Showing 23 results for Mediation
M Davari, M Homaee, H Khodaverdiloo ,
Volume 14, Issue 52 (7-2010)
Abstract
Phytoremediation is a new, in-situ and emerging remediation technology for contaminated soils. This technology, compared to other methods, is a sustainable, natural, relatively cheap and applicable to large scale area. Modeling phytoremediation provides quantitative insight for the governing process as well as for managers to assess the remediated sites. The objective of this study was to introduce a macroscopic phytoremediation model for Ni and Cd- polluted soils. The proposed model assumes that relative transpiration reduction function can resemble total soilNi and Cd concentrations. Combining the related functions of soil and plant responses to soil Ni and Cd concentrations, the phytoremediation rate of Ni and Cd was predicted. In order to test the proposed model, large quantities of soil were thoroughly polluted with Ni and Cd. Upland Cress (Lepidum sativum) and Ornamental Kale (Brassica olerace var. Viridis) seeds were then germinated in the contaminated soils. The experimental pots were irrigated with fresh water to reach field capacity. Upland Cress and Ornamental Kale were harvested three and four times, respectively. At each harvest, relative transpiration, Ni and Cd contents of soil samples and plants were measured. Comparison of the maximum error, root mean square error, coefficient of determination, modeling efficiency and coefficient of residual mass indicated that the non-threshold non-linear model provide high efficiency to predict relative transpiration for Upland Cress and Ornamental Kale, respectively. The results also indicated that the proposed macroscopic model can well predict the phytoemediation rate of the Ni and Cd by Upland Cress (R2>0.83) and Ni by Ornamental Kale (R2=0.78).
A.a. Besalatpour , M.a. Hajabbasi, V. Dorostkar , Gh. Torabi,
Volume 14, Issue 53 (10-2010)
Abstract
Presence of petroleum contaminants in soil may be toxic to human and organisms and act as a source of ground water contamination hence, remediation of these compounds from environment is vital. In this study, first the feasibility of remediation of two petroleum-contaminated soil samples around Tehran Oil Refinery (oil refinery landfill and agricultural soils) was assessed using landfarming technique during a four month experimental period. The elimination of total petroleum hydrocarbons (TPHs) from soils treated through landfarming technique was then investigated in the rhizosphere of agropyron and fescue. The results showed that microbial respiration increased due to landfarming processes in both soils. Urease activity in the landfarming treatment for agricultural soil was 21, 45, 26, and 23% higher than the control at the end of first to the 4th months of experiment, respectively. However, no significant differences were observed between the landfarming and control treatments for landfill soil at the end of experiment. Furthermore, about 50 and 57% reduction in TPH-concentration was observed in the landfarming treatment for landfill and agricultural soils at the end of experiment, respectively. In the phytoremediation study, presence of TPHs in both landfarming and control treatments reduced dry matter yield of the studied plants. Urease activity in the rhizosphere of fescue and agropyron was higher than in the unplanted soil. Degradation of petroleum-compounds in the landfill soil under landfarming treatment was more than 20 and 40% in the presence of fescue and agropyron, respectively. The influence of agropyron on TPH-removal from agricultural soil under the landfarming treatment was also higher than fescue.
Z. Arabi , M. Homaee , M. E. Asadi ,
Volume 14, Issue 54 (1-2011)
Abstract
In this study, the effects of enhancing synthetic chelators (HEDTA, EGTA) and low molecular weight organic acids (LMWOA) such as citric acid were compared on cadmium (Cd) solution in soils that were artificially contaminated. Also Cd phytoextraction capability by radish (Raphanus Sativus L.) was studied. The experiment was laid out in a randomized complete factorial design where each treatment was replicated three times. Concentration treatments of cadmium using CdCl2 were 0(control), 5, 20, 60 and 100 mg Cd kg-1. After complete growth of plants, 6, 20 and 20 mMkg-1 soil HEDTA, EGTA and Citric Acid were added per pot, keeping a control without any chelator application. In order to determine cadmium concentration ten days after adding chelates, samples were taken from the plants and soil of pots. The results showed that in all treatments the concentration of soluble Cd in soil was higher than the control. Also the results showed that synthetic chelators as compared with LMWOA (Citric Acid) have increased the solution remarkably. Among the other chelates, HEDTA had significant effects on Cd solution. In the current study, Cd concentration in shoot and root of (Raphanus Sativus L.) was increased with enhancement of Cd concentration in soil. Cd concentrations in shoots of radish were higher than those in roots. This could refer to higher bioavailability and solubility of Cd. In the current study, in all the treatments with HEDTA Cd concentrations in shoot and root of (Raphanus Sativus L.) were increased as compared with other chelates..
