Analyzing the Growth and Characteristics of Pseudomonas aeruginosa Biofilm and Estimating its Cr(VI) Removing Potential from Water

Industrial wastewater often contains highly carcinogenic and mutagenic inorganic pollutants and harmful heavy metals such as Chromium (Cr), which are highly reactive and toxic, even at low concentrations. Efficient remediation or removal of Chromium is necessary to prevent its adverse impacts on humans and the environment. We have employed biofilm grown on a glass surface as a sustainable tool to reduce water's Cr(VI) levels. We studied biofilm formation using four different bacterial strains. Among those, Pseudomonas aeruginosa was selected based on its biofilm formation ability, estimated by qualitative and quantitative means. Maximum biofilm formation was observed on a glass surface using tryptone soya broth (TSB) at 37 degrees C and pH 7.5. The biofilm was characterized using Field Emission Scanning Electron Microscopy (FESEM) and stereo microscopy. The biofilm tolerated up to 10 ppm of chromium supplementation in the culture medium. The Cr(VI) concentration was determined using a UV-Vis spectrophotometer, and total chromium content was obtained using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). With preformed biofilm on glass, Cr(VI) concentration was reduced by 97% within eight hours with a reduction rate of 12.27% per hour. In comparison to biofilm during formation, preformed biofilm gave better results. The Field Emission Scanning Electron Microscopy (FESEM)-Energy Dispersive Spectroscopy (EDS) (FESEM-EDS) analysis depicted very minimal Cr(VI) adsorption into the cells, indicating the reduction of more harmful Cr(VI) to less toxic Cr(III). The present findings can lead to the development of an efficient treatment strategy for chromium-contaminated water.