Cassandra: An open source Monte Carlo package for molecular simulation.

Cassandra is an open source atomistic Monte Carlo software package that is effective in simulating the thermodynamic properties of fluids and solids. The different features and algorithms used in Cassandra are described, along with implementation details and theoretical underpinnings to various methods used. Benchmark and example calculations are shown, and information on how users can obtain the package and contribute to it are provided. © 2017 Wiley Periodicals, Inc.

Evaluation of the bioremoval of Cr(VI) and TOC in biofilters under continuous operation using response surface methodology.

In the present study, the bioremoval of Cr(VI) and the removal of total organic carbon (TOC) were achieved with a system composed by an anaerobic filter and a submerged biofilter with intermittent aeration using a mixed culture of microorganisms originating from contaminated sludge. In the aforementioned biofilters, the concentrations of chromium, carbon, and nitrogen were optimized according to response surface methodology. The initial concentration of Cr(VI) was 137.35 mg l(-1), and a bioremoval of 85.23% was attained. The optimal conditions for the removal of TOC were 4 to 8 g l(-1) of sodium acetate, >0.8 g l(-1) of ammonium chloride and 60 to 100 mg l(-1) of Cr(VI). The results revealed that ammonium chloride had the strongest effect on the TOC removal, and 120 mg l(-1) of Cr(VI) could be removed after 156 h of operation. Moreover, 100% of the Cr(VI) and the total chromium content of the aerobic reactor output were removed, and TOC removals of 80 and 87% were attained after operating the anaerobic and aerobic reactors for 130 and 142 h, respectively. The concentrations of cells in both reactors remained nearly constant over time. The residence time distribution was obtained to evaluate the flow through the bioreactors.

Removal of petroleum hydrocarbons from aqueous solution using sugarcane bagasse as adsorbent.

In the present work, the adsorption ability of sugarcane bagasse to remove oil by-products from aqueous solution was evaluated. The objective was treating the contaminated wastewater while enriching the bagasse for its later use as fuel in boilers. Adsorption experiments were carried out in an agitated reactor at room temperature to obtain kinetic curves and adsorption isotherms of gasoline and n-heptane on sugarcane bagasse. The results showed the great potential of bagasse as an adsorbent, since it was able to adsorb up to 99% of gasoline and 90% of n-heptane in solutions containing about 5% of these contaminants. In the adsorption kinetics of gasoline, the equilibrium was reached after just 5 min. This result shows that the adsorption is very favorable. Langmuir, Freundlich, Temkin and D-R models did not describe well the adsorption behavior obtained for these systems.