Showing papers in "International Journal of Environmental Science and Technology in 2019"

Textile dye wastewater characteristics and constituents of synthetic effluents : a critical review

Abstract: Textile industries are responsible for one of the major environmental pollution problems in the world, because they release undesirable dye effluents. Textile wastewater contains dyes mixed with various contaminants at a variety of ranges. Therefore, environmental legislation commonly obligates textile factories to treat these effluents before discharge into the receiving watercourses. The treatment efficiency of any pilot-scale study can be examined by feeding the system either with real textile effluents or with artificial wastewater having characteristics, which match typical textile factory discharges. This paper presents a critical review of the currently available literature regarding typical and real characteristics of the textile effluents, and also constituents including chemicals used for preparing simulated textile wastewater containing dye, as well as the treatments applied for treating the prepared effluents. This review collects the scattered information relating to artificial textile wastewater constituents and organises it to help researchers who are required to prepare synthetic wastewater. These ingredients are also evaluated based on the typical characteristics of textile wastewater, and special constituents to simulate these characteristics are recommended. The processes carried out during textile manufacturing and the chemicals corresponding to each process are also discussed.

Heavy metal stress and responses in plants

Abstract: Heavy metals such as Fe, Mn, Cu, Ni, Co, Cd, Zn, Hg and arsenic are for long being accumulated in soils through industrial waste and sewage disposal. Although some of these metals are essential micronutrients responsible for many regular processes in plants, their excess, however, can have detrimental effects and can directly influence the plant growth, metabolism, physiology and senescence. Plants have different mechanisms to fight stress, and they are responsible to maintain homeostasis of essential metals required by plants. These mechanisms also focus on prevention of plants exposure to heavy metals present in the soil or providing tolerance to the plant by detoxifying the metals. Other mechanisms are specific and are initiated when the respective stress is encountered. The first line of defense provided by a plant is to reduce the uptake of metals when stimulated with toxicity of heavy metals and includes the help offered by cellular and root exudates that restricts metals from entering the cell. Many plants have exclusive mechanisms for individual metal ions and are involved in sequestering these ions in compartments avoiding their exposure to sensitive components of the cells. As a second line of defense, other mechanisms for detoxification of these metals are introduced that chelates, transports, sequesters and detoxifies these metal ions in the plant’s vacuole. During the time of metal toxicity, oxidative stress is pronounced in the cells and production of stress-related proteins and hormones, antioxidants, signaling molecules including heat-shock proteins synthesis is initiated.

Review on applications of particle swarm optimization in solar energy systems

Abstract: Solar energy is one of the most important factors used in the development of the countries. Since it is a renewable energy source, it reduces the demand on the non-renewable energy sources such as fossil fuels, oil, natural gas, nuclear, and other sources. Therefore, many researchers have sought to improve the performance of solar energy systems via applying several metaheuristic methods such as particle swarm optimization (PSO) which simulates the behavior of the fish schools or bird flocks. PSO has been used in different applications including engineering, manufacturing, and medicine. The main process of the PSO is to determine the optimal position for each particle inside the population. This is performed through updating the position using the velocity of each particle and the shared information between the particles. The aim of this paper is to provide a review on the PSO’s applications to improve the performance of solar energy systems and to identify the research gap for future work. The literature review used in this study indicates that the PSO is a very promising method to enhance the performance of solar energy systems.

Comparison of different natural fiber treatments: a literature review

Abstract: Interests in the use of natural fibers–fillers in composite materials are growing rapidly due to the low cost and high availability. However, poor surface adhesion and mineralization are the main drawbacks that restrict the use of natural fibers in different applications. Thus, it is essential to perform a treatment that can improve the surface properties of natural fibers before being used in the composites. Such treatments are physical (corona, plasma, etc.), chemical (alkaline, silane, acetylation, etc.), and biological (enzyme), but the benefits of each treatment considering energy consumption and effluent generation should be considered more in-depth. Via a literature review, this study investigated the mechanical performance, energy consumption, and generated effluents of chemical treatments (silane, alkaline, acetylation, and maleated coupling) as the consequence of fiber treatment to propose a more sustainable treatment at the scope of the treatment section in the factory of natural fibers–polymer composites (gate to gate). It was shown during this review study that the maleated coupling is a more sustainable method since it needs no specific energy during the treatment while produces no effluent and improves the mechanical strength performance of the composites more constantly.

