Chemical Reduction of Hexavalent Chromium and Its Immobilisation Under Batch Conditions Using a Slurry Reactor

Water, Air, & Soil Pollution - Risks posed by antifouling agents (irgarol 1051, diuron and dichlofluanid) to the aquatic environment of the Gulf of Napoli have been estimated. Seawater samples...     

Reduction of Hexavalent Chromium in Soil and Ground Water Using Zero-Valent Iron Under Batch and Semi-Batch Conditions

Chemical remediation of soil and groundwater containing hexavalent chromium (Cr(VI)) was carried out under batch and semi-batch conditions using different iron species: (Fe(II) (sulphate solution); Fe⁰ _G (granulated elemental iron); ZVIne (non-stabilized zerovalent iron) and ZVIcol (colloidal zerovalent iron). ZVIcol was synthesized using different experimental conditions with carboxymethyl cellulose (CMC) and ultra-sound. Chemical analysis revealed that the contaminated soil (frank clay sandy texture) presented an average Cr(VI) concentration of 456?±?35 mg kg^?1. Remediation studies carried out under batch conditions indicated that 1.00 g of ZVIcol leads to a chemical reduction of ～280 mg of Cr(VI). Considering the fractions of Cr(VI) present in soil (labile, exchangeable and insoluble), it was noted that after treatment with ZVIcol (semi-batch conditions and pH 5) only 2.5% of these species were not reduced. A comparative study using iron species was carried out in order to evaluate the reduction potentialities exhibited by ZVIcol. Results obtained under batch and semi-batch conditions indicate that application of ZVIcol for the “in situ” remediation of soil and groundwater containing Cr(VI) constitutes a promising technology.     

Simultaneous Removal of Greases and Hexavalent Chromium from Electroplating and Chromate Conversion Coating Waste Solution by Electrocoagulation

Simultaneous removal of oil droplets and hexavalent chromium from synthetic wastewater of chromium plating and chromate conversion coating plants by electrocoagulation in a new cell design was studied under different conditions of pH, initial Cr⁶⁺ concentration, NaCl concentration, and current density. Under optimum conditions, more than 90% of oil content and Cr⁶⁺ were removed. Percent removal was found to increase with decreasing Cr⁶⁺; high Cr⁶⁺ concentrations tend to passivate the aluminum anode and decrease the percent removal of Cr⁶⁺ and oil. The effect of NaCl concentration shows a maximum percent removal at 1.5%. The pH range 4–5 was found to give the highest percent removal. Increase of current density was found to improve the percent removal of Cr⁶⁺ and oil droplets. The favorable effect the combined oil and Cr⁶⁺ removal on the capital and operating costs of wastewater remediation was pointed out. Potential merits of the present cell design compared to the traditional parallel plate cell were highlighted.     

伊乐藻和固定化细菌共同作用对富营养化水体中养分的影响

试验是在室外进行,采用适合冬季生长的沉水植物伊乐藻(Elodeamuttallii)和固定化微生物两者相结合来研究它们在冬春季节对富营养化水体中氮磷养分的影响变化。试验结果表明:采用两者的结合对维持和提高水质效果最为明显,其中对水体中几种形态的氮素都有不同程度的降低作用,这主要是由于除水生植物对水体中氮素的吸收外,还有通过固定化微生物的氨化作用、硝化和反硝化作用,促使氮素以气态的形式去除;在试验的后期,虽然水体中总磷TP和可溶性磷DP的含量在各处理中都表现出上升趋势,但是把伊乐藻(Elodeamuttallii)和氮循环菌相结合却能对水体的磷含量有明显的缓冲作用,这些结果综合表现为水体透明度的相对较高。     

细菌8-A-2对石油烃类运输及正十六烷代谢产物的初步分析

随着石油工业的发展,难降解的石油烃类物质引起的环境污染越来越引起人们的关注[1].目前,应用微生物治理石油烃类物质的污染,较物理或化学方法成本低、投资少、效率高,正受到世界各国的普遍重视[2,3].