جستجوی مقالات مرتبط با کلیدواژه « bioremediation » در نشریات گروه « کشاورزی »

Enzyme activity measurement is one of the significant methods in the bioremediation of soils contaminated with petroleum compounds. Biostimulation, bioaugmentation and their integration are among the types of bioremediation methods used in this experiment. For this purpose, to reduce light naphtha pollution (1%) in a sandy loam soil, a variety of bioremediation treatments, including providing NP elements, adding cow manure and Tween 80 surfactant, bioaugmentation, and integrated treatment were used. This experiment was carried out in a pot (containing 3 kg soil) based on split plot factorial design (pollution factor, bioremediation factor and time) with 3 replications, at room temperature, for 120 days. On days 0, 5, 10, 15, 30, 45, 60, 90 and 120, subsamples were taken from each pot to measure the activity of dehydrogenase and lipase enzymes. The results of the experiment showed that bioremediation treatments led to the reduction of oil pollutants. Likewise, dehydrogenase activity had a completely downward trend from the beginning of the experiment, and the changes of lipase activity in contaminated soil increased until day 10, decreased slightly from day 10 to 15, then, progressed with slight fluctuations until day 60 and decreased again from day 60 onward. Dehydrogenase activity changes in cow manure treatment during the experiment was from 3.39 to 0.35 (μg TPF g-1 h-1), and lipase activity in integrated treatment dropped from 57 to 33.56 (mU g-1). In addition to increasing the active microbial population involved in the decomposition of petroleum compounds and providing optimal conditions for their activity, the use of integrated treatments and cow manure is a suitable method to reduce the concentration of light naphtha.

Oil contamination can be treated by physical, chemical and biological approaches. The first two methods have limitations such as high costs, inefficacy and altering natural ecosystem. Today, biological treatment is a more interesting process to remove petroleum contamination. Bioremediation is a technique in which biological systems such as microorganisms are applied to degrade or transform harmful chemicals. In recent years, employing hydrocarbon degrading bacteria to cleaning a petroleum contaminated soil has become a prevalent, efficient and cost effective technique that converts toxic wastes to non-toxic end products. Soil contamination with oil compounds such as heavy naphtha can threaten soil, environmental and human health. In bioremediation process, soil microorganisms use these hydrocarbons as a carbon source and, while making a microbial biomass, play a role in its decomposition and conversion to carbon dioxide. Furthermore, this type of contamination can affect soil microbial population and its enzyme activity. Soil microbiome, in turn, has effect on this contamination using relevant enzymes. Application and comparison of various bioremediation methods such as biostimulation, bioaugmentation and integrated treatment were the main aims of this study to bio-remove heavy naphtha from contaminated soil. Moreover, mmonitoring of soil enzyme activity changes (including dehydrogenase and lipase) in this condition under different bioremediation treatments was another goal of this research. For this purpose, in a heavy naphtha-contaminated sandy loam, a variety of bioremediation treatments, including biostimulation (including supply of nitrogen and phosphorus elements, addition of manure and Tween 80), bioaugmentation treatment (using a consortium of efficient bacteria) and integrated treatment (including all biostimulation and bioaugmentation treatments together) were tested.

In this study, a sandy loam soil was used. Heavy naphtha was applied at a rate of 7% V/W to soil samples and various bioremediation treatments were performed as mentioned above. This experiment was carried out in a pot scale (containing 3 kg soil) based on split plot factorial design (pollution factor, bioremediation factor and time) with 3 replications, at room temperature for 120 days. During the experiment, the pots were aerated once a week and the soil moisture content was adjusted to 70-80% (W/W) of the soil water holding capacity twice a week. For bioaugmentation of bacterial isolates, a bacterial suspension (108 cfu mL-1) having a consortium of Arthrobacter sp. COD2-3, Stenotrophomonas nitritireducens COD5-6، Stenotrophomonas asidamainiphila COD1-1 with a ratio of 5% V/W were used. In biostimulation treatment, cow manure with 5% W/W was used. In NP treatment, N and P elements from ammonium nitrate and potassium phosphate (K2HPO4), were used with a ratio of 20:5:1 (C: N: P), considering soil organic carbon. Tween 80 as surfactant in the relevant treatments, was used at a rate of 0.3% V/W. In the integrated treatment, all the mentioned treatments were used together. On days 0, 5, 10, 15, 30, 45, 60, 90 and 120, subsamples were taken from each pot to measure the activity of dehydrogenase and lipase enzymes.