Harmful algal blooms (red tide): a review of causes, impacts and approaches to monitoring and prediction

Abstract: Red tide, an impermanent natural phenomenon including harmful algal blooms, causes changing the color of the sea generally to red or almost brown, and has a serious impact on environment along the coast and aquatic ecosystem. Due to recent extensive steady harmful algal blooms events that cause adverse impacts on human healthsome, aquaculture and tourism industry, and the entire economy of the coastal region, the need of society for realizing these phenomena is much greater than the past. In the recent decades, consideration of algal blooms and determination of bloom-former species and fundamental researches about dynamics of blooms are increased worldwide. Development in technology has increased our abilities in monitoring oceans and has provided new opportunities for blooms identification as well as defining the biological, physical and chemical parameters that lead to algae beginning, expansion and disappearance. In spite of these rapidly developing observational capabilities, harmful algal blooms’ proceedings will carry on to be undersampled for the foreseeable future, due to their spacious spaced and temporal coverage. Therefore, reliance on models to help interpreting observations is necessary. To watch red tides, there are different methods: field observation and using sampling data, satellite-based studies, laboratory studies, modeling. (This item includes complex numerical models, conceptual models, simple analytic formula, semi-empirical models and aggregated box models or zero-dimensional models.) This paper proposes different observation and prediction methods ever used worldwide.

A review on the application of different treatment processes for emulsified oily wastewater

Abstract: Oily wastewater, one of the major threats to environment nowadays, mainly originates from petrochemical, heavy metal, food processing, paint, automobile industrial premises. This oil contaminated wastewater is mutagenic and carcinogenic to human health as well as inhibitory to plant growth. Without any proper treatment if such oily water stream disposed into water bodies, apart from increasing the BOD and COD, it also imparts a sunlight impervious layer at the top of the stream restricting the entrance of sunlight followed by disruption of aquatic ecosystem. Hence proper treatment of oily wastewater before its discharge to environment is one of the primary concerns. Researchers have used several technologies such as, gravity sedimentation, coagulation, flotation, coagulation composite flotation, demulsification, membrane separation, flocculation, chemical precipitation and bioremediation have been explored to purify this oil contaminated wastewater to a desired level. Especially, the uniqueness of the treatment will require a through merit analysis of the process, when the wastewater comprises of oil–water emulsion. Hence, in this review an analytical insight on the merits of the process for the treatment of such emulsified system has been provided. The review article also discusses different microorganisms that are required for bioremediation of either oil spill over a large aquatic zone or oil–water emulsion at source point. Finally, the manuscript highlighted some of the effluent treatment plants’ operational process from different industries, which might provide a typical understanding of a comparative view between different treatment processes.

Polycyclic aromatic hydrocarbons: soil pollution and remediation

Abstract: Soil is an important environmental matrix to support the life of all organisms directly or indirectly. Despite being the ultimate sink for all pollutants, it has been neglected for long, which has negatively affected the quality of the soil. Disposal of pollutants has resulted in changes in properties of soils and introduction of toxicity into it. The presence of heavy metals, pesticides, polychlorinated biphenyls and polycyclic aromatic hydrocarbons (PAHs) affects all forms of life since these chemicals have associated toxicity, mutagenicity, and carcinogenicity. PAHs are typical pollutants of soil which result in alteration in grain size, porosity and water-holding capacity of soil and affect diversity/population of microbes adversely. Significant changes in permeability, volume, plasticity, etc., are also brought about resulting in poor quality of contaminated soils. Considering the toxicity and global prevalence of PAHs, remediation of contaminated soils has become a challenge. Therefore, it is important to understand the detailed mechanism of physical, chemical or biological changes in soil. Simultaneously, it becomes pertinent to identify the environmentally sustainable treatment options for remediation of contaminated sites. Whereas physical and chemical treatment methods are either cost, chemical, or energy prohibitive, the biological treatment is emerging as an efficient and effective option which employs microorganisms for mitigation. Microorganisms are known for their enzyme-catalyzed catabolic activity when degradation/mineralization of a pollutant is aimed at and can prove useful in degradation of PAHs. Therefore, the present study reviews the effects of PAHs on soil properties, different remediation techniques and the role of microorganisms in remediating contaminated sites.

A hybrid support vector regression–firefly model for monthly rainfall forecasting

Abstract: Long-term prediction of rainfalls is one of the most challenging tasks in stochastic hydrology owing to the highly random characteristics of rainfall events. In this paper, a novel approach is adopted to develop a hybrid regression model for 1-month-ahead rainfall forecasting at two rain gauge locations (namely: Tabriz and Urmia stations), in northwest Iran. The approach is based on the integration of support vector regression (SVR) and firefly algorithm (FFA) that results in truthful rainfall forecasts. The proposed hybrid model was trained and validated using weak stationary state of monthly rainfall data obtained from the gauges. The efficiency results of the model were also cross-validated with those of stand-alone SVR- and genetic programming-based forecasting models developed as the benchmarks in this study. For both rain gauge locations, the results showed that the hybrid model significantly outperforms the benchmarks. With respect to the average efficiency results at the gauge locations, the FFA-induced improvement in the SVR forecasts was matched by an approximately 30% decrease in root-mean-square error and around 100% increase in Nash–Sutcliffe efficiency. Such a promising accuracy in the proposed model may recommend its application at monthly rainfall forecasting in the present semiarid region.