M. Zarei, N. Saleh-Rastin, Gh. Savaghebi,
Volume 15, Issue 55 (4-2011)
Abstract
A greenhouse experiment was conducted in factorial experiment arranged as a completely randomized design (CRD) to evaluate the role of tree indigenous arbuscular mycorrhizal fungi (AMF) species originated from a polluted soil in phytoremediation of zinc polluted soils using maize as a host plant. The experiment consisted of plants inoculated with AMF (G1(Glomus intraradices), G2(Glomus mosseae) and G3(Glomus versiforme)) and G0 as non-inoculated plants and 5 levels of zinc (0, 10, 50, 100 and 500 mg kg -1) in non-sterilized sandy loam soil with three replications. According to the results of greenhouse experiment, the zinc and phosphorus uptake and also the biological yield of maize plants were significantly increased by inoculation with AMF in comparison with non-inoculated plants and also no zinc toxicity symptoms were observed. Uptake, translocation, and phytoextraction efficiency of plants inoculated with G. intraradices was more than the other treatments up to the level of 100 mg kg -1, but at the level of 50 mg kg -1 these amounts were highest in plants inoculated with G. mosseae. The efficicncy of three AMF in zinc uptake was highest at the low level of zinc. In general, under the high soil pollution (500 mg kg-1), G. mosseae was the most effective fungal species in Zn extraction and translocation while G. intraradices had the highest effectiveness for accumulation of Zn in the roots. The overall situation of G. versiforme was mostly between the two other fungal species.
V. Sarvi Moghanloo , M. Chorom, H. Motamedi , B. Alizadeh, Sh. Ostan,
Volume 15, Issue 56 (7-2011)
Abstract
Soil enzymes are the catalysts for important metabolic process functions including the decomposition of organic inputs and the detoxification of xenobiotics. The aim of this research was to determine the pattern of variation in the activities of dehydrogenase, urease, lipase and phosphatase enzymes, determining the number of hetrotrophic and degrading bacteria and measuring the soil respiration and yield plants during the bioremediation of oil contaminated soils. To this aim, the soil deliberately contaminated with crude oil at a 1 and 2 wt% rate and in four treatments including: plant multiflorum (T1), plant multiflorum with mycorrhiza inoculation (T2), plant multiflorum with oil degrading bacteria inoculation (T3), plant multiflorum with mycorrhiza and oil degrading bacteria inoculation (T4) was employed for bioremediation of oil contaminated soil. The above parameters were determined in five stages during bioremediation and ultimately for the yield of plants at the end of this period .The results showed that the activity of urease and hydrogenase anzymes were increased or decreased parallel to contaminant increase and decrease. In contrast, the activity of lipase anzyme was decreased with contaminant increase and increased with contaminant decrease. Therfore, it can be a good choice for monitoring of bioremediation of contaminated soils. The results showed that the number of degrading and hetrotrophic microorganisms were increased by increasing the amount of contamination and the number of degrading and heterotrophic bacteria were decreased parallel to contaminant decreasing especially in those samples treated with mycorrhiza inoculation. The plant yield and amount of degradation of oil compounds were highest in mycorrhiza plus degrading bacteria treatment.
