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This study investigated the concentrations and compositions of specific elements in total suspended particulate (TSP) samples and the associated ecological, carcinogenic, and non-carcinogenic risks related to the inhalation, ingestion, and dermal absorption of heavy metals. The study focused on adult and pediatric populations in the highly dust-polluted city of Zabol, Iran, during 2022-2023. The samples were analyzed by using inductively coupled plasma optical emission spectrometry (ICP-OES). The concentration of metals in milligram per kilogram (mg/kg) was as follows: Al (75053) > Ca (8206) > Fe (5439) > Mg (5323) > Zn (15.27) > Pb (3.66) > Cr (3.38) > Cd (0.011); according to the results, the highest amount of metals related to aluminum and calcium in dust particles. The calculated individual indices, including the ecological risk index (ERI), pollution factor (Cfi), and geographic accumulation index (I geo ), indicated that calcium exhibited minimal pollution, while the metal samples (Al, Mg, Fe, Cd, Cr, Pb, and Zn) were categorized as uncontaminated. The results revealed that the ecological risk factor (Er) is below 40, indicating a low level of contamination. Additionally, the pollution level determined by the ecological risk potential (RI) was less than 150, suggesting a low probability of contamination. Ingestion posed the highest average hazard quotient (HQ) values for both children and adults in terms of non-carcinogenic risk assessment, while cutaneous and inhalation exposures showed lower values. Furthermore, the hazard index (HI) for heavy metals remained below the safe threshold of 1. The risk index (RI) values for lead, cadmium, and chromium were all below 1 × 10 -6 in both adult and pediatric populations. The United States Environmental Protection Agency (USEPA) guidelines suggest an acceptable level of carcinogenicity for all heavy metals, indicating a potential risk of cancer associated with the presence of these metals in suspended particles in Zabol., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Gas stations distributed around densely populated areas are responsible for toxic pollutant emissions such as volatile organic compounds (VOCs). This study aims to measure VOCs emission from three different kinds of gas stations to determine the extent of pollution from the gas stations and the most frequent type of VOC compound emitted. The concentrations of ambient VOCs at three refueling stations with a different type of fuels in Mashhad were monitored. The result of this study showed that CNG fuel stations are less polluting than petrol stations. In all the studied sites, the highest concentrations were related to xylene isomers, irrespective of the fuel type. Total VOCs at the supply of both compressed natural gas (CNG) and gasoline stations was 482.36 ± 563.45 µg m -3 . At a CNG station and a gasoline station, total VOC concentrations were 1363.4 ± 1975 µg m -3 and 410.29 ± 483.37 µg m -3 , respectively. The differences in concentrations of toluene and m,p-xylene between the fuel stations can be related to the quality and type of fuel, vapor recovery technology, fuel reserves, dripless nozzles, traffic density in these stations, meteorological conditions and the location of sampling sites. The combination of a sine function and a quadratic function could model the fluctuation behavior of air pollutants like m,p-xylene. In all the sites, the highest concentrations were related to xylene isomers, irrespective of the type of fuel. The changing rate of m,p-xylene pollutant in each station was also modeled in this study., (© 2024. The Author(s).)

