Biosorption Processes for Removal of Toxic Metals from Wastewaters

Excessive and cumulative release of toxic metals from industrial effluents due to rapid industrialization has posed hazard to aquatic ecosystem integrity and environmental/ human health. The inadequacy and high cost of traditional metal treatment technologies coupled with the imposition of stricter environmental regulations and guidelines for industrial point source discharges have increased the demand for economically feasible alternative methods. Application of natural and abundant sorption material known as biosorbents comprising microbial biomass, agriculture waste, and industrial waste biomass, has gained international attention in scientific world as a low-cost and effective method for removal of heavy metals from aqueous solutions. However, this method has not been able to gain the attention of industry for large-scale applications thus far. This research was aimed to further evaluate the potential of biosorption technique in more realistic conditions appealing to industry by exploiting locally available biosorbents undergoing minimum pretreatment steps, combining living and non-living microbial biosorbents without any heat-inactivation, employing continuous-flow systems, and regenerating the used biomass for recovery of the mixture of heavy metals. The toxic metals of interest for biosorption in this work were copper, lead, and zinc, and biosorbents selected were cells of Saccharomyces cerevisiae as a microbial biomass and Acer saccharum tree leaves as an agro-waste. Sorption performances of the biosorbents were evaluated through classical adsorption equilibrium isotherms and kinetics in batch systems, and supplemented by dynamic continuous flow studies, which may serve as a basis for equipment sizing and scale up of the biosorption systems. Batch sorption studies revealed that pseudo-second order and Langmuir isotherm models were suitable to describe the metals sorption kinetics and equilibrium, respectively. Evaluation of biosorption performance and selection of best biosorbent using the Langmuir isotherm constants correctly were thoroughly discussed based on dynamic equilibrium between the metal species and biosorbents active sites. Design of experiment technique was used to determine model equations describing the removal efficiencies of mixture of the target metals by Saccharomyces cerevisiae with respect to operating conditions such as pH, metal concentration, and biomass dose. The selectivity order of Pb2+\u3e Cu2+\u3e Zn2+ was achieved by yeast cells with Pb2+ ions removal efficiencies reaching up to 98%. Process optimization helped to evaluate the simultaneous effects of pH, initial metal concentration, and biomass dose on competitive biosorption of metals by yeast cells. Characterization of metal-biomass interactions responsible for biosorption was studied employing zeta potential, BET, FT-IR, and SEM-EDX techniques. The results suggested the involvement of electrostatic interactions, ion exchange, interaparticle sequestration, and a weak surface binding in adsorption of the metals by the selected biosorbents. The use of unmodified yeast cells in a self-contained continuous system was shown to be an effective metal biosorption method by minimizing biomass pretreatment and preparation steps as well as achieving an on-line and concurrent biosorbent production and metal biosorption within the same system. Biosorptive performance of maple leaves in multiple column sorption-desorption cycles showed no degradation on metal capacity of the biomass (18.3 mg Cu/g) with increasing cycles despite shortening breakthrough times. Biomass regeneration efficiencies up to 98% were achieved using a weak acid as eluent. The presented simplified mass transfer model based on rapid local equilibrium and an apparent dispersion coefficient well simulated the dynamic operation of the packed bed biosorption column. Research conducted in this thesis can be of value to industries searching for efficient, simple, and green alternative metal treatment methods to meet the regulatory limits for the heavy metals discharges at a lower cost

HYDRODYNAMICS OF SMALL BUBBLES IN NON-NEWTONIAN AQUEOUS SOLUTIONS OF XANTHAN GUM

Free motion of small air bubbles in the volume range of 1-1000 mm3 (microlitre) has been studied in a column with different concentrations of xanthan gum ranging from 520 to 2580 ppm (w∕w). Two high-speed cameras were used to capture the continuous movement of bubbles up to 2000 frames per second. The sizes as well as the rise velocities of bubbles were measured by means of an image analysis software connected to the cameras. A precise method has been developed to create bubbles with high accuracy and controlled specified volumes. One of the main objectives of this work was to investigate the presence of the often-reported discontinuity in the rise velocity versus volume of air bubbles in non-Newtonian fluids. No abrupt velocity change was observed in our studies for the bubble volume range from 1 to 100 microlitre, which has been reported to occur by some other researchers. A thorough rheological study on the working concentrations of xanthan gum has been performed to interpret the observations with the existing hypothesis in literature for velocity­ volume discontinuity. To be able to evaluate the results of the rise velocity for xanthan gum solutions in respect to the jump velocity, the same measurements were repeated using two different concentrations of CMC, namely, 0.4% and 0.6% w/w as a second non-Newtonian fluid

