Interaction of acetamiprid with extracellular polymeric substances (EPS) from activated sludge: A fluorescence study

Extracellular polymeric substances (EPS) are important components of activated sludge and it plays an important role in removing pollutants. The interaction between EPS and organic pollutants is still little known. In the present study, the interaction of soluble/bound EPS with acetamiprid, a neonicotinoid insecticide, was investigated using the three-dimensional excitation–emission matrix (EEM) fluorescence spectroscopy. The fluorescence spectra of EPS revealed that there were two classes of protein-like fluorophores in soluble/bound EPS and one class of fulvic acid-like fluorophore, in addition, in bound EPS. The quenching of protein-like fluorescence by acetamiprid indicated that static quenching (at peak B) and combined quenching (at peak A) occurred simultaneously. The interaction of acetamiprid with EPS was observed to have resulted in the formation of acetamiprid-EPS complexes. The binding constants of the soluble EPS for acetamiprid were greater than those of the bound EPS, indicating the soluble EPS had stronger binding capacity for acetamiprid than the bound EPS. This study confirmed that EPS (soluble/bound) play important roles in biosorption of organic pollutants by activated sludge and also indicated that they may serve as a protective barrier against toxic organic matter, for the microorganisms.Key words: Extracellular polymeric substance (EPS), activated sludge, fluorescence quenching, binding constant, acetamiprid

Uranium Bioreduction and Biomineralization

Following the development of nuclear science and technology, uranium contamination has been an ever increasing concern worldwide because of its potential for migration from the waste repositories and long-term contaminated environments. Physical and chemical techniques for uranium pollution are expensive and challenging. An alternative to these technologies is microbially mediated uranium bioremediation in contaminated water and soil environments due to its reduced cost and environmental friendliness. To date, four basic mechanisms of uranium bioremediation-uranium bioreduction, biosorption, biomineralization, and bioaccumulation-have been established, of which uranium bioreduction and biomineralization have been studied extensively. The objective of this review is to provide an understanding of recent developments in these two fields in relation to relevant microorganisms, mechanisms, influential factors, and obstacles

Removal of malachite green from water by Firmiana simplex wood fiber

This study shows that wood fiber of Phoenix tree (Firmiana simplex) is an effective adsorbent for malachite green (MG). MG sorption behavior onto the wood adsorbent was investigated in this study. Basic condition was favorable for MG adsorption to the adsorbent. The pseudo second order equation well described MG adsorption onto the wood adsorbent. The Freundlich Isotherm could describe the sorption data. The positive value of Delta H-0 showed that adsorption of malachite green onto the wood adsorbent was endothermic. The negative values of Delta G at various temperatures indicate the spontaneous nature of the adsorption process