Showing 52 results for Oil
A Koolivand, K Naddafi, R Nabizadeh, A Jonidi Jafari, M Yunesian, K Yaghmaiean, S Naseri,
Volume 9, Issue 3 (12-2016)
Abstract
Background and Objective: The performance of in-vessel composting process, as one of the most effective methods of oily sludge treatment, depends on factors such as nutrients and temperature. Therefore, it is crucial to investigate the trend of changes of these factors. The aim of the present study was to investigate the trend of changes of organic carbon, nitrogen, phosphorus, and temperature during the composting of bottom sludge of crude oil storage tanks.
Materials and Methods: The sludge was mixed with the immature compost at the various ratios of sludge to compost including 1:2, 1:4, 1:6, 1:8, and 1:10 with the initial C/N/P of 100/5/1 and then was composted for a period of 10 weeks. The process of mixing and moisture adjustment of the mixtures was done 3 times a day during the composting period. Sampling and analysis were performed every week for organic carbon, nitrogen, and phosphorus and every day for temperature.
Results: The research indicated that the concentrations of organic carbon, nitrogen, and phosphorus were decreased sharply during the first weeks of the process and then they were decreased gently. At the final stage of the composting, the ratios of C/N and C/P increased from 20:1 and 100:1 to 26:1 and 166:1, respectively. In addition, the temperature of the reactors was kept in the mesophilic range during the process period.
Conclusion: The similar trend of decrease of organic carbon, nitrogen, and phosphorus in the composting reactors is an indication of decreasing the activity of the microorganisms involved in petroleum hydrocarbons degradation.
N Sistani, M Moeinaddini, N Khorasani, Ah Hamidian, Ms Ali-Taleshi, R Azimi Yancheshmeh,
Volume 10, Issue 1 (6-2017)
Abstract
Background and Objective: Urban and industrial development has increased concentration of heavy metals in the environment. The goal of this study was to assess the impact of Kerman steel complex on their surrounding soil by heavy metals.
Materials and Methods: This study was a snapshot and its type was descriptive-analytical research. Heavy metals contents from 60 soil samples (top soil, 0-15 cm) near two Steel Complexes were analyzed using flame atomic absorption spectroscopy (AAS). Source identification and pollution degree indices including enrichment factor (EF) and its percentage (EF%), geo-accumulation index (Igeo), contamination factor (Cf), degree of contamination (Cd) and modified degree of contamination (mCd) were calculated to assess the soil pollution level.
Results: The average concentration of Ni, Zn, Fe, Pb, Cr and Cd were 9.98, 54.38, 15063.33, 20.86, 3.54 and 0.038 mg/kg, respectively. The order of average EF for heavy metals was Pb > Zn> Cd> Fe> Ni> Cr. Cf index also showed that 90% of the samples were moderately to significantly polluted with lead element. The results of EF% indicated that Fe (68.18%) had higher enrichment than others. The average values of Cd and mCd indices were 2.90 and 0.48, respectively, that showed low degree of pollution.
Conclusion: In this study, Pb and Cd concentration were related with activities of the steel complexes and other metals had a combination of natural and anthropogenic emission sources. The steel complexes should plan to reduce pollutants emission to their environment.
Sl Mousavi, A Shakeri, M Nakhaei,
Volume 10, Issue 2 (9-2017)
Abstract
Background and Objective: Polycyclic aromatic hydrocarbons (PAHs) constitute a large class of organic compounds that are composed of two or more fused aromatic rings. Due to their potential mutagenic, carcinogenic and teratogenic effects on human health, PAHs have attracted particular concern. Therefore, in this study it was attempted to measure the PAHs concentration in the study area to evaluate the health risk.
Materials and Methods: 36 samples were taken from the central district in Bandar Abbas county to investigate the degree of contamination, sources and health risk of polycyclic aromatic hydrocarbons (PAHs). Analysis of the samples was performed using gas chromatography. خطای ترجمهAlso, PMF Model was used to determine the possible sources.
