الهام عبدالله زاده شرقی

Detergent is one of the main environmental pollutants which can penetrate into wastewater treatment plants and negatively affect their performance. Detergents have a direct and indirect effect on human health and other living organisms. For this reason, their effects need to be managed and controlled. Wastewater containing detergents is a renewable resource that can be recycled and reused. The treatment of this type of wastewater is very challenging due to its complex composition, the large volume of discharge into the environment caused by the increase in the use of detergents with the increase in the global population. In this article, the types of synthetic surfactants and their effects on human health and the environment, the characteristics of wastewater containing detergents considering the source of production, the methods of wastewater treatment containing surfactants and the studies conducted in this regard are reviewed. In the following, the economic review of wastewater treatment containing detergents and the challenges and future perspectives of wastewater treatment processes containing surfactants are also stated.

Dyeing wastewater is one of the most important environmental problems in the textile industry. This wastewater contains harmful pollutants that can damage human health and the environment. Electrocoagulation (EC) is a promising technology for dyeing wastewater treatment. This technology passes an electric current through the wastewater, which generates metal hydroxides that act as coagulants to remove pollutants. This article first introduces the EC system and its operation mechanism, then discusses the components that affect the system's performance in removing dye and chemical oxygen demand. The article also summarizes the studies that have been conducted on the use of this process in the treatment of textile dyeing wastewater. In addition, the economic aspects of the EC process and recommendations for its improvement are provided. Finally, the challenges and prospects of the process are discussed. This article provides an effective overview of the current advances and achievements in the EC process for dyeing wastewater treatment, which provides new insights into improving dyeing wastewater treatment with promising environmental applications.

Pharmaceutical wastewater contains high concentrations of organic matter, high salt and difficult biodegradability, so it must be treated before discharge to the environment. In this study, it is aimed to evaluate the treatment of pharmaceutical wastewater (methadone feedstock and neutralized capecitabine) using chemical and biological methods.

The laboratory evaluation of this study was performed in two parts: The first part included the study of wastewater treatment of methadone production using chemical coagulation and flocculation method with FeCl3, PAC and Alum as coagulants (at concentrations of 100 mg/L, 500 mg/L, and 1000 mg/L), and cationic flocculant (at concentration of 1 mg/L), and at two pH values of 7.5 and 14 in the Jars test apparatus. The second part included of the treatment capability of wastewater produced during neutralization section of capecitabine drug according to the following steps: a) the chemical pretreatment using PAC and Alum coagulants (at concentration of 4000 mg/L) and anionic, cationic and neutral flocculants (at concentration of 20 mg/L), followed by the anaerobic biological treatment for 67 hr, and b) the anaerobic biological treatment for 41 hr followed by the chemical treatment using PAC and Alum coagulants and anionic and cationic flocculants. In this study changes in chemical oxygen demand (COD), pH, turbidity and total dissolved solids (TDS) of wastewater were investigated.

At pH=7.5, the best treatment efficiency of methadone feedstock production wastewater was observed at 100 mg FeCl3/L (COD removal of 35.8±0.8%, turbidity removal of 99.4±0.1%, and TDS removal of 7%) and at pH=14, the best performance was obtained using 1000 mg FeCl3/L (COD removal of 42.5±0.0%, turbidity removal of 97.6±0.1%, and TDS removal of 51.6%). The highest combined chemical and biological treatment efficiencies were obtained for wastewater including neutralized capecitabine by Alum coagulant and cationic flocculant (COD removal of 61.3%). While, the highest combined biological and chemical treatment efficiency for this wastewater was obtained by Alum coagulant and anionic flocculant (COD removal of 39.0%).

Due to the characteristics of the pharmaceutical industry wastewater, the use of chemical methods, in addition to having good removal efficiency as the main stages of treatment, can also be used as pre-treatment for biological processes.

In recent decades, population growth, declining oil resources, and high production of municipal wastewater have raised many concerns for communities. Due to the shortage and limitations of fossil fuels, renewable energy sources are of particular importance. Municipal wastewater has become a remarkable source of energy due to its continuous production and treatment worldwide. The conventional activated sludge process has been used for more than a century to treat municipal wastewater. This process, despite its advantages such as high effluent quality and reliability, due to problems such as aeration, oxidation of organic matter present in the wastewater and waste production can hardly be considered as a sustainable method for wastewater treatment. In order to recover the energy present in the wastewater efficiently, it is necessary to change the process and up-concentrate the organic matter in it. Several physical, chemical and biological processes are used to increase the up-concentration of organic matters present in the wastewater and capture them onto the sludge surface, which improve energy recovery through anaerobic digestion. Due to the special disadvantages of physical and chemical processes, attention is drawn to the biological process. This study will provide a comprehensive assessment of the energy available in municipal wastewater and the methods used to increase the concentration of organic matter. It will also assess the limitations of physical and chemical methods and examine the biological process of high rate activated sludge, mechanisms, operational parameters, and recent studies on this process.