The results showed that during the experiment, bioremediation treatments reduced heavy naphtha contamination and the highest value for removal rate of this compound was 81% in the integrated treatment. Contamination also affected the enzymatic activity of soil so that the activity of dehydrogenase and lipase in all bioremediation treatments showed a decreasing trend. Dehydrogenase enzyme activity in cow manure treatment decreased from 1.67 to 0.59 (μg TPF g-1 h-1) and activity of soil lipase enzyme decreased from 33.82 to 26.24 (mU g-1) in the integrated treatment during the experiment. Among the bioremediation treatments, cow manure and integrated treatment had a greater effect on the elimination of heavy naphtha contamination than other treatments (p <0.01). It seems that the use of the above treatments were able to remove more heavy naphtha by providing optimal nutritional, moisture and aeration conditions while intensifying the activity of soil microorganisms.

In this study, to reduce heavy naphtha contamination in the soil, bioremediation treatments including biostimulation, bioaugmentation and integrated approaches were used. According to the results of changes in dehydrogenase and lipase activity in naphtha-contaminated soil, each treatment was able to reduce contamination individually, while the integrated treatment was both biostimulatory and bioenhancing treatments. However, in the integrated treatment, the efficiency of bioremediation process was higher, due to the simultaneous use of biostimulation and bioaugmentation treatments. The use of integrated treatment in soils contaminated with petroleum compounds, including heavy naphtha, can help to biologically eliminate these contaminants.

Periphyton is a complex biological community comprising microorganisms and organisms from different physiological groups that collectively attach to various submerged surfaces in wetland ecosystems. Periphytic biofilms play a critical role in the wetland ecosystem’s dynamicity and possess a considerable capacity for decontamination. The following article examines the various aspects of periphytic biofilms’ capacity for removing some of the most critical environmental pollutants, including organic pollutants, pharmaceuticals, heavy metals, microplastics, and excess nutrients. The paper provides comprehensive discussions on the critical pollutant removal mechanisms employed by the periphytic communities. Additionally, the paper endeavors to contribute to the available knowledge regarding utilizing and developing periphyton-derived bioremediation technologies by presenting the most recent research findings, discussing common challenges in periphyton’s biotechnological application, and delineating crucial research gaps to postulate future research questions. Applying periphyton in pollutant removal aligns with the most recent paradigm of bioremediation technologies advocating the use of microbial consortia instead of single microbial species. In this regard, research results convey that the simultaneous presence of multiple microbial groups together in a biological community (such as periphyton) increases the microorganisms’ resistance to unfavorable environmental conditions and enhances the biological community’s capacity for decontamination. Based on the studies presented in this article, periphytic biological communities can employ different mechanisms to transform and biodegrade a wide array of pollutants.

Petroleum contamination is treated by physical, chemical and biological approaches. The first two methods have limitations such as high costs, inefficacy and altering natural ecosystem. Today, biological treatment is a more interesting process to remove petroleum contamination. Bioremediation is a technique in which biological systems such as microorganisms are applied to destroy or transform (degrade) harmful chemicals. In recent years, employing hydrocarbon degrading bacteria to clean a petroleum contaminated soil has become a prevalent, efficient and economical technique that converts toxic wastes to non-toxic end products. This technique has reduced the harmful effects on health and ecology. Soil contamination with petroleum compounds such as heavy naphtha can threaten soil, environmental and human health. In bioremediation process, soil microorganisms use these hydrocarbons as a carbon source and, while making a microbial biomass, play a role in its decomposition and conversion to carbon dioxide. Bioremediation methods include biostimulation and bioaugmentation, which are promising methods for treating oil pollution. Application and comparison of various bioremediation methods such as biostimulation, bioaugmentation and integrated treatment was the main aim of this study to bio-remove heavy naphtha from contaminated soil. For this purpose, in a heavy naphtha-contaminated sandy loam, a variety of bioremediation treatments, including biostimulation (including supply of nitrogen-phosphorus elements, addition of manure and Tween 80 surfactant), bioaugmentation treatment (using a consortium of efficient bacteria) and integrated treatment (including all biostimulation and bioaugmentation treatments) were tested.