The potential of novel data mining models for global solar radiation prediction

Abstract: Advance knowledge of solar radiation is highly essential for multiple energy devotions such as sustainability in energy production and development of solar energy system. The current research investigates the capability of four data mining computation models, namely random forest (RF), random tree, reduced error pruning trees and hybrid model of random committee with random tree reduce (RC) for predicting daily measured solar radiation at four locations of Burkina Faso, i.e., Bur Dedougou, Bobo-Dioulasso, Fada-Ngourma and Ouahigouya. Daily data of seven climatic variables, namely maximum and minimum air temperature, maximum and minimum relative humidity, wind speed, evaporation and vapor pressure deficit, for the period 1998–2012 are used for solar radiation prediction. Different combinations of input variables are used according to correlation coefficient between the predictors and predictand, and the best input combination is selected based on the sensitivity of model output measured in terms of statistical indices. The obtained results are found consistence for all the meteorological stations. The highest accuracy in prediction is found when all the climate variables are used as input. The RC and RF showed the minimal absolute error in prediction at all the stations. The RMSE and NSE are found in the range of 0.03–0.05 and 0.77–0.91 for RC and 0.03–0.05 and 0.78–0.92 for RF at different stations. The results indicate that the proposed data mining models can be used for accurate prediction of solar radiation over the Burkina Faso.

Photocatalytic degradation of metronidazole from aquatic solution by TiO 2 -doped Fe 3+ nano-photocatalyst

Abstract: Indiscriminate consumption of antibiotics, their discharge into the environment, and the development of resistant genes in a natural ecosystem are ever-increasing global threats. Metronidazole is applied to treat infection diseases caused by anaerobic bacteria and protozoa. In this research, TiO2/Fe+3 was used as a heterogeneous nano-photocatalyst for the degradation of metronidazole with UV-C radiation as the energy source. Parameters tested in the removal process were pH = 3, 7, and 11; antibiotic concentration of 80 mg/L; contact times of 30, 60, 90, and 120 min; and nano-photocatalyst of TiO2/Fe+3 with concentrations of 30, 60, 90, 250, 500, 750, and 1000 mg/L. The photocatalytic degradation kinetics of metronidazole was studied. Optimal conditions were achieved on synthetic solutions; then, all experiments were performed on wastewater from the pharmaceutical industry. Antibiotic concentrations were measured using an HPLC device. All tests were replicated three times according to the standard methods of water and wastewater experiments, the 20th edition. Data were analyzed using SPSS 19 and the statistical test ANOVA. The optimal conditions for removing metronidazole from synthetic solution included, 500 mg/L for nano-photocatalyst concentration, pH = 11 and 120 min contact time. Removal efficiency of antibiotic under optimal conditions was 97% from synthetic solutions and 69.85% from pharmaceutical wastewater. Finally, Fe+3–TiO2/UV-C were identified as a promising technique for the removal of metronidazole with high efficiency from aqueous solutions.

Exploring urban resilience thinking for its application in urban planning: a review of literature

Abstract: Environmental and urban problems are rooted in both ecology and urbanism contexts. The main issue in this regard is to plan, design and manage urban settlements where human beings would be able to have the desirable quality of life according to sustainable principles. The increase in social, economic and spatial vulnerabilities in cities, and the excess of degradation factors of natural environment resources show the necessity of considering resilience thinking. This paper aims to apply resilience thinking to urban studies and to identify the required basis for further research on urban resilience through a descriptive analytical review of the theoretical literature. A recent research on urban resilience in urbanization, which is a novel topic in urban resilience studies is addressed in this article. This paper aimed at introducing indices of urban resilience through a particular approach to the relationship between urban form and urban resilience. Given the literature review of urban resilience, our results show that while most research topics rely on environmental dimensions and reduction in natural hazards, such as global warming and climate change, the need for further research on spatial morphology and urban spatial structures is evident. Furthermore, additional research is needed to explore the criteria of urban resilience measurement specifically in the locational-spatial aspect.