Economic and Social Factors Affecting Environmental Pollution with an Emphasis on Mazut Consumption in Iran

The main purpose of this study is to investigate the effect of economic and social factors on the emission of carbon dioxide, which has been used as a measure of environmental pollution in Iran for the period of 1352-1397. In order to measure the economic and social factors affecting environmental pollution, it is necessary to study the short-term and long-term relationship between fuel oil consumption, urbanization, economic growth, and carbon dioxide emissions in Iran. For this purpose, the autoregression model with extended distribution intervals (ARDL) was used. The results show that the error correction coefficient obtained in this model shows that in each period, 33% of the short-term failure error can be made to achieve a long-term comparison. According to the estimate, the increase in fuel oil consumption, urbanization, and economic growth have a positive effect on carbon dioxide emissions both in the short term and in the long term. Also, the long-term results indicate that with an increase of one percent of gross domestic production, fuel oil consumption and urban population increase carbon dioxide emissions by 0.849, 0.166, and 1.566 percent, respectively. Therefore, the first step to reduce carbon dioxide emissions in the country is to pay attention to the amount of fuel oil consumption, hence policies can be made to use alternative energies such as renewable energies to reduce carbon dioxide emissions

The Impact of Economic Growth, Energy Consumption, and Urbanization on the CO2 Emission of a Selected Group of OPEC Countries: A Spatial Econometric Approach

The swift expansion of urban areas in OPEC member countries and the great reliance their economy has on the consumption of crude oil have led to drastic environmental changes in these states. Therefore, it is important to investigate the factors influencing the emission of CO2 such as economic growth, energy consumption, and urbanization in these countries. Economic growth and energy consumption are among the other influential factors. In this article, the effect of economic growth, energy consumption, and urbanization on the emission of CO2 has been studied. Thus, a sample of eight OPEC members was chosen for the duration of 2008 to 2018. Due to the effects of proximity, a spatial econometric approach was taken to investigate the spillover effects of neighboring countries. The results showed the existence of spatial reliance between the countries under study. The separate analysis of the spillover demonstrated that the effect of both economic and local urban population growth (direct) and spillover (indirect) increased the emission of CO2 in each country and its neighboring state, but the amount of direct effect was more than the indirect on other countries. The reality that environmental pollution resulting from economic growth and the development of urban areas and the increase of the consumption of nonrenewable energy in each of the studied countries also influence the environment of their neighboring states has laid the foundation for cooperation between neighboring OPEC countries to develop the technology to produce clean, renewable energy

Efficacy of Furosemide 0.125 Percent topical gel and KOH 10 Percent topical solution in the treatment of patients with warts: a comparison study

Background. Warts are a common skin disease affecting individuals of all ages worldwide. This clinical trial aims to compare the effectiveness of furosemide 0.125 Percent topical gel and KOH 10 Percent topical gel in treating patients with warts. Methods. Patients diagnosed with warts by dermatologists were included in the study and treated with either 0.125 Percent furosemide or 10 Percent KOH for two months. Patients were examined and imaged at the beginning of the study and in weeks 4 and 8 to assess the number, diameter, and height of warts and complications. Results. The study included 40 patients (48 lesions) with common warts, with 20 patients in each intervention group. In the furosemide group, the average diameter of warts decreased from 4.25 ± 1.43 mm in the first visit to 4.14 ± 1.47 mm in the final visit. In contrast, the average diameter of warts in the KOH group decreased from 3.89 ± 1.67 mm to 3.02 ± 1.49 mm. No complications were reported in the furosemide group, whereas seven complications related to redness and burning were observed in the KOH group. Conclusion. Furosemide 0.125 Percent is effective and safe for treating skin warts. However, it is less effective than KOH in reducing the diameter and height of warts. This study's findings suggest that furosemide can be a promising alternative to KOH in treating warts, especially for patients with sensitive skin or those who experience complications with KOH treatment. Further research is needed to determine the optimal treatment duration and dosage of furosemide for treating warts. Practical Implications. We can find new ways to reduce complications in treating warts