In this experiment, sandy loam soil was used. Heavy naphtha contamination was applied at a rate of 7% in soil samples and various bioremediation treatments were performed as mentioned above. This experiment was carried out in a pot scale (3 kg pots) based on split plot factorial design (pollution factor, bioremediation factor and time) with 3 replications, at room temperature for 120 days. During the experiment, the pots were aerated once a week and the soil moisture content was adjusted to 70-80% of the soil water holding capacity twice a week. For bioaugmentation of bacterial isolates, a consortium of Arthrobacter sp. COD2-3, Stenotrophomonas nitritireducens COD5-6، Stenotrophomonas asidamainiphila COD1-1 with a ratio of 5% V/W were used. In biostimulation treatment, cow manure with 5% W/W ratio was used. In NP treatment, which was related to the supply of nitrogen and phosphorus elements, N and P elements from sources of ammonium nitrate and potassium phosphate with a ratio of 20:5:1 (C: N: P) were used. Also, to use Tween 80 surfactant in the relevant treatments, a rate of 0.3% V/W was used. In the integrated treatment, all the mentioned treatments were used together to remediate oil contamination. On days 0, 5, 10, 15, 30, 45, 60, 90 and 120, samples were taken from each pot to measure the biological activity of basal respiration (BR) and substrarte-induced respiration (SIR).

The results showed that the bioremediation treatments reduced heavy naphtha contamination. Contamination also affected soil microbial activity, so that BR and SIR increased in all bioremediation treatments in the early days, but over time they decreased, due to the reduction of carbon source and also the reduction of soil nutrients. The amount of BR and SIR in the combined treatment changed from 0.67 to 0.53 and 3.30 to 2.73 (mg CO2 g-1 h-1), respectively. Also, the amount of petroleum compounds before and after bioremediation treatments showed that 81% of heavy naphtha was decomposed by the integrated treatment. Among the bioremediation treatments, the integrated treatment had a greater effect on the elimination of heavy naphtha contamination than the biostimulation and bioaugmentation treatments (p <0.01). The use of integrated methods not only increases the active population of microorganisms in the decomposition of petroleum compounds and provides optimal conditions for their activity, but also stimulates the native population of microorganisms and is convenient for removing petroleum compounds. It seems to be a good method.

According to the microbial respiration results in naphtha-contaminated soil, each treatment was able to reduce contamination on its own, while the integrated treatment was biostimulatory and bioenhancing treatment. However, in the integrated treatment, the efficiency of bioremediation process was higher, due to the simultaneous use of biostimulation and bioaugmentation treatments. The use of integrated treatment in places contaminated with petroleum compounds, including heavy naphtha, can help to biologically eliminate these contaminants.

The significance of mangrove species in the world is undeniable and planting artificial mangrove forests is a desirable solution to preserve mangroves. The mangroves provide us with superior ecological services and one of their main services is the bioremediation of heavy metals. Hence, this study aimed to assess the effects of artificial mangroves of Velayat Park of Bandar Abbas on the contamination, adsorption pattern and ecological risk of heavy metals in the sediment samples. Thirty samples were collected from two paralleled sampling sections included those without mangroves and containing mangroves. Each sampling area consisted of upper, middle and lower sections. After drying samples using an oven, the dried sediments were sieved by a 63-micrometer sieve and digested by nitric and hydrochloric acid mixture. The concentration of As, Cu, Fe, Ni, Pb, V, and Zn was determined using ICP. The studied factors suggested a high level of ecological risk for as and Pb and the highest risk was observed in the samples without mangroves and a lower risk was reported for samples containing mangroves. Comparing the results with sediment quality guidelines and other studies indicated a dangerous concentration of As. Pearson correlation coefficient values exhibited that artificial mangroves have significantly affected the adsorption pattern of heavy metals (p-Value < 0.05). The principal component analysis (PCA) showed that As and Pb are dominantly derived from oil products leakages and industrial sewages while Cu, Fe, Ni, V and Zn are predominantly derived from natural and geological sources.

Crude oil is a complex combination of many hydrocarbon and non-hydrocarbon compounds, including heavy metals, which affect the physical and chemical properties of the soil, cause the soil particles to stick and connect and then cause the soil to become stiff and impenetrable. Contamination of soil with petroleum hydrocarbons is a significant environmental problem, which has received remarkable attention in recent decades. Petroleum hydrocarbons are resistant and hazardous pollutants. Some petroleum hydrocarbons such as benzene are mutagenic and carcinogenic materials for humans. There are many physical and chemical methods to remediate oil-contaminated soils. Phytoremediation is a relatively new technology for refining contaminated soils in which resistant plants are used to remove or reduce the concentration of inorganic, radioactive, and organic pollutants, especially petroleum compounds, from the environment.

