Advanced Materials Research Vols. 356-360

Abstract: A full-field investigation was conducted of thermal desorption remediation of soil polluted by 1, 2-dichloroethane (1, 2-DCA). The effects of soil type, system temperature, thermal desorption time, and stirring speed on the residual concentration of 1, 2-DCA were determined. The residual concentration of 1, 2-DCA decreased with increasing viscosity, system temperature, thermal desorption time, and stirring speed. Optimal thermal desorption conditions for moderately polluted clay soil were a system temperature of 130°C and thermal desorption time of 50 min with stirring. Optimal thermal desorption conditions for heavily polluted clay soil were a system temperature of 130°C and thermal desorption time of 90 min with stirring. This study provides technological parameters and theoretical guidance for engineering.

Abstract: The anaerobic activated sludge inoculated with an isolated SRB was immobilized on the granular activated carbon and the kinetics for the immobilized anaerobic sludge treating the sulfate in tannery wastewater was studied. Also, the aerobic activated sludge containing enriched SOB was immobilized and the kinetics for the sulfur conversion was studied with the immobilized aerobic sludge through treating sulfide (the reduction product of SO₄^2-) in tannery wastewater. The results showed that the kinetics for treating SO₄ ^2- with the immobilized SRB in the actual tannery wastewater could be expressed as follows: lnC =-0.04941 t+6.79764. The kinetics for the sulfur conversion with the immobilized SOB through treating the sulfide in the actual tannery wastewater could be expressed as follows: lnC =0.01109 t+3.09996. The established dynamic equations could predict the capacity of sulfate removal and sulfur conversion in tannery wastewater.

Abstract: In this study, a commercial activated carbon was assessed as adsorbent for post-combustion CO₂ capture. The breakthrough adsorption experiments were conducted in a fixed-bed column with simulated flue gas of 12% CO₂. The effects of feed flow rate and adsorption pressure on breakthrough time and CO₂ adsorption capacity were evaluated. The column efficiency was introduced to estimate the percentage of the utilization of the bed adsorbent capacity. At a higher flow rate, the breakthrough time, breakthrough capacity and column efficiency decreased. Conversely, increasing adsorption pressure was favorable to CO₂ adsorption by the increase in breakthrough time, CO₂ adsorption capacity and the column efficiency. During the experiments, temperature changes were detected at three positions inside the column to track the movement of breakthrough front.

Abstract: In this study, the feasible condition for diesel oil degradation of EM was investigated in artificial seawater medium. Under the optimal growth and degradation condition of pH 8.0, 30°C, inoculation amount of 3%, substrate concentration of 0.5%, and NaCl concentration of 20 g/L, the n-alkanes of diesel oil was degraded in high efficiency with total degrading rate of 72.3%, and the average n-alkanes (C₁₀- C₂₁) removal could reach 74.8% within 15 days. The results indicated that EM could be used in the bioremediation of marine oil pollution.

Abstract: A bacterial strain S_9-1 capable of degrading sulfonylurea herbicide pyrazosulfuron-ethyl (PSE) was isolated from contaminated soil through the enrichment incubation method. Based on morphology, colony and cultural properties, physiological and biochemical characteristics, living-cell absorption spectra, internal photosynthetic membrane, and phylogenetics of its 16S rRNA gene sequence, S_9-1 was preliminarily identified as belonging to the genus Rhodopseudomonas, a group of photosynthetic bacteria (PSB). The effects of PSE concentration, pH, and temperature on biodegradation were examined. The degradation rate was found to decrease with increasing PSE concentration. Optimal growth pH and temperature were found to be 7.0 and 30°C, respectively. The strain was able to degrade 47.51% of PSE at a concentration of 100 mg ml^-1 after 7 days of incubation at 30°C and could tolerate 800 mg ml^-1 PSE. S_9-1 was also able to completely co-metabolically transform 100 mg ml^-1 PSE at 30°C, pH 7.0, and 7500 lux in 15 days. As the concentration of PSE increased, the degradation process took longer to complete. The fragment encoding acetolactate synthase (ALS) gene from S_9-1 was cloned and sequenced. Comparison of deduced amino acid sequences was implemented, and the conserved sites were analyzed. To our knowledge, this is the first report of PSB in PSE biodegradation. These results highlight the potential of this bacterium as a detoxifying agent for use with PSE-contaminated soil and wastewater.

