Influence of carrier filling ratio on the performance of moving bed biofilm reactor in treating coking wastewater.

This study aims to evaluate the effect of carrier filling ratio on the performance of a moving bed biofilm reactor in degrading chemical oxygen demand, phenol, thiocyanate, and ammonia from coking wastewater at 20h of hydraulic retention time. The operational experiments under different carrier filling ratios ranging from 20% to 60% were investigated. The maximum removal efficiency of 89%, 99% and 99% for COD, phenol and thiocyanate, and minimum sensitivity to the increasing contaminants concentration in the influent were achieved at 50% carrier filling ratio. The Haldane competitive substrate inhibition kinetics model was used to describe the relationship between the oxygen uptake rate of ammonium oxidizers and the concentration of free ammonium. The highest biofilm microbial community functional diversity (Shannon's diversity index, H') and evenness (Shannon's evenness index, E') were obtained at 50% carrier filling ratio in all runs using a Biolog ECO microplate.

[Distribution characteristics of lead in different particle size fractions of surface soil of a lead-acid battery factory contaminated site].

In this research, six topsoil samples (0-20 cm) were collected in the heavy-metal lead contaminated soil of one lead battery factory in south-west China as research object, which were later divided into seven particle size fractions, and analyzed for the lead concentration as well as the correlation between the lead concentration and the organic matter content. The result showed that five soil samples were contaminated with lead with different pollution levels, and there were two different trends in the changes of lead concentration as of the change of soil particle size. The lead concentration of the three samples from sewage treatment workshop, the workshop A and the workshop B, showed a first declining and then ascending trend with the decreasing particle size. The lead concentration of the soil samples of the packing workshop and the former production workshop A showed a decreasing trend when the particle size decreased. The lead concentration and the organic matter content showed a positive linear correlation (R2 = 0.8232). Soil organic matter has the ability of lead enrichment, and the ability declines with the decreasing particle size. Soil texture may be an important factor for the interaction between soil organic matter and lead distribution.

Analysis and removal of organic pollutants in biologically treated landfill leachate by an inorganic flocculent composite of Al(III)-Mg(II).

A novel inorganic flocculent composite of Al(III)-Mg(II) poly-magnesium-aluminum-sulfate (PMAS) is used to remove organic matter from biologically treated leachate in some landfills in Beijing, China. Jar-test experiments are employed to determine the optimum conditions for the removal of organic matter, which is represented as UV(254). Under optimum conditions, the removal of COD, BOD(5), and color is also determined. Moreover, gas chromatography coupled with mass spectrometry (GC-MS) is used to analyze the organic matter in the biologically treated leachate before and after treatment by the coagulant. The experimental results indicate that the removal of COD, BOD(5), UV(254), and color by coagulation with PMAS can reach above 65%, 60%, 85%, and 85%, respectively, under optimal conditions. This greatly weakens its pollution extent and improves its visual appeal. Forty-one kinds of organic pollutants in the biologically treated leachate were determined. Some of them belong to the Black List of water environmental preferred controlled pollutants, as judged by the United States and China. The species of alkyl, alkene, acyclic alcohol, and acyclic acyl amines are about 85% removed, some of them are removed completely, while the species of acids, esters, and ketones are removed at about 65%. Those contaminants with benzene rings, such as aromatic hydrocarbons, hydroxybenzene, aromatic alcohol, and aromatic acyl amine, are about 50% partially removed.

Filtration by a novel nanofiber membrane and alumina adsorption to remove copper(II) from groundwater.

The elevated level of heavy metals in groundwater poses a substantial risk potentially to local resource users and the natural environment. Micellar-enhanced filtration (MEF) and alumina adsorption are considered from the viewpoint of copper(II) removal in groundwater, by taking copper(II) as an example. In MEF, copper(II) cations are collected electrostatically on micelles of sodium dodecyl benzene sulfonate (SDBS) and separated from the mother liquor by filtration using a novel nanofiber membrane prepared from chloridized polyvinyl chloride by high-voltage electrospinning process. After MEF with 10-layer filtration and SDBS concentration of 5 mmol/L, the removal of copper(II) in groundwater is above 70%. However, the final solution contains a large amount of surfactant causing serious second contamination in groundwater. This problem is overcome by alumina adsorption, where negatively charged surfactants are adsorbed on positively charged alumina particles and then recovered by conventional filtration. The hybrid process of MEF and alumina adsorption is successfully applied to removing almost 100% of copper(II) from groundwater. Finally, the characterization of the membrane and filtration mechanism are presented here.

[Gene expression, purification and functional analysis of LiPrmA].

Leptospira interrogans (L. interrogans) genomic DNA was used as template to amplify the full-length gene for ribosomal protein L11 methyltransferase (liPrmA) by PCR. The pET22b-/liprmA expression plasmid was successfully constructed in Escherichia coli (E.coli.) strain TOP10 and confirmed by restriction enzyme digest and sequencing. Through optimizing expression of the recombinant liPrmA-6xHis fusion protein in expression host E. coli. BL21, the yield of soluble target protein reached 40 mg (liter culture)-1. The LiPrmA was purified to apparent homogeneity in a single step using Ni-NTA His Bind chromatography. Amino acid homologous analysis showed that liPrmA shared significant identity with other prokaryotic PrmA and eukaryotic putative PrmA in the catalytic region including AdoMet binding domain. Methylation activity experiments showed purified liPrmA was able to catalyze the ribosomal protein L11 of L. interrogans methylated under the presence of S-adenosyl-methionine (AdoMet).