Results: The total PAHs concentration had a mean value of 1.48 mg/kg in the soil samples. The total incremental life time cancer risk (ILCR) due to exposure to PAHs in soil is 1.06 × 10−6 for an adult and 4.95 × 10−6 for children. The results estimated for ILCR indicated that residents live in the central district of Bandar Abbas county are potentially exposed to cancer risk via both dust ingestion and dermal contact.
Conclusion: The ecological risk assessment of PAHs showed that the levels of all types of PAHs were lower than the lower value of effects range, except for dibenzo(a,h) antheracene and acenaphthene. The estimated results of ILCR indicated that Bandar Abbas county central district residents are potentially exposed to cancer risk via both ingestion and dermal contact. The PMF analysis identified four sources that were included fossil fuel combustion (14%), biomass combustion (13%), vehicular emissions (36%) and fossil fuel combustion/unburned petroleum (37%).
Ar Mansoorian, A Vaziri, Mr Zamani, F Heidaryan Naeini,
Volume 10, Issue 3 (12-2017)
Abstract
Background and Objective: In the field of environmental risk assessment, Cyanide is one of the most important pollutants of water, soil and air that has an important impact on the ecosystem and environment of the contaminated area. Therefore, the present study aimed to prove the biological effectiveness of Vetiveria zizanioides in phytoremediation of soils contaminated with cyanide.
Materials and Methods: This research study was conducted on a gold mine wastewater. The dried effluent samples amended with soil with various cyanide concentrations. Seven treatments with different concentrations of cyanide were obtained (mean cyanide content in G soil, 14.77 mg/kg, F soil, 10.13 mg/kg, E soil, mg/kg 8.09, D soil, mg/kg 7.53, C soil, 3.32 mg/kg, B soil, 2.52 mg/kg and A soil without cyanide (as control). After two months, the amount of cyanide in the soil, roots and leaves of the plant, as well as the total protein and proline content, and the number and length of the leaves of the plant were measured and then statistically evaluated by SPSS15 Tukey and t Paired Samples T Tests.
Results: The results of this study showed that the increase of cyanide had a significant effect on the amount of proline (proline in the plant increased), total protein (in the plant increased), number of leaves (decrease in number) and the length (length reduction) of the leaves of the vetiver. The amount of cyanide in the leaves and roots of the plant was increased. Cyanide content was decreased in the different treatments. Cyanide content was decreased in G 50.93%, F 38.20%, E 27.19%, D 38.37%, C 17.77% and B 16.66%.
Conclusion: The results indicated that increase of the amount of cyanide in soil resulted in observational changes in the morphological and biochemical characteristics of the plant. However, Vetiveria zizanioides exhibited very high resistance to soil cyanide and the planting of vetiver in highly contaminated soils can lead to a reduction of cyanide up to 50 percent. Vetiveria zizanioides had higher resistance to cyanide and showed better phytoremediation than the other plants.
B Mohammad Moradi, S Sobhanardakani, M Cheraghi,
Volume 10, Issue 4 (3-2018)
Abstract
Background and Objective: Heavy metals are the most frequent pollutants of urban soils. In general, human health and especially children are directly at risk if the soil is being accidentally ingested orally or nasally. Therefore, this study was conducted to assess potential ecological risk index (RI) of Pb, Cd, Cr and Cu in surface soils of urban parks in Tehran City in 2016.
Materials and Methods: A total of 60 surface soil samples were collected from Mellat, Laleh, Velayat, Ekbatan and Pirouzi parks. The heavy metals contents in samples were determined using ICP-OES after acid digestion of soil samples. Also, RI of heavy metals was determined. All statistical analyses were performed according to the Shapiro-Wilk test, One-Way ANOVA, One Sample T-Test and Pearson Correlation Coefficient.
Results: The lowest and highest contents of the metals (mg/kg) with an average of 0.52 ± 0.25 and 153.81 ± 31.83 were related to Cd and Pb, respectively. Pb and Cu were higher than MPL. Also, the highest surface soil contamination was related to Velayat Park located at the south of Tehran. The value of RI was 99.16 and therefore the soil contamination was categorized in low ecological risk.
