جستجوی مقالات مرتبط با کلیدواژه « wastewater treatment » در نشریات گروه « محیط زیست »

Activated sludge process is one of the most widely used methods of urban wastewater treatment. The purpose of this study is to use nanobubbles to supply oxygen to the aeration reactor in the activated sludge process and to evaluate its performance in terms of increasing the efficiency of wastewater treatment, reducing energy consumption, reducing the amount of excess sludge and its impact on environmental factors. The results showed that the use of nano-bubble compared to the use of macro-sized bubbles increased the concentration of dissolved oxygen in the aeration reactor up to 3 mg/liter, 18% reduction in energy consumption, 10% reduction in the initial investment in the construction of the wastewater treatment plant. 15% reduction in operating costs of the sewage treatment plant. Increasing the efficiency of removing organic pollutants and reducing the hydraulic retention time in the aeration system, reducing the size of the treatment plant by 10% due to the increase in the efficiency of removing organic substances, and as a result, reducing the hydraulic time and reducing the same amount of land for the construction of the aeration reactor and facilities for the production and distribution of air in the aeration reactor. The presented model, which is obtained by using nano-bubbles in the aeration process of bioreactors, is very effective as a new and innovative technology in preserving, cleaning, and sustaining the environment.

The presence of pharmaceutical wastewater can pose significant challenges to the environment. Since conventional wastewater treatment processes are not efficient for the complete separation of drug materials, solvent extraction through a hollow fiber membrane contactor could be a promising alternative. In this study, a developed polysulfone (PSF) hollow fiber membrane was fabricated using a non-solvent phase separation (NIPS) method to extract penicillin G from aqueous solutions in the membrane contactor system. From the characterization experiments, the prepared polysulfone membrane demonstrates an outer surface contact angle of 69.6°, critical water entry pressure (CEPw) of 250 kPa, total porosity of 72.2%, and collapsing pressure of 500 kPa. The extraction of penicillin G from the aqueous phase was performed with a 5% w/w solution of Aliquat 336. The effect of the operating parameters on the extraction flux of penicillin G was investigated using the response surface method (RSM). The optimum penicillin G flux of 1.46×10-3 kg/m2s was found at an operating pressure of 100 kPa, an aqueous phase flowrate of 70.5 ml/min, and an organic phase flowrate of 200 ml/min. Therefore, the developed PSF hollow fiber membrane contactor can be considered a proper choice to remove antibiotics (penicillin G) from aqueous solutions.

The wastewater obtained from sugar production cannot be naturally degraded due to the presence of various color precursors, colored impurities, lime carbonation sludge and other organic impurities. In this study, optimization of the effective parameters for the sugar industry wastewater treatment is investigated using photo- Fenton process and response surface methodology.

 This empirical research was conducted on a laboratory scale on refined wastewater obtained from sugar beet factory (Qazvin, Iran), in ternms of the intensity of contamination, considering the reduction of the three factors including COD, phenolic, and color content using the advanced oxidation process (photo- Fenton process). In order to optimize the ocndions for wastewater treatment, the results of these experiments wre ultimately optimized by response surface methodology.

The results obtained that the optimal condition for color and phenolic removal were: pH of 6.1' reaction time 15 minutes' Fenton's reagent (Fe2+/H2O2) concentrations: 20/1500 of ppm. Under these conditions, the color and phenolic reduction were achieved 73.92% and 93.9%, respectively.

The photo- Fenton process has a good efficacy in treating the sugar industry wastewater in the removal of important pollution parameters such as color impurities, phenolic compounds, and COD.Also, the statistical results showed that the pH parameter, Fenton's reagent concentration and contact time were significant during treatment process (p<0.05).

Aquaculture is one of the fastest growing sectors of agriculture in the world today. The intensive development of the aquaculture industry has been accompanied by an increase in environmental impacts. The production process generates substantial amounts of polluted effluent, containing uneaten feed and feces. Discharges from aquaculture into the aquatic environment contain nutrients, various organic and inorganic compounds such as nitrogenous compounds (ammonium, nitrite, and nitrate), phosphorus, dissolved organic carbon and organic matter. Ammonia (NH3) is the product of fish respiration and decomposition of excess organic matter. Chemoautotrophic bacteria (Nitrosomonas and Nitrobacter) tend to oxidize ammonium ions to nitrite and nitrate ions. Interest in closed aquaculture systems is increasing, mostly due to biosecurity, environmental and marketing advantages over conventional extensive and semi-intensive systems. When water is reused, some risks such as pathogen introduction, escapement of exotic species and discharging of waste water (pollution) are reduced and even eliminated. In current review, we will discuss on inorganic nitrogen removal techniques in aquaculture.