A.r. Melali , M.a. Hajabbasi, M. Afyuni, A. H. Khoshgoftarmanesh,
Volume 15, Issue 56 (7-2011)
Abstract
The petroleum refinery sludge is an important source of environmental pollution. Burning and burying of the sludge may have adverse effects on environment and human health. Thus, other mechanisms for decreasing the toxic effects of hydrocarbon substances in the sludge must be used. In this study, Isfahan refinery sludge was dewatered, air dried and mixed by 0, 10, 20, 30 and 40% w/w ratio with two calcareous soils, viz., Mahmoud Abad (Typic Haplocalcids with clay texture) and Bagh Parandegan (Anthropic Torrifluvents with silty loam texture). Different mixtures of soil and sludge were farmed for 21 days and irrigated on a daily basis to field capacity. Then, 100 seeds of Tallfescue (Festuca arundinacea) and Agropyron were planted in polluted soils with 3 replicates in 3 kg pots for 5 months. Result showed that Tallfescue and Agropyron yields decreased in sludge contaminated treatments. In the 40% sludge treatment, Tallfescue decreased the total petroleum hydrocarbons content by 65 percent. The highest degradation for agropyron was in the 30% sludge treatment which showed about 55% reduction in total petroleum hydrocarbons. The 40% sludge treatment resulted in the minimum yields of root and shoot plants. The highest degradation of TPHs occurred in the Tallfescue rhizospher of 40% sludge. Maximum degradation of TPHs on the Agropyron rhizospher was in 30% sludge mixed with Bage parandegan soil, but maximum yield of plant was in 20% sludge. Our study shows that Tallfescue rhizospher is most effective for decreasing TPHs, and that the phytoremediation in soils with more clay can adsorb and fix the toxic components and then at higher levels of pollutions can let the plants grow.
M. Rahmanian, H. Khodaverdiloo, M. H. Rasouli Sadaghiani, Y. Rezaie. Danesh, M. Barin,
Volume 15, Issue 58 (3-2012)
Abstract
Arbuscular mycorrhizae (AM) and Plant Growth Promoting Rhizobacteria (PGPR) associations are integral and functioning parts of plant roots. These associations have a basic role in root uptake efficiency as well as improvement of plant growth in degraded environments including heavy metals contaminated soils. This study was conducted to evaluate the effects of heavy metal-resistant soil microbe's inoculation on bio-availability of Pb and Cd in soil, plant growth as well as metal uptake by Millet (Pennisetum glaucum), Couch grass (Triticum repens) and wild alfalfa (Medicago sativa). A soil sample was treated by different levels of Pb and Cd (soil 1). Native microbial inoculums were obtained from alfalfa rhizosphere soils adjacent to Pb and Cd mines in Zanjan region (soil 2), then added with weight ratio of 1:5 (w/w) to soil 1. Host plants including millet, couch grass, and alfalfa were grown in pots and kept in greenhouse conditions. At the end of growing period, shoot dry matter and Pb and Cd concentrations in plant and soil were measured. Results indicated that plants yield and Pb uptake were significantly higher in non-inoculated treatments (p ≤ 0.05). However, Cd uptake by plants was greater in inoculated treatments (p ≤ 0.05). Couch grass showed the most accumulation potential of Cd and Pb among the studied plants.
N. Mazloom, R. Khorassani, A. Fotovat, Y. Hasheminezhad,
Volume 17, Issue 66 (2-2014)
Abstract
The reclamation of salt-affected soils which occur on 831×106 ha can be effective in increasing agricultural production. Cultivation of plant species which are resistant to salinity can improve the soil by increasing the solubility of calcite and releasing the calcium in soil solution. This study was conducted as a column experiment with a saline-sodic soil (SAR = 23.8, EC= 12.88 dS m-1, pH= 7.7, CaCO3= 15.15 %). Three plant treatments including Sesbania acuelata, Cyanodon dactylon and Rubia tinctorum, and three chemical treatments including gypsum in two levels (50% and 100% gypsum requirement) and sulfuric acid with a control were arranged. All treatments were replicated 3 times. The soil columns were similarly leached by 41 liters of tap water during 30 days in 8 stages. After leaching, SAR and EC in soil, the amounts of sodium in leachate and total amount of sodium in plants shoot were determined. Results showed that the SAR was decreased compared to control by the plant treatments and the chemical amendments by about 59% and 65%, respectively. Moreover, two plants of Cyanodon dactylon and Rubia tinctorum had maximum amount of leachate sodium, which shows an impressive role of these plants in dissolution and leaching of exchangeable or sediment sodium in comparison with the other treatments. According to salient performance of phytoremediation in improvement of physicochemical properties of soil compared to chemical amendments, phytoremediation can be recommended as a profitable low-cost and effective method for remediation of saline-sodic soils.
