Study on Growth Influencing Factors and Desulfurization Performance of <i>Sulfate Reducing Bacteria</i> Based on the Response Surface Methodology

Abstract

<i>Sulfate reducing bacteria</i> (SRB) can simultaneously and efficiently remove SO₄ ^2- and heavy metal ions from acid mine drainage (AMD). Environmental factors have a great influence on AMD treated by SRB metabolic reducing sulfate. Providing a suitable growth environment can improve the effect of SRB on AMD. In this paper, the wet soil around the tailings reservoir was used as seed mud to enrich SRB. Based on the single factor experiment method and the response surface methodology (RSM), the effects of temperature, environmental pH value, S^2- concentration, and COD/SO₄ ^2- on the growth of SRB were analyzed. The effects of environmental factors such as temperature and pH on the desulfurization performance of SRB were investigated. The results showed that the growth curve of SRB was "S" type. SRB was in the logarithmic phase when cultured for 14-86 h, with high activity and vigorous growth metabolism. When the temperature is 32∼35 °C, the activity of SRB is the highest. With the gradual increase of the S^2- concentration in the culture system, SRB activity will be inhibited and even lead to SRB cell death. The environmental pH value that SRB can tolerate is 5∼8, and when the environmental pH value is 7∼8, the SRB activity is the strongest. The chemical oxygen demand (COD)/SO₄ ^2- that is most suitable for SRB growth is 2. The optimal growth conditions of SRB obtained from RSM were as follows: culture temperature at 34.74 °C, initial pH being 8.00, and initial COD/SO₄ ^2- being 1.98. Under these conditions, the OD₆₀₀ value was 1.45, the pH value was 9.37, the oxidation reduction potential (ORP) value was -399 mV, and the removal percentage of SO₄ ^2- was 88.74%. The results of RSM showed that the effects of culture temperature, environmental pH, and COD/SO₄ ^2- on the desulfurization performance of SRB were extremely significant. The order of affecting the removal of SO₄ ^2- by SRB was environmental pH > temperature > COD/SO₄ ^2-.