Effect on different TiO2 photocatalyst supports on photodecolorization of synthetic dyes: a review

Abstract: This review focuses on the investigation and development of various support materials in TiO2 photocatalyst system with special emphasis on the photodecolorization of synthetic dyes. Efforts have been devoted to find suitable support material of TiO2 for improving its recovery efficiency and adsorption capability. The relationship between the structural characteristics and physicochemical reactivity properties of the supported TiO2 photocatalysis has been highlighted. The vicinity of photocatalysis and support system significantly accelerated the transfer step between adsorption and overall oxidative of decolorization process. Comparison of the photodecolorization with several synthetic dyes has been made and concluded that the photocatalytic activities have been influenced by the structural and surface properties of the photocatalyst.

A comprehensive review on state-of-the-art photo-, sono-, and sonophotocatalytic treatments to degrade emerging contaminants

Abstract: Emerging contaminants (ECs) are commonly originated from personal care products, cosmetics, pharmaceuticals, pesticides, dioxins, polycyclic aromatic hydrocarbons (PAHs), and alkylphenolic compounds. Due to the huge development of these industries, these ECs have been constantly detected in wastewater, groundwater, and surface water in hazardous quantity. The discharge of these ECs into the environment causes considerable non-esthetic pollution and could be a great threat to the entire ecosystem. The common wastewater treatment plants (WWTPs) which consist of biological, physical, and chemical treatments such as activated sludge, filtration, adsorption, and coagulation are found to be ineffective for desired removal of ECs. In turn, various emerging advanced oxidation processes (AOPs) such as ultrasonic and ultraviolet irradiation with or without the presence of catalyst have raised great attention due to their great potential in remediation of ECs. This paper presents a critical review on types, recent occurrence, sources, environmental impacts, and emerging treatment methods applicable to treat ECs. The current research and applications of ultrasonic, ultraviolet, and combination of both irradiations to treat ECs in wastewater are particularly reviewed. The effect of key parameters on photo-, sono- and, sonophotocatalytic degradation of ECs are commendably accessed such as ultrasonic power, ultrasonic frequency, light intensity, ultraviolet wavelength, solution pH, oxidizing agents, chemical additives, catalyst dosage, and modification of catalyst. The possible reaction mechanisms of ECs degradation process and kinetic model study are also elucidated in detail. Lastly, future research directions and conclusions are proposed to strengthen the understanding on their fate in water. All this information is vital to predict the negative impacts of ECs on the receiving environment effectively.

Integrating GIS and multi-criteria decision analysis for landfill site selection, case study: Javanrood County in Iran

Abstract: The current study presents the integration of geographical information system (GIS) and multi-criteria decision analysis (MCDA) for municipal landfill site selection, a case example in Iran. In the first step, useful criteria were determined based on the literature review, national standards and regulations, expert opinion, data availability and regional characteristics. Several criteria including distance from groundwater resources, distance from surface water, distance from urban and rural areas, distance from protected areas, land use, distance from faults, distance from roads and the slope were selected, and a hierarchical structure was formed for landfill suitability. The maps of the criteria were prepared using ArcGIS 10.2. Using different fuzzy membership functions, the maps were standardized. An AHP-based pairwise comparison was applied to calculate the weights of the parameters, and standardized maps were overplayed using the weighted layer combination approach to gain the landfill suitability map in the study area. The final map was assorted into four suitability classes, i.e., high, moderate, low and unsuitable regions. The result indicates that almost 92% of the study area is inappropriate and cannot be considered as landfill. The comprehensive field visits were performed to further assessment, and finally, three candidate sites were suggested. The result illustrated that an integrating approach of GIS and MCDA is effective in landfill site selection.

Enhancement of anoxic phosphorus uptake of denitrifying phosphorus removal process by biomass adaption

Abstract: Economical and efficient phosphorus (PO4-P) removal technologies with low oxygen and organic carbon demand are needed to avoid eutrophication and reduce wastewater treatment costs. A sequencing batch reactor (SBR) treating synthetic wastewater with similar characteristics to real domestic wastewater using peptone and meat extract as carbon sources and nitrate as terminal electron acceptor was set up to enhance anoxic PO4-P uptake of denitrifying phosphorus removal process. In the anaerobic/anoxic/oxic SBR, activated sludge inoculum was gradually adapted to prolonged anoxic and shortened aerobic phase durations of 3.5 h and 1 h, respectively. During biomass adaption, anoxic PO4-P uptake fraction from total PO4-P (anoxic + aerobic) uptake was enhanced from 70.5 to 90.4%. SBR long-term operation results showed that dosed nitrate loading and aeration phase duration affected PO4-P and total nitrogen (TN) removal. The highest PO4-P removal of 22.4 mg PO4-P g−1 mixed liquor suspended solids (MLSS) and average TN removal efficiency of 74.2% were achieved with 1-h aeration duration. The best dosed nitrate loading ranges for effective PO4-P and TN removal were 11.3–13.7 and 11.1–19.4 mg N g−1 MLSS d−1, respectively. Chemical oxygen demand and dissolved organic carbon removal efficiencies remained unaffected by changes in operating conditions with average values up to 96.3% and 98.0%, respectively. Pyrosequencing results demonstrated that during biomass adaption microbial community changed and adapted sludge probably contained some novel denitrifying phosphorus accumulating organisms. Therefore, this research shows that biomass adaption enabled to achieve efficient denitrifying phosphorus removal without acetate/propionate addition in the conditions similar to real domestic wastewater.