J. Abedi Koupai, S. S. Eslamian, S. Y. Hasheminejad, R. Mirmohammad-Sadeghi,
Volume 18, Issue 69 (12-2014)
Abstract
Phytoremediation models are important to understand the processes governing phytoremediation and the management of contaminated soils. Little effort has been made for evaluating the potential of the phytoremediation of metals based on the mathematical models. Therefore, the purpose of this study was modeling the phytoremediation of the nickel-contaminated soils. For this purpose, a model was recommended for estimating the rate of the phytoremediation of nickel from the soil by means of relative transpiration reduction and concentration of nickel in the plant functions. To evaluate the model, soil was contaminated with different levels of nickel by nickel nitrate. Then, the pots were filled with contaminated soil and Basil (ocimum tenuiflirum L.) seeds were planted. To avoid the dry tension, the pots were weighed and irrigated to the point of field capacity (FC) at short time intervals (48 hours). The plants were harvested in four times. At each harvesting stage, the relative transpiration values and nickel concentration in the soil and plant samples were measured. The performance of the model was evaluated by statistical methods such as Maximum Error, Root Mean Square Error, Coefficient of Determination, Efficiency of Model and Coefficient of Residual Mass. Results demonstrated that in the case of nickel contamination in soil, changes in the relative transpiration of Basil can be measured by the two proposed models and the linear model (R2=0.94) has a better performance compared to the nonlinear one (R2=0.84). Also the model obtained from the combination of linear function and nickel's concentration in soil has a relatively good (R=0.7) fit with the measured values of the remediation rate of nickel in soil.
F. Nikseresht, M. Afyuni, A. H. Khoshgoftarmanesh, V. Dorostkar,
Volume 18, Issue 69 (12-2014)
Abstract
Phytoremediation is one of the best methods for cleaning heavy metal contaminated soils. In this method, tolerant plants with high absorption potential are used to clean up the pollutant. The purpose of this greenhouse study was to find the most suitable plants with the highest Zn translocation factor and shoot concentration. Soil samples were collected from zinc and lead Bama mine in Isfahan province, Iran. To compare the hytoextraction power, Heliantus annus.L., Thlaspi caerulescens, Trifolium pretense L. and Amaranthus retroflexus were planted in 8 kilogeram pots. The experiment was conducted in completely randomized design with three replications. After seventy days, plants root and shoot were harvested and Zn concentration was measured. The result showed that Thlaspi caerulescens had significantly higher root and shoot Zn concentration (3125 and 4041 mg kg-1, respectively). The highest bioaccumulation factor and translocation factor was observed in Thlaspi caerulescens. Based on this research, Thlaspi caerulescens was one of the suitable Zn hyper accumulators for cleaning up the Zn pollution.
S. Jahanbakhshi, M. R. Rezaei, M. H. Sayyari-Zahan,
Volume 18, Issue 70 (3-2015)
Abstract
Phytoremediation is one of the cleanup methods of polluted soil that is possible accumulation of heavy metals in plant tissues, exclusion of these elements from contaminated soil. Therefore, to achievement the objective, this research was done in pot culture using completely randomized design at the University of Birjand in 2011. Two species Spinacia oleracea and Lepidium sativum were used to remove or reduce the concentration of Cadmium (Cd) and Chromium (Cr). In this study, different levels of Cadmium (CdCl2) concentrations including 5, 50, 100 mg kg-1 and also chromium (CrCl3) concentrations 50, 100, 150 mg kg-1 were used respectively and control as well for each species with three replications. Results indicated that the Cd and Cr concentration in shoot of Spinacia oleracea and Lepidium sativum significantly affected by their concentration in soil (p<0/01). Results revealed that increasing of Cd and Cr concentrations in soil, showed an increase concentration of both metal in shoot of Spinacia oleracea. increasing of Cd concentrations in soil, showed an increase concentration of it in shoot of Lepidium sativum but the concentration of Cr was less. Also, comparison of cadmium and chromium concentrations in shoot of Spinacia oleracea and Lepidium sativum showed that two species showed same behavior of Cd and different behavior Cr concentration. So the analysis of data showed that both of species are appropriate for absorption of Cd and Cr and phytoremediation technology as well. It can be concluded that in high soil Cr concentration for phytoremediation Lepidium sativum is not appropriate.
