Iranian Journal of

Background and Objective: The purpose of this cross-sectional study is to evaluate the microbial contamination of food-handlers' hands and food contact surfaces in food preparation and distribution centers.
Materials and Methods: This study was performed in 2019 in Fardis city of Alborz province. In this study, 100 samples of food contact surfaces and 48 samples of staff hands were collected from three traditional bakery units, pastry centers and snack shops and the microbial load was determined using a luminometer device. The samples were then analyzed for the presence of coliforms, Escherichia coli and Staphylococcus aureus bacteria.
Results: Among the samples studied, 62 samples (62%) of contact surfaces and 27 samples (56.25%) of food-handlers' hands had microbial load more than 30 RLU.  According to the results, the main cause of microbial contamination of equipments were 44.40% of Coliform bacteria and 11.10% of Staphylococcus aureus on the equipment of confectionery centers,  10% of Escherichia coli, 20% of coliforms and 20% of Staphylococcus aureus were detected on food tools and 2.30% of Escherichia coli, 14% of coliforms and 14% of Staphylococcus aureus –on the tools of traditional bakeries.Moreover coliform bacteria was noticed onconfectionary-handlers' hands and all three types of bacteria were also found on the hands of bakers.
Conclusion: The results showed that the cleanliness of food contact surfaces and the personnel hands hygiene was in poor condition which may pose serious threat to public health. Therefore, adequate personal hygiene practices, food safety and inspections should be implemented to protect the health of society.

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.

Background and Objective: Wastewater treatment and stabilization always imposes costs and consequently a lot of energy on wastewater treatment plants. To achieve the purification and stabilization of as much sludge as possible, breaking complex components into simpler components is considered a critical step. Therefore, this study aimed to evaluate the feasibility of treating the produced sludge in the municipal wastewater treatment plant using ozonation method.
Materials and Methods: In this study, sludge was obtained from the return line of activated sludge from the wastewater treatment plant in the south of Tehran. An ozonation generator with a discharge rate of 3 L/min and an ozone concentration of 40-35 mg/L was discharged to the reactor and the residual ozone concentration was measured by iodometric method. Finally, the total suspended solids and volatile, soluble chemical oxygen demand, total organic carbon, and biochemical oxygen demand during ozonation processes were measured using the Standard Method.
Results: The results of this study showed that the amount of TSS and VSS in the activated return sludge decreased from 4060 to 2100 mg/L and from 3300 to 1850 mg/L during the ozonation process, respectively. However, SCOD, TOC, and SBOD had an upward trend of about 18, 11.7, and 14 times in the same reaction time, respectively.
Conclusion: According to the results of this study, it can be concluded that the ozonation system can be proposed as a suitable process for the decomposition of sludge produced in wastewater treatment plants and increasing the biodegradability of these sludges.

Background and Objective: The high concentration of petroleum hydrocarbons, along with some other parameters such as aromatics, paraffin, naphthene, and heavy metals, has led to the sludge of oil sludge listed as hazardous materials with a specific source by the US Environmental Protection Agency. Therefore, the purpose of this study is to investigate the potential of oil-contaminated soil in changing the biodegradability indices of oil sludge.
Materials and Methods: Moisture, pH, total organic carbon, total nitrogen, total phosphorus, elemental analysis, and amount and type of TPH of oil sludge samples were identified. The microbial consortium was isolated from contaminated oil soil around the oil refinery and poultry manure. Finally, biodegradability indices of oil sludge were examined.
Results: The results showed that the amount of organic carbon and nitrogen in oil sludge samples were 32.65 and 0.21%, respectively. Also, iron, calcium, and potassium with 5862, 2921, and 524 mg/kg, respectively, were the most elemental components in petroleum sludge. According to the SARA analysis, the highest TPH compounds in oil sludge samples included saturated compounds, aromatics, resins, and asphaltene with 70.45%, 15.2%, 10.9%, and 3.45%, respectively.
Conclusion: According to the results of biodegradability indicators of oil sludge, it can be concluded that the isolated consortium can be proposed as a suitable tool for the treatment of petroleum sludge at the bottom of crude oil storage tanks.
 

Background and Objective: Today, the issue of health aspects in urban waste management, especially recycling, has received a lot of attention during Covid-19 around the world. Therefore, the purpose of this research is to investigate the knowledge, attitude, and performance of workers of one of the waste recycling centers in Tehran metropolis regarding health aspects during the spread of Covid-19.  
Materials and Methods: This was a descriptive-analytical cross-sectional study and the study population was all workers working in one of the recycling centers of Tehran Municipality. The data collection tool was a researcher-made questionnaire with validity and reliability in four sections: demographic, knowledge, attitude, and practice of workers toward Covid-19 and solid waste.
Results: Findings of the study showed that the highest number of workers employed were in the age group of 20 to 40 years (60 percent). The level of knowledge was about 80 percent and the lack of awareness was 20 percent. The level of workers' positive attitude, negative attitude, and lack of attitude were 79.71, 14.56, and 5.72 percent, respectively. The level of positive practice among workers was about 67.43 percent and the negative practice was 32.57 percent.
Conclusion: The results clarified that in order to succeed in waste management programs in recycling centers, municipal waste managers should pay more attention to educational aspects, especially through the focus on programs and their development and adaptation for different age groups, especially 20 to 40 years.
 