Conclusion: Although the value of RI categorized as low ecological risk, due to mean concentrations of Pb and Cu were higher than MPL, control of soil-contamination sources, periodic monitoring of surface soil in the urban parks where citizens spend most of their free time. Additionally, it should be avoided to construct urban parks close to the regions with high traffic intensity.
Gr Jahed Khaniki, P Safaei, R Barik Gugjlu, A Mohajer,
Volume 10, Issue 4 (3-2018)
Abstract
Background and Objective: Hydrogen peroxide is one of the compounds that is primarily produced by the oxidation of oil and fat and causes various diseases, including atherosclerosis and coronary artery disease .The aim of this study was to survey the peroxide value of edible oils used in sandwich and falafel shops in Tehran in 2016.
Materials and Methods: In this study, sampling from a number of fast food centers was done randomly. After the transfer of samples to the chemistry laboratory of environmental health engineering department, the peroxide number was determined based on the national standard procedure 4179. The data was analyzed by SPSS software for descriptive statistical parameters and t-test.
Results: According to the National Iranian Standards, from total of 50 samples of the sandwiches taken, 20 samples (40 %) were consumable and 30 samples (60 %) were inedible. Also, from 40 samples of falafel taken, 14 samples (35 %) were consumable and 26 samples (65 %) were inedible. The maximum peroxide values of sandwiches and falafel were 29.79 and 31.22 meq/kg, respectively.
Conclusion: The findings show that Peroxide value in the sandwich and falafel shops were higher than the standard, and thus it seems that having an educational plan for staff regarding the correct methods of frying food is necessary.
A Misaghi, M Saeedi, N Noori, Mr Rezaeigolestani,
Volume 11, Issue 1 (6-2018)
Abstract
Background and Objective: Natural antimicrobial compounds have a valuable capacity to be used in a variety of foods to inhibit growth of foodborne pathogens and spoilage bacteria. The aims of this study were to produce active biodegradable films by incorporation of different percentage of oregano essential oil (OEO) and ethanolic extract of propolis (EEP) into poly-lactic acid (PLA) films, and to evaluate physical and antimicrobial properties of the resulting films.
Materials and Methods: The active films were produced by solvent casting method, and their thickness and major color parameters were measured using a digital micrometer and a colorimeter instrument, respectively. Afterwards, antibacterial effects of the films were assessed against four common foodborne pathogens, including Staphylococcus aureus, Escherichia coli, Vibrio parahaemolyticus and Listeria monocytogenes, by means of disk diffusion test.
Results: Physical examinations showed that thickness of resultant films significantly was increased (p<0.05) by addition of different concentrations of active agents. Additionally, the presence of them in the structure of films decreased the lightness and increased the redness and yellowness, simultaneously. While none of the neat PLA film or films with just EEP had no antibacterial effect, all films containing higher percentages of OEO (5 and 10%) were effective against all four tested bacterial strains, and these effects were more significant in case of the gram-positive bacteria. The maximum inhibition zone was recorded for the film containing 10% of OEO and 2% of EEP, which the relevant values were 56.66, 45.46, 17.91 and 17.65 mm for Staphylococcus aureus, Listeria monocytogenes, Vibrio parahaemolyticus and Escherichia coli, respectively.
Conclusion: Based on the findings of this study, the presence of just EEP in the initial formulation of poly-lactic acid films was not effective against the four tested foodborne pathogens, while the addition of this compound to the films containing OEO increased the effective antibacterial properties of the resulting films. As a result, the simultaneous use of these two compounds in the structure of hydrophobic films, such as poly-lactic acid film, can be used to produce active food packaging films.
Ah Baghaie,
Volume 11, Issue 2 (9-2018)
Abstract
Background and Objective: Today, landfill management of municipal waste and soil pollution with heavy metals are major environmental problems. This research was conducted to evaluate the effect of Shazand municipal waste compost and Saveh pomegranate peel biochar on decreasing Pb availability in soil and sorghum plant.