A. Parnian, M. Chorom, N. Jafarzadeh Haghighi Fard, M. Dinarvand,
Volume 18, Issue 70 (3-2015)
Abstract
Cadmium is a trace element which is harmful to life and is considered as a dangerous pollutant. This element leads to pollution and reduction of water quality and sometimes even to toxicity through contaminated sources such as wastewater (municipal and industrial). Due to the growing population's need for more water resources and increased water resource pollution, a need for new and inexpensive methods for remediation and improving water quality is felt. Phytoremediation with aquatic macrophytes is an effective and inexpensive method for improving water quality and wastewater. In this study, biological removal of cadmium from simulated wastewater was reviewed within 11 days of cultivation of Lemna gibba in Hoagland nutrient solution, at four different concentrations of cadmium (0, 1, 2, 4, and 6 mg L-1). Maximum Bioconcentration Factor and maximum Uptake Index were calculated from 6 mg L-1 metal concentration. Maximum (4.71 g/day) and minimum (2 g/day) Biomass production measurement was obtained from 0 mg L-1 and 6 mg L-1 of pollutant concentration. The plant used in this study was able to accumulated cadmium with the efficiency of up to 91%. However, the pollutant remediation was not completed in a short time. Thus, pollutants' bioremediation from wastewater solutions by Lemna gibba, a native hydrophyte of southern Iran’s pounds, is efficient and appropriate.
P. Ahmadpour, M. Soleimani,
Volume 19, Issue 73 (11-2015)
Abstract
Cadmium (Cd) is a metal with high toxicity and solubility in water, which is a serious environmental threat to human health. Phytoremediation is an environment-friendly method and a promising new and cost effective technology that uses plants to clean organic and inorganic contaminated media. This study was conducted to evaluate the potential of Jatropha curcas for remediation of soils contaminated with Cd. Seedlings were planted in the soil spiked with Cd in amounts of 0, 25, 50, 75, 100 and 150 mg kg-1 (Cd0, Cd25, Cd50, Cd75, Cd100 and Cd150) for a period of five months. Biocentration factor (BCF, metal concentration ratio of plant roots to soil), translocation factor (TF, metal concentration ratio of plant shoots to soil) and removal efficiency (RE, total metal removed by plant biomass to total metal loaded in soil) were determined. Cd concentrations among plant parts were in the following trend: roots>stems>leaves. The highest total Cd concentration (up to 1100 mg kg-1) and the highest RE were found in Cd150 and Cd25, respectively. BCF and TF of the plant were more and less than 1, respectively. Hence, although this species has a potential to be used in phytostabilization of Cd-contaminated soil, more researches in the field condition are needed.
S. Molaei, H. Shirani, M. Hamidpour, H. Shekofteh , A. A. Besalatpour,
Volume 19, Issue 74 (1-2016)
Abstract
This experiment was conducted to evaluate the effect of vermicompost, pistachio kernel and shrimp shell on the immobilization and availability of Cd, Pb and Zn in corn in polluted soils. Treatments consisted of two levels of pistachio kernel, shrimp shell and vermicompost (5 and 10 % w/w). In control treatment, no amendment was added to the soil. The experiment was carried out as a completely randomized design with 3 replications. Plants grew for two months in the greenhouse. Then, all the plants were harvested and their shoots and roots were separated, washed with distilled water and oven dried at 65 °C to a constant mass. The measured characteristics were dry weight of shoots and roots, leaf area, greenness index, chlorophyll fluorescence, maximal quantum yield of PS photochemistry (Fv/Fm), performance index (PI), and total concentrations of Cd , Pb and Zn in shoots and roots. Results showed that plant growth parameters (dry weight of shoots and roots, leaf area) and photosynthetic characteristics (chlorophyll fluorescence, Fv/Fm, and PI) were higher in plants grown in vermicompost and pistachio kernel treatments as compared to those grown in control. Plants died in shrimp shell treatment after two weeks. The concentration of Cd, Zn and Pb in shoots and roots of plants grown in vermicompost and pistachio kernel treatments were lower than those grown in control.
