Showing papers in "Environmental Engineering Research in 2020"

Microbial electrolysis cells for electromethanogenesis: Materials, configurations and operations

Abstract: Anaerobic digestion is a traditional method of producing methane-containing biogas by utilizing the methanogenic conversion of organic matter like agricultural waste and animal excreta. Recently, the application of microbial electrolysis cell (MECs) technology to a traditional anaerobic digestion system has been extensively studied to find new opportunities in increasing wastewater treatability and methane yield and producing valuable chemicals. The finding that both anodic and cathodic bacteria can synthesize methane has led to the efforts of optimizing multiple aspects like microbial species, formation of biofilms, substrate sources and electrode surface for higher production of the combustible compound. MECs are very fascinating because of its ability to uptake a wide variety of raw materials including untreated wastewater (and its microbial content as biocatalysts). Extensive work in this field has established different systems of MECs for hydrogen production and biodegradation of organic compounds. This review is dedicated to explaining the operating principles and mechanism of the MECs for electromethanogenesis using different biochemical pathways. Emphasis on single- and double-chambered MECs along with reactor components is provided for a comprehensive description of the technology. Methane production using hydrogen evolution reaction and nanocatalysts has also been discussed.

Study on isotherm, kinetics, and thermodynamics of adsorption of crystal violet dye by calcium oxide modified fly ash

Abstract: The natural Fly ash modified with calcium oxide has been employed to eliminate the crystal violet dyestuff from the simulated solution. Herein, the effect of different physicochemical factors like primary dye concentration, sorption contact time, the quantity of the adsorbent, temperature, along with initial simulated solution pH, evaluated for illustrating the mechanism of adsorption. Furthermore, the equilibrium study was conducted, and equilibrium models like Langmuir, Freundlich, and DubininRaduskevich (D-R) were fitted to obtain analytical results to endow with more insight into the process. The results acknowledged that the Langmuir model is well apt and suggests that the adsorption mechanism happens in a monolayer on the fly ash surface. Pseudo-first order, Pseudo-second order, and the intraparticle diffusion model evaluated, and the interpretation suggests the sorption method is obeying the Pseudo-second order and intraparticle diffusion model. The ascertained negative values of Gibbs free energy affirmed the unconstrained process for all symbiotic associations, and the obtained data 78.70 kJ mol enthalpy values manifested that exothermic mechanism was governing the reaction. The above assessment confirms the application of Calcium oxide pre-treated fly ash as a cheap adsorbent to eliminate the crystal violet dyestuff from the simulated solution.

Estimation of physicochemical characteristics and associated metal contamination risk in the Narmada River, India

Abstract: River Narmada is the fifth largest holy river of Madhya Pradesh (M.P) flowing in the central part of India. The river receives large quantity of untreated/partially treated wastewater enriched with heavy metals and supplementary toxic organic pollutants. This study aims to assess the water quality status in river Narmada using indices like comprehensive pollution index (CPI), heavy metal pollution index (HPI), risk assessment index (RAI) and cancer risk index (CRI), for human use. The presence of faecal coliform and high chemical oxygen demand > 20 mg/L indicates that the water is unsuitable for drinking purposes. The average CPI and HPI evaluated to be 1.98, and 1.35, respectively signifies the moderately polluted river water. Considerably, the RAI > 1 and CRI > 1 is obtained at all sampling locations that alarms the possible cancer risk to human if untreated river water is used. Principal component analysis of data confirmed pollution in the river from both natural and anthropogenic sources. The strongest Pearson correlation coefficient between Cu-Pb (0.998) and Zn-Cu (0.986) indicates the input of wastewater in the river probably from electroplating industries. The river water is unsuitable for human intake. It is required to control direct flow of wastewater in river to restore ecological health.

Bioprecipitation of calcium carbonate mediated by ureolysis: A review

Abstract: Ureolysis-driven microbially induced carbonate precipitation (MICP) is a naturally occurring process facilitated through microbial activities and biogeochemical reactions to produce calcium carbonate (CaCO3) mineral. MICP serves as an alternative ground improvement binder method to conventional technologies which is sustainable, requires low energy for its treatment process, results in a minimal carbon footprint and could offer economic benefits. In the last two decades, MICP has drawn great interest from the scientific community because of its practicality to stabilize granular soils, repair concrete cracks and remediate heavy metals. To obtain successful MICP application, it is vital to understand the conditions that favor its process. This paper, therefore, provides an overview of literature on CaCO3 precipitation mediated by ureolysis-driven MICP and its mechanism. The review includes a discussion on sources of urease enzyme from microorganisms used to induce CaCO3 crystal formation required for implementation of MCIP for ground improvement. Moreover, the key factors that influence the outcome of MICP and bio-engineering testing methods typically used to evaluate MICP performance are also highlighted. Finally, this review also provides insight on the current drawbacks (i.e. ammonium production, scale-up bioprocess and treatment cost) affecting MICP technology and recommendations for future consideration.