Sufficient amounts of about 50 kg of soil contaminated with petroleum hydrocarbons were collected from regions (0-30 cm soil depth) adjacent to the oil wells west of Kermanshah province. Uncontaminated soil samples were also taken from sites at the lowest distance to the contaminated sites. The aim of this study was to compare the efficiency of different plants to remove total petroleum hydrocarbons from oilfield soils. In this study, after determining the total amount of petroleum hydrocarbons, the contaminated and uncontaminated soils were mixed in 4 treatments with different weight ratios (0, 10, 25, and 35%). This experiment was established as completely randomized design with 3 replications for 6 different plants (Barley, Grass, Alfalfa, Hemp, Camelina, and Vicia ervilia). One treatment without plant was considered to remove soil matrix effects on petroleum hydrocarbon concentrations. Plants were harvested at the end of their growing season (90-120 days). Soils and plant samples from the experimental pots were analyzed for their important properties (including some physiological characteristics of the plants, as well as the percentage of reduced petroleum hydrocarbons in the soils). The gravimetric method was used to determine the concentration of petroleum hydrocarbons in the soil. After measuring the properties of the soil and plant, the normality of the data was checked by the Anderson–Darling test, and the homogeneity of the variance of the treatments was checked by using Levene's test. Analysis of data variance was done using ANOVA and average data comparison was done using LSD test at 5 and 1 percent probability levels (SAS 9.4 and SPSS 26).

In general, the growth of most plants showed a decreasing trend in proportion to the increase in soil pollution levels. However, the growth decline rates of different plants were not similar. Camelina was very sensitive to oil pollution and the plant could not tolerate pollution even at 10% level. After camelina, alfalfa was highly sensitive to oil pollution. The highest dry weight of the aerial parts of the hemp plant in the soil without oil contamination was observed at the rate of 111.22 grams in the pot. The leaf area of all studied plants in contaminated soils decreased compared to the control treatment (without contamination) so with the increase in the percentage of contamination, the leaf area of the plants was significantly reduced. The highest amount of leaf surface was observed in unpolluted soil and in the hemp plant. Except for the Camelina plant, which was completely destroyed at different levels of pollution, the rest of the plants showed a noticeable decrease in growth. The total petroleum hydrocarbons in soil were measured again 120 days after the start of cultivation, and its difference with the total amount of petroleum hydrocarbons at the beginning of cultivation was determined as the reduction of petroleum hydrocarbons and reported as a percentage. According to the mean comparison results, the percentage of reduced petroleum hydrocarbons was not significantly different among cultivated and non-cultivated treatments, although, it was significantly affected by soil pollution levels. Since all the studied soils contained natural bacteria and were not sterilized, the eliminated part of petroleum hydrocarbons is probably decomposed and removed by native bacteria in the soils. Therefore, the strengthening of native bacteria in these soils may increase the decomposition and degradation of petroleum hydrocarbons.

The results of this research show that the presence of petroleum hydrocarbons in the soil caused a decrease in growth and other physiological characteristics in all studied plants. Although the Camelina was able to germinate in soils contaminated with petroleum hydrocarbons, the presence of these pollutants in the soil prevented the optimum growth of the plant, so its use in subsequent studies of phytoremediation of oil-contaminated soils, was not recommended. The results showed that there is no statistically significant difference between cultivated and non-cultivated treatments at different pollution levels, and the reduction of the total petroleum hydrocarbons in the soil was probably done by native microorganisms in the soil. It is recommended to take into consideration the efficiency of the plant species used, the type of polluting hydrocarbons, and the duration of contamination in future research to obtain better results.

