| AIM: To investigate the possibilities of resourceful utilization of the copperaccumulator plant Elsholtzia Splendens Nakai and post remediation treatment of zinchyperaccumulator plant Sedum plumbizincicola. Safety treating or reuse thephytoremediation plants will lead to avoiding the secondly contamination, enhancing theremediation efficiency.METHODS: In experiments of different growth conditions and stages on plantgrowths and Cu concentration, Elsholtzia Splendens Nakai plants were from mine areasin Zhuji city and Tongling city, phytoremediation demonstration site in the suburb ofHangzhou city, and the green house of the Institute of Soil Science. The ElsholtziaSplendens grew in filed germinated at the end of March, and the one grew in green housewas sown on April 28, 2005, about one month later than the filed plants. Samples fromthese four places were collected for four times, they were July 28, August 28, September28 and October 28, respectively, and were prepared for metals determination.Taking the dried Elsholtizia Spledens Nakai plant powder as the raw material forcomposting, inoculating the microorganism agents (mixed with cellulose utilizationmicroorganisms and EMs), researches on different combination of microbes andenvironmental factors were conducted. Two hundred and seventy grams of plant sampleswere weighed and put into the fermentation bottle, 3.76 grams of urea was added to makethe C/N ratio to 35. At the 5th, 10th, 15th, 25th, 35th, 45th, and 60th day, sub-sampleswere taken to measure the contents of nutrients and heavy metals.For the post pytoremediation treatment of Sedum plumbizincicola plant, thepyrolysis and incineration technologies were adopted. For incineration, platform andflow bed test platform experiment were conducted. Pyrolysis experiments wereconducted under the nitrogen flux of 350 ml per minute, and the temperature were 350°C, 450 °C, 550 °C, and 650 °C, respectively. For incineration experiment;under the airflux were of 350 ml per minute, the temperature were 550 °C, 750 °C, 850 °C, and 950°C, respectively. At the mean time, under the air condition for flow bed incineration, hadthe temperature of 850 °C and the flux of 8000 ml per minute, calcium carbonate oractive carbon were added to control heavy metals contents in haze and the residual.RESULTS: In the pot experiment, Elsholtzia Splendens plant Cu concentration waslow while spiked Cu was less than 200 mg kg-1. But when the spiked Cu reached to 200mg kg-1, the plant Cu content increased significantly. It seems that for the tested soil,spiked with 200 mg kg-1 Cu was a turning point for plant Cu uptake. At the earlyflowering stage, the Cu remediation amount of Cu400 treatment was 27.2 mg/pot, theremediation efficient was only 4.95%;But at the blossom stage, the Cu remediationamount increased to 143 mg/pot, and remediation efficient was also increased to 26.0%,significantly higher than that of in the early flowering stage.Under filed condition, Elsholtzia Splendens plant had high growth rate and biomass;this might because of the high plant root parameters such as the root length, rootproportion, and particularly high root point number. The root point number were 124,144, for Elsholtzia Splendens Nakai grown in Zhuji city or Tongling city, respectively.For Zhuji population, the plant biomass was Greenhouse > native area > demonstrationsite. Cu contents of Tongling population were as follows: Greenhouse > native area >demonstration site, and the maximum Cu concentrations were 639, 306 mg kg-1,respectively.In the composting experiment, the sample's total N decreased, and total Cdecreased with the incubation time. And among the 4 treatments, inoculating themicroorganism agent (mixed with cellulose utilization microorganisms and EMs) had thebest effect, the C/N ratio decreased from 35 to 17.6, matched the criteria of first grademanure product. While concerning for the outdoor temperature, water content 75%treatment produced good compost, making the C/N to 13.7, the η C/N was about 60.8%,met the standard of first level. By means of the effect of cooperation of microorganisms,the Elsholtizia Spledens plant was composted quickly. The sample water content played amuch important role than the surrounding temperature.In the Sedum plumbizincicola post harvest research, the heavy metal content of thehaze was low in the pyrolysis technology and incineration, less than 15% and 9%,respectively. Under the pyrolysis condition, Pb, Zn contents in the haze were lower thanthat of incineration, especially for Pb, which was less than 3%. Heavy metal contents inthe residual were ten to hundred times higher than in the haze. Heavy metal recovery ratefor the pyrolysis method was more than 45%, ranged from 45% to 85%;and the lowtemperature (350 °C) had the higher recovery rate than the corresponding hightemperature (650 °C). The heavy metal recovery rate in residuals for incineration methodwas low, ranged from 5% to 85%. The recovery rate could be divided into three levels: (1)Cu and Cd had the highest recovery rate, the undulation scope was 45% to 85%;(2)followed by Zn, Pb, the undulation scope was 20% to 50%;(3) Cd was the lowest,undulate was approximately about 10%. In addition, heavy metal contents in pipeline andmineral wool should not be neglected. It was ten times higher than in the haze. Forincineration method, the Cd, Pb accounted for quite great proportion, achieved 56% and60% of the mass balance coefficient, respectively.CONCLUSION: Concerning for weather conditions, Elsholtizia Spledens Nakairequire proper environments, it is necessary to constructing suitable environment, ortaking the suitable agronomical measurement, such as fertilizer, the irrigation, adjusts thepH, and so on, this will improve Elsholtzia Splendens Nakai growth, or increase themetal content. In the blossom stage, the heavy metal contents in each treatment werehigher than other periods, and the heavy metal removing rate reached the maximum.Plant biomass within blossom stage was also high. So, it might be the best harvest time.In the raw material composting process, treatment of inoculating cellulosedecomposing bacterium and EM compound, with outdoor temperature of 25-37 °C, watercontent of 75%, produced the best compost. This may remarkably accelerate cellulosedegeneration degree, save composting time, and improve product physics and chemistrycharacters. Therefore, composting may be one kind of the plant resourceful utilizationway with economic benefits.In the Sedum plumbizincicola post harvest processing, the plants biomass reducesto below 15%, and the volume was markedly reduced, which took advantages of deepenprocessing;But along with temperature enhancing, concerning for the heavy metaldistribution, pyrolysis technology has many obvious superiority than incineration method.Under the pyrolysis condition, the Pb, Zn contents in the haze were lower than theproduct in the latter pattern, especially for Pb, content was less than 3%;Compared withthe former treatment, heavy metal recovery rate of pyrolysis technology was more than45%, ranged from 45% to 85%, the heavy metal recovery rate in residual of theincineration method was somewhat low, ranged from 5% to 85%. So, pyrolysistechnology might be a reasonable way for phytoremediation plant eco-friendly treat. |
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