In recent years, with the industrialization of societies, population growth, and pollution around the world, the tendency to the use of biosurfactants has increased.Microorganisms produce a wide range of surface-active compounds called biosurfactants, which are amphiphilic compounds with hydrophilic heads and hydrophobic tails. These compounds are mainly classified according to their molecular weight, physico-chemical properties, and microbial origin. Low molecular weight biosurfactants reduce the surface tension of water/air or water/oil, while bioemulsifier with high molecular weight are effective in stabilizing emulsions. Biosurfactants,due to their properties and potential advantages over chemical counterparts such as low toxicity, high biodegradability, critical micelle low concentration and tolerance of temperature, ionic strength and pH, are widely used in various industries such as petroleum, food, medicine, cosmetics, detergent, ariculture and environmental bioremediation. However, due to the high cost of production, their large-scale production and applications are limited. That's why industries and researchers are looking formethods such as using low-cost substrates such as molasses, vegetable oils, and whey to reduce the high cost of these green products in the industrial scale. In this study, several important aspects of biosurfactants, such as classification, characteristics, factors affecting production, evaluation indicators and test methods, and their application in various industries have been discussed.

In this research, the performance of coagulation and flocculation process for the removal of pollutants from raw wastewater as well as anaerobic unit effluent of biological treatment of textile dyeing factory wastewater treatment plant was investigated. For this purpose, the Jar test unit as a batch reactor, FeCl3, PAC, and Alum as coagulants, and two polyelectrolytes, namely, Zetafloc 7563 and Megafloc 3045PWG as cationic and anionic flocculants were used and the effect of coagulant dosage and type as well as flocculant type on removal of COD, turbidity and color were investigated in two stages. The results of coagulation and flocculation experiments on raw wastewater showed that Alum at concentration of 40 mg/L was the most effective coagulant with COD, turbidity and color removal efficiency of 73.1±1.5%, 93.7% and 71.7%, respectively. However, the results of coagulation and flocculation experiments on the effluent from biological anaerobic treatment unit showed that the highest percentage of COD and turbidity removal were 52.2±2.6% and 99.1%, respectively that corresponds to PAC with concentration of 2000 mg/L. Additionally, the COD removal efficiency of FeCl3 coagulant at concentration of 400 mg/L was 52.2±3.5%. The difference in the results of the two stages was due to the change in the nature of the pollutants after exposure to biological treatment and different pH of the wastewater used in these stages.
Discussion and A general review of the results showed that use of physicochemical treatment applying only coagulation and flocculation process could not reduce the pollutants present in the dyeing wastewater for reuse, while this method could be considered as a pretreatment or one of the secondary treatment steps and post treatment.

Industrial wastewaters containing high amounts of compounds such as sulfate can cause serious risks to human health and environment. Therefore, proposing practical solutions with the lowest cost and the highest efficiency for pollutants removal is of special importance. The purpose of this study is to find a suitable method for treatment wastewater containing very high amounts of sulfate. This research is an experimental-research study in which four different practical methods have been investigated for treatment of sulfate containing wastewater including chemical precipitation with lime, electrocoagulation, biological degradation and thermal distillation. After examining the performance of different methods and considering the special characteristics of wastewater, the results showed that the methods of chemical precipitation (removal efficiency of 5%) and electrocoagulation (removal efficiency of 7%) were less efficient. The distillation process also showed an acceptable performance in removing TDS and sulfate from this wastewater (removal efficiency of 98.7%) and the biological method could function well after wastewater dilution (the removal percentage of sulfate in the first 24 hours for wastewater with dilutions of 10, 25 and 50%, are about 55, 40 and 17%, respectively). According to the results obtained from this study, methods of chemical precipitation and electrocoagulation are proposed only as a pre-treatment method and biological treatment can be used as a supplementary treatment after pre-treatment. Distillation is also not recommended as a practical method due to high cost and energy consumption.

  Development of communities, population growth, and enhancement of the health indicators has led to a significant increase in dairy and meat consumption, and consequential growth in
the livestock industry. As the result, the environmental problems which cause by such industrial wastewater has increased. Livestock wastewater considered as a very non-biodegradable and polluted wastewater. In this study, the performance of livestock wastewater pre-treatment, by using coagulation and flocculation method, in order to reduce the pollutants concentration and improve wastewater properties were investigated. In the experimental methods, the Jar test unit was used as a batch reactor; FeCl3, PAC, and Alum as coagulants; and two polyelectrolytes: Zetafloc and Megafloc as cationic and anionic
flocculants. The effects of coagulant dosage and type, flocculant type, and pH on the removal of COD and turbidity from wastewater were investigated in three stages. The wastewater with initial
COD and turbidity of 12250 mg/L and 7125 NTU, respectively, was collected from a livestock unit. The optimum conditions in the coagulation and flocculation process to achieve the maximum removal efficiency for COD (29.6%) and turbidity (52.8%) were obtained in an experiment
with FeCl3 at a concentration of 400 mg/L, pH=8, and using an anionic flocculant. Conclusion The results of the present study showed that the coagulation and flocculation process
can be an effective method for livestock wastewater pre-treatment