 This research is in terms of the nature of the review, which has studied the subject by reviewing scientific sources.

The most common way to remove nitrogenous waste material in aquaculture system, is including; water exchange, aeration, cut off feeding, use of zeolite mineral and the biological control.

the most suitable method for controlling inorganic nitrogen compounds is consumption and reduction of nitrogen in the same place by bacteria (biochemical method).

Heavy metals are not chemically degraded, in order to prevent the entry and accumulation of this toxic pollutant along with factory effluents into the environment, so far, different methods have been used, but finding new methods with more efficiency in this area is necessary. In this research, a new class of compounds called organic metallic materials has been used to remove industrial effluent lead. These organic metallic materials contain iron and benzene tricarboxylate. To identify the characteristics of these materials, electron microscope images and Nitrogen adsorption and desorption isotherms has been used. To determine the optimal conditions for using these materials for lead removal from the effluent, the effect of parameters: time (10-120 min), the amount of adsorbent (0.2-0.5 mg/L), pH (3.5 -12.5) and temperature (10-75 ° C) were evaluated. The results show that the composition of MIL-100 (Fe) has a better performance than the other materials in this study and complete removal of lead was achieved with an initial concentration of 10 mg/l and an adsorbent dose of 0.25 mg / l, at a temperature of 50 ° C, pH =4.3 and contact time of 120 min. Other properties of this material in removal of industrial effluent lead such as magnetic properties, reusability in five consecutive periods, large surface area, low cost, high efficiency and easy to use, make it an ideal option for large-scale use.

With the increase of industries and industrialization of societies, water pollution has intensified and the need for water, wastewater and materials treatment processes has increased. In this regard, MXenes as a new group of two-dimensional materials, also known as carbide / nitride functionalized metal nanosheets, have attracted the global attention of researchers due to their unique properties and range of potential industrial applications. In this study, meanwhile examining the synthesis of MXene and introducing its various structures, it was found that MXene, due to the high specific surface area of plate structures, high hydrophilicity and proper regeneration creates a suitable combination for nitrate separation as well as inhibition of bacterial growth. Also, their use in removing dyes increases the stability of the membrane structure and prevents the agglomeration of particles. In addition, MXene can be well used in the separation of nuclear waste due to its high adsorption rate and good selectivity.

The removal of heavy hydrocarbons and biological wastewater is generally difficult. Finding a suitable way to eliminate or reduce these factors is one of the goals of this research. Materials and

Although there are special processes for removing or reducing the hydrocarbon and biological load of water, but in industrial wastewater containing hydrocarbon, the evaluation of advanced oxidation processes can reduce not only the burden of the wastewater but also reduce the Biological bad effects. Therefore, in the present study, an experimental study of COD, BOD and O & G reduction using Fenton reaction with ultra-violet irridiation has been investigated.

A sample of industrial waste from one of the refineries was prepared. According to the results, the optimal conditions for COD removal was observed as follow: irradiation time 30 minutes, pH=3, temperature=35°C, water content=85 ml of oxygen dissolved in water than 250 ml of wastewater and COD removal was observed up to 45.44%. The optimal conditions for removing O&G were: 23 min, pH=3, temperature 35°C, dissolved oxygen content of 85 ml, compared to 250 ml of wastewater. Also O&G was eliminated to 89.8%. The optimal conditions for removing BOD were: the irradiation time is 20 minutes, pH=4, the temperature is 25°C, the soluble oxygen content is 65 ml, compared to 250 ml of the wastewater and the removal of BOD was observed to be 49.82%. Discussion and

Laboratory study of COD, BOD and O&G reduction in wastewater was investigated by using Fenton reaction with ultraviolet irridiation. It was found that the Fenton method with ultraviolet irridiation is a suitable method for the removal or reduction of COD, BOD and O&G in refinery wastewater.