Prediction of water quality parameters using evolutionary computing-based formulations

Abstract: Rivers, as one of the crucial components of water resources, play a substantial role in human life. Due to a wide range of water consumptions, water quality is emphatically recommended assigning at a permissible level. Enormous field investigations have been carried out to quantify indicators of water quality parameters which have a great impact on the water quality. In this way, there are not explicit equations to predict WQPs with an allowable degree of accuracy. In the present work, gene expression programming (GEP), evolutionary polynomial regression (EPR), and model tree (MT) have been employed to estimate three indices including biochemical oxygen demand (BOD), dissolved oxygen, and chemical oxygen demand (COD). To develop the proposed models, nine input parameters $${\text{Ca}}^{2 + }$$ , $${\text{Na}}^{ + }$$ , $${\text{Mg}}^{2 + }$$ , $${\text{NO}}_{2}^{ - }$$ , $${\text{NO}}_{3}^{ - }$$ , $${\text{PO}}_{4}^{3 - }$$ , $${\text{EC}}$$ , $${\text{PH}}$$ , and $${\text{turbidity}}$$ were selected as effective variables. Results of training and testing stages for these approaches have been investigated. Performance of the models indicated that the relative superiority of the EPR approach compared to the GEP and MT models. Gamma test was applied to determine important parameters for predicting BOD, COD, and COD indices. It was found that $${\text{PO}}_{4}^{3 - }$$ , $${\text{Ca}}^{2 + }$$ , and pH have the most significant effect on BOD, COD, and COD, respectively.

Statistical optimization studies for polyhydroxybutyrate (PHB) production by novel Bacillus subtilis using agricultural and industrial wastes

Abstract: Substituting petroleum-derived polymers with biodegradable and biocompatible polyhydroxybutyrate (PHB) is a challenge to sustain the environmental system. This study intends to optimize the cultural conditions for PHB production by nonpathogenic Bacillus subtilis isolated from Jatropha field. Various agricultural and industrial wastes such as corn bran, corncob, wheat bran, rice bran, dairy waste, and sugarcane molasses were utilized for PHB production. Among these wastes, rice bran was the best carbon source for PHB production (0.31 g/l) with 30.4% of the dry cell weight (DCW). Cultural parameters influencing PHB production were studied employing Plackett–Burman and Box–Behnken designs. Accordingly, pH, incubation time, and inoculum size were found to be the most influential factors on PHB production. Using optimized conditions, sixfold augment in PHB content (0.81 g/l, 62.6% DCW) was attained using rice bran. PHBs obtained from glucose and rice bran were characterized using 1H NMR, FT-IR, TGA, and DSC analysis. Structures of PHBs were comparable, whereas the findings of thermal studies revealed that rice bran-derived PHB showed higher thermal stability with lower melting temperature than glucose-derived PHB. These results substantiate the potential use of this safe isolate utilizing inexpensive substrates for PHB production that could be adopted in medical applications.

The effect of ZnO-based carbonaceous materials for degradation of benzoic pollutants: a review

Abstract: The presence of dyes and benzoic derivatives in wastewater and water resources is one of the issues gaining global attention. Persistence, toxicity, and carcinogenic potential of these compounds create a severe impact on aquatics and human beings which make its removal essential before discharging into the environment. Photocatalytic processes driven by ZnO nanostructure semiconductors have great potential for water decontamination because of low cost, environmentally friendly, and complete mineralization of pollutants. Despite its high efficiency under ultraviolet light, zinc oxide with a 3.37 eV of band gap has a limited application under irradiation of visible light. Furthermore, the process time of photocatalytic activity was decreased by fast recombination of pairs of electron–hole. Therefore, to overcome this problem, the composition of carbonaceous materials doped with ZnO in the form of binary or tertiary nanocomposite has been studied. Due to their unique properties, carbonaceous materials have been chosen as a way to synthesize a high-efficiency semiconductor photocatalyst. Our review article considers on the new development of ZnO-doped carbonaceous material for the degradation of dyes and benzoic compounds.

