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A soil–plant biological system was developed from chromium(Cr) polluted soil treated by the compost-phytoremediation method. The transformation and migration of the Cr in this system is comprehensively studied in this research. The results illustrated that the co-composting treatment can reduce the Cr availability from 39%(F1 was about 31% of total, F2 was about 8% of total) to less than 2% by stabilizing the Cr. However, herbaceous plants can accumulate the concentrations of Cr from 113.8 to 265.2 mg/kg in the two crops,even though the concentration of soluble Cr in the substrate soil was below 0.1 mg/L.Cr can be assimilated and easily transferred in the tissues of plants because the lowmolecular-weight organic-acids(LMWOAs) derived from the plant root increase the bioavailability of Cr. The amount of extracted Cr dramatically increased when the organic acids were substituted in this order: citric acid malic acid tartaric acid oxalic acid acetic acid. On average the maximum(147.4 mg/kg) and the minimum(78.75 mg/kg) Cr were extracted by 20 mmol/L citric acid and acetic acid, respectively. The desorption of Cr in different acid solutions can be predicted by the pseudo second-order kinetics. The exchangeable Cr, carbonate-bound Cr, and residual Cr decreased, while Fe–Mn oxide bound Cr and organic bound Cr increased in the soil solid phase. According to the experimental results, the organic acids will promote the desorption and chelation processes of Cr, leading to the remobilization of Cr in the soil. 相似文献
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铬渣产生量大，毒性强，严重污染环境危害人体健康。本文介绍了铬渣各种无害化处理方法的解毒机理和实践应用，在无害化处理的基础上，阐述了铬渣在建材工业上的应用，并就铬渣的污染防治提出了建议。 相似文献
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胺萃取法处理含氰废水工艺的研究 总被引：7，自引：3，他引：7
对黄金选冶过程中排放的含氰废水用N235作萃取剂从含氰废水中萃取铜、锌进行了研究,探讨了预处理有机相、温度条件、相比、平衡pH、相接触时间和萃取级数等因素对萃取的影响。试验结果表明,在选定的条件下,铜的萃取率达99%以上,从负载有机相中反萃铜,反萃率可达99%。同时还可以回收氰化物,根据试验结果,提出了处理含氰废水的工艺流程 相似文献
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Elevated arsenic and selenium concentrations in water cause health problems to both humans and wildlife. Natural and anthropogenic activities have caused contamination of these elements in waters worldwide, making the development of efficient cost-effective methods in their removal essential. In this work, removal of arsenate and selenite from water by adsorption onto a natural goethite(α-FeO OH) sample was studied at varying conditions. The data was then compared with other arsenate, selenite/goethite adsorption systems as much of literature shows discrepancies due to varying adsorption conditions. Characterization of the goethite was completed using inductively coupled plasma mass spectrometry, X-ray diffraction, Fouriertransform infrared spectroscopy, scanning electron microscopy, and Brunauer–Emmett–Teller surface area analysis. Pseudo-first order(PFO) and pseudo-second order(PSO) kinetic models were applied; including comparisons of different regression methods. Various adsorption isotherm models were applied to determine the best fitting model and to compare adsorption capacitates with other works. Desorption/leaching of arsenate and selenite was studied though the addition of phosphate and hydroxyl ions. Langmuir isotherm modeling resulted in maximum adsorption capacities of 6.204 and 7.740 mg/g for arsenate and selenite adsorption,respectively. The PSO model applied with a non-linear regression resulted in the best kinetic fits for both adsorption and desorption of arsenate and selenite. Adsorption decreased with increasing pH. Phosphate induced desorption resulted in the highest percentage of arsenate and selenite desorbed, while hydroxide induced resulted in the fastest desorption kinetics. 相似文献
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A study on the removal of Co(Ⅱ) from aqueous solutions by water treatment residuals(WTR)was conducted in batch conditions. The sorption process of Co(Ⅱ) followed pseudosecondorder kinetics, with 30 hr required to reach equilibrium. Using the Langmuir adsorption isotherm model, a relatively high maximum sorption capacity of 17.31 mg/g Co(Ⅱ) was determined. The adsorption of Co(Ⅱ) was dependent on pH values and was affected by the ionic strength. Results show that Co(Ⅱ) adsorption was a spontaneous endothermic process and was favorable at high temperature. Most of the adsorbed Co(Ⅱ) stayed on the WTR permanently, whereas only small amounts of adsorbed Co(Ⅱ) were desorbed. The shifting of peaks in FT-IR spectra indicated that Co(Ⅱ) interacted with the WTR surface through strong covalent bond formation with Fe(Al)–O functional groups. It was concluded that WTR can be a suitable material from which to develop an efficient adsorbent for the removal of Co(Ⅱ) from wastewater. 相似文献
