Water Pollution
Rasool Zamani-Ahmadmahmoodi; Esmaeil Pirali Kheirabadi; Hossein Rahimi Pordanjani
Abstract
Introduction: Aquaculture includes the propagation and husbandry of aquatic plants, animals, and other organisms for various purposes, including commercial, recreational, and scientific use, which has gained significant attention in recent times. However, its uncontrolled development like any other production ...
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Introduction: Aquaculture includes the propagation and husbandry of aquatic plants, animals, and other organisms for various purposes, including commercial, recreational, and scientific use, which has gained significant attention in recent times. However, its uncontrolled development like any other production activity, can have adverse environmental effects, Thus, the removal of water pollutants is crucial. This study aimed to investigate the impact of a mechanized water disinfection device that uses ultraviolet (UV) radiation at different doses to reduce microorganisms in the effluent of rainbow trout farms. Also, the efficiency of the device in deactivating pathogens was investigated in different flow rates and water turbidity levels.Materials and Methods: The study was conducted in a rainbow trout farm with a 30-ton capacity, located in Kiyar County, approximately 30 kilometers from the center of Chaharmahal and Bakhtiari province. The UV device, at various doses (60, 120, 180, and 240 mW/cm2 = joule), was applied to the farm's effluent, considering different levels of turbidity and flow rates (ranging from 2.5 to 25 liters per second). Water samples were collected both before and after the installation of the UV disinfection device. Subsequently, the average counts of total coliforms, fecal coliforms, fungi, and yeast were calculated with three replications. Probit regression was utilized within the SPSS software environment, with a statistical significance level of 0.001, to examine changes in the removal percentage of microorganisms at different UV doses. Graphs were created using Microsoft Excel 2016 software.Results: The findings indicated that increased water flow rates and water turbidity reduced the efficiency of removing the targeted microorganisms. The findings indicated that increased water flow rates and water turbidity reduced the efficiency of removing the targeted microorganisms. Moreover, higher UV doses led to a higher removal percentage of total coliforms, fecal coliforms, fungi, and yeast. For instance, at a dose of 56 mJ/cm2, the total counts of total coliforms, fecal coliforms, fungi, and yeast decreased by 1.7, 3.2, 0.7, and 0.86 logs, respectively. However, complete removal of yeasts required significantly higher UV doses, depending on water flow rates and turbidity (up to a maximum of 240 mJ/cm2). Additionally, the results of the probit regression indicated that at doses of 40.50 mJ/cm2, 20.22 mJ/cm2, 30.31 mJ/cm2, and 14.36 mJ/cm2, approximately fifty percent of the yeast population (P<0.001), fungi (Z=13.5, P<0.001), fecal coliform (Z=22.77, P<0.001), and total coliform (Z=6.8, P<0.001) would be removed.Discussion: In summary, this research demonstrated that at a dose of 20 mJ/cm2, the gradual elimination of microorganisms begins, but at doses higher than 120 mJ/cm2, the intensity of elimination decreases. Therefore, adjusting the doses of ultraviolet radiation based on the water quality of fish farms can help maintain system health and subsequently increase productivity. The insights obtained from this study can be valuable for commercial water treatment systems and recirculating aquaculture systems. More studies are needed for the efficiency of removing viruses in water by UV rays. It is recommended to construct a sediment pond and employ various water filtration methods, including sand filters, before utilizing ultraviolet rays. This approach aims to decrease the presence of suspended particles in the water and enhance the efficiency of the disinfection system.
Water Pollution
Maedeh Parichehre; Fardin Sadeghzadeh; Bahi Jalili; Mohammad Ali Bahmanyar; Abd Wahid Samsuri
Abstract
Introduction: The increase of various industries and the ever-increasing growth of the population of the planet have caused all kinds of contamination in the environment. One of the most important contaminants in water, which has many risks for human health and living organisms and important environmental ...