Dye degradation and antibacterial activity of green synthesized silver nanoparticles using Ipomoea digitata Linn. flower extract

Abstract: A new greener approach for the synthesis and stabilization of silver nanoparticles using aqueous flower extract of Ipomoea digitata Linn. is reported in this study. The nature of silver nanoparticles was analyzed by various techniques. The silver nanoparticles produced a peak centered near 412 nm which confirmed the synthesis. Scanning electron microscopy portrayed the polydispersed nature of the nanoparticles, and a distinct peak at 3 keV in energy-dispersive X-ray spectrum confirmed the elemental silver. X-ray diffraction studies showed the presence of 111 reflection plane of a face-centered cubic structure. The zeta potential value was − 25.1 mV which substantiated the stability of the nanoparticles. The antibacterial potential of silver nanoparticles was verified using well diffusion method. The silver nanoparticles appreciably inhibited growth of multi-drug resistant bacteria like Escherichia coli and Staphylococcus epidermidis. The nanoparticles also exhibited a good catalytic reduction for methylene blue dye in the presence of NaBH4. It followed a pseudo-first order kinetics with a rate constant of 0.1714 min−1.

Radiation shielding properties of some ceramic wasted samples

Abstract: The radiation has great importance in human life; it enters into various fields of agricultural, industrial, medical and food sterilization, for example, in the medical field, X-ray is used to diagnose many cases of a disease. The exposure to radiation has great risks to human life and must be protected against it. There are several ways to protect the human body from radiation; one of these ways is shielding; in the present work, eight types of ceramic materials have been used as a shielding material and tested against gamma ray, each type of ceramic modified as glazed and unglazed. The radiation sources 137Cs and 60Co were used to calculate attenuation coefficients and half-value layers by gamma-ray spectrometer system with scintillation detector NaI(Tl). The obtained results show that the photon attenuation coefficient for all samples decreases with increasing energy, while half-value layers increase with increasing energy. The results of the study showed that glazed ceramics are better than unglazed in the attenuation of gamma radiation which makes their use of shielding better.

Parametric study of electro-Fenton treatment for real textile wastewater, disposal study and its cost analysis

Abstract: Treatment of real textile wastewater by electro-Fenton method was investigated using Ti/RuO2 electrodes. The performance of the treatment process was evaluated in terms of %chemical oxidation demand removal; %color removal; and energy consumed, at three electro-Fenton process parameters: current, electrolysis time and ferrous sulfate concentration. To determine the optimum operating conditions, multiple responses optimization based on Box–Behnken design with desirability function was used. The optimum value of parameters were found to be current= 0.32 A, time = 90 min and ferrous sulfate concentration = 0.53 mM. Box–Behnken design suggested the %chemical oxidation demand removal; %color removal; and energy consumed were 100%, 90.30% and 1.27 Wh, respectively at optimized process parameters. The predicted performance parameters agree well with the experimental data. Second-order kinetic model was fitted to the experimental data, at optimum conditions. GC–MS analysis confirmed that dye components were totally eliminated after electro-Fenton treatment of textile effluent. To determined the toxicity of the treated textile effluent bioassay analysis was performed. It was identified that the generated by-products were non-toxic in nature. The total cost to treat the 1 m3 of real textile wastewater by electro-Fenton at optimum conditions was $ 3.13.

Removal of organic pollutants from wastewater using chitosan: a literature review

Abstract: The production of organic effluents derives from several industry areas, and the increase of this production accompanied those industries growth. The components of those effluents have high toxicity, which may cause serious damages to the affected environment. For this reason, the research for alternative materials (derived naturally or from industrial residues) for wastewater treatment has increased. Thus, biopolymers, such as chitosan, are a sustainable alternative, since they come from renewable and biodegradable sources. Chitosan has properties, such as adsorption capacity and flocculation and coagulation abilities, which allow it to replace, partially or completely, synthetic materials. Several methods have been applied for the treatment of those organic effluents in order to achieve their maximum limit for wastewater disposal or reuse set in each country. Among those treatments, adsorption can be considered the most advanced and efficient for residual treatment, removing selectively several organic compounds. Therefore, this paper reviewed the applicability of chitosan in phenol and oil removal from industrial effluents. Several authors highlighted its use as an environmentally friendly alternative, once chitosan presented a pollutant removal capacity similar or even better than those commonly used materials. The majority of the studies reviewed indicated the best condition for adsorptive capacity of natural or modified chitosans at acidic pH, due to the great influence of the electrostatic attraction mechanism. In addition, the review encourages further researches for more in-depth studies such as those of mechanism of adsorption, simultaneous pollutant adsorption and industrial-scale process.

