Zhang X.-Q.,Harbin Institute of Technology |
Tian Y.,Harbin Institute of Technology |
Wang Q.,Heilongjiang Provincial Research Institute of Environmental Science
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2014
Sludge reduction can be achieved through the predation by oligochaeta worm-Limnodrilus sp.. To analyze the effect of aeration intensity on the process of sludge predation, changes in worm activity, sludge properties and sludge reduction efficiency under different intensities of aeration were investigated. The results showed that these worms had limited tolerance to aeration intensity. The number of injured worms increased with the increasing aeration intensity and retention time in sludge, and fewer injured individuals (1.7% of the total)was found under the mild intermittent aeration. The lactate dehydrogenate activity of worms was higher under the aeration intensity of 2.8~9.5 m3/(m2·h), which may imply the higher level of material metabolism and energetic consumption of the worms at those aeration conditions. Less nitrate accumulation was found in the supernatant of sludge during the predation under the lower aeration intensity, and the increase in sludge volume index (SVI) caused by lack of dissolved oxygen was restrained by the worms, showing their performance for improving sludge settling. The sludge reduction of worms for the intermittent aeration of 2.8 m3/(m2·h) was more stable than those for continuous aerations.
Cheng X.,Beijing Forestry University |
Ye J.,Harbin Institute of Technology |
Sun D.,Beijing Forestry University |
Chen A.,Heilongjiang Provincial Research Institute of Environmental Science
Chinese Journal of Chemical Engineering | Year: 2011
A group of Zn-Al layered double hydroxides (LDHs) were synthesized at different temperatures from 25-90 °C in order to investigate the influence of synthesis temperature on characteristics of the LDHs and their phosphate adsorption behaviour. The results reveal that an increase in the synthesis temperature generally improves the specific surface area of the sample and the phosphate adsorption capacity. The significantly enhanced crystallinity of the Zn-Al-30, synthesized at 30 °C, leads to a remarkable decrease in the specific surface area and consequently a poor phosphate adsorption capacity. It is suggested that the surface adsorption plays an important role in the phosphate uptake by the Zn-Al LDHs. Zn-Al-70 presents a relatively higher crystallinity and a lower specific surface area, compared with Zn-Al-60 and Zn-Al-80, but the highest phosphate adsorption capacity, indicating that surface adsorption is only one of the pathways for phosphate removal. The phosphate adsorption by the Zn-Al follows a pseudo-second-order kinetic equation. The adsorption isotherms fit Langmuir models, and the maximum adsorption capacities of the Zn-Al-25, Zn-Al-50 and Zn-Al-70 are estimated to be 17.82, 21.01 and 27.10 mg·g -1 adsorbent, respectively.
Qiu S.,Harbin Institute of Technology |
Zeng H.,Heilongjiang Provincial Research Institute of Environmental Science |
Liu Z.,Harbin Institute of Technology |
Xu S.,Harbin Institute of Technology |
Ma F.,Harbin Institute of Technology
Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology | Year: 2014
According to the characters of HABS industrial wastewater of high pH, high COD and high concentration of sulfite, a pilot reactor with catalytic oxidation-Fenton combined treatment process was built, and the pilot scale experiments were employed to discuss the optional parameters. A pilot scale is 5 t/d. After optimized, the optimal optional parameters in catalytic oxidation stage were pH 8, aeration rate 50 m3/h, HRT 90 min. The optimal optional parameters in Fenton stage were dosage of H2O2(30%) 1.00 mL/L. The effluent quality can meet the first class requirements of Sewage Discharge Standard in GB8978-1996, which suggests the process is economical and feasible.
Zhang X.,Harbin Institute of Technology |
Tian Y.,Harbin Institute of Technology |
Wang Q.,Heilongjiang Provincial Research Institute of Environmental Science |
Chen L.,Harbin Institute of Technology |
Wang X.,Harbin Institute of Technology
Bioresource Technology | Year: 2012
Changes in heavy metal distribution and speciation during the reduction of sewage sludge with the worm, Limnodrilus hoffmeisteri were assessed. In sludge containing 108.3. ±. 2.2, 455.5. ±. 10.3, and 39.4. ±. 1.8. mg/kg of Cu, Zn, and Pb, respectively, more than 81% of these metals remained in the sludge after predation by the worms, while 4.1-9.7% of these metals were released into the liquid. The maximum uptake values of Cu, Zn, and Pb by the worms reached 180.5, 587.4, and 55.8. mg/kg, respectively. The predation did not increase metal bioavailability in the final sludge as reflected by a 9.5-12.5% decrease in labile Cu and unchanged levels in labile Zn and Pb. The sewage sludge reduction efficiency of L. hoffmeisteri was 27.6-29.2%. These results indicated the relatively moderate changes in speciation and distribution of Cu, Zn, and Pb and the stable performance of worms in reducing sewage sludge. © 2012 Elsevier Ltd.
Cao J.-L.,Chinese Research Academy of Environmental Sciences |
Xi B.-D.,Chinese Research Academy of Environmental Sciences |
Xu Q.-G.,Chinese Research Academy of Environmental Sciences |
Wang Z.-B.,Heilongjiang Provincial Research Institute of Environmental Science |
And 3 more authors.
Huanjing Kexue/Environmental Science | Year: 2011
Based on current researches, described the sources, toxicities, analytical methods and occurrence of PFOA and PFOS in wastewater treatment plants, lakes, rivers, coastal areas and tap waters in different countries in the world. According to the limited concentrations of PFOA+PFOS in effluents of wastewater treatment plants (WTPs) put forward by Germany, the concentrations of PFOA+PFOS in WTP effluents in Singapore, Germany, Korea and England were assessed. The results showed that the concentrations of PFOA+PFOS in WTP effluents in Singapore were higher than the liminted concentration of 300 μg/L. Researches done by China, Japan, USA, and other countries showed that the concentrations of POFA and PFOS in rivers and coastal areas reached to ng/L, and the concentrations in Tennessee River, USA were the highest, reached to 100 ng/L. The risk assessments of PFOA and PFOS in tap water in some cities in China were assessed according to the risk quotients (RQ). The assessment results showed that tap waters from 19 cities in China were all below the risk level.