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Introduction: The increase of various industries and the ever-increasing growth of the population of the planet have caused all kinds of contamination in the environment. One of the most important contaminants in water, which has many risks for human health and living organisms and important environmental risks, is anionic compounds in high concentration. Chromium is one of these contaminants that causes contamination in the environment and brings many risks to human health and other living organisms. Various methods have been evaluated to remove heavy metals from water, which often include chemical or energy-intensive processes. Therefore, it is important to modify these sources with the help of affordable adsorbents and with low energy consumption. Previous studies showed that biochar, metal-coated biochars and carbon-metal composites are highly effective in removing chromium contaminants with a concentration of 20 mg/liter from water, but so far the effect of these adsorbents on removing this anionic contaminant in high concentrations has not been investigated.Materials and Methods: In this research, the efficiency of different adsorbents (biochar, copper-coated biochar, aluminum-coated biochar, iron-coated biochar, biochar-copper composite, biochar-aluminum composite and biochar-iron composite) on the removal of chromium, with a concentration of 300 mg per liter, from water was investigated. Metal-coated biochars were prepared from the combination of metals (copper, iron and aluminum) with a concentration of 10000 mg/kg with biochar produced at 600 degrees Celsius and various biochar-metal composites were prepared from the combination of these metals with rice straw and then the samples were pyrolyzed at 600 degrees Celsius. In order to determine the efficiency of the adsorbents, 0.5 grams of each adsorbent was mixed with 40 ml of chromium solution with a concentration of 300 mg/l and pH= 6 and shaken for three hours until they reached equilibrium. Then the samples were centrifuged for 5 minutes at 6000 rpm and after the filtration, the final concentration of the contaminant was obtained and the percentage of chromium removal was calculated.Results: The results of the present study showed that all of the applied adsorbents were effective in removing high concentrations of chromium from water. The lowest removal rate of this contaminant was related to the biochar sample, which only removed 15.28% of this contaminant from water; And the highest amount of removal was achieved using iron composite, which removed 44.45% of the contaminant from the aqueous solution. According to the results of this research, it can be observed that coating biochar and rice straw with metals has been able to increase the efficiency of this adsorbent in removing chromium from water. For example, iron composite and iron-coated biochar were able to remove 44.45 and 30.86% of chromium contaminant from the aqueous solution, respectively, while rice straw biochar was only able to remove 15.28% of this contaminant from water.Discussion: The results of present study showed that iron coated biochar and biochar-iron composite had more ability to remove chromium contaminant from aqueous solution than other metal coated biochars and biochar-metal composites and were able to perform more successfully. Therefore, the use of these adsorbents can be effective in the treatment of chromium-contaminated water.
Water Pollution
Mohammad Ebrahim Farashiani; Marziyeh Alinejad; Seyyedeh Masoomeh Zamani
Abstract
Rapid population growth has increased the need for agricultural and food products and paved the way for the development of agricultural activities. Due to the limited land for cultivation, the increasing need for food will be possible only by achieving maximum productivity per unit area and increasing ...
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Rapid population growth has increased the need for agricultural and food products and paved the way for the development of agricultural activities. Due to the limited land for cultivation, the increasing need for food will be possible only by achieving maximum productivity per unit area and increasing crop quality. The use of chemical fertilizers and pesticides as well as irrigation are among the effective methods to increase the productivity of agricultural products, among which, the use of chemical fertilizers has always been one of the most important priorities in improving the agricultural activities of producers. Farmers consider the use of these chemical inputs to increase crop yield, improve soil fertility and increase their income. Recent studies have shown that excessive and untimely use of fertilizers has several adverse effects on the environment and human health. These effects include leaching and displacement of compounds in different soil layers, groundwater and surface water pollution, accumulation of heavy metals and nitrates, increased wetland feed, air pollution and accumulation of nitrogen gases, sulfur and greenhouse gas emissions, global warming, and extinction. He noted the ozone layer and the acidification of rain and the accumulation of chemicals in plant, animal and human tissues. The purpose of this study is to identify the environmental and biological effects of improper use of chemical fertilizers and to provide a practical solution to reduce consumption and environmental pollution.
Water Pollution
Mehdi Mehdinasab
Abstract
Water floods and floods in residential areas have always been one of the most common natural disasters in Iran after the earthquake that endanger human life. Between 2000 and 2008, approximately 99 million people are affected by floods worldwide each year. Kashkan River Basin with 8 sub-basins with an ...
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Water floods and floods in residential areas have always been one of the most common natural disasters in Iran after the earthquake that endanger human life. Between 2000 and 2008, approximately 99 million people are affected by floods worldwide each year. Kashkan River Basin with 8 sub-basins with an area of 9275.66 square kilometers, constitutes 22.4 percent of total Karkheh basin, with 290km length and 26 percent slope of the steepest and most flooded Karkheh basin. The results of statistical analysis on the instantaneous discharge data of Kashkan basin showed that from 1963 to 2019, 58 floods with average discharge moment of 1062.78 cubic meters occurred. In terms of time distribution, 65 percent of the floods in March, April and May and in terms of discharge rate 36 percent of the floods are more than 1000 cubic meters. The highest frequency of floods was observed in 1990-90 with 19 percent of floods and 14 percent of floods were severe, 22 percent moderate and 64 percent small flood. According to the Gamble distribution, a 200-year flood with a probability of 0.995 percent flood occurring at an instantaneous discharge of 4489.77 cubic meters with a tolerance of 535.06 cubic meters in the Kashkan Basin. As a result of the floods on 1 April, 14 people were killed and the damage was estimated to be 103.014 billion USD. The main causes of floods with an instantaneous discharge of 6,000 cubic meters per second in the Kashkan Basin can be attributed to precipitation with an average rainfall of 112.3 mm on 1 April and 321.5 mm for 9 days from 24 Mars to 1 April, respectively. Kashkan Basin, The occurrence of a flood with an instantaneous discharge of 3350 cubic meters on 5 March 2019, the absence of a significant reservoir dam for flood control, Impact of Babazid Bridge as a dam and runoff behind the bridge up to a radius of 5 kilometers and reaching the bridge ramp to the breaking point, thereby increasing the amount and velocity of the flood discharge to Poldokhtar, Decrease in river bed between 1 and 13 m in coastal wall reconstruction after flood on 4 February 2005 as a result of reduced capacity of Kashkan River in Poldokhtar during floods.