Background and Objective: Pharmaceutical compounds can cause potential risks to aquatic and terrestrial organisms. So far, different methods have been used to eliminate these pollutants, photocatalytic processes are one of the most efficient processes to eliminate pharmaceutical compounds. In this study, the efficiency of a novel MOF-based nanocomposite, PMo/UiO-66 as a photocatalyst for amoxicillin degradation under visible light irradiation was evaluated.
Materials and Methods: The study of the chemical decomposition of amoxicillin using the PMo/UiO-66 system was conducted at different stages. First, the PMo/UiO-66 MOF nanocomposite was synthesized using the solvothermal method, then the properties of the synthesized nanocomposite were investigated using XRD, FTIR, and SEM techniques. The effect of different operational parameters such as pH (3, 6, and 9), catalyst concentration (15, 20, 25, and 30 %w/w), initial concentrations of amoxicillin (20, 30, 40, and 50 mg/L) at different times on the removal efficiency was investigated. The reusability of the catalyst for four cycles was assessed.
Results: The results showed that PMo/UiO-66 nanocomposite at pH 6, 25 %w/w nanocomposite concentration, and the amoxicillin concentration of 20 mg/L led to complete decomposition of amoxicillin after 120 min. The kinetic of amoxicillin removal followed the first-order model. Reusability tests showed that the photocatalytic efficiency of the synthesized catalyst was not substantially reduced after four cycles.
Conclusion: The current study confirmed that the PMo/UiO-66 system has an appropriate efficiency for photocatalytic removal of amoxicillin under optimized test conditions.

Background and Objective: The purpose of this study is to identify and comprehensively evaluate international studies related to bioaugmentation and biostimulation methods for the remediation of soils contaminated with petroleum compounds.
Materials and Methods: This systematic review study was conducted in April 2022. The present systematic review study was conducted to address two main questions: 1) Is biostimulation an effective process in the bioremediation of soils contaminated with petroleum hydrocarbons; and 2) Is bioaugmentation an effective process for bioremediation of soils contaminated with petroleum hydrocarbons? Global electronic databases (PubMed, Web of Science, and Scopus) were used to identify relevant studies. After a comprehensive review of studies, 123 studies consistent with the purpose were selected.
Results: The results showed that biostimulation methods can have profound changes in bacterial, Archaebacteria, and soil fungal communities in terms of activity, frequency, and composition. In general, the nutrients and electron receptors added in the biostimulation process improve soil microbial activity, increasing the overall abundance of bacteria, and fungi and promoting selective replication of bacterial, archival, and fungal polyaromatic hydrocarbons (PHC) destroyers. The use of bioaugmentation technology in an environment contaminated with petroleum hydrocarbons has a positive effect on the refining process. However, it is necessary to precisely select the appropriate microbial strains. The most important factor in the removal of hydrocarbons in the soil is the selection of oil-decomposing microorganisms that can survive in high concentrations of pollutants.
Conclusion: Therefore, the result indicated that biostimulation and bioaugmentation can efficiently improve the THP removal efficiency in contaminated soil by considering the environmental conditions.
 

Background and Objective: Phenol compounds are commonly applied as raw materials in the production of pesticides, herbicides, and dyes. These compounds are toxic to animals, plants, and microorganisms. In this study, the sonophotocatalytic degradation of 2,4-dinitrophenol in aqueous solutions was investigated using organic-mineral polymer catalysts containing Zink and Cobalt oxides under visible light and ultrasonic (US) irradiation.
Materials and Methods: The characteristics of the synthesized catalyst were determined using XRD, FTIR, and SEM techniques. The effect of several key parameters, including pH (3-9), catalyst dosage (0.3-1 g/L), time (0-90 min), US power (100-200 W/m²), and initial concentration of 2,4-dinitrophenol (20-100 mg/L), on the degradation efficiency was also investigated.
Results: After 75 minutes of sonophotocatalytic processing, complete degradation of 2,4-dinitrophenol (20mg/L) was achieved with catalyst dosage of 0.5 g/L, pH of 9.0, and US intensity of 200 W/m². Kinetic studies indicated that the sonophotocatalytic degradation process followed a first-order kinetic model. The results of radical scavenging experiments confirmed that HO° and O₂˚^- radicals are the main oxidative species involved in the degradation of 2,4-dinitrophenol. Furthermore, the reuse of the catalyst for five consecutive tests showed a slight decrease in removal efficiency.
Conclusion: The results demonstrate that the sonophotocatalytic process, using the modified organic-mineral polymers with mixed Zink and Cobalt oxides catalyst, can be an effective method for removing 2,4-dinitrophenol from aqueous media.
 

Background and Objective: Earthworms are important in soil formation. They maintain soil structure and fertility and can be used as indicators to evaluate various changes and impacts. Therefore, the present study was developed to investigate the effects of diesel pollutant on the population and survival of the earthworm species E.fetida in the co-vermicomposting process.
Materials and Methods: This experimental study was conducted over 90 days to investigate the effects of diesel concentration on the survival of E.fetida in the co-vermicomposting process. One kilogram of soil contaminated with diesel, vermicompost, and raw activated sludge was added to each reactor in a ratio of 0.25:0.35:1. 10. Additionally, 20 adult E. fetida were added to the reactors with diesel concentrations of 10 and 30 g/L after the adaptation process.
Results: The survival of earthworms and the formation of cocoons in reactor number 3 were higher than in other reactors. Additionally, the amount of diesel removal in reactor number 3 (diesel concentration: 10 g/kg dried soil +20 E.fetida) was higher (70.5%) compared to the other reactors.
Conclusion: The results of the study showed that earthworm reproduction is more sensitive than survival or weight change to higher concentrations of diesel-contaminated soil. The presence of petroleum compounds in the soil is harmful for the growth of E.fetida, and its acute effects on the production of earthworm cocoons were observed.