Indoor air quality significantly impacts the well-being and health of elderly residents in nursing homes. This study was conducted to explore the connection between indoor and outdoor PM (Particulate Matter) concentrations in nursing homes and their association with the facilities' location and construction characteristics. The findings revealed that indoor PM 2.5 and PM 10 concentrations ranged from 0.2 to 124 μg/m 3 and 2-188.4 μg/m 3 , respectively, which were approximately 12.67 and 1.25 times higher than their outdoor counterparts. A strong correlation (P < 0.05) was identified between indoor PM levels and various factors, including proximity to parks, passenger terminals, and gas stations, as well as building attributes such as single-glazed windows, ceramic floor coverings, and the use of radiators. The risk assessment indicated that carcinogenic risk factors were well within acceptable limits for all nursing homes. However, it's important to note that certain PM components, particularly polycyclic aromatic hydrocarbons (PAH), may have long-term adverse effects on the health of nursing home residents. Even though indoor PM levels met the standards established by the U.S. Environmental Protection Agency (USEPA) for particulate matter risk assessments, the study emphasized that even low levels of indoor air pollutants can affect the health and well-being of older adults, particularly considering the increased vulnerability associated with aging. Consequently, the study underscores the importance of nursing home location selection and the regular monitoring of particulate matter concentrations. These measures are essential for enhancing air quality within nursing homes, ultimately contributing to the improved well-being and health of their residents., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Introduction: Millions of passengers around the world are concerned with the possibility of SARS-CoV-2 contamination on public transportation. Therefore, this study aimed to investigate the presence of SARS-CoV-2 virus in indoor air and subway surfaces in Mashhad., Methods: In this study, air and surface sampling were done at two times in the morning (7-8:30 a.m.) and evening (3:30-5 p.m.), simultaneously in two wagons for men and women in line 1 of Mashhad Metro in March 2021 to detect the virus and measure the concentration of particulate matter. Totally, 30 air and 30 metro samples were collected and examined by reverse transcriptase-polymerase chain reaction (RT-PCR)., Results: The results showed that three and two cases in the air and surface samples were infected with the SARS-CoV-2 virus, respectively. There was a significant relationship between the mean concentration of suspended particles PM 1 (particulate matter smaller than 1 μm) with PM 2.5 (particulate matter smaller than 2.5 μm) and PM 10 (particulate matter smaller than 10 μm) (p < 0. 05). There was also a significant relationship between the mean concentration of suspended particles PM 2.5 and PM 10 . The results showed that the mean PM 2.5 measured in the indoor air of the Mashhad metro wagon had a significant relationship with WHO and US EPA and national standards, and its value was higher than the standards (p < 0.05). The average particle concentrations of PM 1 , PM 2.5 , and PM 10 were equal to 40.46, 42.61, and 48.31 μg/m 3 ., Conclusion: According to the results of the pollution detected in this study, COVID-19 may be transmitted by air and environmental surfaces. Our study emphasizes the need for continuous assessment of the presence of the virus in public transportation. Detection of viral RNA in subways indicates the necessity of adequate disinfection in public settings, strictness in disinfection methods, strengthening of educational activities for sanitary measures, physical spacing plan, and increasing ventilation of wagons., (© 2023. The Author(s) under exclusive licence to Sociedade Brasileira de Microbiologia.)

Background: Working conditions play a significant role in the process that causes cardiovascular disease. In this regard, it is required to monitor the health conditions of workers to design proper interventions to encourage healthy behaviors. This investigation was performed to determine preventive behaviors against cardiovascular disease based on the health belief model (HBM)., Materials and Methods: This research was a cross-sectional and descriptive study with 228 subjects of oil industry workers under shift work schedules in the oil regions of Khuzestan, Iran. The HBM questionnaire provided the theoretical framework for this study. Participants completed the questionnaires in person at work. Data were analyzed using SPSS 24.0. Descriptive statistics including frequencies, percentages, and means, and linear regression analysis were calculated for variables., Results: Findings of the study showed that most workers were of a weak level of knowledge (55.3%), self-efficacy (82.5%), perceived severity (83.8%), perceived susceptibility (75.4%), perceived benefit (57.5%), and behavior (82.5%). Furthermore, results showed that most of the workers considered smoking (3.51 out of 5) and proper diet for good heart function (2.54 out of 5). In this study, the item of exercise was the lowest among all the preventive behaviors (1.39 out of 5). Self-efficacy was the strongest predictor of health belief about cardiovascular disease., Conclusion: To decrease the increasing burden of cardiovascular disease in our population, and fight against this rank-one killer, multiple useful prevention strategies must be adopted. Educational theory-based interventions and applying designed programs to improve the adoption of preventive behaviors are a necessity., Competing Interests: There are no conflicts of interest., (Copyright: © 2022 Journal of Education and Health Promotion.)