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Chromium and/or arsenate removal by Fe(II) as a function of pH, Fe(II) dosage and initial Cr(VI)/As(V) ratio were examined inbatch tests. The presence of arsenate reduced the removal e ciency of chromium by Fe(II), while the presence of chromate significantlyincreased the removal e ciency of arsenate by Fe(II) at pH 6–8. In the absence of arsenate, chromium removal by Fe(II) increased toa maximum with increasing pH from 4 to 7 and then decreased with a further increase in pH. The increment in Fe(II) dosage resultedin an improvement in chromium removal and the improvement was more remarkable under alkaline conditions than that under acidicconditions. Chromium removal by Fe(II) was reduced to a larger extent under neutral and alkaline conditions than that under acidicconditions due to the presence of 10 mol/L arsenate. The presence of 20 mol/L arsenate slightly improved chromium removal byFe(II) at pH 3.9–5.8, but had detrimental e ects at pH 6.7–9.8. Arsenate removal was improved significantly at pH 4–9 due to thepresence of 10 mol/L chromate at Fe(II) dosages of 20–60 mol/L. Elevating the chromate concentration from 10 to 20 mol/Lresulted in a further improvement in arsenate removal at pH 4.0–4.6 when Fe(II) was dosed at 30–60 mol/L. 相似文献
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Batch experiments were conducted to investigate the phosphorus（P） adsorption and desorption on five drinking water treatment residuals（WTRs） collected from different regions in China. The physical and chemical characteristics of the five WTRs were determined. Combined with rotated principal component analysis, multiple regression analysis was used to analyze the relationship between the inherent properties of the WTRs and their P adsorption capacities. The results showed that the maximum P adsorption capacities of the five WTRs calculated using the Langmuir isotherm ranged from 4.17 to8.20 mg/g at a p H of 7 and further increased with a decrease in p H. The statistical analysis revealed that a factor related to Al and 200 mmol/L oxalate-extractable Al（Alox） accounted for 36.5% of the variations in the P adsorption. A similar portion（28.5%） was attributed to an integrated factor related to the p H, Fe, 200 mmol/L oxalate-extractable Fe（Feox）, surface area and organic matter（OM） of the WTRs. However, factors related to other properties（Ca,P and 5 mmol/L oxalate-extractable Fe and Al） were rejected. In addition, the quantity of P desorption was limited and had a significant negative correlation with the（Feox＋ Alox） of the WTRs（p 〈 0.05）. Overall, WTRs with high contents of Alox, Feoxand OM as well as large surface areas were proposed to be the best choice for P adsorption in practical applications. 相似文献
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This study aims to investigate the effect of a magnetic field on nitrous oxide(N2O) emission from a sequencing batch reactor treating low-strength domestic wastewater at low temperature(10℃).After running for 124 days in parallel,results indicated that the conversion rate of N2O for a magnetic field-sequencing batch reactor(MF-SBR) decreased by34.3% compared to that of a conventional SBR(C-SBR).Meanwhile,the removal efficiencies for total nitrogen(TN) and ammonia nitrogen(N... 相似文献
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An experimental group of homing pigeons (Columba livia f. domestica) learned to associate food with a magnetic anomaly produced by bar magnets that were fixed to the bowl in which they received
their daily food ration in their home loft; the control group lacked this experience. Both groups were trained to search for
two hidden food depots in a rectangular sand-filled arena without obvious visual cues; for the experimental birds, these depots
were also marked with three 1.15 × 106 μT bar magnets. During the tests, there were two food depots, one marked with the magnets, the other unmarked; their position
within the arena was changed from test to test. The experimental birds searched within 10 cm of the magnetically marked depot
in 49% of the test sessions, whereas the control birds searched there in only 11% of the sessions. Both groups searched near
the control depot in 11 and 13% of the sessions, respectively. The significant preference of the magnetically marked food
depot by the experimental birds shows that homing pigeons cannot only detect a magnetic anomaly but can also use it as a cue
for locating hidden food in an open arena. 相似文献
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针对某集团公司排放的环氧氯丙烷生产废水、造纸废水,采用高温碱破对环氧氯丙烷生产废水预处理后,与等体积的造纸废水（经混凝沉淀－厌氧预处理后的排水）形成混合废水,该混合废水采用“水解酸化+卡鲁塞尔氧化沟”组合工艺进行处理。工程实践表明,该组合工艺能够稳定有效处理混合废水,出水水质能达到当地工业园区污水处理厂的排放标准（ρ（COD）≤500 mg/L）,组合工艺处理成本约为5.47元/t,具有处理效果好、运行成本低等优点。 相似文献
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对高负荷条件下硝化反应和聚磷茵有效除磷进行了探讨;介绍了脱氮除磷过程中互相矛盾的几个主要因素：并针对环境条件、碳源需求以及对反硝化聚磷的诱导与控制等领域内的研究方向进行了综述。 相似文献
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磁处理净化污水应用实例分析研究 总被引：10，自引：0，他引：10
介绍将磁处理作为强化措施引入南医人工生态系统处理污不的应用及实验研究，实际工程效果表明，该技术有效地强化了南医人工生态系统处理有机污水的能力，糸补了实际工程中由于地理位置、气侯条件等影响因素所造成的不足。同时本文还对其强化机理进行了综合实验和分析。 相似文献
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固定化微生物技术在废水脱氮中的应用 总被引：1，自引：0，他引：1
综述了固定化微生物技术在废水脱氮处理中的应用。固定化微生物脱氮技术与其它生物脱氮技术相比，除无污泥膨胀、污泥量少、操作管理简单等优点外，还可以提高硝化反硝化速度、增强硝化反硝化菌的抗毒性及节省碳源消耗等。 相似文献