The leather industry is one of the most polluting industries in the country (Iran), which annually produces several hundred tons of industrial sewage. Electrocoagulation is one of the purification methods for this wastewater. This research aimed to remove COD and turbidity from real wastewater originating from one of the leather tanning units in Charmshahr industrial park with use of electrocoagulation process. The research was conducted in laboratory scale in a 480-millimeter EC reactor. The wastewater was collected from a leather tanning unit. The main variables considered were current intensity (1.5, 2.5, 3.5 and 5 A), retention time (5, 10, 15 and 30min), initial pH (5, 6 and 8.6) and electrode material (i.e., iron, aluminum, and steel). The optimum conditions in the electrocoagulation process to achieve the maximum removal efficiency for COD equal to 63.57% were obtained in an experiment with time of 5 minutes, the current density of 23.5% mA/cm2, pH=8.62 and 2 steel electrodes. Also, in an experiment with time of 30 minutes, the current density of 23.5 mA/cm2, pH=8.62 and 4 electrodes, the removal rate of 62.88% was obtained. The results of the present study showed that the electrocoagulation can be an effective method for tannery wastewater pre-treatment and the optimum conditions can be obtained using aluminum electrodes, time of 5 minutes, the current density of 7 mA/cm2 and pH of 8.62.

Dwindling of conventional oil reserves and increasing global demands have caused increased exploitation of heavy crudes accounting for a large fraction of the world's crude oil resources. Formation of stable water-in-crude oil emulsions in hydrocarbon reservoirs or in production processes are inevitable increasing environmental problems as well as costs of transportation and refining. Heavy crude oil viscosity also makes several problems during extraction and transportation. Viscosity reduction processes of heavy crude oil for pipeline transportation have been subject of many researches. In this paper, challenges involved in use of these energy resources have been evaluated using a comprehensive literature review.

The main aim of the present study was evaluating the performance of a biological hybrid system comprising anoxic bioreactor and aerobic membrane bioreactor (MBR) with immersed micro-filter membrane for the nitrate removal from drinking water during 34 days of operation. Operational conditions were constant hydraulic retention time equal to 17 h and 36 h for anoxic bioreactor and MBR, respectively, influent nitrate-N concentration of 33.9 mg NO3-N/L, and C/N ratio equal to 2. The results demonstrated that nitrate removal efficiency in anoxic bioreactor was in the range of 73-97%. The effluent nitrite-N concentration from the hybrid system was in the range of 0.01-0.02 mg NO2-N/L. Both nitrate and nitrite concentrations in the effluent of system were always below the the World Health Organization (WHO) limit. The effluent chemical oxygen demand (COD) of the hybrid system was always less than 15 mg/L and COD removal efficiency of the system was 92.8±0.1 %. The effluent turbidity was also less than 2 NTU that represented membrane efficacy in preventing microbial mixture washout. The results of this research show that hybrid biological system of anoxic bioreactor-MBR has a very good potential for removing nitrate from drinking water.

Membrane bioreactor (MBR) is the combination of a membrane process with a suspended growth bioreactor and has been widely used for removing organic and inorganic contaminants as well as microorganisms from municipal and industrial wastewaters due to its distinct advantages over conventional technologies. In order to achieve the high quality of treated wastewater and reduce fouling in the MBR systems, several factors must be optimized. In the current study, at first, different types of MBRs were reviewed in terms of aeration, configuration, material and the membrane modules. Then the operational parameters affecting the performance of the MBR such as the hydraulic retention time, sludge retention time and concentration of feed inlet and also the parameters related to biomass characteristics such as biomass concentration, particle size distribution, microbial products (extracellular polymeric substances and soluble microbial products) and morphology of biomass were reviewed.

Today’s, discharge of toxic industrial effluents into the environment is one of the major problems of societies. Recently, graphene as member of carbon allotropes have attracted researcher's attention to color removal due to high surface area. Graphene is a monolayer of sp2-hybridized carbon atoms arranged in a two dimensional lattice. Dyes contain aromatic rings in their chemical structure that can be adsorbed well by grapheme through the π- π interactions. Several researches have been investigated on the use of dispersed graphene nanosheets as an efficient adsorbent for removal of dyes. The results indicated graphene can adsorb dyes very well but their performance has been limited by extend of dispersion. Now, the high cost of production is the major obstacles to its industrial using. In this paper, the commonly used methods for the synthesis of graphene and its application in the removal of color compounds from industrial wastewater have been reviewed.