Removal of antibiotics from wastewater and its problematic effects on microbial communities by bioelectrochemical Technology: Current knowledge and future perspectives

Abstract: In this review, antibiotics are considered an emerging pollutant that has drawn worldwide attention in recent years. Therefore, the effective removal of antibiotic contaminants has become a hot issue in the field of environmental research. Most antibiotics applied to humans eventually enter municipal Wastewater Treatment Plants (WWTPs), because there are no appropriate commercially available pretreatment techniques. However, increasing anthropogenic activities, the high demand for animal-protein in developing countries as a nutritional alternative, and the extensive usage of antibiotics are mainly responsible for the persistence of antibiotic pollutants. One of the serious concerns regarding the presence of antibiotics in water and their potential role in exacerbating the emergence of antibiotics-resistance bacteria (ARB) and antibiotics-resistance genes (ARGs). In recent years, bioelectrochemical technologies are found promising for suppressing antibiotic contaminants through microbial metabolism and electrochemical redox reactions. Therefore, this review provides up-to-date insight research on bioelectrochemical systems (BESs), which improves the removal of the antibiotic in an efficient way. The focus of this review has been on the environmental sources of antibiotics, their health effects and possible degradation pathways, bacterial-antibiotics resistance mechanisms, and treatment of antibiotic-contained water using BES technology.

Performance and emission characteristics of biodiesel-blend in diesel engine: A review

Abstract: Many researchers delve for an alternative fuel to overcome the fossil fuel crisis. Developed countries have embarked focus on renewable energy like wind energy, geothermal, biofuel, ocean energy and solar energy. Biodiesel is considered to be one of the most felicitous one kinds of renewable energy with similar properties of diesel fuel. Biodiesel is gaining prominence due to the global fossil fuel crisis and emission control challenges. Biodiesel blends are formulated in numerous proportion with diesel to run the diesel engine and it has significantly reduced the harmful pollutants from contaminating the environment. This review paper summarizes the outcome of biodiesel blends on properties, performance and emission-quality of a diesel engine under different operating conditions. Results from the literature provide a comparative data between conventional diesel and diesel-biodiesel blend which indicates that the diesel-biodiesel blend provides shorter ignition delay and lesser heat release rate as well as slightly higher efficiency. The emissions like CO, HC and particulate matter are reduced while choosing biodiesel blends. Biodiesel blend with additives such as alcohol can be the appropriate solution for the fuel crisis. Finally, the review concludes the advantages and future scope of biodiesel as a better competent for diesel fuel.

Application and development of pyrolysis technology in petroleum oily sludge treatment

Abstract: With the enhancement of public awareness of environmental protection, the harm of oily sludge has gradually been paid attention to. As a kind of dangerous solid waste, the arbitrary disposal of oily sludge will cause quite serious harm to both the environment and human beings. Research on the treatment methods of oily sludge has become a hot spot recently. At present, treatment methods of oily sludge are various, mainly including pyrolysis, direct combustion, freeze-thaw treatment, biological treatment, solvent extraction, thermochemical cleaning, ultrasound-assisted treatment or joint technology, etc. Based on the consideration of economic benefits, social benefits and treatment difficulties, pyrolysis has been considered to be the most appropriate method for oily sludge treatment. Syngas, liquid oil and char can be obtained from pyrolysis of oily sludge, which can meet different needs. In this paper, the pyrolysis technology of oily sludge is reported in detail, including pyrolysis methods, operational parameters and pyrolysis products of oily sludge. On the basis, the advantages and limitations of oily sludge pyrolysis technology are discussed, together with the report of feasibility of pyrolysis technology of oily sludge. Moreover, the development trend of pyrolysis technology of oily sludge is prospected for the future work.