A review on positive and negative impacts of nanotechnology in agriculture

Abstract: Nanotechnology holds huge potentials in several fields and is envisaged as a technology to lead the way toward sustainable environment-friendly development in the coming years. The basic theme of nanotechnology is to use particles having size in nanometer range for various applications in medical fields, cosmetics industry, and agriculture and food technologies. The benefits associated with nanotechnology include among others increase in yield and quality of produce in agriculture, improved cosmetic products, directed delivery of medicines and sensor applications. Advancement in the development of nanosensors has made recognition of disease causing elements, toxins and nutrients in foods, and elements in environmental samples, easier and cost effective. However, immense focus on nanotechnology in past few decades has led to its unrestricted development and consequently enormous use of nanoparticles (NPs). It is considered that NPs may pose risks to the environment and biological systems. It is also becoming evident that the size, structure and type of nanomaterials, such as graphene/graphene oxide with gold NPs, carbon and carbon nitride nanotubes, have different effects on plants and environment. Hence, long-term life cycle analyses are needed to assess impacts of NPs. This review presents a brief overview of applications of nanomaterials in agriculture and discusses its positive and negative aspects in agricultural field. The review emphasizes that future development of nanotechnology must be based on scientific evaluations of benefits and risks associated to it in long term.

Marine shell industrial wastes–an abundant source of chitin and its derivatives: constituents, pretreatment, fermentation, and pleiotropic applications-a revisit

Abstract: Unscientific dumping of shellfishery waste is a major environmental concern worldwide and a serious threat to the coastal area. The shell wastes constitute of many commercially valuable products, such as, chitin, calcium carbonate, proteins, and carotenoids. Processing of shell wastes is a source of wealth. Chitin is one of the constituents of the shell wastes and also the most abundant biopolymer next to the cellulose. Calcium carbonate and proteins are the other valuable constituents of the shell wastes and can serve as a better animal feed supplement. Extraction of chitin and other valuable products from a complex mixture is cumbersome and requires consecutive pretreatment processes. Both chemical and fermentation routes of pretreatment strategies have been adopted to extract the chitin from the shell wastes, which are critically reviewed with their merits and demerits. The application of process intensification techniques, such as ultrasonication and microwave radiation, is also emphasized along with the recent advancement in the field of pretreatment processes. Pleiotropic industrial applications of chitin and its analogues are also discussed.

Decolorization and removal of toxicity of textile azo dyes using fungal biomass pelletized

Abstract: Industrialization and other human impacts have placed increasing pressure on aquatic environments, with the generation of large quantities of toxic aqueous effluents containing different substances, such as synthetic dyes and other organic pollutants. It is estimated that between 10 and 15% of all dyes used in textile processes and other industries are discharged into wastewater, causing extensive aquatic pollution. Biological methods have been employed for the removal of color and toxicity from effluents containing azo dyes. Therefore, biosorption tests were performed with the dyes Acid Blue 161 e Procion Red MX-5B in simple and binary solutions, whereas biodegradation treatment was performed with the dyes only in binary solution. For biosorption, the dyes were removed by the fungi Aspergillus niger, Aspergillus terreus and Rhizopus oligosporus. The fungal biomass demonstrated good adsorption capacity to these compounds. The elimination of the toxicity of the solution after biosorption demonstrated the effectiveness of the treatment. Intense molecular changes after biodegradation treatment with the A. terreus fungus were demonstrated by the FTIR analysis. However, toxicity tests with Lactuca sativa seeds and Artemia salina nauplii indicated the presence of highly toxic metabolites in the reaction medium at the end of the treatment. Based on the findings, biosorption is more suitable for this type of treatment, since it was also capable of removing the molecules from the medium, with the advantage of impeding the formation of highly toxic by-products.

Re-suspension of road dust: contribution, assessment and control through dust suppressants—a review

Abstract: High level of particulate matter pollution in the urban areas of major cities is significantly affecting the human health due to its toxic chemical constituents. Re-suspension of road dust along with tyre and brake wear are the dominant sources of PM pollution in the urban area in both developed and developing countries. This paper mainly reviews the contribution of road dust in ambient PM level, factors affecting re-suspension of road dust and chemical reagents available for dust suppression. The emission of road dust re-suspension significantly varies based on amount of silt deposited on the road, type of road (paved and unpaved road, concrete material of the paved road), number and types of vehicles movement. The chemical reagent such as calcium magnesium acetate, magnesium chloride and calcium chloride are reported to significantly reduce the PM emissions from road dust in developed countries. Therefore, the efficacy of these chemicals in reducing the road dust from the urban road in developing countries needs to be evaluated along with the cost–benefit analysis and comparison with the conventional approach of dust control (road cleaning and washing). However, the associated factors in different countries may vary significantly as compared to Western countries.