In many developing countries, traditional irrigation of agricultural lands using raw and untreated wastewater has consequences such as contamination of agricultural products as well as the spread of disease. Hence, the adverse environmental and health effects of improper wastewater disposal have led to design and implementation of treatment plant and wastewater collection network.
Since the early 1990s, the "Life Cycle Assessment" is a "cradle to grave" approach to assess systems that has been widely used in many countries around the world and has been able to overshadow the view of decision makers towards systems and processes. Sareyn City did not have a treatment plant system and a sewage collection network and also due to the touristic area and peak of passengers in the first six months of each year, discharge of domestic sewage has been occurred by the hotels and even houses to canals in the city. In addition to the adverse effect on the aesthetics of the city, it was considered as a threat to public health in the region and due to the high groundwater level and the existence of water resources, there were potential risks in the infiltration of domestic wastewater into groundwater and hot springs, and of course microbial contamination of water and people, and the prevalence of epidemics and intestinal diseases. The effluent is also used by farmers to irrigate agricultural land which can also have environmental and health effects. Therefore, the purpose of this study is to evaluate the possible environmental and health effects of effluent from the treatment plant that is used for irrigation.

For the present study, first the quality of the effluent was analyzed and the necessary data were collected and calculated then by using Simapro software, the system was evaluated in terms of environmental and different effect classes. Also, the possible effects of the effluent on farmers who use it to irrigate agricultural fields were investigated from a health perspective by using the risk assessment information system method. to examining the system from an environmental perspective by using life cycle assessment, four steps of the LCA regarding the wastewater treatment system were determined as follows: Definition of goal and scope: The purpose of this study is to investigate the effects of effluent on the wastewater treatment system of Sareyn City in order to monitor the environmental and health performance of the wastewater treatment plant after the operation of the system, which is used as water for irrigation of downstream farms. Functional unit: The operational unit is the measurement of the performance of the production system. The primary purpose of the operations unit is to provide a reference for linking inputs and outputs to ensure comparable results. In this study, the operating unit of one liter of wastewater was considered to compare different wastewater treatment processes. System boundary: In this research the boundaries of the system were demarcated from the entrance of the treatment plant to its output (operational phase). Check list and System vector analysis and its interpretation: In this research, energy and raw materials consuming and the amount of methane and carbon dioxide emissions per day calculated to treat a liter of wastewater. Information obtained was analyzed by using Simapro software and basic data of Greenhouse gas protocol, IPCC 2013 and BEES+. For the health risk assessment two scenarios were considered: 1- Activation of the treatment plant based on the performance of the first 6 months (high tourist load) 2- Activation of the system for the second 6 months. The health effects of two scenarios were analyzed based on the rate of Chronic Daily Intake and the hazard quotient for both groups of children and adults through different routes of exposure.

