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

The use of microalgae is an effective path in the process of advanced wastewater treatment in order to remove nutrients. In this study, living microalgae, Dunaliella salina was cultivated and then used in a series of batch experiments for the removal of nitrate and phosphate from wastewater.

The effect of changes in NO3- and PO43- concentrations (2.5-13 mg/l) on the removal efficiency using D. salina was evaluated during the 12-day growth period in the laboratory of Offshore Fisheries Research Center, Chabahar, 2017.

Results indicated that the maximum nitrate and phosphate removal efficiency using D. salina were 51.5% and 93.4%, respectively. The range of initial nitrate and phosphate concentrations were 0, 2.5, 5, 7.5, 10 and 12 mg/l and among them, the highest efficiency of nutrients removal after the control sample was obtained in 2.5 mg / l concentration of nitrate and phosphate. Phosphate removal efficiency was higher than nitrate at all concentrations and this shows that living microalgae D. salina has a good compatibility for growth in phosphate-contaminated wastewater. However, nitrate removal percentage is also significant and applicable to wastewater treatment systems. The Langmuir and Freundlich equilibrium models were also investigated in absorption process from solutions by living microalgae and the results of experiments were more consistent with Langmuir equilibrium model with R2 levels of 0.87 and 0.56 for nitrate and phosphate, respectively.

The results of this investigation suggested that D. salina is suitable as a biosorbent material for recovery and biosorption of nitrate and phosphate ions from aqueous solutions and wastewaters.

Wetlands are one of the most prominent ecosystems in the world. These vital and diverse habitats are among life-giving systems that have no alternative. However, none of the world's ecosystems have experienced human-centered injuries and damages as much as wetlands. One of the main threats to Gilan wetlands are human factors such as urban, domestic and industrial wastewater, overfishing and converting wetland marginal lands into agricultural lands. In this study, RGB images were used to assess the water quality parameters of Anzali wetland (Beheshti Island Station) and the related data were compared to the values obtained from the TSS measurement. Based on the obtained data, the intensity of red color (R) in the macroscopic images (with the naked eye) from the wetland can be an environmental indicator to measure TSS concentration. The results of RGB analysis for red color with a correlation coefficient of 0.8513, for green color (G) with a correlation coefficient of 0.832 and for blue color (B) with a correlation coefficient of 0.663 were obtained. Finally, a correlation coefficient (R2=0/8035) between the decrease of RGB values and the increase of TSS concentration was obtained. Other parameters such as pH and Secchi Depth test were also measured in this study.

environmental and economic limitations that are imposed dramatically on textile and dyeing industry leads to the development of environmentally friendly processes for modifying the properties of fibers and improving the existing traditional processes. Many efforts have been done for decreasing costs and disposed contaminants which one of them is using natural polymers. The purpose of this study is applying beta-cyclodextrin natural polymer as an appropriate alternative with favorable environmental effects for other chemical additives in dyeing.

In this study, wool fiber amended/treated by β-Cyclodextrin biocompatible polymer and its dyeing features such as the effect of β-Cyclodextrin composition (%20-0/5), dyeing pH (3-7) and density of the dye (%5-75) on the dyeing capabilities of wool with madder dye color was evaluated and compared. And finally, physical changes of crude fiber and amended fiber after dyeing was amended/treated using SEM analysis.

According to the results, as the β-Cyclodextrin amount increased, the color strength of the samples are considerably enhanced and dye ability (K/S) is better in the case of modified wool rather than aluminium-mordanted wool and pristine wool. Besides, exhaustion of modified wool in neutral pH rather than acidic pH has been increased dramatically while no appreciable changes was observed in pristine wool dye ability with pH changes. Color strength (K/S) data were in the following order of the β-Cyclodextrin modified wool>.

In general, according to the conditions of modifying wool with β-Cyclodextrin biocompatible polymer and changes in dyeing conditions, not only removing chemical compounds from the wastewater of textile industrial can beapplied, but also the amount of consumed dye and unabsorbed dye remaining in wastewater can be reduced which is environmentally very important.

Today, treated wastewater is widely used on agricultural soils adjacent to urban areas of developing countries to meet water shortages. On the other hand, due to the pollution increase, the limited available resources are threatened. For the production of crops, unconventional water is used in many countries of the world if it has the necessary standard, and municipal wastewater treatment plants are a very reliable source due to their ability to deliver sustainable water in all seasons. In recent years, several studies have been conducted in the field of the effluent quality of municipal wastewater treatment plants and the possibility of using them in various applications, including agriculture, in different regions of Iran. Due to the water crisis that has arisen, especially in arid and semi-arid regions of the country, it is necessary to study and analyze the possibility of further use of this unconventional water resource. However, wastewater recycling can have various health and environmental effects.