Materials and Methods: Treatments consisted of applying Shazand municipal waste compost (0, 10 and 20 ton/ha) and Saveh pomegranate peel biochar (0 and 15 g/kg) in a Pb polluted soil (0, 600, 800 and 1000 mg Pb/kg soil). After 8 weeks of sorghum planting (Kimya CV.), the soil physio-chemical properties and soil and plant Pb concentration were measured.
Results: Applying 20 ton/ha municipal waste compost with 15 g/kg biochar increased soil pH by 0.4 units and decreased soil Pb availability by 11%. The similar results were observed for the root and shoot Pb concentrations, when the same amount of manure in a Pb polluted soil was applied (1000mg Pb/kg soil) that decreased the root and shoot Pb concentration by 1.8 and 2.2 times, respectively.
Conclusion: The result of this experiment showed that applying Shazand municipal waste compost and biochar can increase soil sorption properties and decrease soil or plant Pb concentration. However, the role of these organic amendments on supplying plant nutritional needs cannot be ignored.
Ghr Siyahati Ardakani, M Mirsanjari, Hr Azimzadeh, E Solgi,
Volume 11, Issue 3 (12-2018)
Abstract
Background and Objective: The establishment of pelletizing and steel industries in Ardakan suburbs has increased the pollutants such as heavy metals into the environment. The purpose of this study was to investigate the contamination of the area soil by heavy elements around these industries using the pollution index (PI), comprehensive pollution index (NIPI), accumulation index (Igeo) and enrichment index (EF).
Materials and Methods: 57 soil samples were prepared by systematic-random sampling from 0 to 5 cm depth and levels of As, Cd, Cr, Mo, Ni, Pb, V and Zn were analyzed by ICP-OES.
Results: The highest and lowest mean of Igeo (0.49 and 0.36) and PI (2.16 and 1.17), were related to nickel, and the highest EF was calculated for Zn at about 25.1 and the lowest were detected for molybdenum approximately that was 17.1. The EF index of lead, vanadium and zinc, which was 15.8%, 5.3% and 1.8%, respectively, classified the study area in a medium enrichment class. Hot spots of lead, vanadium, nickel and zinc was at the nearest distance to these industries and downstream of wind direction.
Conclusion: Indicators of Igeo and EF showed a low level of soil pollution. The PI and NIPI indices in most stations were classified in medium pollution class, and the highest of these indicators was related to the surface soil of station 30, which was located near the steel industry. Therefore, it can be concluded that the activities of these industries had affected the soil contamination of the study area.
E Khanpour-Alikelayeh, A Partovinia, A Talebi, H Kermanian,
Volume 12, Issue 4 (2-2020)
Abstract
Background and Objective: Petroleum compounds are major contributors to aquatic environmental pollution. In recent years, biological treatments as environmental-friendly and cost-effective techniques have been used alongside the various physico-chemical methods. Microbial cell immobilization in hydrogel carriers has been the focus of researchers due to various advantages such as ease of microbial species control, non-direct exposure of pollutants to the cells, increasing cell resistance during different types of stresses and reusability. The main goals of this study were introduction to electrospraying technique in order to size reduction of alginate beads and comparison of heavy crude oil biodegradation using an isolated strain of Bacillus licheniformis in free and immobilized cells.
Materials and Methods: The oil-degrading strain was isolated from oil-polluted site on Kharg Island. Microbial cells were examined in both free and immobilized systems under different conditions (pH=5,7) and initial crude oil concentration (1500,3500 ppm). Electrospraying technique was used for alginate beads production. Residual crude oil content was analyzed by gas chromatograph and gravimetrically method.
Results: The maximum oil removal (61%) was obtained for the immobilized cells at a concentration of 3500 ppm in neutral medium. Overall, according to the results, after the 14th day, the biodegradation through the immobilized cells was significantly (p<0.05) higher than the free cells. Moreover, the cell immobilization caused the microorganisms to be more resistant to the harsh environments.
Conclusion: This study showed that the immobilized microbial cell system has a great potential for oil wastewater treatment. The electrospraying technique can be used to overcome to the mass transfer limitations.