Contaminated soil can be remediated by employing various types of microbes, such as bacteria, which have the ability to enhance plant growth and combat pathogenic microorganisms. Biological control is an environmentally adaptable method that utilizes living microorganisms like bacteria, fungi, and viruses to suppress plant pathogens through mechanisms such as competition, parasitism, antibiosis, and induced resistance. This study aims to assess the effectiveness of bioremediation bacteria as biological control agents against fungal pathogens affecting sugarcane. To achieve this objective, previously identified bacterial strains with potential in bioremediation of Atrazine and Metribuzin herbicides, including Brucella sp. (66A, 44A, and 65A), Pseudomonas putida 10A, Ensifer adhaerens 20m, Pseudomonas aeruginosa 15A, and Stenotrophomonas sp. 22A, were evaluated for their ability to inhibit the growth of Thielaviopsis ethacetica, Cytospora sacchari, Fusarium proliferatum, Bipolaris drechslera, Curvularia sp., Alternaria sp., and Nigrospora sp. The experiments were conducted using the dual culture method in a completely randomized design with three replications under laboratory conditions. The diameter of the bacterial inhibition zone and the percentage of fungal growth inhibition were calculated. The results indicated that P. aeruginosa 15A exhibited the highest growth inhibition against T. ethacetica, Curvularia sp., and Alternaria sp. On the other hand, Stenotrophomonas sp. 22A significantly inhibited C. sacchari, while both Stenotrophomonas sp. 22A and Brucella sp. 65A showed considerable inhibition against F. proliferatum. Bipolaris drechslera was most effectively inhibited by Brucella sp. 66A and Brucella sp. 44A, while P. aeruginosa 15A and Brucella sp. 66A exhibited prominent inhibition against Nigrospora sp. Notably, P. putida 10A did not display antagonistic properties against the tested fungi under laboratory conditions, whereas P. aeruginosa 15A significantly affected the growth of all examined fungi. Based on these findings, this study provides evidence that certain bioremediation isolates possess significant potential for biological control of specific fungal pathogens affecting sugarcane in laboratory conditions. Consequently, the antagonistic properties against important fungi in sugarcane can be utilized in agricultural activities. This strategy has the potential to decrease the reliance on fungicides in sugarcane farming, benefiting both the economy and the environment. Additionally, it can contribute to the maintenance and improvement of product quality and yield, while supporting sustainable cultivation..

The increasing accumulation of plastic waste is one of the main environmental challenges currently facing human societies. Environmental toxicity of nano∕microplastics as newly known pollutants is a constant threat to terrestrial, marine, and atmospheric ecosystems. Nanoplastics are well able to pass through cell membranes and enter the cell, disrupting all vital functions of living organisms, including humans, plants, and microorganisms. Nano∕microplastics are considered a serious global pollutant due to their resistance to decomposition. Therefore, increasing efforts have been made to eliminate or reduce nano∕microplastics through eco-friendly technologies. Bio-enzymes have been evaluated as efficient agents for plastic degradation. A variety of plastic-degrading enzymes have been discovered among microbial communities. However, naturally occurring plastic degrading enzymes are not suitable for synthetic plastic degradation due to poor thermos-stability and low catalytic activity. Therefore, exploration in various environments to discover new plastic-degrading enzymes with desirable properties and functions has been increasingly considered. In the biological approach, the decomposition of nano/microplastics, increasing the efficiency of depolymerization, and optimizing the activity and thermal stability of the enzymes involved, have been investigated in various ways. Recent research efforts have made significant progress in discovering and engineering plastic decomposing enzymes, showing great promise for the suitable treatment for plastics biodegradation.

The objective of this study was to eliminate chromium(VI) from a contaminated soil through reducing it to chromium(III) by immobilized Shewanella sp. bacteria on algae biochar and to investigate its accumulation in barley. A sandy loam soil was contaminated with 50 mg kg-1 Cr(VI) and incubated for two weeks. Then, the barley pot experiment in the contaminated soil was performed in the autumn of 1400 in the research greenhouse of University of Guilan in a completely randomized design with three replications. Treatments included Shewanella sp. (S), algae biochar (B), algae biochar + Shewanella sp. (BS), and immobilized Shewanella sp. bacteria on algae biochar (IB). Soil contaminated with Cr(VI) and non-contaminated soils were also included as positive (C+) and negative (C-) controls, respectively. After 30 days, the plant was harvested and dry weight of root and shoot were measured. Total chromium and Cr(VI) contents in the root and shoot of plant and also in the soil were measured. The Cr(III) content was calculated from the difference between the total chromium and the Cr(VI) contents. Growth ratio, Cr(VI) accumulation factor in roots and shoots and the transfer factor in plants were calculated. The highest and lowest amounts of Cr(III) in roots, shoots and soil were obtained in IB and C+ treatments, respectively. In Cr(VI) contaminated treatments, the highest and the lowest values of root and shoot dry weight were obtained in IB and C+ treatments, respectively. Cr(VI) reduction in soil in BS treatment was more than S and B treatments. The lowest and the highest plant growth ratios were obtained in C+ (23.8%) and IB (60%) treatments, respectively. The BS and IB treatments further reduced the transfer factor. Therefore, immobilized bacteria on biochar can be effective in remediation of chromium contaminated soils.