Background: Human resources management plays an important role in social development and economic growth. Absence from work due to health problems can make obstacles to the growth of economy. This study conducted aimed to estimate the absenteeism costs of COVID-19 among the personnel of hospitals affiliated to Mashhad University of Medical Sciences in Mashhad, Iran., Methods: This cross-sectional study was conducted between February 19, 2020, and September 21, 2020. The absenteeism costs were calculated using the human capital approach. Finally, we applied the linear regression to assess the impact of variables on the lost productivity of absenteeism due to COVID-19 among the personnel of hospitals affiliated to Mashhad University of Medical Sciences., Results: The results of this study showed that 1958 personnel had COVID-19. The total of absenteeism days in our study were 32,209 days, with an average of 16.44 absenteeism days. Total costs due to absenteeism were estimated to be nearly $1.3 million, with an average of $671.4 per patient. The results of regression model showed that gender (male), age (> 50 years), employment Type (non-permanent) and monthly income had a positive relationship with the absenteeism cost. Also, there are a negative significant relationship between absenteeism cost with job (physicians) and work experience., Conclusions: Absenteeism costs of COVID-19 in the hospitals of Mashhad University of Medical Sciences represent a significant economic burden. The findings of our study emphasize the emergency strategies to prevent and control COVID-19 among the healthcare workers. It can decrease the economic impacts of COVID-19 and improve human resources management during the COVID-19 pandemic., (© 2021. The Author(s).)

Vermicomposting is one of the best technologies for nutrient recovery from solid waste. This study aims to assess the efficiency of Artificial Neural Network (ANN) and Multiple Linear Regression (MLR) models in predicting nutrient recovery from solid waste under different vermicompost treatments. Seven chemical and biological indices were studied as input variables to predict total nitrogen (TN) and total phosphorus (TP) recovery. The developed ANN and MLR models were compared by statistical analysis including R-squared (R 2 ), Adjusted-R 2 , Root Mean Square Error and Absolute Average Deviation. The results showed that vermicomposting increased TN and TP proportions in final products by 1.5 and 16 times. The ANN models provided better prediction for TN and TP with R 2 of 0.9983 and 0.9991 respectively, compared with MLR models with R 2 of 0.834 and 0.729. TN and C/N ratio were key factors for TP and TN prediction by ANN with percentages of 17.76 and 18.33., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Metal-organic frameworks (MOFs) are currently recognized as unique platforms for environmental studies. This study evaluated the potential of nine MOFs from ZIF-8, ZIF-67, and UIO-66 families for the removal of ciprofloxacin (CIP), a toxic, bio-accumulative, and persistent fluoroquinolone antibiotic. ZIF-67-SO 4 , with a rhombic crystalline morphology and 1375 m 2 /g BET surface area, has the highest CIP adsorption efficiency among the studied MOFs. The mathematical sorption model predicted that the highest CIP removal (99.2%) occurs when adsorbent dose, pH, and agitation time are adjusted to 6.82, 832.4 mg/L, and 39.95 min, respectively. Further studies revealed that the CIP adsorbed onto ZIF-67-SO 4 in monolayer (q max : 2537.5 mg/g) and chemisorption controlled the rate of the process. Mass transfer kinetic coefficients improved significantly by sonication at 35 KHz in comparison with mechanical agitation. Thermodynamic parameters (minus signs of ∆G° [7.8 to 14.2], positive signs of ∆H° (58.9 KJ/mol), and ∆S° (0.23 KJ/mol·K)) demonstrated the spontaneous, endothermic, and chemical sorption of CIP. The level of cobalt leached from ZIF-67-SO 4 structure varied 1.2-4.5 mg/L, depending on pH, mixing time, and agitation type. In conclusion, the excellent adsorption properties of ZIF-67-SO 4 for CIP, made it an outstanding candidate for environmental protection purposes., Competing Interests: The authors declare no conflict of interest.