Bahareh Ghoreishi, Hassan Aslani, Mohammad Shaker Khatibi, Sepideh Nemati Mansur, Mohammad Mosaferi,
Volume 13, Issue 1 (4-2020)
Abstract
Background and Objective: Application of sewage sludge contaminated with heavy metals may cause health and ecological concern. Ecological risk and heavy metals content of sewage sludge from wastewater treatment plants of East Azerbaijan province were evaluated in the present study.
Materials and Methods: Nine composite samples were taken and analyzed for heavy metals. The geo-accumulation index (Igeo), contamination factor(CF) , and potential ecological risk index were calculated.
Results: Variation of the heavy metals concentrations were in the following order: Zn>Cu>Pb>Cr>Ni>As>Hg>Cd. The contents of some heavy metals were several order of magnitude higher than the crustal average (CA) values. Considering the Maximum Permissible Standards (MPS) and the Muller's index, the Cd, Cu, and Zn pollution were found to be in the moderate range, whereas As and Pb were in strongly polluted category; and Hg was in extremely polluted category. Considering MPS, the single-factor pollution index (PI) and the Nemerow’s synthetic pollution index (PN) were lower than 1 and 0.7 respectively. This indicated that the sludges were unpolluted with most heavy metals and could be safely applied for agricultural uses. However, a high potential ecological risk for As and Cd; very high risk for Pb; and extremely high risk for Hg were calculated when considering the CA values. There were significant differences between the levels of heavy metals and MPS (p <0.05).
Conclusion: Although the metal concentrations were below the MPS according to the US EPA regulations, sludge samples showed a high degree of potential ecological risk for the environment in comparision with the CA values,. Periodic monitoring of sludge quality are strongly recommended.
Abbas Taati, Mohammad Hasan Salehi, Jahangard Mohammadi, Reza Mohajer,
Volume 13, Issue 2 (8-2020)
Abstract
Background and Objective: Heavy metal contamination of surface soils has become a serious concern. The aim of this study was to evaluate the potential risk of heavy metal (loid) pollution on human health in the surface soils of Arak industrial areas, the capital of Markazi province in western Iran.
Materials and Methods: 235 surface soil samples were collected from a depth of 0-5 cm. Concentrations of lead, cadmium, nickel, zinc, copper and arsenic were determined by digestion with nitric acid (4 N). The level of soil pollution in the region was measured using geo- accumulation index (Igeo) and enrichment factor (EF). The model proposed by the U.S Environmental Protection Agency (USEPA) was used to assess the health risks of heavy metals.
Results: The Mean concentrations of Pb, Cd, As, Cu, Ni, and Zn were 37.88, 1.17, 151.78, 13.48, 92.98 and 104.04 mg/kg, respectively. The calculated enrichment factor values for soil samples varied from deficiency to significant enrichment. The mean geo-accumulation index (Igeo) for Pb, Cd, Cu, Ni, Zn and arsenic were 0.37, 1.59, -2.53, -0.48, -0.63 and 2.9, respectively. The results of the health risk assessment showed that hazard quotient (HQ) for children and adults through the ingestion route was higher than dermal contact and inhalation pathway. The Hazard index values for all studied metals were lower than the safe level of 1 except for As. Arsenic showed the highest risk of carcinogenicity (CR) for children (2.37 x 10-4) through ingestion.
Conclusion: The carcinogenic risk (CR) of As in children and adults is higher than the safe limit of 1 × 10-4, which indicates an unacceptable risk.
Mohsen Mohammadi Galangash, Rezvan Ghasemi Zolpirani, Mohammad Naimi Joubani,
Volume 13, Issue 3 (11-2020)
Abstract
Background and Objective: Contamination of roadside soils with heavy metals is a serious threat to soil ecosystems and organisms and human health. Therefore, the purpose of this study was to determine the concentration of heavy metals in the roadside soils of the Rasht-Qazvin old road.
