge can be removed effectively by super critical water oxidation.

Abstract: Coke was modified as adsorbent for advanced treatment of coking wastewater and different factors on the impact of wastewater COD removal have been studied. The results showed that pH and temperature effect little on the COD removal and COD of coke wastewater could be reduced from 93mg/L to 48mg/L in the condition of 60 min adsorption time , 300r/min speed revolve and 13g adsorbent dosage. per 200ml water.

Abstract: The treatment on the secondary biochemical effluent of pulp and paper wastewater by Fenton oxidation was studied and the influence of H₂O₂ dosage, Fe²⁺ dosage, pH and reaction time on the treatment effect was investigated by the orthogonal test and single-factor test. The treatment effect was eminent when the H₂O₂ dosage was 3.75mmol/L, Fe²⁺ dosage was 3.20mmol/L, pH was 4.00 and the reaction time was 80.00min. The removal rate of UV₂₅₄ and chromaticity significantly increased as H₂O₂ dosage was 1.88 ~ 3.75mmol /L, but the COD removal rate declined as H₂O₂ dosage was more than 2.81mmol/L; each removal rate increased and then decreased slightly with the increase of Fe²⁺ dosage, each removal rate dropped obviously as pH was more than 5.00; within 80.00min, the removal rate increased significantly, it changed little with the continuous increase of reaction time. Under the optimal conditions, the COD removal with Fenton oxidation was more effective and its removal rate could achieve 88.33%, it was advantageous compared with ozone oxidation; but the elimination effect of UV₂₅₄ and chromaticity to pulp and paper wastewater with ozone oxidation was better, the two removal rate achieved 83.70% and 92.00% in a short time, respectively. Although it could reach such a removal effect by Fenton oxidation, it did not have the superiority in reaction time.

Abstract: Electrokinetic remediation is in-situ remediation technique. Potassium dichromate was chosen as the pollutant and its initial concentration was 500mg·kg-1 in Kaolin soil. This experiment, we are to study the feasibility ,the factors which influence the whole course, including applied voltage, treatment time, soil moisture, OH^- produced at the cathode and its control. It indicate that, there is separating out oxygen at anode, hydry at cathode. Cr₂O₇^2-and CrO₄^2- absorb electron to change to Cr³⁺, and unite to Cr (OH)₃. The experiment results show OH^- produced at the cathode has crucial effects on the removal efficiency of chromium; secondly the applied voltage and treatment time have important influence on the efficiency, and the soil moisture affects the efficiency in some degree.