Abstract: A new kind of suspending combination ecological filter bed was constructed, which took floating baskets as basic units and took flyash cenospheres and attapulgite clay ultra light filter material as loading material. It integrated plant absorption, filter material adsorption with biofilm colonization to purify wastewater. Experiment showed that by the use of filter bed, TP, TN and COD can be removed effectively. Three kinds of plants, including green vegetables, spinach and American-four-season-green grass were cultivated in the filter bed and grew better than those planted in soils. Germination rate and speed of growth were faster than the controlled group. The application of filter bed didn't need land occupation and civil engineering construction. Meanwhile, it can restore the polluted water, reduce the operation costs and fulfill the recycling of eutrophia water.

Abstract: Due to the geographical location, sediment deposition resulted in a heavy internal pollutant loading and destroied the ecological system in Neijiang, a typical waterfront shallow lake. Based on the field investigation and laboratory experiment the characteristics of deposited sediments including deposition thickness, pollutant contents and pollutant release intensity were analyzed and then the sediment dredging schemes for Neijiang were proposed. Finally the impacts of sediment dredging on internal pollutant loading were quantificationally evaluated. It was found that:(1) the deposition thickness, pollutant contents and release intensity of sediments in Neijiang were all distibuted asymmetrically; (2) sediment dredging significantly decreased the basal elevation of Neijiang and cut down the internal pollutant sources by removing the surface contaminated sediments; (3) After dredging the internal pollutant loading under different hydrological conditions in Neijiang was evidently reduced.

Abstract: The enhancement of alkaline industrial wastes on the desulfurization performance and utilization of limestone has already been found. In order to explore the reason of this phenomenon from the kinetic point of view, two typical alkaline wastes, carbide slag with a high calcium content and Bayer process red mud with more metal impurities, were adopted to research. Kinetic behavior of calcination reaction was calculated using the isoconversional method of Kissinger-Akahira-Sunose method (a differential method) and Flynn-Wall-Ozawa method (an integral method) at four different heating rates: 10, 20, 40 and 80 K•min^-1. Values calculated by these two methods are very close, and the calculated result shows that calcination rate constant of modified limestone is obviously greater than that of original limestone, under the same calcination temperature, which means that alkaline wastes are advantageous to the thermal decomposition of limestone.

Abstract: Effectiveness of combinations of seven different ecotypes of wetland plants including Thalia dealbata, Iris tectorum, Acorus calamus,Zizania aquatica, Nymphaea tetragona,Georgi, Myriophyllum aquaticum, Thalia dealbata purifying water was investigated by hydrostatic simulation experiment method. The research showed that combinations of various wetland plants had significant purification effects on eutrophic water body, plant community was stable, and plants grew well. Chemical Oxygen Demand (COD) removal efficiencies of various combinations were higher than 97%, and 25.9% higher than that of the blank control group; the average highest total phosphorus (TP) removal efficiency of plant combinations was 97.6%. Compared with COD and TP, Total nitrogen( TN)removal efficiency was lower, ranging from 90.4% to 83.1%.Different wetland plants had different purification effectiveness for different pollutant. The combination N+Z+A+ZI had the highest TNremoval efficiency, reaching 90.4%. Combinations N+Z+A+ZI and N+Z respectively won the first and second place in the disposal of TP,reaching 99.68%, 99.34%. For Chemical Oxygen Demand COD removal, the combination N+Z+C+T did the best and the highest removal efficiency reached 97.6%. Fuzzy comprehensive evaluation method is used to select the following combinations with stronger capacities of removing N and P in sewage: N+Z+A+ZI, N+Z, N+Z+C+T. They can be promoted and applied in purification of eutrophic water body in ecological projects.

Abstract: In order to find the best substrates of constructed wetlands for saline waste sewage treatment, Bio-ceramic, quartz sand, zeolite and medical stone were used as filtering media for saline sewage treatment with proper proportion microbe, isolated from the sewage of the Wuqing sewage treatment plant. In this paper, the purification of the vertical-flow constructed wetlands (VFCWs) with different substrates was studied, and the component of the nitrogen in the influent and effluent was analyzed. The concentrations of chemical oxygen demand (COD), ammonia (NH⁴⁺ -N), total phosphorus (TP), total nitrogen (TN) and the salinity of the influent during the experimental period were 150mg•L^-1, 36 mg•L^-1, 8mg•L^-1, 36mg•L^-1 and 1.6%. Under the condition that the hydraulic loading rate was 0.25m•d-1, the average removal efficiency of COD, TP and TN were obtained about 68.81%, 32.01% and 20.72 %, respectively with Bio-ceramic; 61.92%, 31.75% and 34.33%, respectively with quartz sands; 69.47%, 35.44% and 55.28% , respectively with zeolite; and 64.77%, 32.63% and 34.72%, respectively with medical stone. This result proves that comprehensive purification of the system with zeolite is the best.