فصلنامه سلامت و محیط زیست
سال سیزدهم شماره 1 (پیاپی 47، بهار 1399)

Considering 829000 annual diarrhoeal deaths due to water pollution worldwide, the World Health Organization has emphasized that countries should reduce this rate by upgrading their wastewater treatment systems. The purpose of this study was to evaluate the performance of a modified up flow septic tanks reactor for treatment of synthetic wastewater.

In this experimental study, a modified septic tank system based on the upstream hydraulic regime, and also a conventional septic tank system was designed, manufactured, and operated. The municipal wastewater was used to operate, and synthetic wastewater was used to maintain. The major performance indicators of septic tanks include: volatile solids (VS), volatile suspended solids (VSS), total suspended solids (TSS) and chemical oxygen demand (COD) were sampled and measured in triplicates. The experiments were done in three hydraulic retention times of 24, 48, and 72 hr. Finally, the results of the study were analyzed by statistical tests in the SPSS software.

The average removal of TSS, VS, VSS, and COD in HRT 24 h for the conventional reactor were 55.07, 27.36, 30.82, and 55.52%, respectively, and for the upstream-modified reactor at HRT 24 h were 66.57%, 34.05%, 38.47%, and 65.57%, respectively.

Changing septic tanks to up flow regimes and creating a cylindrical shape in conventional septic tanks, the removal efficiency of conventional septic tanks was improved, and the effluent contamination load was reduced.

Conversion of houses into residential towers in worn-out urban textures increases population. Schools of the vicinity would face with multiplicity and limited space for students, leading to noise pollution. The purpose of this study was to evaluate the noise levels during morning and afternoon shifts among two primary schools in Zanjan.

Measurements had been done using sound level meter, KIMO DB100. The equivalent noise level (Leq) measured during school year (2018-2019) in 10 stations. The measurements were done in three seasons (autumn, winter and spring) and in each season for two weeks. The data of the two schools were used for drawing charts and zoning by ArcGIS using IDW method. In addition, questionnaires were distributed among the teachers and school’ neighbors. The data were analyzed by SPSS software.

The results showed that all the stations were tackled with noise pollution. The highest levels were related to school’s shift change and break times. The morning shift schools experienced higher levels of noise in comparison to the afternoon ones (1.87 and 2.1 dB, respectively for boys and girls). Leq values for boys’ school was 2 dB higher than that of the girls’. The noise level in the schools were 72 dB, which is 17 dB higher than the standard level 55 dB.

The residents living close to the schools were exposed to noise pollution for almost 10 hours a day. This could be regarded as harmful. The zoning maps showed that southwest side of the yard, adjacent to the neighboring residential buildings, had the highest levels of noise. This study demonstrated the site selection for the schools were not properly done.  Having a control strategy is needed.

Increased untreated wastewater and unsustainable development of agriculture has deteriorated water quality of rivers. The aim of this study was to determine the quality of water in Gorganrud River basin using NSFWQI IRWQISC and Liou Pollution Index and compare them with the global standards. To do this, GIS software.was used

In this study, 5 sampling stations were selected based on standard criteria including land use type, accessibility and standard distributions along the river. 12 water quality parameters including dissolved oxygen, fecal coliform, pH, biochemical oxygen demand, chemical oxygen demand, temperature, organic phosphate, nitrate, ammonium, turbidity, total dissolved solids and electrical conductivity in river for one year were measured from June 2019 to May 2019 follwoing standard methods.

The amount of phosphate and turbidity was increased along the river from station 2 to the mouth of the river. This was due to the presence of agricultural and municipal sewage. There was a significant difference in BOD, fecal coliforms and nitrates with those of the standard values. Water quality indicators showed the great effects of urban wastewater and human waste in the river area. The best quality was observed in Station 1 (75; Good Quality), which was less exposed to human activity and development. Based on the conformity of the results of the indicators with the terrestrial reality, the results of the IRWQIsc index (Iranian surface water quality) showed the best results due to compatibility to the land uses and the trend of variables.

The presence of urban sewage and unsustainable agricultural in the city of Gonbad Kavous is the most important reason for the decline in water quality (poor quality class). In this regard, a comprehensive management in water resources and environmental impact assessment is needed.

Heavy metals contamination, particularly in aquatic environments, is an important concern.  Since Mahbad river is the source for supplying drinking water to the city and the dam established on it is used for catching fish and sale in the market, heavy metals concentrations in the sediments of Mahabad River and the Dam, and the possible health risk of the fish consumption were investigated.

Sediment samples from 21 sites in Mahabad dam, and river, and 16 fish samples (Sander lucioperca and bramis brama species) were collected. After preparation, the samples were analyzed using ICP-MS method. For data analysis, enrichment factor (EF), potential ecological risk index (RI), health risk indices, principal component analysis (PCA) and Mann-Whitney test were used.