The aim of this study is to develop the process relies on the UV irradiation of ZnO and I - , i.e. UV/ZnO /I - (UZI), to create both oxidizer and reducer agents simultaneously for photo-degradation of the Ciprofloxacin (CIP). This paper shows that while applying UV irradiation, UV/ZnO and UV/I - for 20 min can lead to achieve 37.5%, 58.12%, and 61.4% photo-degradation of 100 mg L -1 CIP at pH 7, respectively. Moreover, the UZI treatment can provide 91.54% photo-degradation efficiency. The LC-MS analysis of the UZI effluent indicates that 10 min process was adequate to degrade CIP into simple ring-shaped metabolites while 15 min treatment, mostly of CIP intermediates were linear and biodegradable organic compounds. Furthermore, fourteen little fragments were identified in the CIP photo-degradation via UZI, during the photoreaction time of 2.5 to 20 min. Then, a pseudo first-order kinetics equation was utilized to model the observed photo-degradation process. Finally, the computational results show that the increased concentration of the CIP solution from 100 to 400 mg L -1 decreases the observed rate constant (k obs ) from 0.4125 to 0.2189 min -1 while increases the photoreaction rate (r obs ) from 41.25 to 87.56 mg L -1  min -1 ., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The extent of environmental pollution caused by wastes in industrial estates has attracted the attention of scientific and executive resources of the world to the correct disposal and recycling of these materials. This study is a cross-sectional descriptive study which was conducted in the Khayyam industrial estate of Neyshabur in 2017. To survey the management of industrial wastes status, based on the fieldwork, different days were selected in each week to complete the questionnaire designed by the Iranian Environmental Protection Agency. The completion of questionnaires was started from a specific path daily. Finally, the collected data were entered into the SPSS 18 software and were analyzed to determine the wastes management status of the industrial estate. Excel software was used to draw the charts. The total industrial wastes produced in Khayyam industrial estate were 3555 tons per year, waste per capita was 2177.9 g per day per worker. Most existing industries in Khayyam industrial estate were food and pharmaceutical, which include 43.94%. Recycling (79.55%) and burial (14.39%) were the first and second levels of final disposal of industrial wastes. The results of this study show that the wastes management of Khayyam industrial estate has a relatively acceptable situation. Unfortunately, the waste dumping in the open space can lead to the generation of moisture and the release of pollutants to the environment and cause pollution of water and soil through leakage as well as damage to workers. Proper control and correct management are essential for maintaining the health and protection of the environment.

Naegleria species are the ubiquitous free-living amoebas that are found worldwide in soil and water. Among Naegleria spp., N. fowleri can cause primary amebic meningoencephalitis (PAM). Ninety water samples were collected from the pond of parks. Also, the water quality parameters were measured at the sampling site (such as temperature, pH, total dissolved solids (TDS), electrical conductivity (EC) and Turbidity). After filtering, the samples were cultured on Bacto-agar enriched with Escherichia coli . A PCR assay was conducted on the culture-positive samples in the ITS1, 5.8SrDNA and ITS2 regions, and then the PCR products were sequenced. The pond water of parks was contaminated with some Naegleria spp. (except N. fowleri ) and a Vahlkampfia avara . There was no significant relationship between water quality parameters and the presence of Naegleria (p > 0.05). Our protocol investigates to detect Naegleria spp. from ponds water of parks in Mashhad city and the relations between the water quality parameters and its presence.

