Environmental Science and Technology

Correction to: Mitigation of the liquefaction potential of soil by Ca-carbonate precipitation induced by indigenous urease-producing Staphylococcus sp. IR-103 The original version of this article unfortunately contained a mistake.

Thermal and catalytic methods used for destruction of chemical warfare agents Abstract The decontamination of chemical warfare agents (CWAs) from structures, environmental media and even personnel has become an area of particular interest in recent years due to increased homeland security concerns. This article reviews applications of catalytic methods used for decontamination of CWAs. Most attention was given to the following methods: thermocatalysis, photocatalysis and enzyme catalysis among the many methods of catalytic CWA decomposition. Unfortunately, there are not enough data obtained with real CWAs due to the difficulty in handling, so we have described also data available for CWAs simulants. These methods can be useful for decontamination systems that can reduce the damage caused by possible terrorism.

Kinetics and equilibrium study of lead bio-sorption from contaminated water by compost and biogas residues Abstract Lead (Pb) poses serious threats to plants, animals and humans once entered into the food chain via the contaminated effluents; thus, it has become imperative to remove Pb from the water stream. This study examined the potential and feasibility of compost and biogas residues for the bio-sorption (q) and removal (R) of Pb from contaminated water. To explore the objectives, a series of batch experiments was conducted at various adsorbent masses (0.5, 1.0 and 1.5 g/100 mL), Pb concentrations (30, 60 and 90 mg L−1) and contact time (15, 30, 60 and 120 min). Lead bio-sorption was decreased with increasing Pb concentration from 30 to 90 mg L−1 and sorbent biomass from 0.5 to 1.5 g/100 mL. At equilibrium state, relatively greater sorption and removal were observed from compost (q = 2.29–11.61 mg/g, R = 65–80%) as compared to biogas residues (q = 1.59–7.45 mg/g, R = 41–69%) depending upon Pb concentration and sorbent biomass in aqueous solution. Our results were better fitted with Freundlich equilibrium adsorption isotherm model (qmax = 2.882 mg/g, R2 = 0.99) and pseudo-second-order kinetics (qmax = 8.43 mg/g, R2 = 0.99). FTIR spectra indicated the presence of –OH, C–O, C=O, C=C and sp3 C–H functional groups on both adsorbents which might be involved during Pb adsorption. Compost was more porous material with well-developed cavities and had greater surface area than biogas residues (135 vs. 43 m2/g); therefore, compost has great sorption potential for heavy metal remediation from aqueous solution as compared to the biogas residues.

Simultaneous removal of oil, total Co and 60 Co from radioactive liquid waste by dissolved air flotation Abstract This report presents a kinetic study of the simultaneous removal of oil, total cobalt and 60Co from radioactive liquid waste by dissolved air flotation. We studied the effects of the incorporation of an inclined lamella module in the flotation cell on the overall removal efficiency. The results showed that the removal of oil is greater than the levels observed in the total cobalt and 60Co. It was established that the removal of Co depends on the oil's separation. This finding is explained by the chemical behaviour of Co, as well as the physico-chemical characteristics of the liquid residue. However, the evidence showed that the efficiency of the dissolved air flotation system with the inclined lamella module is greater than the conventional dissolved air flotation system. In addition, the comparison between the efficiency and the value of the kinetics constant θ showed that they share a directly proportional relationship. Finally, it was established that the kinetic constant θ estimation through the kinetic equation represents a simple way of assessing and controlling the dissolved air flotation process.