The EF and RI values of the studied heavy metals in the sediments were low. The max concentrations of lead, zinc, copper, arsenic and manganese were 36, 162, 74, 22.8 and 3221 mg/kg, respectively. This was more obvious in the samples taken from the downstream of the dam. However, accumulation of the heavy metals in fish tissues resulted in high values for total hazard quotients (THQ), particularly for As (1.19); high hazard index (above 1); and high estimated daily intake (EDI) for copper (1.64) in the study area.

The results of this study revealed that the conditions for elements’ mobility and bioavailability was suitable in the river and Mahabad Dam. Therefore, assessing the mobility and bioavailability of the heavy metals in the sediments of the region, and measurement and continuous monitoring of the heavy metals concentrations in the water, sediment and fish of the study area are needed.

Microplastics (MPs) pollution are considered as a major growing global environmental problem in the past few decades. Dams could be an important reservoir for microplastics accumulation, therefore, in this study the presence of microplastics in sediments of Taleqan Dam and its upstream river was investigated in order to: 1) determine the local status of microplastic pollution and 2) determine the abundance and characteristics of the identified microplastics.

Sediment sampling was performed at 15 stations in the upstream of the river and the dam reservoir. After the sample preparation, separation method based on density difference was used for separation of the microplastics from the sediment, and stereo microscope and SEM-EDX were used for counting microplastics and investigation of their characteristics.

Based on the results, maximum of the counted microplastic particles were observed in Taleqan City area with 2050 particles/300 g and minimum number was observed in the dam reservoir with 478 particles/300 g of sediment. The dominant shape, color, and size of the counted particles were polyhedral, colorless (transparent), and 100-250 μm, respectively.

The results showed that the concentration of microplastics in the stations near the urban and rural areas were higher due to the entry of sewage and the release of municipal solid wastes. Also, their concentrations were high in the stations close to the dock area of the dam due to the greater traffic of the locals and tourists and dumping of wastes in the shoreline of the lake.

Much of the nitrate consumption by humans in the daily diet comes from vegetables. The high concentration of nitrate in edible parts of vegetables causes toxicity, anemia for children and nitrous amine production in adults. Nitrous amine may results in cancer. Samples were collected from four main vegetable markets in Kermanshah city in summer 2019 to investigate the concentrations of these compounds in edible vegetables with high consumption.

After preparation of the samples in a laboratory, the nitrate were extracted and its concentration was determined by a spectrophotometer at wavelength 410 nm.

The results showed significant differences in nitrate concentrations for the vegetable samples taken from the different markets (p>0.05). The highest concentration of nitrate were observed in the leafy, tuberous, and fruit-bearing vegetables. The highest nitrate concentration among the leafy vegetables was observed in cress with an average of 2052.14 mg/kg Fresh Weight; among tuberous vegetables was potato with an average of 127.01 mg/kg Fresh Weight; and among fruit-bearing vegetables was cucumber with an average of 37.20 mg/kg Fresh Weight.

The nitrate concentrations for celery, and red onion at the Azadi market were higher than the permissible limit, according to the national standard. Also, the nitrate concentrations in sugar beet leave and potato at the Toopkhaneh Market and nitrate concentration in cress at all the markets were higher than the permissible limit. It is recommended that the concentration of nitrate of edible vegetables should be determined at regular time intervals as well as during different seasons.

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.

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.

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 Mullerchr('39')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).

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.

In the present study, EC and TDS quality parameters of Karun River were modeled using data-mining algorithms including LSSVM, ANFIS, and ANN, at Mollasani, Ahvaz and Farsiat hydrometric stations.

Eight different inputs including the combination of Cl-1, Ca+2, Na+1, Mg+2, K+1, CO32-, HCO3, and SO42- with discharge flow (Q) were selected as non-random and random calibration inputs for these algorithms. Then, in order to guarantee the accuracy of the results, the simulation was performed by random calibration and the results of the two methods were compared. In the next step, the EC and TDS parameters were modeled based on the four parameters of Na+1, Cl-1, Ca+2, and Q and a lag time of zero to three months.

Modeling results indicated that Na+1, Cl-1, and Ca+2 have the highest influence on modeling of EC and TDS parameters. The LSSVM algorithm was the most accurate in modeling EC and TDS parameters. Among the studied stations, the highest precision for EC and TDS modeling belongs to Ahvaz and Mollasani station, which has 16% and 36% higher coefficient of determination. LSSVM has highest accuracy in modeling the oscillation and peak EC and TDS parameters in during times.

The methods and models applied in the present study especially the LSSVM algorithm, can be a useful decision-making tool for predicting and qualitative management of rivers, including rivers in the Karun catchment area. The results of modeling the quality parameters of the rivers were reliable and usable by using both non-random and random calibration methods. However, the accuracy of the random calibration method was slightly higher.

Reactive Red 198 is a mono azo dye widely used in the textile industry of Iran. The toxicity of reactive dyes is higher than other dyes and causes disorders such as irritation, cancer and mutation in humans. The overall objective of this study was to determine the efficiency of a Constructed Wetland pilot system with conventional and baffled horizontal subsurface flow to remove reactive red 198.