Background: Free-living amoeba (FLA) are wide-spread protozoa that are found in different environmental sources including water, soil, dust, hospital units and ventilation areas. These amoebas can act as opportunistic or non-opportunistic pathogens. Among FLAs, some genera such as Acanthamoeba are important because of their potential pathogenic ability in humans. The purpose of this study is to identify of Acanthamoeba isolated from pond water of parks in a tropical and subtropical region in the Middle East, and its relation with physicochemical parameters.From August to December 2015, 90 samples were collected from pond water of parks of 13 regions of Mashhad City. Physicochemical parameters were measured in situ. After filtering, the samples were cultured on Bacto-agar enriched with Escherichia coli. PCR analysis was conducted on the culture-positive samples, and then the PCR products were sequenced. Statistical analysis was performed by SPSS software and Fisher's Exact and Mann-Whitney test., Results: Among the samples that were examined, 19 samples (21.1%) were positive for Acanthamoeba. The sequencing revealed that Acanthamoeba isolates belonged to T4 genotype of Acanthamoeba. There was no significant relationship between physicochemical parameters and the presence of Acanthamoeba., Conclusion: The prevalence of Acanthamoeba in pond water of parks was relatively high, but there was no significant relationship between physicochemical parameters and the presence of Acanthamoeba.

Data on the chemical, physical and biological of effluent from wastewater treatment are provided in table format in the current article. Samples were taken in Peak Flows at effluent Treatment Plants. Sampling and tests were conducted according to the standards methods. The collected data were analyzed by SPSS software and excel program. Nickel metal showed higher amounts than the standards required for irrigation agricultural land. Data could be useful from environmental and agricultural sciences to those concerned about heavy metals, Alkalinity, EC, COD, BOD 5 and Microbial concentrations threats.

While fluoride (F) is an essential anion to keep the human body healthy, high F intake could lead to serious health problems. The monitoring of F in drinking water as the main route of F intake, is a key factor in preventing its negative health consequences. Here, we present the F levels in drinking water distribution networks of Khorasan Razavi province in Iran which collected during 2016-2017. The non-cancer human risk attributed to F in municipal and rural regions, also, estimated by calculating the chronic daily intake (CDI) and hazard quotient (HQ) for adults and children. Samples taken from drinking water distribution network in 112 different locations across the Khorasan Razavi and the F concentration determined using standard SPADNS Method. Having a minimum of 0.09 and 0.16 and a maximum of 1.7 and 1.1 mg L -1 , the mean F level in municipal and rural samples were 0.74 and 0.59 mg L -1 , respectively. The mean CDI values for F in municipal samples were 1.3×10 -2 , 3.34×10 -4 , and 8.56×10 -6 mg kg -1 day -1 , for men, women, and children, respectively. The CDI for rural samples were 1.51×10 -2 , 3.88×10 -4 , and 9.96×10 -6 mg kg -1 day - 1 , for men, women, and children, respectively. The mean HQ of F for men, women, and children in municipal and rural samples were 2.17×10 -1 , 5.56×10 -3 , and 1.43×10 -4 , and 2.44×10 -1 , 6.26×10 -3 and 1.61×10 -4 , respectively. Locations with a HQ>1, needs appropriate strategies for reducing the F level in drinking water to prevent the potential health risks.

Phenol is a hazardous organic chemical that introduced into the environment by industrial and pharmaceutical discharges. As a versatile option for phenol removal, adsorption would be viable if it accompanying with low cost adsorbents. This article described a natural, very cheap and local available adsorbent for phenol removal. Phenol showed a high affinity to Citrullus colocynthis waste ash which mainly composed of SiO 2 (41.6%), Al 2 O 3 (17.3%) and MgO (15.9%). Up to 70% of phenol adsorbed in the first 30 min of agitation. The phenol removal was increased by increasing adsorbent dose (0.5-10 g/L) and decreasing pH (2-12) and pollutant concentration (10-100 mg/L). The positive value of ∆ H ° in thermodynamic data (0.06) revealed that the process is endothermic. The high and positive value of ∆ S ° (13.01) and negative values of ∆ G ° (- 5.36 to - 7.28), showed a high affinity of phenol to the adsorbent and the spontaneous nature of the adsorption. Isotherm modelling revealed that the phenol molecules adsorbed in multilayer with the maximum adsorption capacity of 173.2 mg/g. The rate limiting step in the sorption process was chemisorption, based on the kinetic data.