A. Yousefi, A. M. Amini, O. Fathi, A. Yadegari,
Volume 20, Issue 76 (8-2016)
Abstract
Water, as a limiting factor, has played a decisive role in shaping and development of Iranian culture and civilization. Water scarcity and a great variety of water users lead to conflicts in rivers' environment. Conflict resolution is conceptualized by the methods and processes involved in peaceful facilitating and ending of the conflict through active communication about their thinking and causes of disagreement as well as persistence in collective negotiations. Currently, the Zayandeh-Rud River basin (ZRR) has been facing severe water scarcity. The aim of this study is to evaluate the methods of water conflict resolution in the ZRR from the viewpoint of farmers and authorities. The statistical population of this study includes all farmers in ZRR and selected staff of Regional Water Authority and Agricultural Organization (Jahad-Keshavarzi) in both Isfahan and Chaharmahal & Bakhtiyari provinces. Data were collected through a sample of 171 farmers and census of authorities through face-to-face interviews based on a comprehensive structured questionnaire. Before the survey, the reliability and validity of the questionnaire was initially evaluated on a pre-test study respectively by using Cronbach’s alpha coefficient and Kaiser-Meyer-Olkin (KMO) criteria. The results showed that the main factors in creating the conflict are drought, increased water use in industry and increased water consumption in other provinces. Furthermore, the most suitable methods of water conflict resolution are the conditions where everybody is able to speak freely, mediation and negotiation. On one hand, in the current situation, farmers prefer violent manners and on the other hand, authorities consider negotiation as the most appropriate solution to the conflict.
M. H. Rasouli0-Sadaghiani, H. Khodaverdiloo, M. Barin, S. Kazemalilou,
Volume 22, Issue 1 (6-2018)
Abstract
The use of plants and soil microorganisms is a promising technique for the phytoremediation of heavy metal-contaminated soils. This study was carried out in order to evaluate the soil microbial potential with four Cd concentration levels (0, 10, 30 and 100 mg kg-1); the study also addressed the inoculation of arbuscular mycorrhizal fungi (AMF) species (a mixture of Glomus species including G. intraradices, G. mosseae and G. fasciculatum) as well as plant growth promoting rhizobacteria (PGPR) (a mixture of Pseudomonas species including P. putida, P. fluorescens, and P. aeruginosa) with the Centaurea cyanus plant. The soil sample was spiked uniformly with Cd nitrate salt to create different Cd concentrations. The contaminated soils were then sterilized and subsequently inoculated with AMF and PGPR. The results indicated that with increasing the soil Cd concentration, colonization percent, abundance of rhizobateria, shoot biomass, and shoot relative biomass were significantly decreased, while the proline content and the shoot Cd concentration were significantly increased (P≤0.05). The mean of Cd extracted in AMF and PGPR treatments was 1.8 and 2.8 and the translocation factor was 1.2 and 1.5 times higher, as compared to the corresponding control treatments, respectively. It could be concluded that microbial inoculation, in addition to improving plant growth, plays an important role in the Cd phytoremediation efficiency by plant.
Z. Noori, M. A. Delavar, Y. Safari,
Volume 24, Issue 4 (2-2021)
Abstract
The present study was intended to improve the chemical properties of a saline-sodic soil using the individual application of alfalfa residue and two biochars produced from sugarcane bagasse and walnut shell, at the weighting ratio of 5%; their concomitant application with gypsum, aluminum sulfate and the mixture of these two chemical amendments was considered. The experiment was conducted in three replications using the factorial experiment in a completely randomized design. After four months of incubation, the soil samples were measured for their main chemical properties. The results showed that alfalfa residues were the most effective treatment to reduce the soil pH; so the concomitant application of this organic amendment with gypsum lowered the soil pH from 9.13 in the control (untreated soil) to 7.24. It was also observed that the addition of gypsum and/or aluminum sulfate to the soil led to the increase of the soil electrolyte concentration and consequently, the increase of soil electrical conductivity to three times greater than control, through an increase of ions, like calcium and sulfate in the soil solution. Increasing the soluble sodium concentration by replacing exchangeable sodium by other similar ions showed that the studied treatments enhanced the sodium adsorption ratio (SAR), which could be regulated by washing. Concomitant application of the walnut-shell biochar with gypsum had the most increasing effect on the soil SAR, enhancing it from 22.6 in the control to 54.3. Potassium was released from organic amendments, improving the soil general conditions; addition of chemical amendments elevated soil exchangeable potassium contents; however, the elevated soil available phosphorus contents were less influenced by chemical amendments application. As the conclusion, it seems that the positive impacts of the applied chemical and organic amendments would supplement each other; as a result, the concurrent use of both treatments not only improves the bad soil chemical properties, but also enhances the soil fertility.
