Use of a packed-bed airlift reactor with net draft tube to study kinetics of naphthalene degradation by Ralstonia eutropha

Biodegradation of naphthalene by Ralstonia eutropha (also known as Cupriavidus necator) in a packed-bed airlift reactor with net draft tube (PBALR-nd) was studied; the Kissiris pieces were the packing material. The reactor hydrodynamics has been characterized under abiotic conditions and the dependencies of the superficial gas velocity (U _G) on the gas holdup (ε_G), liquid mixing time, and mass transfer coefficient were determined. The improving role of the net draft tube in this small column reactor (height 42 cm, ID 5 cm) was confirmed. The flow regime was described using the ε_G α U _G ⁿ expression, and bubbly flow was observed in PBALR-nd at U _G < 2.83 cm/s. In the second step of the present work, the kinetics of biodegradation was modeled using the Haldane and Aiba equations. The fitting of the experimental results to the models were done according to the nonlinear least square regression technique. The biokinetic constants (q _m, K _s, and K _i) were estimated and q _m as the specific biodegradation rate was equaled to 0.415 and 0.24 mg_naph./mg_cell?h for the Haldane and Aiba equations, respectively. The goodness of fit reported as R ² and root-mean-square error (RMSE) showed the adequate fitness of the Haldane and Aiba models in predicting naphthalene biodegradation kinetics. On the basis of the HPLC results, a hypothetical pathway for the biodegradation was presented.     

Biogenic synthesis of gold nanoparticles using Satureja rechingeri Jamzad: a potential anticancer agent against cisplatin-resistant A2780CP ovarian cancer cells

Environmental Science and Pollution Research - Drug resistance of cancer cells is a major issue in cancer treatment. Plant-mediated nanoparticle synthesis has been applied in recent years to...     

The effects of socioeconomic parameters on household solid-waste generation and composition in developing countries (a case study: Ahvaz,Iran)

Environment problems associated with the generation of waste are part of societal changes where households play an important role. These societal changes influence the size, structure and characteristic of given households. For the effective planning of solid-waste handling infrastructure, it is essential to know the quantity of waste generation and its composition. This paper presents the findings of a study carried out in an urban municipal area in Iran to determine the household solid-waste generation rate and waste composition based on field surveys and to determine the related socioeconomic parameters. The dependent variables were waste generation and composition, and independent variables were family size, family employment, age, number of room and education. Over 400 sample households were selected for the study using a stratified random sampling methodology and from five different socioeconomic groups. Waste collected from all groups of households were segregated and weighted. Waste generation rate was 5.4 kg/household/day. Household solid waste comprised of ten categories of wastes and with the largest component (76.9%). The generation and composition of household solid waste were correlated with family size, education level and households income. This paper adequately suggests new insights concerning the role of socioeconomic parameters in affecting the generation of household waste.     

Optimal deployment of emissions reduction technologies for construction equipment

The objective of this research was to develop a multiobjective optimization model to deploy emissions reduction technologies for nonroad construction equipment to reduce emissions in a cost-effective and optimal manner. Given a fleet of construction equipment emitting different pollutants in the nonattainment (NA) and near -nonattainment (NNA) counties of a state and a set of emissions reduction technologies available for installation on equipment to control pollution/emissions, the model assists in determining the mix of technologies to be deployed so that maximum emissions reduction and fuel savings are achieved within a given budget. Three technologies considered for emissions reduction were designated as X, Y, and Z to keep the model formulation general so that it can be applied for any other set of technologies. Two alternative methods of deploying these technologies on a fleet of equipment were investigated with the methods differing in the technology deployment preference in the NA and NNA counties. The model having a weighted objective function containing emissions reduction benefits and fuel-saving benefits was programmed with C++ and ILOG-CPLEX. For demonstration purposes, the model was applied for a selected construction equipment fleet owned by the Texas Department of Transportation, located in NA and NNA counties of Texas, assuming the three emissions reduction technologies X, Y, and Z to represent, respectively, hydrogen enrichment, selective catalytic reduction, and fuel additive technologies. Model solutions were obtained for varying budget amounts to test the sensitivity of emissions reductions and fuel-savings benefits with increasing the budget. Different mixes of technologies producing maximum oxides of nitrogen (NO(x)) reductions and total combined benefits (emissions reductions plus fuel savings) were indicated at different budget ranges. The initial steep portion of the plots for NO(x) reductions and total combined benefits against budgets for different combinations of emissions reduction technologies indicated a high benefit-cost ratio at lower budget amounts. The rate of NO(x) reductions and the increase of combined benefits decreased with increasing the budget, and with the budget exceeding certain limits neither further NO(x) reductions nor increased combined benefits were observed. Finally, the Pareto front obtained would enable the decision-maker to achieve a noninferior optimal combination of total NO(x) reductions and fuel-savings benefits for a given budget.     