Treatment with a non-thermal plasma (NTP) is a new and effective technology applied recently for conversion of gases for air pollution control. This research was initiated to optimize the efficient application of the NTP process in benzene, toluene, ethyl-benzene, and xylene (BTEX) removal. The effects of four variables including temperature, initial BTEX concentration, voltage, and flow rate on the BTEX elimination efficiency were investigated using response surface methodology (RSM). The constructed model was evaluated by analysis of variance (ANOVA). The model goodness-of-fit and statistical significance was assessed using determination coefficients (R 2 and R 2 adj ) and the F-test. The results revealed that the R 2 proportion was greater than 0.96 for BTEX removal efficiency. The statistical analysis demonstrated that the BTEX removal efficiency was significantly correlated with the temperature, BTEX concentration, voltage, and flow rate. Voltage was the most influential variable affecting the dependent variable as it exerted a significant effect (p < 0.0001) on the response variable. According to the achieved results, NTP can be applied as a progressive, cost-effective, and practical process for treatment of airstreams polluted with BTEX in conditions of low residence time and high concentrations of pollutants.

Background: Annually, large quantities of dyes are produced and consumed in different industries. The discharge of highly colored textile effluents to the aquatic environments causes serious health problems in living organisms. This paper investigates the performance of each of the electro-oxidation and electro-reduction pathways in the removal of reactive red 120 (RR120) from synthetic textile effluents using a novel electrochemical reactor., Methods: In the current study, a two-compartment reactor divided by cellulosic separator was applied in batch mode using graphite anodes and stainless steel cathodes. Central Composite Design was used to design the experiments and find the optimal conditions. The operational parameters were initial dye concentration (100-500 mg L -1 ), sodium chloride concentration (2500-12,500 mg L -1 ), electrolysis time (7.5-37.5 min), and current intensity (0.06-0.3 A)., Results: The results showed that electro-oxidation was much more efficient than electro-reduction in the removal of RR120. According to the developed models, current intensity was the most effective factor on the electro-oxidation of RR120 as well as in power consumption (Coefficients of 12.06 and 0.73, respectively). With regard to the dye removal through electro-reduction, electrolysis time (coefficient of 8.05) was the most influential factor. Under optimal conditions (RR120 = 200 mg.L -1 , NaCl = 7914.29 mg.L -1 , current intensity = 0.12 A, and reaction time = 30 min), the dye was removed as 99.44 and 32.38% via electro-oxidation and electro-reduction mechanisms, respectively, with consuming only 1.21 kwhm -3 of electrical energy., Conclusions: According to the results, electro-oxidation using graphite anodes in a cell divided by cellulosic separator is very efficient, compared to electro-reduction, in the removal of RR120 from aqueous solutions.

Copper, as an inseparable part of many industrial discharges, threatens both public and environmental health. In this work, an electrochemical cell utilizing a cellulosic separator was used to evaluate Cu removal using graphite anodes and stainless steel cathodes in a continuous-flow mode reactor. In the experimental matrix, Cu concentration (1-5 mg L -1 ), electrolysis time (20-90 min), and current intensity (0.1-0.4 A) were employed. Results showed that the maximum removal efficiency of copper was obtained as 99%. The removal efficiency was independent of initial copper concentration and directly related to electrolysis time and current intensity. Energy consumption was more dependent on current intensity than electrolysis time. Under optimal conditions (75.8 min electrolysis time, 0.18 A current intensity, and 3 mg L -1 copper concentration), the removal efficiency was obtained as 91% while 7.05 kWh m -3 electrical energy was consumed. The differences between the actual and predicted data under optimal conditions were 0.42% for copper removal and 0.23% for energy consumption, which signify the performance and reliability of the developed models. The results exhibited the suitability of the electrochemical reduction for copper removal from aqueous solutions, which was facilitated under alkaline conditions prevailing in the cathodic compartment due to applying a cell divided by a cellulosic separator.

