Study of the effect of pH and dissolved heavy metals on the growth of sulfate-reducing bacteria by a fractional factorial design

Liu

et al. 2015

RSC Adv.

This study reports the adsorption of Zn(II) and Pb(II) on montmorillonite-supported zero-valent iron nanoparticles (nZVI-Mont). The kinetics of Zn(II) and Pb(II) adsorption were evaluated for various contact times. The adsorption of Zn(II) and Pb(II) at different initial concentrations was examined by injecting 0.5 g of adsorbents to achieve equilibrium. The adsorption of Zn(II) and Pb(II) was an exothermic process.The pseudo-second-order kinetic model fits well with the adsorption of Zn(II) and Pb(II) (r 2 > 0.99 at all temperatures tested). The Zn(II) adsorption process was a simultaneously physical and chemical process, fitting the Freundlich (r 2 ¼ 0.981), Temkin (r 2 ¼ 0.983) and the D-R isotherm models (r 2 ¼ 0.988) well.However, the Pb(II) adsorption only fits the Freundlich isotherm model. The activation energies of the Zn(II) adsorption onto nZVI-Mont were in a range from 11.71 kJ mol À1 to 46.37 kJ mol À1 and the activation energies of the Pb(II) adsorption onto nZVI-Mont were in a range from 0.26 kJ mol À1 to 17.67 kJ mol À1 . The negative values for the Gibbs free energy (DG o ) and enthalpy of adsorption (DH o ) revealed that the adsorption process was spontaneous and exothermic, respectively. In addition, the adsorption mechanisms for Zn(II) and Pb(II) are significantly different.

Section: Thermodynamic Studiesmentioning

confidence: 99%

“…[1][2][3][4] These metal ions can accumulate in the environment, damage the environmental balance and potentially threaten human health. [1][2][3][4] These metal ions can accumulate in the environment, damage the environmental balance and potentially threaten human health.…”

Section: Introductionmentioning

confidence: 99%

Physicochemical studies toward the removal of Zn(ii) and Pb(ii) ions through adsorption on montmorillonite-supported zero-valent iron nanoparticles

Liu

et al. 2015

RSC Adv.

“…After 24 days, the effluent pH gradually decreased, while the effluent ORP value gradually increased. This indicated that the reduction of carbon source released by bagasse, low pH and high concentration of metal ions reduce the biological activity of SRB [24], resulting in a decrease in the ability of microbial metabolism to produce alkalinity and a decrease in the pH of the effluent. The proliferation and activity of SRB were inhibited, resulting in an increase in the effluent ORP value.…”

Section: Analysis Of the Change Of Ph And Oxidation Reduction Potentimentioning

confidence: 99%

Dynamic Experimental Study on Treatment of Acid Mine Drainage by Bacteria Supported in Natural Minerals

Dong

et al. 2020

Energies

In order to solve the problem of pollution of acid mine drainage (AMD), such as low pH value and being rich in SO42−, Fe and Mn pollution ions, etc., immobilized particles were prepared by using sugar cane-refining waste (bagasse), a natural composite mineral (called medical stone in China) and sulfate-reducing bacteria (SRB) as substrate materials, based on microbial immobilization technology. Medical stone is a kind of composite mineral with absorbability, non-toxicity and biological activity. The adsorption capacity of medical stone is different according to its geographic origins. Two dynamic columns were constructed with Column 1 filled by Fuxin’s medical stone-enhanced SRB immobilized particles, and Column 2 filled by Dengfeng’s medical stone-enhanced SRB immobilized particles as fillers. The treatment effect on AMD with SRB-immobilized particles enhanced by medical stone from different areas was compared. Results showed that Column 2 had better treatment effect on AMD. The average effluent pH value of Column 2 was 6.98, the average oxidation reduction potential (ORP) value was −70.17 mV, the average removal percentages of SO42−, Fe2+ and Mn2+ were 70.13%, 83.82% and 59.43%, respectively, and the average chemical oxygen demand (COD) emission was 555.48 mg/L.

“…28 The main reason for the rapid increase of pH in the beginning of stage I is the adsorption of H + by particles. As the reaction progresses to the second stage, the soluble carbon source continuously decreases, the SRB dissimilatory reduction activity decreases as well, and the high-concentration heavy metal ions and high acidity inhibit the metabolic activity of SRB in the particles, 29 resulting in the amount of alkaline substances produced by microorganisms is reduced. Therefore, the pH of the effluent decreased to varying degrees.…”

Section: Dynamic Experimental Studymentioning

confidence: 99%

Experimental study on the treatment of acid mine drainage by modified corncob fixed SRB sludge particles

Dong

et al. 2019

RSC Adv.