The effect of mycorrhizal fungi and organic fertilizers on quantitative and qualitative traits of two important satureja species

The quantitative yield and essential oil percentage and composition of two important savory species in response to various fertilizers were explored in a field experiment as a factorial study based on a randomized complete block design with three replications in north Lorestan, Iran, in 2017–2019. The first factor was assigned to three mycorrhizal fungi (Funneliformis mosseae, Rhizophagus irregularis, and Glomus fasciculatum), phosphate biofertilizer (Baravar-2), fish manure (800 kg/ha), cattle manure (20 t/ha), vermicompost (5 t/ha), and a control (no fertilization); the second factor was assigned to two savory species, including Satureja khuzestanica and S. rechingeri. The results of the combined analysis of variance for the second and third years showed that the simple effects of fertilizers and species were significant on all recorded traits, except for some constituents of the essential oil. Among the mycorrhizal fungi, R. irregularis and S. khuzestanica outperformed S. rechingeri in all traits, except for essential oil content and yield. The interaction between year and species was significant for all traits. The essential oil content of S. rechingeri in the third year (5.1%) was 18% higher than that of S. rechingeri in the second year (4.3%) and 41% higher than that of S. khuzestanica in the third year (3.6%). According to the results, the foliar application of vermin compost at a rate of 5 t/ha can contribute to the sustainable production of both savory species, improving their growth and essential oil yield

The effect of foliar application of magnetic water and nano-fertilizers on phytochemical and yield characteristics of fennel

Environmental factors, especially nutrients, can influence the production of medicinal plants. Thus, the present study assessed the response of some morphological and physiological characteristics of fennel ecotypes to the foliar application (magnetic water, organic and chemical fertilizers). The study was a factorial experiment based on the randomized complete block design, with three replications and 25 treatments at the research farm of the Agricultural and Natural Resources Research and Education Center of West Azerbaijan province, Iran, in the spring and summer of two consecutive years, 2014–2015 and 2015–2016. The first factor was assigned to fennel landraces (Gaziantep, Hamedan, Urmia, Yazd, and Shiraz) and the second factor to the foliar application (nitrogen nano-fertilizer, magnetic water, urea, chicken manure, and the control). Results showed that interaction of fertilizer treatment and landrace increased fresh and dry weight, biological yield, and seed yield significantly. In the first year, the highest fresh weight (166 g) and dry weight (35.5 g) were observed in the Gaziantep landrace fertilized with chicken manure. The highest anethole and fenchone contents (81.75% and 7.92%, respectively) were observed in the landraces treated with chicken manure. Based on the percentages, the Urmia landrace had the highest anethole percentage (83.2%), and the Shiraz landrace had the lowest one (77.5%). The highest fenchone contents (9.61%) and the lowest (2.18%) were observed in the Yazd and Urmia landraces. Due to the positive effect of application of chicken manure on improving the studied traits of fennel, it is recommended to include chicken manure inputs to enhance the efficiency of crops, reduce environmental pollution, and move toward sustainable agriculture

Evaluation of onion cultivation energy balance in east Azerbaijan province

One of the estimating methods of agricultural development and production stability in agricultural locations is the use of energy flow method. In this consideration energy flow in agricultural ecosystems of onion in East Azerbaijan was calculated by the use of gathered information and data via questionnaire and statistics of related Province’s agricultural Jihad organization and farms. The related data of inputs and outputs were altered to equal amounts of consumer and productive energy and then energy efficiency was calculated. Energy amounts of used factors and input in this type of cultivation was estimated 22307134 kcal/ha and output (production) energy amount of onion yield was 18594060 kcal/ha. Also energy efficiency value (output/input) was 0.833 percent. Data show that most of the consumer energy of onion cultivation of East Azerbaijan province is related to irrigation water use and chemical fertilizers and energy that used in machinery. In such a condition it is suggested that through precise determining of the vegetable’s water need, replacing modern irrigation methods in regard to current methods, preventing irregular use of inputs specially nitrogen fertilizers, applying proper managing methods in dry regions and using fertilizer on the base of soil test and production potential by increasing usage of function, energy could be optimum

Defining the actinic keratosis field: a literature review and discussion

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