Present study aims to examine the dynamics of maturation and qualification indicators in various vermicompost treatments and selection of the best treatment along with best maturation time in this regard. In this empirical study, dynamics of chemical (pH, electrical conductivity (EC), total nitrogen (TN), phosphorous, lignin, water soluble carbon (WSC), C/N, NH4/NO3) and biological (dehydrogenase enzyme (DEH) and DEH/WSC) properties were investigated in four various treatments, including various ratios of compost produced from municipal solid waste (MSW) and carbonaceous materials (50:50, 70:30, 85:15 and 100:0) over 100 days. Results showed a significant fluctuation in EC, DEH and DEH/WSC proportions over the process. In addition, a noticeable increase was observed for the dynamics of TN, phosphorous and lignin. In contrast, the C/N, NH4/NO3 and WSC values gradually decreased during the process. Moreover, it was observed that the length of 75 days for the process is an appropriate time for maturation of all treatments. However, the first and second treatments resulted in better outcomes compared with the other types of treatments. From the point of view of quality obtained vermicompost was nitrogen enriched product in all treatments. Whereas, for the phosphorous elements this method is appropriate for the first treatment only., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Improving the soil quality with organic matter and N, P and K contents are some of sewage sludge benefits. Adjusting carbonaceous materials such as plant wastes to dewatered sludge compost results in increasing the moisture content and improving C/N ratio. This study was conduced for three months in 2005, in Laboratory of Chemistry of Water and Wastewater in the School of Public Health of Isfahan University of Medical Science, to determine the C/N ratio and heavy metals concentration of bulking agents in sawdust, leaves, rice hulls and dewatered sewage sludge. Dewatered sludge was collected from Isfahan sewage treatment plant. Sawdust was collected from sawmills. Leaves were collected from municipality of Isfahan and rice hull from rice mills, then in samples determined C/N ratio and heavy metal according to standard methods. The results showed that concentrations of chromium and cadmium in the mixture of dewatered sewage sludge and bulking agents were lower them those of the standard level. Means of cobalt (115.44 mg kg(-1)), nickel (57.44 mg kg(-1)) and zinc (273.48 mg kg(-1)) concentrations were maximum in dewatered sludge but mean concentration of cobalt (25.66 mg kg(-1)) in rice hull samples and mean zinc (8.99 mg kg(-1)) and nickel (5.106 mg kg(-1)) concentrations in sawdust samples were minimum. The optimal conditions sewage sludge composting, each kilogram of sludge needs 350 g of saw dust, 470 g of leaves and 388 g of rice hull. Amount of heavy metals present in the bulking agents is lower than the amount mentioned for the compost.

Traditional thermophillic composting is commonly for treatment of sludge. A related technique as vermicomposting process, using earthworms to breakdown sludge, is also becoming popular. These two techniques have their inherent advantages and disadvantages. The combined approach suggested in this study to enhance the overall process and improve the products qualities. Two systems, vermicomposting and combined compost-vermicomposting processes, have been investigated in this study. The sludge used in this study was obtained from the drying beds of South Isfahan wastewater treatment plant. The sludge mixed with sawdust to provide C/N ratio of 25/1. Eisenia fetida was the species of earthworms used in the vermicomposting processes. The results obtained indicate reduction in the amount of volatile solids, total carbon and C/N ratio with the vermicompost age, which indicates the reduction in the biodegradable organic content and mineralization of sludge. Also increase in phosphorus concentration by the end process because of mineralization of organic matter. The results indicate that, a system that combines the two mentioned processes not only shortens stabilization time, but also improves the products quality. Combining the two systems resulted in a product that was more stable and homogenous; the product could meet the pathogen reduction requirements.