In today's world, the extensive human use of pesticides to control agricultural pests and their entry into water resources is a threat to aquatic ecosystems. In this study, Reduction of Chloriprifos organophosphate pesticide from aqueous environment was investigated by bioremediation method by Anodonta cygnea oyster as a bio filter. During a period of twelve days, three treatments with three replications were exposed to three different concentrations of pesticide, 30, 20, 15 mg / l. And indices of toxin concentration, light absorption, water pH and oyster filtration rate were measured to determine the reduction of toxin concentration. At the end of the experiment, the amount of pesticide concentration for treatments with concentrations of 30, 20 and 15 mg/L pesticides were 19 ± 0.1, 4.6 ± 0.153, 3 ± 0.133, with a reduction efficiency of 36.67%, 76.83%, 100% respectively. Percent, Light absorption rate 0.44 ± 0.001, 0.011 ± 0.002, 0.000 ± 0.000 with a reduction efficiency of 38.04%, 77.75%, 100% and a pH of 7.53, 99/7, 6/8 were estimated. Filtration rate for treatments with concentrations of 30 and 20 mg/L pesticides decreased and for treatment with 15 mg/L pesticide concentration had an increasing trend. There was a significant difference between changes in toxin concentration, light absorption miran and filtration rate at the beginning and end of the experiment (P˂0.05). Anodonta cygnea species as a suitable bioremediator for the removal of chlorpyrifos pesticides in agricultural wastewater treatment systems or contaminated natural water environments is recommended, however, further studies are needed in this area.

The growing need for food and the increase in agricultural production, and consequently the increasing demand for water on the one hand, and the harmful environmental effects of agricultural drainage water on natural ecosystems and receptive water resources on the other, have led the world to look for methods and techniques that, along with reducing the harmful and adverse consequences of drainage water, make it possible to reuse them to meet part of human needs. In many areas facing water shortages for irrigation, drainage water is used to meet the crop's water requirement. Due to high volume and special quality, agricultural drainage water have a high potential for pollution in the environment, especially water resources. According to water shortage in Iran and population growth and increasing water needs in various uses, planning for the protection and quality management of water resources and optimal use of unconventional water, especially agricultural drainage water as alternative water resources has become more necessary.

For this purpose, the present study investigated the efficiency of a natural reed bed on a real scale in qualitative treatment of incoming drainage water of Khuzestan sugarcane during a period of one year (2010-2011). According to the trend of qualitative changes and wastewater treatment stages at the reed bed level, the length of the reed bed was divided into three parts, namely three stations ST1, ST2, and ST3 with a length and width of 3.5*1.2 hectares, respectively. The efficiency of the natural reed bed was evaluated by measuring parameters such as BOD, COD, PO4, and TP.

The results of the T-Test showed that there are significant differences in terms of BOD values between ST0-ST1, ST0-ST2, ST0-ST3, ST1-ST2, ST1-ST3, and ST2-ST3 study stations. The highest difference in BOD was observed between ST0 and ST3 stations equal to 6.96 mg/l. In addition, the lowest difference in BOD was detected between ST0 and ST1 equal to 1.73 mg/l. At the ST3 station, which is the farthest from the entry point, the highest percentage of BOD removal was obtained. There was a significant difference of 1% for COD between study stations. The largest difference in COD was observed between ST0 and ST3 stations equal to 9.62 mg/L followed by ST1-ST3 stations equal to 7.12 mg/L. There was also a significant difference of 1% levels in PO4 and TP of study stations and the highest difference in PO4 and TP with 0.2724 and 0.3790 mg/l, respectively, between stations. ST0-ST3 was observed. The results showed that the performance of the reed in eliminating the studied parameters was very good and acceptable. The removal efficiency of BOD, COD, PO4, and TP to the last station was noticeable and acceptable in all four seasons. Under different retention times (1.26, 1.10, 1.30, and 1.60 days), the removal percentage of BOD, COD, PO4, and TP was significant in ST1, ST2, and ST3 stations and with increasing the distance from the entry point, of the drain, the reed efficiency increased. Considering the different performances of the three stations in improving the quality of drainage and considering the efficiency target above 50% of all organic matter and phosphorus compounds, the ST2 station can be assumed as the optimal limit in terms of efficiency and cost.

