| dc.description.abstract | Chromium is a widely used raw material in textile, tanning, electroplating, and wood
preservative industries, which releases significant amounts of hexavalent
chromium contaminated wastes into inland waters and aquatic environments,
causing hazardous effects on biota, i.e., cancers, organ disorders, morphological
changes, functional alterations, etc. Therefore, many pollutant removal strategies
including chemical, physical and biological remediation methods are used in the
chromium-based industry to prevent such adverse effects. This study mainly
compared the effectiveness of physical and biological methods for hexavalent
chromium removal. The physical remediation was done using agricultural waste;
straws as a natural adsorbent, which is abundant in Sri Lanka. Bioremediation was
investigated using previously isolated hexavalent chromium tolerant bacterial
strain Bacillus subtilis KCB07C10. Bacterial biofilms of B. subtilis KCB07C10 were
formed on straw and visualized by scanning electron microscopy. Straw, bacterial
isolate, and biofilm were exposed to 16.0 mg/L of hexavalent chromium in Tris
minimal medium (modified), and hexavalent removal was measured
spectrophotometrically by 1,5-diphenylcarbazide analysis during 24 hours of time
intervals up to 96 hours. The study describes that the complete removal of
hexavalent chromium can be achieved by both B. subtilis KCB07C10 immobilized
straw and planktonic cell suspension within 48 and 96 hours, respectively, while the
adsorbing straw indicated 51.47 % removal during the study period. It can be
concluded that the efficiency of hexavalent chromium removal differs significantly
among the adsorbents, planktonic bacteria, and biofilms in question (p=0.022) and
that hexavalent chromium removal can be efficiently performed by B. subtilis
KCB07C10 biofilm on straw. | en_US |