In this study, the effluent quality of the Shiraz municipal wastewater treatment plant was investigated using the daily data during 2018 and 2019 for use in various purposes such as irrigation of crops, irrigation of green spaces, drinking of livestock and poultry, fish farming, discharge into streams, artificial recharge of groundwater based on national and international standards. In this regard, at first, the values of various physical and chemical parameters such as acidity, electrical conductivity, total dissolved solids, total suspended solids, total volatile solids, total solids, chemical oxygen demand, biochemical oxygen demand, turbidity, dissolved oxygen, detergents, phosphate, total phosphorus, nitrate, nitrite, ammonia, Kjeldahl total nitrogen, free chlorine, and fat-oil-grease were determined in raw and treated wastewater. Then, while comparing the values of these parameters with the standard of the Environmental Protection Organization of Iran, the removal efficiencies of these parameters were calculated and finally, the quality of the effluent was investigated for use in various sectors.

The results showed that the removal efficiency of BOD5, COD, TSS, NH3, detergents, and fat-oil-grease in this treatment plant is 85, 85, 67, 64, 94, and 68.5%, respectively. The quality of the effluent is only suitable for agricultural purposes based on the standard of the Environmental Organization of Iran, and according to other standards, it is not capable of such use. This effluent can be used to irrigate ornamental fruit trees, fodder crops, plenteous trees and green spaces side of the roads outside the city, field crops, industrial crops, and forestry, as well as drinking livestock and poultry. However, there are limitations for urban green space irrigation, fish farming, discharge to surface waters (such as Maharloo lake in the vicinity of the wastewater plant), and groundwater recharge, although some of these limitations can be improved by upgrading the function of the treatment plant. By irrigating unfruitful plants and forest parks around Shiraz and even part of urban green space, the pressure on water resources can be reduced to a great extent. On the other hand, the continuation of irrigation with this effluent, which contains organic and nutritious substances in a large proportion, has caused an increase in soil nitrate, and it will be possible to leach and transfer it to surface and underground water sources.

The amount of quality parameters of the treatment plant effluent is within the standard of Iranian Environmental Protection and can be used as a sustainable water source in areas that are not directly related to humans. In using this sustainable water source for permitted uses, all health issues for the workers of each sector must be observed, and the effluent must be continuously disinfected.

Today, the lack of water reserves on the ground, especially in dry climates including our country, has caused the purposeful reuse of wastewater to provide new water sources as a new solution. Currently, countries that are facing the problem of lack of water resources are investigating the feasibility of using wastewater under the title of unconventional waters. But unfortunately, very little research has been done in this regard.

In order to investigate the amount of changes in some elements and characteristics of the soil under irrigation with wastewater, for 3 years, an experiment was conducted as a randomized complete block design with three repetitions. Sampling was done from two depths of soil 0-30 and 30-60 cm, and the parameters of sodium, total calcium and magnesium, acidity and electrical conductivity of the soil in three study locations (without irrigation, irrigation with treated wastewater, and irrigation with water of river) was measured and analyzed.

The effluent from Zahedan treatment plant has caused an acceptable increase in the amount of sodium, total calcium and magnesium, and soil acidity compared to the control area. But regarding the electrical conductivity, irrigation with sewage decreased this amount.

Effluent causes an effective and acceptable increase of some soil elements, which can be an effective help in soil regeneration and to be used as one of the water sources especially in dry areas that are facing a shortage of water resources.

The issue of water supply is the most important side service of every industrial unit, which turns into industrial wastewater during various uses, it is important to obtain industrial wastewater recovery methods. In the present study, manganese removal experiments by graphene adsorbent were carried out continuously in different conditions. Then the effect of effective parameters on manganese absorption such as pH (from acidic environment 2 to basic environment 12), contact time (from 5 to 30 minutes), initial concentration 20ppm and amount of adsorbent used (0.02 gr, 0.04 gr, 0.06 gr, 0.08 gr and 0.1 gr) ) was investigated. An atomic absorption device was used to measure the amount of manganese in the solution. The results showed that the optimum playing medium for the adsorbent was equal to 10. In the study of the effect of adsorbent heat on the absorption percentage, it was observed that the nanographene used has an extremely high absorption power in removing pollutants. The results showed that the process of removing manganese from the aqueous solution follows the pseudo-quadratic equation with very high accuracy. The maximum removal of manganese from the aqueous solution was 2ppm by 0.08gr of nanographene in 10 alkaline environment and 30 minutes contact time, and the absorption percentage was 99.05%.Graphene has a very good performance in removing manganese metal from wastewater. In fact, the larger the size of the absorbent surface and pores, the higher the absorption rate.

Due to the increase in population and more wastewater production and the existence of limited water resources, the use of human wastewater in agricultural activities is a necessity. The present qualitative research, while investigating the consequences of the use of wastewater, seeks to develop appropriate strategies for the use of wastewater in agricultural activities in the village of Belan, Kurdestan province. Using the criterion-based sampling method, 14 farmers were studied as a sample. Semi-structured interviews and direct observation were used to collect information. The validity of the findings was confirmed by triangulation and Qualitative data analysis was performed using Maxqda software. The results showed that increasing the area under cultivation, increasing yield, water supply, and less use of chemical fertilizers are positive impacts of wastewater use. Moreover, the increase of pests, increase of weeds, occurrence of physical and mental disorders, unpleasant odor, a decrease in soil quality, pollution of the rural environment, and increase in migration are among the negative impacts of using wastewater. The use of standards for wastewater treatment, preparation of soil sensitivity map, use of the appropriate irrigation method, attention to plant type, and disinfection of wastewater are also among the strategies suggested by users.