Materials and Methods: 10 out-of-town sampling sites were selected via the field observation of the entire area. surface soil sampling with three replicates was performed around the Rasht-Qazvin old road. Heavy metals concentrations were measured using ICP-OES following samples preparation and acid digestion. The pollution level of heavy metals was assessed using geoaccumulation index (Igeo) and potential ecological risk index (PERI).
Results: The results showed that the average concentrations of Zn, Cu, Ni and Pb in the roadside soils were 58.07, 19.96, 20.26 and 23.21 mg/kg, respectively. The findings showed that concentration of Zn and Ni were higher than background values and the amount of Zn exceeded WHO standard limit. The potential ecological risk index (PERI) with an average value of 86.24, indicated low level of pollution for all of the studied metals. The results of geoaccumulation index (Igeo) revealed moderately contamination level of Ni.
Conclusion: Old roads are generally known as one of the sources of pollution for the surrounding lands. Although the concentration of pollutants around the road is expected to be very high, we did not detect elevated levels of heavy metals. This fact can be explained by the current road repairs and widening, agricultural activities on marginal lands and wind blows in mountainous regions which leads to the dispersion of the soil pollutants.
Shahla Karimian, Sakine Shekoohiyan, Gholamreza Moussavi,
Volume 13, Issue 4 (2-2021)
Abstract
Background and Objective: Landfills as municipal solid waste are considered as the source of pollution. The present study aimed to assess the ecological risk of heavy metals in Tehran landfill soil and the adjacent residential area.
Materials and Methods: Having consulted with the specialists and considered the waste processing facilities, 12 sampling points were selected and sampled in four seasons. Soil samples were digested using HNO3: HClO4: HCl: HF. The levels of metals were measured using ICP-OES which further applied for the calculation of ecological risk. Kolmogorov-Smirnov, Kruskal-Wallis, and Pearson correlation coefficient analyses were run to determine the significant differences between metals concentrations in various seasons and sampling points.
Results: Metal concentration showed to follow theorder: Al > Fe > Mn > Zn > Cr > Pb > Cu >Ni > Co > As > Cd. Kruskal-Wallis results and pairwise comparison showed a statistically significant difference between metal concentrations across sampling points and seasons, especially in rainy seasons. Pearson correlation coefficient displayed a strong relationship between the mean concentrations of Cu - Pb, Cu - Zn, and Pb - Zn with obtained values of 0.932, 0.874, and 0.883, respectively. Cu exhibited the highest contamination factor at the compost and fermentation sites (13.2 and 9.89, respectively). The geo-accumulation index proved the anthropogenic sources of pollution. The potential ecological risk index (ERI) for the sampling sites ranged from 67.3 to 154, with the order of Cd > Cu > Pb > Ni > As > Cr > Zn > Co > Mn.
Conclusion: Due to the obtained moderate to severe ecological risk and exceeded background concentrations of heavy metals, it can be concluded that metal changes and soil pollution are both affected by landfill activities.
Mohamad Amin Daneshfar, Mehdi Ardjmand, Seyed Aboutaleb Mousavi Parsa,
Volume 13, Issue 4 (2-2021)
Abstract
Background and Objective: Improper treatment of PAHs in oily drilling cuttings cause adverse effects on the environment. The present study aimed to investigate the efficiency of two bioremediation and fixation methods for PAHs removal from oily drilling cuttings. The efficiency of the two mentioned methods were analyzed and subsequentelythe more effective one was selected using environmental protection approach.
Materials and Methods: The sampling of oily drilling cuttings at the beginning and end of the treating process was performed for the studied methods, according to standard protocols. The amounts of PAHs, are determined by Soxhlet apparatus and gas chromatography-mass spectrometery.
Results: The results showed that the removal efficiency of PAHs from oily drilling cuttings was 97% (440.3 mg/kg) for bioremediation and 78% (354.7 mg/kg) for the fixation method, respectively. The findings showed that the bioremediation method provides the standard requirements for the discharge of PAHs to the environment.
Conclusion: Bioremediation is more effective than the fixation method for removing PAHs compounds and exhibits higher environmental protection performance.