In general, this system can be used as an efficient system in reducing common drainage water pollutants to the level of drainage water treatment standards and acceptable reduction of BOD, COD, PO4, and TP parameters of agricultural drainage water and improving the quality of this drainage water for discharge to surface and groundwater and also reuse for irrigation in agricultural fields.

Phthalic acid esters are synthetic compounds used as emollients in polymer and plastic compounds. The entry of these compounds into the environment and the human food cycle and the development of a variety of cancers has raised global concerns. The purpose of this research was to investigate the concentration of phthalic acid esters (PAEs) in the soil exposed to the leachate (landfill) and finding a microbial consortium capable of the degradation of these pollutants. The concentration of phthalic acid esters in the soil was measured by the ultrasonic method and GC-MS. The results showed that the concentration of diethyl hexyl phthalate (DEHP) in soil (4.52 mg/Kg) was 6 times that of its international standard (0.7 mg/Kg). Microbial enrichment was performed in a mineral salt medium containing phthalic acid esters (30 o C and 120 rpm) and a microbial consortium capable of degrading phthalic acid esters was isolated. To investigate the biodegradation of phthalic acid esters by consortium, the residual phthalate concentration was extracted with ethyl acetate and measured by GC-MS. The results showed that the this consortium was able to degrade more than 96% of low molecular weight phthalates of dimethyl phthalate, diethyl phthalate and dibutyl phthalate (medium molecular weight phthalate) (30 o C and 120 rpm). In the case of DEHP (the world's most widely used plasticizer), the consortium was able to degrade it by 55% at 400 mg/L. Besides, phthalic acid esters separately were degraded almost completely by this consortium (5 days incubation, 30 oC, 120 rpm). Our results demonstrate the biodegradation of phthalic acid esters by this consortium and recommend its use for bioremediation of phthalates in contaminated soils.

The combination of phytoremediation and porous concrete is a new technology used as a natural purification of porous concrete and resistant plants to remove or reduce the concentration of pollutants. In this study, the performance of porous concrete as a bed and plant on reduction of urban effluent pollution has been investigated. A channel with dimensions of 9 meters length, 30 cm wide and 20 cm height was constructed along with the wastewater treatment lagoon of Isfahan University of Technology. Then, blocks were made of porous concrete with dimensions of 30 × 30 × 15 cm, and placed in the channel. The vetiver grass with two different densities (12 and 27 plants) were placed between the porous concrete blocks. After 5, 7 and 9 hours, the wastewater samples were taken from the inlet and outlet basins. The reduction of BOD, COD, TSS and total coliform during the 5 hours retention time, were 16.1, 27.5, 20.6, and 19.1 percent, respectively. In the retention time of 7 hours, reduction were equal to 20.5, 33, 26.1 and 25.3 percent, respectively. The reduction of BOD, COD, TSS and total coliform during the 9 hours retention time, were 25.9, 38.5, 31.9 and 30.5 percent, respectively. In general, this research showed the performance of system was optimistic in reduction of BOD, COD, TSS and Total coliform

Polycyclic aromatic hydrocarbons (PAHs) are a group of environmental contaminants in the soil that have caused concerns due to toxicity, mutagenic and carcinogenic effects. The bioremedial process has been considered as a suitable solution for the improvement of contaminated soils by many researchers. Therefore, the aim of this study was to isolate, identify and evaluate the growth potential of bacteria degrading petroleum compounds isolated from soil contaminated with petroleum products in the presence of phenanthrene for biological improvement. In this study, 25 soil samples were first collected from 0-35 Cm depth of oil-contaminated areas located in southern Iran (the Bushehr region) and then isolated from suitable culture media of oil-degrading bacteria. Afterward, the isolated bacteria were identified by biochemical methods such as oxidase test and catalase test, and microbial methods such as gram staining, spores staining, and fluorescence staining. In this study, out of 60 oil-degrading bacteria, 19 bacteria called PDB 1-19 were determined in the presence of phenanthrene. Finally, PDB 19 Chryseobacterium spp, PDB 8 Sphingobacterium spp, PDB 13 Acinetobacter johnsonii, and PDB 10 Achromobacter xylosoxidans were selected as the most efficient bacteria. The results of this study show that by identifying and screening effective bacteria, utilizing their microbial potentials, and creating optimal conditions, they can be used to bioremediate oil-contaminated soils at industrial and applied scales.