Preparation and optimization of multifunctional electrospun polyurethane/chitosan nanofibers for air pollution control applications

Abstract: Urban air pollution caused by fine particles, the increasing development of nanotechnology and the spread of contagious diseases, as well as bioterrorism, has raised concerns about aerosols and bioaerosols. This research aims to study the effect of various parameters on the diameter and uniformity of electrospun polyurethane/chitosan nanofibers and to evaluate their filtration performance and antimicrobial activity against nanoaerosols and Escherichia coli (E. coli) bacteria as a model bioorganism, respectively. Using response surface methodology, the main and interactive effects of four parameters including polyurethane/chitosan weight ratio, applied voltage, needle tip-to-collector distance and polymer flow rate were investigated on the mean diameter and uniformity of electrospun nanofibers. The nanoparticle filtration efficiency of the polyurethane/chitosan electrospun nanofiber filter was determined after preparation under recommended optimum conditions using a standard filtration test rig. There was an increase in the mean diameter of nanofibers and decrease in the uniformity of them with increase in polyurethane polymer solution concentration. The mean diameter of nanofibers decreased significantly with increasing applied voltage and chitosan content in polyurethane/chitosan blended polymer solution. A significant, positive correlation was seen between needle tip-to-collector distance, polymer flow rate and the mean diameter of nanofibers. The prepared nanofiber filters showed an acceptable range of quality factor and pressure drop for using in filtration applications such as industrial filtration processes and personal respiratory protection equipment. The results of the performing bacterial disk diffusion method indicated that electrospun polyurethane/chitosan nanofibers have good antibacterial activity against E. coli bacteria as a model microorganism.

Fate of the nanoparticles in environmental cycles

Abstract: Nanoparticles (NPs) are ubiquitous in everyday life. Due to their physicochemical, bespoken properties, they are currently exploited in a large amount of professional, recreational and daily-care items. Textiles, building materials, sunscreens, household cleaning products, agrochemical-specific biomolecules, tattoo inks are all sources of NPs. Inevitably the extended employment of NPs has an impact on the environment, which depends not only on their properties, but also on the method used for their disposal and on the physical and biochemical characteristics of the disposal location. These parameters eventually determine both the NPs bioaccumulation and their ecotoxicity. In this review, the environmental fate of the most commonly used NPs, i.e., Ag-NPs, ZnO-NPs and TiO2-NPs, are overviewed, taking into account the most up-to-date studies. Furthermore, the issues related to the trophic transfer and to the current nanomaterial regulations are reported.

District flood vulnerability index: urban decision-making tool

Abstract: Flood vulnerability assessment as an essential part of the urban flood management is done by various methods by several researchers. In fact, the improvement in assessment methods is related to the necessity for enhanced decision-making procedures; for instance, economic or infrastructural investments in cities can be assigned in the best form. To achieve this aim, introducing indices for evaluating vulnerability and identifying more vulnerable zones and then doing relevant comparisons can be useful. District flood vulnerability index (DFVI) developed by the author uses 25 indicators in its calculation. Nevertheless, it is obvious that some of these indicators have no effect on the consequences. This paper presents the results of the analysis for the selection of the most significant indicators of the DFVI construction. This index is appropriate for urban district scaling (or: the urban district scale) and the various components of flood vulnerability (social, economic, environmental and physical). DFVI was made by analyzing the indicators’ relevance and by studying the main indicators needed to depict reality of the urban district floods in an effective way. For this purpose, expert elicitation was done by Delphi and AHP method in two separate phases. Then, all these results were combined in order to construct DFVI equations. Finally, the index was implemented in Kuala Lumpur city’s districts. This paper outlines which district of cities (in this case Kuala Lumpur) are most vulnerable to flood hazard with regard to the system’s components, that is, social, physical, environmental and economic.

Detecting vegetation stress as a soil contamination proxy: a review of optical proximal and remote sensing techniques

Abstract: Soil contamination is a worldwide crisis, which diminishes food and agricultural production. Alterations in the soil environment due to soil contamination cause biophysical and biochemical changes in vegetation. Due to dynamic nature of these changes, early monitoring can permit for preventive interferences before intense and sometimes inevitable vegetation and soil problems occur. As plants are rooted in soil substrate, vegetation changes can be used as bio-indicators of soil conditions. Traditionally, vegetation changes have been usually determined by visual analysis or detected after major destructive sampling during the growth period. As the characteristics of vegetation influence its spectral properties, effective remote and non-contact detection methods offer an alternative and near real-time way for detecting plant changes, even prior to visual symptoms and negative effects appearance. The aim of the current study is to review the potential of optical proximal and remote sensing techniques at different platforms for indirect assessment of plant–soil interactions via monitoring vegetation anomalies related to soil contamination. It is strongly felt that this rapidly progressing technological direction will permit extending the use of the techniques to geology, soil science and precision agriculture and an overall broad range of applications.