Enhanced removal of Fe,Cu,Ni,Pb,and Zn from acid mine drainage using food waste compost and its mechanisms

Heavy metals(HMs)in acid mine drainage(AMD)pose serious threats to aquatic life and soil.Biosorbents are promising materials to remove HMs from wastewater.Herein,food waste compost was used as a low-cost and sustainable biosorbent to remove Fe^(3+),Cu^(2+),Ni^(2+),Pb^(2+),and Zn^(2+)from an AMD and other model solutions with an initial pH of∼2.24.Batch adsorption tests were conducted to systematically investigate the influences of initial pH,compost dose,the presence of Fe^(3+)and SO_(4)^(2−)ions,and the pH-induced Fe precipitates on the removal performance.The involved removal mechanisms were explored by conducting stepwise precipitation tests,sequential extraction tests,and Fourier transform infrared spectroscopy(FTIR)characterization.It was found that the addition of the compost removed over 90%of Zn,Ni,Cu,and Pb at pH 5.80,5.50,4.50,and 3.00,respectively.At low compost doses,the presence of Fe^(3+)and SO_(4)^(2−)ions hindered the removal since the competition effect of Fe^(3+)ion and lower absorbability of metal-sulfate complexes,respectively.Sequential extraction tests revealed that higher fractions of Fe,Cu,and Pb were strongly immobilized through complexation and precipitation relative to Ni and Zn.Additionally,the pH-induced Fe precipitates did not favor the removal of the HMs,probably due to the adsorption of organic components released from the compost.This study suggests that compost has the potential to remove HMs from acidic wastewater without pre-neutralization.

Dark matter direct search sensitivity of the PandaX-4T experiment

The Panda X-4T experiment, a 4-ton scale dark matter direct detection experiment, is being planned at the China Jinping Underground Laboratory. In this paper we present a simulation study of the expected background in this experiment. In a 2.8-ton fiducial mass and the signal region between 1-10 keV electron equivalent energy, the total electron recoil background is found to be 4.9 × 10^(-5) kg^(-1) d^(-1) keV^(-1). The nuclear recoil background in the same region is 2.8 × 10^(-7) kg^(-1) d^(-1) keV^(-1). With an exposure of 5.6 ton-years, the sensitivity of Panda X-4 T could reach a minimum spin-independent dark matter-nucleon cross section of 6 × 10^(-48) cm^2 at a dark matter mass of 40 Ge V/c^2.

A retrospective survey of Brucella melitensis human infection in Hainan Province,China

In China,brucellosis has spread from the northern provinces to the southern coastal area,and Brucella melitensis has become the overwhelmingly dominant species nationwide.Although human Brucellosis cases have been reported in many parts of Hainan Province,investigations into the source of infection have been rare.In this case,we have used the techniques of bacteriology,genome sequencing,and WGS-SNP to investigate the source of infection on a patient with a traveling history between Hainan and Inner Mongolia autonomous regions.We collected a 5mL blood sample under sterile conditions from this suspected case of Brucellosis infection and incubated it in a culture bottle.A week later,Brucella colonies were purified and identified under the standard bacteriology procedures to show that the strain appeared as B.melitensis bv.3.Subsequently,a draft genome sequencing of this strain was obtained.AWGS-SNP comparison analysis of Chinese B.melitensis selected(n=36)fromGenBank revealed that the strain in this studywas more similar to the strains isolated from China's northern parts,especially those from the Inner Mongolia Autonomous Region.These data indicated that the source of infection of the patient was in the Inner Mongolia Autonomous Region,but the actual location where this patient became infected was unclear.We suggest that travelers from the southern part of China be cautious when visiting the traditional endemic areas of Brucellosis.

The size distribution of airborne bacteria and human pathogenic bacteria in a commercial composting plant

Composting plants are regarded as one of the important sources of environmental bioaerosols.However,limitations in the size distribution of airborne bacteria have prevented our comprehensive understanding of their risk to human health and their dispersal behavior.In this study,different sizes of airborne bacteria were collected using an eight-stage impactor from a full-scale composting facility.Size-related abundance and communities of airborne bacteria as well as human pathogenic bacteria(HPB)were investigated using 16S rRNA gene sequencing coupled with droplet digital PCR.Our results indicate that the bacterial concentrations from the eight stages were approximately 10^(4)-105copies/m^(3).Although no statistical correlation was detected between the particle size and the Shannon index,the influence of size on bacterial lineages was observed in both composting and packaging areas.For airborne bacteria from different stages,the dominant phyla were Firmicutes,Proteobacteria,and Actinobacteria,and the dominant genera was Bacillus.Seven out of eight HPB with a small geometric mean aerodynamic diameter had a high concentration in composting areas.Based on diameters of 2.42 to 5.09μm,most HPB in the composting areas were expected to be deposited on the bronchus and secondary bronchus.However,in the packaging areas,the deposition of HPB(diameters 3.70 to 8.96μm)occurred in the upper part of the respiratory tract.Our results on the size distribution,abundance,and diversity of these bacteria offer important information for the systematic evaluation of bacterial pathogenicity and the potential health impacts on workers in composting plants and the surrounding residents.

Bacteremia complicated with pneumonia caused by Corynebacterium diphtheriae

Due to the use of vaccines,infections caused by Corynebacterium diphtheriae are now rare.Here we describe a case of bacteremia complicated with pneumonia caused by C.diphtheriae in a 69-year-old male patient.The patient presented at the emergency department with a 2 days history of fever of unknown origin.Subsequent examinations revealed pneumonia and bacteremia.Non-toxigenic C.diphtheriae strains were isolated from blood and sputum.The patient had antimicrobial therapy with good improvement.We highlight the important role of C.diphtheriae in causing bacteremia and pneumonia,and its accurate and timely diagnosis is needed to avoid poor visual outcomes.