Sugarcane bagasse into value-added products: a review

Environmental Science and Pollution Research - Strategic valorization of readily available sugarcane bagasse (SB) is very important for waste management and sustainable biorefinery. Conventional SB...     

Studies on arsenic transforming groundwater bacteria and their role in arsenic release from subsurface sediment

Ten different Gram-negative arsenic (As)-resistant and As-transforming bacteria isolated from As-rich groundwater of West Bengal were characterized to assess their role in As mobilization. 16S rRNA gene analysis confirmed the affiliation of these bacteria to genera Achromobacter, Brevundimonas, Rhizobium, Ochrobactrum, and Pseudoxanthomonas. Along with superior As-resistance and As-transformation abilities, the isolates showed broad metabolic capacity in terms of utilizing a variety of electron donors and acceptors (including As) under aerobic and anaerobic conditions, respectively. Arsenic transformation studies performed under various conditions indicated highly efficient As³⁺ oxidation or As⁵⁺ reduction kinetics. Genes encoding As³⁺ oxidase (aioA), cytosolic As⁵⁺ reductase (arsC), and As³⁺ efflux pump (arsB and acr3) were detected within the test isolates. Sequence analyses suggested that As homeostasis genes (particularly arsC, arsB, and acr3) were acquired by most of the bacteria through horizontal gene transfer. A strong correlation between As resistance phenotype and the presence of As³⁺ transporter genes was observed. Microcosm study showed that bacterial strain having cytosolic As⁵⁺ reductase property could play important role in mobilizing As (as As³⁺) from subsurface sediment.     

Sorption of organic contaminants to a low carbon subsurface core

Sorption of 1,2,4-trichlorobenzene, o-chlorotoluene and dimethylphthalate to a series of subsurface samples collected with depth is reported. Desorption of sorbate from the sorbent matrix provides better precision than conventional solution phase concentration differences when sorption is low. Clay mineral content influences sorption on low carbon sorbents.     

Removal of arsenic from drinking water by chemical precipitation--a modeling and simulation study of the physical-chemical processes.

A dynamic mathematical model was developed for removal of arsenic from drinking water by chemical coagulation-precipitation and was validated experimentally in a bench-scale set-up. While examining arsenic removal efficiency of the scheme under different operating conditions, coagulant dose, pH and degree of oxidation were found to have pronounced impact. Removal efficiency of 91-92% was achieved for synthetic feed water spiked with 1 mg/L arsenic and pre-oxidized by potassium permanganate at optimum pH and coagulant dose. Model predictions corroborated well with the experimental findings (the overall correlation coefficient being 0.9895) indicating the capability of the model in predicting performance of such a treatment plant under different operating conditions. Menu-driven, user-friendly Visual Basic software developed in the study will be very handy in quick performance analysis. The simulation is expected to be very useful in full-scale design and operation of the treatment plants for removal of arsenic from drinking water.