J. Abedi Koupaei, M.m. Dorafshan, A.r. Gohari,
Volume 26, Issue 3 (12-2022)
Abstract
One of the most significant techniques for saline wastewater treatment is bioremediation. Halophytes are known as the plants that can tolerate the high concentration of salts, in such salinity common plants cannot be often able to survive. In this research, the feasibility of desalination by using halophyte (Chenopodium quinoa Willd.) was studied. Quinoa plants were grown in the hydroponic system in 12 containers including 9 containers with plants and 3 containers without plants as control. Fifteen plants were planted in each container and three salinity levels including 2, 8, and 14 ds/m for two different periods (15 and 30 days) were studied in a multi-factors completely randomized design. Three replications of each salinity level were conducted and the Electrical Conductivity (EC) parameters, including Calcium, Magnesium, Sodium, and Chloride ions were determined before and after treatment by Quinoa plants. The results showed that the Quinoa plants reduced 5.33%, 8.12%, and 9.35% of the EC at EC~2 dS/m (Marginal Water), EC~8 dS/m (Brackish Water), and EC~14 dS/m (Saline Water), respectively. Moreover, Calcium, Magnesium, Sodium, and Chloride ions decreased up to 10%, 7.62%, 5.60%, and 7.01%, respectively depending on the salinity levels. Therefore, the Quinoa plant has a relatively low potential in unconventional water treatment especially saline wastewater.
A.r. Eftekhari, M. Mirmohammad Sadeghi, A. Jalalian,
Volume 27, Issue 2 (9-2023)
Abstract
The use of biotechnology-based methods in the field of geotechnical engineering has led to the birth of new knowledge of biogeotechnology and several studies have been conducted using this new knowledge in various geotechnical issues including reducing permeability and increasing shear strength, especially in sandy soils and the desired results have been obtained. Nevertheless, little research has been done using biogeotechnology in the field of improving the mechanical properties of clay soils, especially in reducing the swelling of expansive soils, which is considered one of the types of problematic soils. The main cause of swelling of expansive soils is the presence of montmorillonite clays in these types of soils. Using chemical additives to stabilize expansive soils such as lime and cement is a common practice. However, environmental concerns related to greenhouse gas production caused by the production of chemical substances and the destructive effects of these substances on the environment and soils have encouraged researchers to use other sustainable stabilization alternatives. Microbial Induced Carbonate Precipitation (MICP) is a technique that can be a promising solution to solve this problem. The objective of the present study was to investigate the effect of the MICP method on the swelling of expansive clay soils and its effect on the mechanical strength of this type of soil. One-dimensional swelling tests, uniaxial compressive strength tests, and Atterberg limits tests were performed on clay soil with a liquid limit of 53 using Sporosarcina pasteurii bacteria, calcium chloride, and urea as nutrients. Taguchi's method was used for the design of the experiments and the statistical analysis of the results. This method designs experiments through partial factorial and reduces their number without a significant effect on the results. Bacterial concentration, nutrient molarity ratio, treatment time, and soil moisture were selected as four factors with Four levels of variation. The results showed that the (MICP) method was effective in reducing the swelling potential of expansive soils and also caused a significant increase in the unconfined compressive strength of the soil and its undrained shear strength.
B. Attaeian, S. Hosseinzadeh Alikordi, S. Mortazavi,
Volume 28, Issue 2 (8-2024)
Abstract
Mine exploitation has led to the rangeland's destruction. In this study, the phytoremediation of Pb-contaminated soils by Chrysypogon zizanioides was investigated in the soil around the lead mine of Lashkar region, located in Malayer county. In the initial measurement, the amount of soil Pb contamination in the rangeland was estimated to be 600 milligrams per kilogram of dry soil. By evaluating the environmental effects of lead in the region, the coefficients of geoaccumulation index, pollution degree, and potential ecological risk were observed in the infinite to very high range. The research was conducted in a completely randomized design with 4 Pb pollution levels (0, 300, 600, and 1600 mg/kg) in 4 replications in the greenhouse of Malayer University for 130 days. At the end of the period, lead concentration in soil, root, shoot, BCF bioaccumulation index, TF transfer coefficient, shoot, and root productivity in vetiver plants were measured. The results showed the increasing effect of soil Pb concentration on the amount of root and shoot Pb concentrations. At the level of 1600 mg/kg contamination, the Pb concentration in the shoot and root reached 242.94 and 242.02 mg/kg, respectively. At most levels of contamination except the level of 1600 mg/kg, the BCF indicators in the root and shoot and the TF coefficient were less than one. TF <1 indicates the lack of high concentration of Pb in harvesting organs and the health of the aerial production. So, vetiver is recommended for the rangeland reclamation in the study area.