Possibility of utilizing natural coagulants ( Trigonella foenum-graecum and Astragalus gossypinus ) along with alum for the removal of turbidity Abstract Water, especially drinking water, might need to be treated before being utilized. Coagulants play a significant role in water treatment. In spite of having adverse effects on human health, aluminum sulfate, alum and other chemical coagulants are commonly used in coagulation processes. Utilization of natural and herbal materials such as quince seeds, fleawort, tragacanth, starch and yeast as coagulant aids has been experimentally investigated in this study. The aims of the present paper are: (1) to determine the optimal dose of Trigonella foenum-graecum (fenugreek) and Astragalus gossypinus (tragacanth) seeds as coagulant aids along with alum for the coagulation of raw water from Minab water treatment plant) located 7 km away from Bandar Abbas–Minab road at the east of Bandar Abbas in Iran, with a total area of 11.5 ha) and (2) to study their influence on reducing the water turbidity at a pilot scale. According to the obtained results, the optimum amount of alum (without additives) was calculated as 35 mg/L for water with the initial turbidity of 70–75 NTU, as the average turbidity interval. Using A. gossypinus and T. foenum-graecum seeds as coagulant aids, the optimum amount of alum reached 22 mg/L. The performance of A. gossypinus, as a coagulant aid, was much better in low concentrations. It was used in doses of 0.25, 1 and 2 mg/L along with 20, 22 and 28 mg/L of alum for low, intermediate and high turbidity levels (28, 70 and 120 NTU) and led to turbidity removal percentages of 85, 94.5 and 96.4, respectively. The optimum amounts of T. foenum-graecum seeds for the three mentioned turbidity levels were calculated as 1, 2 and 4 mg/L. The turbidity removal percentages of 91.5, 95.7 and 97.8 were obtained using the mentioned amounts of T. foenum-graecum seeds along with 20, 22 and 25 mg/L of alum, respectively. Similar results were obtained by using both additives along with alum.

Bioreduction of toxic hexavalent chromium by novel indigenous microbe Brevibacillus agri isolated from tannery wastewater Abstract The present study is focused on the microbial bioreduction of hexavalent chromium generated from tannery waste. For the study, the treated and untreated tannery effluents were collected from an unexplored site of Manpura, Macheri, Jaipur (India). A few bacterial strains capable of tolerating and reducing hexavalent chromium were isolated, and the most capable one that reduced 85% of hexavalent chromium was identified to be Brevibacillus agri by 16S rDNA gene sequencing. This isolate could tolerate high concentrations of chromium up to 850 mg/l of potassium dichromate and showed maximum reduction of about 85% for 100 mg/l of hexavalent chromium at temperature 37 °C and pH 7.0 in 48 h. The potential of the partially purified enzyme to reduce hexavalent chromium was measured by diphenyl carbazide assay. Purified enzyme showed 0.26 units bioactivity to reduce Cr, in the presence of reduced nicotinamide adenine dinucleotide and Km and Vmax were observed to be 1.9 mM and 0.045 mM/min (mg protein), respectively. The current study, therefore, showed Brevibacillus agri capable of reducing hexavalent chromium without usage of toxic chemicals and, henceforth, prevented generation of harmful by-products.

Kinetic and equilibrium studies for cadmium biosorption from contaminated water using Cassia fistula biomass Abstract Cadmium (Cd) contamination of the water resources is one of the serious environmental issues. The present study aims to (1) evaluate the biosorption potential of Cassia fistula biomass for the removal of Cd from contaminated water and validate the experimental results with kinetic and equilibrium sorption models, (2) assess the removal of Cd from groundwater samples in the presence of other competing ions in the solution. The C. fistula biomass was characterized using Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller technique and scanning electron microscopy to understand the role of its physical properties in Cd biosorption and removal. The effects of biosorbent dose, initial Cd concentrations, contact time and presence of competing cations in groundwater samples at constant pH and temperature (27 ± 1.5 °C) were studied. At equilibrium (90 min), Cd removal (98–16%) and biosorption (6.26–0.34 mg/g) were recorded depending on the experimental conditions. The Langmuir model yielded a better approximation of the experimental data at equilibrium \(\left( {Q_{\hbox{max} } = 7.24{\text{ mg/g, }}R^{2} = 0.99} \right)\) rather than Freundlich model. The pseudo-second-order kinetic model explained well the kinetic behavior of Cd biosorption. Results revealed a decline in the Cd removal (12.7 and 6% at 0.25 and 1.0 g/100 mL, respectively) in the presence of cations in the water samples. The results proved that C. fistula is a very effective and environment friendly alternative adsorbent for the removal (98%) of Cd from the aqueous system.