Bioclimatic passive design strategies of traditional houses in cold climate regions

Environment, Development and Sustainability - Providing indoor thermal comfort is one of the most significant factors in architecture that it is observed in traditional buildings all around the...     

Biodegradation of phenol by Ralstonia eutropha in a Kissiris-immobilized cell bioreactor

This study examined the biodegradation of phenol by Ralstonia eutropha in a Kissiris-immobilized cell bioreactor (ICB), operated in a repeated batch recycling mode. The steady biodegradation rate of 23.7 mg/g/h, over a wide range of the initial phenol concentrations up to 1400 mg/L in the ICB, indicated an increased tolerance limit of the Kissiris-immobilized cells towards phenol. Both Haldane and Luong substrate inhibition models were used to describe biodegradation kinetic of free cells system. The Haldane equation gave the following values for the biokinetic parameters: micro(max) = 0.36 h(-1), Ks = 40.48 mg/L, and Ki = 181.9 mg/L. However, according to the Luong model, these parameters were micromax) = 0.23 h(-1), Ks = 24.8 mg/L, Sm = 1018 mg/L, and n = 1.3. By following appropriate operational conditions and use of the ICB, it was found to be possible to extend the efficiency of the highly porous structure of the siliceous mineral Kissiris in cell immobilization. This holds significant promise for pollutant biodegradation issues.     

Susceptibility mapping of groundwater salinity using machine learning models

Environmental Science and Pollution Research - Increasing groundwater salinity has recently raised severe environmental and health concerns around the world. Advancement of the novel methods for...     

Synthesis and utilization of a mesoporous nickel oxide as a novel catalyst for degradation of phenol

Mesoporous nickel oxide (MNO) was synthesized by sol–gel method with saponificated chlorophyll-a (Chl-a) as template and Ni (II) acetate as starting material. XRD, surface area, pore volume, pore diameter and pore size distribution of MNO were determined. It exhibited high surface area and uniform pores with very sharp pore size distribution centered at 3.6 nm. High resolution transmission electron microscope images confirmed the results. MNO showed a high activity toward degradation of phenol at low temperature under atmospheric pressure of oxygen.     

Noise exposure of pregnant mice induces heart defects in their fetuses

To determine the effects of noise exposure on hearts of newborn mice, 48 pregnant mice were exposed to recorded aircraft flight noise (100?dB) for 150?min from the 2nd day of pregnancy to 7th day after delivery. Mice of the same age were selected as control group. The weights and crown-rump lengths of the fetuses and the newborns were measured, and their hearts were removed under deep anesthesia on the 1st, 7th, and 14th days after birth and prepared histologically. Quantitative changes of the hearts were measured stereologically by the Cavalieri method. The ultrastructural changes of cardiac myocytes were examined using transmission electron microscopy. No histological changes were observed, but the volumes of newborns’ hearts in the experimental groups increased significantly compared to the control group. Photomicrographs of cardiac muscle cells revealed nuclear envelope changes, chromatin condensation, and increased mitochondria and myofibrils in noise-exposed newborns. It is concluded that the newborns of pregnant mice exposed to noise stress have hypertrophic hearts with ultrastructural changes.     

Simultaneous determination of binary solution of triphenylmethane dyes in complex matrices onto magnetic amino-rich SWCNT using second-order calibration method

This study suggested a new method for simultaneous quantification of two dyes in complex matrices using second-order data by spectrophotometry. Second-order data was generated simply without any expensive instrument using two independent variables including wavelength and the monotonic addition of sodium dodecyl sulfate. Solid-phase extraction (SPE) based on amino-rich magnetic single-walled carbon nanotube as an adsorbent was employed prior to second-order data generation. SPE optimization was performed by Box-Behnken design, and parameters and their interaction which were dependent on the simultaneous extraction of dyes were examined. Competitive Langmuir and Freundlich isotherms for a binary system and individual dyes could all represent the equilibrium data well. The second-order data was processed by parallel factor analysis (PARAFAC and PARAFAC2) and multivariate curve resolution-alternating least squares (MCR-ALS). Figures of merit of the model including a limit of detection of 3.0 and 2.5 ng mL^?1 for crystal violet and malachite green, respectively, were estimated using the MCR-ALS method. The combination of the second-order calibration and SPE presents an easy and versatile method for determination of the mixture of two dyes in the presence of uncalibrated interferences in environmental water, synthetic, and fish samples with the recoveries of 94–104.