In order to remove Reactive Red 198, two cells were constructed in parallel with 2 × 0.6 × 0.5 m. In the conventional and baffled cell, native straw of Phragmites australis was used. In the research process, COD concentration and reactive dye concentration were investigated. The effect of retention time and type of plant on the efficiency were also investigated.

The results showed that the maximum removal efficiency of the reactive red dye 198 was obtained at 100 mg/L inlet pollutant concentration and 3.5 days retention time, which was related to the baffled cells. Also, the presence of the baffles in the constructed wetland system increased the removal efficiency. The presence of straw in both cells was directly affected the removal efficiency. The effect of the retention time in the conventional cell was more effective in removal efficiency than the baffled cell. The pollutant inlet concentration was also inversely correlated with the removal efficiency.

According to the results, it can be concluded that the baffled and conventional horizontal subsurface constructed wetland can be used for low concentrations and at low retention time as a well-functioning system in the removal of reactive Red 198.

Synthetic wetlands are engineering systems that use natural plants, soils and organisms to purify municipal polluted water and remove nitrate.

In this study, three systems were considerd as soil culture, three systems as plant cultivation on floating plates and three other systems without plant and porous bed as. The experiments were done three times within six months. The hydraulic retention times were 1, 3 and 5 days. The experimental design consisted of a factorial split-plot design. The analysis of variance showed that the efficiency of nitrate removal was affected by the type of constructed wetland, HRT, and temperature changes (p≤0.01).

At the HRT of 1 day, the average efficiency of nitrate removal by the soil culture, plant cultivation on floating plates and control  were 14.34%, 12.09% and 10.51%, respectively. At the HRT of 3 days, the average efficiencies were 17.62%, 15.76% and 13.54%, respectively. At the HRT of 5 days, the efficiencies were increased and they were 17.75%, 17.66% and 16.08%, respectively.

The results showed that the soil culture were more efficinet in removing nitrate .Also, the Cyperus alternifolius plant has the potential of nitrate phytoremediation.

Increased use of pesticides and chemical fertilizers in agriculture in order to increase the productivity of fertile lands has led to pollution of water resources with a variety of pollutants, including herbicides. In this study, a new polymer magnetic nanoadsorbent named PV/S-g-3D-GO/N was synthesized and used to remove 2,4-D and MCPA herbicides from aquatic environment.

To investigate the synthesized nanoadsorbent structure FTIR, FESEM, TEM, XRD, VSM and TGA techniques were used and the effect of parameters affecting the optimal removal of herbicides by the adsorbent, including pH, temperature, contact time, adsorption dose and initial herbicide concentration was investigated. The kinetic, isotherm and thermodynamic studies of adsorption were also investigated.

The results showed that in the optimal adsorption conditions including pH 3 for both herbicides, contact time of 180 min for 2.4-D herbicide and 300 min for MCPA herbicide, absorption dose 5 g/L and temperature 50°C for both herbicides, the maximum absorption capacity (qmax) was 5.62 mg/g for 2.4-D and 4.94 mg/g for MCPA. The synthesized nanoparticles that were used to remove 2,4-D and MCPA herbicides from real samples were totally successful (100% removal efficiency). For both herbicides studied, the isothermal data followed the Longmuir model (2,4-D: R2 = 0.995; MCPA: R2 = 0.998), and the kinetics of the adsorption process was a pseudo-second-order model (2,4-D: R2 = 0.991; MCPA: R2 = 0.999).

The results of the present study indicate that the synthesized nano-adsorbent can be used to remove phenoxic herbicides from agricultural runoff as well as water sources contaminated with the studied herbicides.

  Arsenic has long been considered as a heavy metal and toxic pollutant due to its potential to harm the human health and the environment. Adsorption is one of the mechanisms for arsenic removal from wastewater. Therefore, the purpose of this research was to investigate the feasibility of synthesized chitosan-zirconium magnetic nano fiber on arsenic adsorption from wastewater and to evaluate its kinetic and isotherm models.

Synthesis of nanofibers was performed by electrospinning method and the optimal formulation was determined following the experimental design. Then, kinetics and isotherms of arsenic adsorption on the as synthesized nanofibers were investigated. The prepared nanofiber was characterized using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopes (FESEM), Infrared Fourier Transform (FT-IR) and Vibrational Sampler Magnetic Meter (VSM).

The optimal formulation was obtained: 2.84% chitosan, 0.97% nano-zirconium and 0.94% nano-iron. The adsorption of arsenic on synthetic fibers was found to follow quasi-first-order kinetics and the Freundlich isotherm. Furthermore, the effect of initial concentrations of arsenic, contact time, temperature and pH on arsenic adsorption were surveyed. The optimal condition for nitrate arsenic adsorption was obtained at initial concentration of 70 mg/L, 45 min contact time and at pH 3.

According to the results, the synthesized nanofiber displayed a regular network structure with the distribution of the Zr-nanoparticles in its shape. Also, according to the form of magnetometric analysis, it was found that chitosan-nanosirconium magnetic nanofibers are well magnetized and are free magnetic.  Finally, it can be concluded that the synthesized nanosorbent has a high potential for arsenic removal from industrial effluents.