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Cheng Y.,Chinese Research Academy of Environmental Sciences | Cheng Y.,Hunan Key Laboratory of Water Pollution Control Technology | Luo Y.,Chinese Research Academy of Environmental Sciences | Luo Y.,Hunan Key Laboratory of Water Pollution Control Technology | And 7 more authors.
Chinese Journal of Environmental Engineering | Year: 2013

In order to investigate the advanced treatment method of ion-exchange wastewater produced in vanadium extraction from stone coal, Type ZWY15 activated carbon was modified by using 1%, 5% and 10% mass fractions hydrogen peroxide, and produced three kinds of modified activated carbons which were 1%AC, 5%AC and 10%AC. The adsorption effect of the modified ACs of low-concentration NH3-N and V etc. in the wastewater was studied. Test results showed that the adding of AC or modified AC can increase the alkalinity of the wastewater. The longer the adsorption time or the bigger the adsorbent dosage, the higher the increasing amplitude of alkalinity will be. And the increasing amplitude of alkalinity can be different because of adding different modified ACs. The adsorption effect of V is significantly improved by modified ACs, the removal rate of V increases 30% at maximum, and that of NH3-N increases about 11%. When the adding dosage is 60 g/L, the 10%AC can decrease the concentration of V in the wastewater to 1.88 mg/L, meanwhile the concentrations of Cr, Cd and Zn in the wastewater reduce to 0.006 mg/L, 0.010 mg/L and 0.036 mg/L, respectively which are all lower than the emission limits in Discharge Standard of Pollutants for Vanadium Industry GB 26452-2011. Source

Cheng Y.-X.,Chinese Research Academy of Environmental Sciences | Cheng Y.-X.,Hunan Key Laboratory of Water Pollution Control Technology | Song W.-L.,Chinese Research Academy of Environmental Sciences | Song W.-L.,Xiangtan University | And 8 more authors.
Research of Environmental Sciences | Year: 2013

An efficient and low-cost technology was developed for high concentration arsenic wastewater recycling by combining the advantages of sulfuration and polymer composite flocculants. In the experiment, the high-arsenic wastewater from a smelter was chosen as the treatment object. The arsenic was recycled using Na2S·9H2O for sedimentation. The Na2S·9H2O dosage, dosing manner, initial pH, reaction time were optimized before the experiments. The arsenic dregs were characterized by X-ray diffraction (XRD) and X-Ray Fluorescence (XRF). The results showed more than 98% of arsenic was recovered under the optimal condition with Na2S·9H2O dosage of 55 g/L, a charging style of twice dosing, an initial pH of 2.0 and a reaction time of 5 minutes. The arsenic content in the treated wastewater was 0.61 g/L, and contents of arsenic and sulfur in arsenic dregs reached as the percentages of 49.15% and 40.98% with other heavy metallic ions. The wastewater from sulfuration process was consequently treated with a polymer composite flocculants. The parameters such as optimal proportioning, dosage, pH and flocculants were investigated first. The results showed that: under the condition of Fe:Si=5:1, flocculant dosage of 7 mL/L and pH of 8, arsenic can be deeply removed, and the remaining arsenic concentration was lower than 0.3 mg/L. These results demonstrated that this method is superior to the common flocculants under the same conditions. Based on above findings, expanded multi-batch experiments using combination technique (sulfuration with a polymer composite flocculants) were conducted as well. And the results showed that: the average recovery rate of arsenic was higher than 98%, and average residual arsenic content was less than 0.3 mg/L. The experimental results proved that the combined technique can achieve the reclamation of high-arsenic wastewater, with promising application on the engineering and commercial uses. Source

Song W.,Xiangtan University | Song W.,Chinese Research Academy of Environmental Sciences | Song W.,Hunan Key Laboratory of Water Pollution Control Technology | Dai Y.,Xiangtan University | And 10 more authors.
Chinese Journal of Environmental Engineering | Year: 2014

The polymer composite flocculants were prepared by PFS, SPAS and DMDAAC (as the modifier). Based on the single factor tests, the Box-Behnken response surface methodology was utilized for evaluating the simple and combined effects of Fe:Si, modifier dosage, modifying temperature on the preparation process of polymer composite flocculants. At the same time, the mathematical model was established between the remaining arsenic concentration and the three influential factors. The results demonstrated that the significance of influence factors followed the order: Fe:Si>modifying temperature>modifier dosage, and the combined effects of modifier dosage & modifying temperature and modifier dosage & Fe:Si were significant. Furhermore, the model fitting degree was good, and the model was significant. The optimal preparation conditions with the lowest remaining arsenic concentration of 18.82 μg/L were determined to be Fe:Si=2.1:1, modifier dosage=0.56% (PFSS solution quality), modifying temperature=79°C. The experimental results using the above optimal conditions had an average remaining arsenic concentration of 19.21 μg/L. The experimental value agreed with the predicted value with 2.07% deviation. Source

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