Evaluation of waste management options using rapid impact assessment matrix and Iranian Leopold matrix in Birjand, Iran Abstract Population growth and the corresponding production of more waste as well as considering the lack of appropriate municipal solid waste management strategies in recent years have confronted the city of Birjand with huge waste disposal problem. This study evaluated different waste management options in Birjand, including open dumping, sanitary landfill, composting and recycling. Environmental impact assessment of these options was performed using two methods: rapid impact assessment matrix and Iranian Leopold matrix (modified Leopold matrix). The rapid impact assessment matrix method provides fast and accurate ways of analysis and reanalysis of specified components. Iranian Leopold matrix chiefly is used for the reorganization of the project impacts in both the building and operation stages. Composting option, with final scores of − 0.5 and − 2.34, respectively, in rapid impact assessment matrix and Iranian Leopold Matrix, had the least negative environmental impact. Also, as a result of both methods, open dumping had the most negative environmental impact. The result of sustainability determination for four alternatives showed that the composting, with S-Value equal 0.01 and − 0.162, respectively, in rapid impact assessment matrix and Iranian Leopold matrix, is more sustainable than the other options. Therefore, composting option was introduced as first priority and the most logical strategy for municipal solid waste management in Birjand. Unfortunately, open dumping is currently the most common method of waste management in this city.

Physicochemical parameters of water from selected boreholes utilized as potable water Abstract The physicochemical characteristics of water samples from selected boreholes in six peri-urban communities were analysed to assess the quality of waters for suitability for human consumption. Samples were collected from sixteen different boreholes at interval of 1 month from July to September 2015 and from December 2015 to February 2016 to cover rainy and dry seasons, respectively. Samples were analysed for temperature, pH, dissolved oxygen, biochemical oxygen demand, alkalinity, acidity, etc. using standard methods. The results were compared with World Health Organization standards. Data obtained for both rainy and dry seasons indicate pH ranges of 6.65–7.50 (mean value 7.09), temperature 27.00–29.00 °C (mean value 28.06 °C), dissolved oxygen 41.60–69.60 mg/l (mean value 49.53 mg/l), acidity 1.46–5.28 mg/l (mean value 3.16 mg/l), alkalinity 8.00–14.00 mg/l (mean value 10.82 mg/l), electrical conductivity 3.50–24.10 µS/cm (mean value 10.69 µS/cm), dissolved oxygen 41.60–69.60 mg/l (mean value 49.53 mg/l) and biochemical oxygen demand 8.00–33.60 mg/l (mean value 21.21 mg/l). Out of the 16 samples analysed, 12 were soft water while 4 were slightly hard water. Most of the physicochemical parameters, except dissolved oxygen and biochemical oxygen demand were within World Health Organization standard. The pollution index for physicochemical composition was mostly greater than 1, indicating heavy contamination of the waters. The results obtained in this study, especially biochemical oxygen demand and dissolved oxygen values, suggest that water from the boreholes sampled is not suitable for human consumption and may constitute a serious health risk to the consumers.

Application of TiO 2 -supported Au for ozone molecule removal from environment: a van der Waals-corrected DFT study Abstract In this paper, we examined the interaction of ozone molecule with TiO2-supported Au nanoparticles by performing first-principles calculations within density functional theory. The structural properties including bond lengths, bond angles and adsorption energies were calculated. The electronic properties were analyzed in view of the Mulliken charges and projected density of states. The results show that the adsorption of O3 molecule on the N-doped TiO2-supported Au nanoparticle is more energetically favorable than the adsorption on the pristine one, suggesting that the N-doped TiO2-supported Au nanoparticle can react with O3 molecule more strongly. It was found that the O3 molecule tends to be strongly adsorbed on the surface of Au nanoparticles through its side oxygen atoms, providing a bridge geometry. On the TiO2 side of TiO2-supported Au overlayer, there is also a strong binding between the fivefold coordinated titanium atoms and the side oxygen atoms of O3 molecule, where the titanium atoms represent a double contacting point with oxygen atoms. Therefore, the obtained results also propose a theoretical basis for the potential applications of TiO2-supported Au nanoparticles in gas sensor devices.

Alexandros Sfakianakis
Anapafseos 5 . Agios Nikolaos
Crete.Greece.72100
2841026182

6948891480

alsfakia@gmail.com