Mohsen Shaban, Daryoush Yousefi Kebria, Marzie Razavi,
Volume 14, Issue 1 (5-2021)
Abstract
Background and Objective: Application of chemical fertilizers in agricultural industry is known as one of the methods of crop enhancement. However, chemical fertilizers application can lead to an increased risk of chemical pollutants entering the human food cycle. The aim of current research was feasibility study and evaluation of nickel from paddy soils in Lorestan province.
Materials and Methods: Sampling was done from 15 stations and randomly from rice cultivation areas in Silakhor plain of Lorestan province. Then, electrokinetic modification method was carried out in three reactors with lengths of 5, 10 and 15cm. After sample preparation, the initial and final concentration of nickel were measured and calculated using inductively coupled plasma - optical emission spectrometry (ICP-OES).
Results: The results showed that electrokinetic modification method was effective in reducing the concentration of heavy metals in agricultural soil samples and reduced the amount of nickel in soil to the permissible limits of the Iranian soil national standards (50 mg/kg). The initial values of nickel in paddy soil of composite samples were 108 mg/kg. Nickel maximum removal efficiency of 90.84% and 93.75% were observed in cathode and anode regions, respectively.
Conclusion: The health and quality of agricultural products depend on the use of safe soil within the limits of environmental standards. The results of this study showed that the EKR process is able to remove nickel from soil. As a result of the present process, nickel concentration has reached the permissible amount and even lower than the soil quality standard set by the Iranian Environmental Protection Agency.
Reza Barati Rashvanlou, Mahdi Farzadkia, Abbas Ali Moserzadeh,
Volume 14, Issue 1 (5-2021)
Abstract
Background and Objective: Hydrolysis of fat, oil and grease by ultrasonic waves is a pre-treatment method before anaerobic digestion which can change their physical, chemical and biological properties. The main purpose of this study was to investigate the efficiency of ultrasonic waves to improve the hydrolysis process and its use as an auxiliary substrate to increase the efficiency of anaerobic digestion process along with municipal sewage sludge.
Materials and Methods: Sampling of fat and oil of the degreasing unit and physical preparation by conducting ultrasonic waves with frequencies of 20 kHz and current density of 0.012-0.14 W/mL within 0-12 min were performed. The efficiency of pretreatment process were performed through tests such as soluble chemical oxygen demand (SCOD), and lipase enzyme activity. In addition, the anaerobic digestion process were evaluated by measuring the TS, VS, VA (volatile acidity), alkalinity, biogas production and biogas methane content.
Results: The results showed that the highest increase in the activity of lipase enzyme under ultrasonic effect with a power of 0.1 w/mL was obtained after 8 minutes. Organic loading with 10%, 20% and 40% FOG/MSS ratios: resulted in 55%, 66% and 64% increase in methane production compared to the control samples, respectively. Organic loading over the 40% FOG/MSS caused a limitation in the simultaneous digestion process.
Conclusion: The results show that ultrasonic wave pretreatment with optimal power and time can improve the hydrolysis of TFOG while increasing the activity of lipase enzyme and also its use as an auxiliary substrate can enhance digestion performance and make digestion more stable.
Neda Pouryousef, Mohammad Ahmady, Nabi Shariatifar, Sara Jafarian, Seyed-Ahmad Shahidi,
Volume 14, Issue 4 (3-2022)
Abstract
Background and Objective: Nowadays, the application of procedures to minimize oxidative and microbial spoilage in marine products is economically and hygienically important. This study was performed to determine the effect of free and nanoliposome forms of poneh (Mentha pulegium L.) essential oil to increase the shelf life and improve the sensory characteristics of silver carp minced fish (Hypophthalmichthys molitrix) during storage time.
Materials and Methods: In this study, the antibacterial properties of 1 and 2% essential oil and nanoliposomes form on the microbial population of minced silver carp fish inoculated with Bacillus cereus and Escherichia coli were measured. Also, chemical tests (DPPH (2,2-Diphenyl-1-picrylhydrazyl assay, measurement of iodine peroxide (PV), pH, total volatile nitrogen (TVB-N) and thiobarbituric acid (TBARs)) and sensory properties of minced silver carp were evaluated during 12 days of refrigerated storage.