Analysis of the results in the Sequencing Batch Reactor System showed that by Greenhouse Gas Protocol method there are four categories, which include carbon-based fossil fuels, biogenic carbon, carbon from the Earth's evolution and carbon uptake. The result showed that in the class of the effect of carbon dioxide per fossil fuel, the effluent from the treatment system with the participation of 99.7% has the greatest environmental impact followed by electricity consumption with 0.284%. In the class of biogenic carbon dioxide, nitrogen (74.6%) and phosphorus (25.4%) of the fertilizer obtained from the treatment process have the most impact, respectively. And in the category of carbon dioxide absorption effect, the highest effect is related to chlorine consumption with participation of 99.9%. The results of the IPCC 2013 method were as follows: Evaluation of effects is shown in terms of the equivalent of kilograms of carbon dioxide. The effluent from sequencing batch reactor treatment system has the greatest (99.9%) direct impact on the global warming potential for a period of 20 years compared to other parameters, followed by on-site electricity consumption, which is related to energy consumption and indicates high energy consumption by the system. Also, like the GHG protocol method, the evaluation criterion is kilogram equivalent to carbon dioxide. In the system evaluation by BEES + method the results showed that in the class of the effect of global warming in terms of grams equivalent to carbon dioxide, the effluent from the treatment has the greatest impact with participation of 99.6% and in the class of acidification effect, electricity and chlorine consumption have the most effect with 85.8% and 13.9%, respectively. Also in the classes of non-carcinogenic and carcinogenic effects, chlorine consumption has the greatest effect with participation of 99.6 and 90.9%, respectively. In the category of the effect of air pollution criteria, electricity consumption has the most impact (83.6%). In the eutrophication effect class, the effluent from sequencing batch reactor treatment has the greatest effect (87.9%). In terms of eco-toxicity, chlorine consumption has the greatest impact with participation of 96.9%. In the smog category, the greatest impact is related to the sequencing batch reactor treatment system, which affects 92.4% of this index. In the category of the effect of natural resources depletion, electricity consumption has the greatest impact (91.2%) and in the classes of the effect of indoor air quality and habitat alteration, none of the parameters have an effect. In the category of water intake, chlorine has the greatest effect with participation of 87.5% and in the ozone layer depletion class; chlorine plays the most destructive role in the environment with participation of 99.98%.
Results of RAIS according to the first scenario showed that regarding the hazard quotient (HQ) through ingestion in children and adult categories, nitrite with the participation of 5,09E + 00 and 3,06E + 00 respectively, has the greatest adverse effects. Similar results were observed in the second scenario with HQ values of 4,09E+00 and 2,46E+00 for children and adults respectively in digestion exposure to nitrite.

The results showed that in each of methods, categories have different effects and the parameters measured in these classes express different results. In the life cycle assessment method, carcinogenicity affects the human health by 90.9%, which is expressed in terms of emissions equivalent to benzene (C6H6) based on airborne emissions. However, in the risk assessment method, which was based on the effluent from the treatment, there was observed no carcinogenic risk. The results of this study showed that the parameters participating in the life cycle assessment method such as chlorine is an important factor with the most adverse effects on the environment and in the risk assessment method, nitrite has the most adverse effect on human health. Also, by comparing two scenarios in the health risk assessment method, it can be seen that the use of the treated wastewater for irrigation, although has no cancer risk is still concerning regarding non-carcinogenic hazards.

Abstract With increasing industrial activities and discharging untreated wastewater which contains various environmental pollutants to aquatic environments, problems such as reducing the penetration of light, anaerobic conditions and complications such as allergies and cancer for humans and other living organisms will occur. Surface absorption is one of the most effective and efficient methods for the removal of environmental pollutants and among the common methods for treatment of wastewater, applying natural adsorbents are more efficient than the other methods and is more economic. Since there are many natural adsorbents in nature, they are very inexpensive, they are even free in some cases; adsorption of contaminants by these materials can be a suitable way to remove the toxic substances of contaminated water and industrial wastewater. In this paper, we study some of bioactive adsorbents in order to remove contamination from industrial wastewater.

Hospital wastewater contains a variety of pollutants, a large amount of pathogenic microorganisms, viruses, radioactive materials, etc., which unless treated and disposed properly, can cause serious damage to human beings and the environment. The purposes of this study are to investigate the wastewater treatment and disposal conditions and the effluent quality in Guilan hospitals.In this study, besides the investigation of wastewater management conditions in Guilan hospitals with wastewater treatment plants, the sewage treatment performance was assessed in one of the hospitals. Qualitative indicators including total coliform, fecal coliform, pH, DO, BOD5, COD, TSS, total phosphate, ammonia, nitrate and silver in the effluent were assessed and the lab results were compared to the standards of Iran Department of Environment.According to statistical results, 10 out of the 34 studied Guilan hospitals have active wastewater treatment systems. Furthermore, the qualitative assessment showed that pH, COD, BOD5, DO, phosphate, nitrate, silver, total coliform and fecal coliform levels in the hospital conform to the standards of Iran Department of Environment. However, reduction of ammonia and TSS levels should be considered. A number of hospitals in Guilan do not have wastewater treatment plant and their wastewater is discharged into municipal wastewater collection systems or drains. On the other hand, a number of hospitals with wastewater treatment plants do not work properly. Therefore, it is important to consider executive decisions regarding new wastewater treatment technologies and upgrading treatment process in existing wastewater treatment plants.