 Surfactants as surface-active substances with combined hydrophobic and hydrophilic properties are widely used in various fields. In soil remediation processes these substances can be used to increase the availability of organic and inorganic contaminants to improve microbial decomposition of organic pollutants or heavy metals adsorption. In recent years, researchers have been seeking to produce and use surfactants that are more environment friendly. In this regard, produced biosurfactants by microorganisms are of special importance due to their environmental benefits. Microorganisms produce a wide range of biosurfactants. Biosurfactants are extracellular compounds that can combine with metals such as zinc, copper, and cadmium and can increase the solubility of these metals and reduce their toxicity. Negatively charged anionic biosurfactants such as rhamnolipids and lipopeptides can increase heavy metals availability by combining to metals and changing the properties of soil solution. In this study, the effect of surfactant application from Pseudomonas putida and Bacillus subtilis and some chelators include sodium citrate, humic acid and Na2-EDTA on soluble cadmium in a contaminated calcareous soil was investigated.

This study was conducted as factorial in a completely randomized design in laboratory conditions at several steps separately. A calcareous soil sample was contaminated with 15 mg kg-1 cadmium from the source of Cd (NO3)2. Contaminated soil incubated for 4 weeks at field capacity. Acid deposition method was used for surfactant extraction from culture medium of Pseudomonas putida KT-2440 and Bacillus subtilis 1795. The structure of extracted biosurfactants was investigated by FTIR. Equilibrium time was obtained by determining the amount of soluble cadmium at times 6, 12, 24, 36, 72 hours by adding 1mM sodium citrate, humic acid and Na2-EDTA to the contaminated soil (ratio of 1 to 5 soil to solution).The concentrations of 0, 0.1, 0.25, 0.5, 1 and 2 mM of humic acid, sodium citrate and Na2-EDTA were used to determine the appropriate concentration of each chelator. To investigate the interaction of chelators and biosurfactants on soluble cadmium, an experimental was conducted as a completely randomized design with factorial arrangement design. Experimental treatments consisted of three types of chelating agents (sodium citrate, humic acid, Na2-EDTA and control), two types of surfactants from Pseudomonas putida and Bacillus subtilis, and five concentration levels of the biosurfactants (0, 25, 50, 100 mg L-1).

The highest amount of soluble cadmium (11.59 mg L-1) was observed in Na2-EDTA treatment at 72 hours, which was significant compared to the other treatments. The lowest amount of soluble cadmium was obtained through application of sodium citrate (0.205 mg L-1) at 36 hours. In all studied concentrations, Na2-EDTA had the greatest effect and sodium citrate had the least effect on soluble cadmium. While the use of Na2-EDTA at all concentrations caused a significant increase in soluble cadmium, sodium citrate had no significant effect on soluble cadmium at studied concentrations. Humic acid at concentrations higher than 0.5 mM significantly increased the soluble cadmium. Increasing the concentration of humic acid and citrate from 1 to 2 mM did not show any significant impact on soluble cadmium. At all levels of biosurfactant application, Na2-EDTA and humic acid caused a significant increase in soluble cadmium concentration. In control and sodium citrate treatments, application of biosurfactants did not cause significant difference in the concentration of soluble cadmium. The highest amount of soluble cadmium was obtained as a result of the application of Bacillus subtilis surfactant and Na2-EDTA. However, increasing the concentration of Bacillus subtilis surfactant from 25 to 100 mg L-1 had no significant effect on increasing the efficiency of Na2-EDTA.  Pseudomonas putida surfactant had no significant effect on soluble cadmium in Na2-EDTA application. While in humic acid treatment, the application of the Pseudomonas putida surfactant at the highest concentration (100 mg L-1) increased the concentration of soluble cadmium. Using Bacillus subtilis surfactant did not have effect on soluble cadmium in application of humic acid.

Among the studied chelators (sodium citrate, humic acid and Na2-EDTA), Na2-EDTA had the greatest effect on soluble cadmium. While sodium citrate had no significant effect on soluble cadmium. Surfactants from Pseudomonas putida and Bacillus subtilis had different effects on increasing the efficiency of studied chelators and soluble cadmium in the studied soil. In Na2-EDTA and humic acid application, surfactant from Bacillus subtilis at a concentration of 25 mg L-1 and surfactant produced by Pseudomonas putida at a concentration of 100 mg L-1 had a significant effect on soluble cadmium, respectively. It seems using biosurfactants and chelators on increasing soluble cadmium in soil can be useful for phytoremediation purposes to increase its uptake by plant. However, further research is needed.