Results: The results showed that the addition of poneh essential oil (free and nanoliposomes) according to the microbial results and the results of chemical experiments can effectively prevent microbial growth and chemical spoilage (p<0.05). Treatment containing 2% nano essential oil of poneh showed the greatest effect on the chemical, microbial and sensory properties of minced fish during the experimental period in comparison with control treatments, 1% poneh nanoliposomes essential oil and 2 and 1% free essential oils.
Conclusion: Therefore, the nanoliposomes form of 2% poneh essential oil can be used as a suitable additive to increase the shelf life of Silver carp fish in the fish industry.
Mohamad Mehdi Ghorbaninejad Fard Shirazi, Sakine Shekoohiyan, Gholamreza Moussavi, Mohsen Heidari,
Volume 15, Issue 1 (4-2022)
Abstract
Background and Objective: Among the emerging contaminants, microplastics threaten public health. This study aimed to determine microplastic and mesoplastics in soil of residential areas adjacent to Tehran Landfill and assess its ecological risk.
Materials and Methods: The present descriptive cross-sectional study was conducted on 20 shallow and deep soil samples from residential areas near the Tehran landfill in July 2021. The microplastics were floated in NaCl and ZnCl2 solutions, and the mesoplastics were separated manually. The identification of physical and chemical properties of polymers was performed by stereomicroscope and FTIR analysis, respectively.
Results: The average amount of micro-plastics in shallow and deep soils estimated 76±34.98 and 24.7±19.79 particles/kgsoil, respectively. The average amount of mesoplastics obtained 5.25±2.91 and 3.55±1.09 particles/kgsoil, in shallow and deep soils, respectively. Paired-samples T-test showed significant differences between shallow and deep soil in terms of plastic particles (p<0.001). The most abundant microplastic particles were the fragment-shaped with the particle size of 0.1-0.5 mm and LDPE polymer types with the percentage of 37.75, 44.64, and 46.15, respectively. Mesoplastic particles, the 0.5-1 cm film-shaped particles and LDPE polymer types with the percentage of 62.76, 61.46, and 50.7 were found as the most prevalent. Microplastics and mesoplastics' potential ecological risks value in all sampling points was less than 150, indicating low ecological risk.
Conclusion: Despite the low PERI of microplastics and soil mesoplastics in residential areas, the Eri index for LDPE was high. Thus, Ecological risk is probable if control measures are not taken against plastic pollution.
Azim Rabieimesbah, Soheil Sobhanardakani, Mehrdad Cheraghi, Bahareh Lorestani,
Volume 15, Issue 1 (4-2022)
Abstract
Background and Objective: Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants produced by anthropogenic activities that contaminate all environmental matrices, including soils, and can enter the food chains. Therefore, this study was conducted for the analysis of PAHs compounds content in agricultural soils of Hamedan city, west of Iran, in 2021.
Materials and Methods: a total of 36 surface soil specimens were collected from 12 sampling sites in agricultural soils and after extraction of analytes based on the soxhlet method, the gas chromatography/mass spectrometry (GC–MS) method was used for the determination of PAHs compounds in the samples. Furthermore, soil samples were further analuzed for the amounts of pH, electrical conductivity (EC), and total organic carbon (TOC). Statistical analysis was performed using SPSS software.
Results: Results showed that 16 PAHs (∑16PAHs) total concentrations ranged from 435 to 3292 µg/kg with an average value of 1806 µg/kg. PAHs with higher molecular weight (≥ 4 rings) were dominant in PAHs profiles accounting for 78%. Based on the results, the mean concentrations of all 16 PAHs were lower than MPC established by MHWaS. Furthermore, the mean concentrations of Pyr, B(a)A, Chy, B(b)F, B(k)F, B(a)P, and B(ghi)P were higher than the MPC established by the Iranian Department of Environment.
Conclusion: Based on the results obtained, as the mean contents of some PAHs were higher than the MPC, therefore, periodic monitoring of soil contamination with PAHs is recommended for the environmental and human health aspects.
