Applied Mechanics and Materials Vols. 295-298

Abstract: The mesophilic (35°C) two-phase anaerobic digestion ( TPAD) process was used to treat mixed sludge from primary sedimentation and secondary sedimentation tanks ( 1:3 ). The results show that when HRT is 10 days and organic loading rate is 1.5kgVS/ (m3•d), the upper-liquid COD of methanogenic phase and acidogenic phase increased along with time, but not obviously; The contents o^{Superscript text}f polysaccharides and proteins in upper-liquid multiplied increased with digestion time, polysaccharides and proteins in acidogenic phase upper-liquid were more than methanogenic phase; The value of CST became larger after being digested by mesophilic two-phase anaerobic digestion, but the dewaterability of sludge in methanogenic phase is better than acidogenic phase.

Abstract: The effects of killing Chlamydomonas, Microcystis Aeruginosa, Cylindrospermopsis, Chlorella and Tetraedron by chlorine dioxide were studied. The reaction orders and rate constants of algae oxidated by chlorine dioxide were determined. The results show that these algae can be killed effectively by chlorine dioxide in raw water. the efficiencies of killing Microcystis Aeruginosa, Tetraedron and Cylindrospermopsis are 89.44%～92.48% during 10 to 15 Minutes. The efficiency of killing Chlamydomonas is high to 98.26%, but the efficiency of killing Chlorella is low, only 60.90%. The reaction orders for various algae are different. The reaction orders of Chlamydomonas, Microcystis Aeruginosa, Cylindrospermopsis, Chlorella and Tetraedron are 1.3, 2, 2.5, 6 and 2, respectively. The apparent rate constants are 2.1×10^-3 μg^-0.3L ^0.3s^-1, 5.6×10^-3μg ^-1Ls ^-1, 8.3×10^-4μg ^-1.5L ^1.5s ^-1, 1.0×10^-5μg ^-5 L ⁵s ^-1 and 3.8×10^-3 μg ^-1Ls ^-1 , respectively.

Abstract: Effects of different electron donors (acetate and hydrogen), acetate and perchlorate concentrations on microbial perchlorate reduction in groundwater were studied. The results showed that acetate and hydrogen addition as an electron donor can significantly improve perchlorate removal efficiency while a longer period was observed for hydrogen (15 d) than for acetate (8 d). The optical ratio of electron donor (acetate)-to-electron acceptor (perchlorate) was approximately 1.65 mg COD mg perchlorate-1. The highest specific reduction rate of perchlorate was achieved at the acetate-to-perchlorate ratio of 3.80 mg COD mg perchlorate-1. The perchlorate reduction rates corresponded well to the theoretical values calculated by the Monod equation and the parameters of Ks and Vm were determined to be 15.6 mg L-1 and 0.26 d-1, respectively.

Abstract: The paper mainly targets at investigating municipal sludge drying technology which is efficient and economical. Use the oven, the microwave and the combination of both to study on the factors of the drying efficiency. The research found that the thinner sludge is easier to be dried, additionally, combining these two ways, which means to dry the sludge with dry box for a short time and then use the microwave to dry the sludge can greatly improve the drying efficiency. The research conclusions will provide a scientific basis for municipal sludge drying and semi-drying engineering practice, with some guiding significance.

Abstract: Adsorption isotherms of new type cationic Gemini surfactant named CGS on quartz sand has been got by using solution concentration difference method. The effect of different factors on adsorption, such as temperature, pH value and salinity, are studied too. The adsorption isotherm of CGS on quartz sand accorded with Langmuir shape. The adsorption quantity increased with the increasing of surfactant concentration at an adagio rate, then the adsorption quantity increased fast, and it reached adsorption saturation when mass concentration was 150 mg/L, and saturated absorption was 6.3 mg/g. The adsorption quantity of CGS increased with the increasing of salt concentration. When heighten temperature and pH value, the adsorption quantity of CGS decreased.

Abstract: Pyrolysis is one promising outlets in disposal of sewage sludge. In the current review paper, some key influent factors on sludge pyrolysis technology and all products were discussed. How the main factors including pyrolysis final temperature, residence time, heating rate and way, the raw sludge characteristics and catalyst, etc influent the products were discussed. Thereafter, another important issue of sludge pyrolysis is the characters and application of the products as well as the key factors affected sludge pyrolysis. The mainly composition, characters and applied prospect were discussed. An important aspect of sewage sludge pyrolysis is how to utilize the pyrolysis oil. Some of the properties and processing of pyrolysis oil were detailedly discussed.

Abstract: The principle and technical characteristics of flue gas simultaneous removal of SO2 and NOx technology are expounded. The application and research progresses about this field are introduced. Besides that, the major research directions of flue gas ammonia combined desulphurization and denitration technology are prospected.

Abstract: A new kind of adsorbent is prepared in the present study, which is expected to capture NOx with high efficiency. NaOH, Ca(OH)2, carbide slag, diatomite, activated alumina are chosen as the major material with a small amount of surfactants and dispersants as the additive. Different recipes were characterized by SEM and N2 adsorption-desorption method. The result showed that the optimum adsorbent has the largest surface area of 95.67m2/g which is Ca(OH)2: NaOH: activated alumina=4:1:1. The test on removal of NOx is conducted. The result showed that the adsorbent is capable of removal efficiency exceeding 98% in 10minutes.

Abstract: Here we report the photocatalytic degradation characteristics of Rhodamine B in the presence of Cr(VI). Some interesting results were observed during the photocatalytic process. Cr(VI) caused a deactivation effect on the catalyst due to the formation of Cr(OH)₃ precipitate blocking the active sites of catalyst. Moreover, a kind of red oligomer precipitate was found during the RhB degradation when Cr(VI) was presented. This precipitate was rarely reported in photocatalytic system.

Abstract: An aerobic granular sludge sequencing batch reactor was carried out at low temperature (101oC) to understand the characteristics of nitrogen removal. The results indicated that nitrification via nitrite could be achieved with an average nitrosation rate of 97.7%. Influent C/N ratio was an important factor influencing the accumulation of nitrite in the effluent. In the experinment, the reactor exhibited a higher removal efficiency for COD with the effluent concentration of COD ranged from 88.2% to 91.8%. In phase I which C/N ratio was 20:1, effluent concentration of ammonium was about 12.9mg/L with the removal efficiency of 77.0%. As the C/N ratio was reduced to 15:1 and 10:1, the effluent concentration of ammonium was around 0.5 mg/L. At the same time, nitrite in the effluent reached up to 21.0 mg/L when the influent COD concentration was induced from 1120mg/L to 560 mg/L with C/N ratio induced from 20:1 to 10:1, however nitrate concentration was remained around 0.4 mg/L throughout the whole experinment.