An overview of recent development in bio-oil upgrading and separation techniques

Abstract: Bio-oil produced from the fast pyrolysis/hydrothermal liquefaction is gaining popularity worldwide as the forerunner to replace fossil fuel. The bio-oil can be produced from agricultural waste, forest residue, and urban organic waste. It is also called pyrolysis oil, renewable fuel, and has the potential to be used as fuel in many applications. The application of bio-oil as transportation fuel helps to reduce the emission of greenhouse gases and to keep up the ecological balance. The bio-oil has the heating value of nearly half of the diesel fuel i.e. 16-19 MJ/kg; but, the inferior properties such as high water content, high viscosity, low pH, and poor stability hinder bio-oil application as a fuel. Thus, this paper provides a detailed review of bio-oil properties, its limitations and focuses on the recent development of different upgrading and separation techniques, used to date for the improvement of the bio-oil quality. Furthermore, the advantages and disadvantages of each upgrading method along with the application and environmental impact of bio-oil are also discussed in this article.

Silica treatment technologies in reverse osmosis for industrial desalination: A review

Abstract: Reverse osmosis (RO) is the main process of current industrial desalination, and its performance is affected by the quality of water source. Natural water contains a certain level of silica, which is originated from metal silicate in the earth crust. Due to its complexity, silica fouling is difficult to control, which often causes less efficient design of RO system for safe operation. In the present work, we review the current state of silica treatment technology in RO desalination. Silica chemistry is investigated in standpoint of the scale formation mechanism among multiple forms of silica species and its synergistic interaction with other foulants such as organic matter. Then, pretreatment methods to remove silica in the RO feed water are outlined. They include softening/coagulation, seed precipitation/aggregation, tight ultrafiltration, ion exchange, adsorbents media, and electro coagulation. We finally highlight the mitigation of RO fouling under silica rich conditions, whose concept can be implemented in different ways of antiscalant dosing, high/low pH operation, and intermediate softening of the RO concentrate, respectively. This review will provide comprehensive information and insight about the optimal operation of industrial RO susceptible to silica fouling.

Ammonia recovery from human urine as liquid fertilizers in hollow fiber membrane contactor: Effects of permeate chemistry

Abstract: The production of the existing nitrogen fertilizer is costly and less environmental-friendly. Various green technologies are currently emerging toward providing alternative options. In this study, a liquid/liquid hydrophobic hollow-fiber membrane contactor was employed at ambient temperature and natural urine pH ~ 9.7 to recover ammonium fertilizers from human urine. Results showed that permeate side chemistry was one of the major factors affecting the ammonia mass transfer. The study on the ammonia capturing performance of diluted sulfuric acid, phosphoric acid, nitric acid, and DI water confirmed that acid type, acid concentration, and permeate side operating pH were the most important parameters affecting the ammonia capturing tendency. Sulfuric acid was slightly better in capturing more ammonia than other acid types. The study also identified increasing acid concentration didn’t necessarily increase ammonia mining tendency because there was always one optimum concentration value at which maximum ammonia extraction was possible. The best permeate side operating pH to extract ammonia for fertilizer purposes was selected based on the dissociation equilibrium of different types of acids. Accordingly, the analysis showed that the membrane process has to be operated at pH > 3 for sulfuric acid, between 3.5 to 11.5 for phosphoric acid, and above 0.5 for nitric acid so as to produce their respective high-quality liquid ammonium sulfate, ammonium monophosphate/diphosphate, and ammonium nitrate fertilizer. Therefore, permeate side acid concentration, pH, and acid type has to always be critically optimized before starting the ammonia mining experiment.

Identification and characterization of low density polyethylene-degrading bacteria isolated from soils of waste disposal sites

Abstract: The current study focused on an environment friendly method for degradation of Low Density Polyethylene (LDPE) using bacteria. A total of 36 bacterial strains were isolated from waste disposal sites in which six strains showed potential biodegradation activities. In this study, we reported 2 new strains i.e. Bacillus siamensis and Bacillus wiedmannii for LDPE degradation. The percent weight loss of LDPE films for isolates was; B. siamensis (8.46 ± 0.3%), B. cereus (6.33 ± 0.2%), B. wiedmannii (5.39 ± 0.3%), B. subtilis (3.75 ± 0.1%), P. aeruginosa (1.15 ± 0.1%) and A. iwoffii (0.76 ± 0.1%) after 90 d of incubation. The LDPE films showed slight surface disruption as observed in Field Emission Scanning Electron Microscopy (FE-SEM) and Fourier Transform Infrared Spectroscopy (FTIR) showed formation of typical carbonyl peaks which were markedly reduced after incubation as measured by carbonyl index. The X-Ray Diffraction (XRD) analysis presented an increase in percent crystallinity and there was no apparent change in total carbon percentage. Different genes responsible for degradation of LDPE like Laccase (167 bp), Alk1 (330 bp) and Alk2 (185 bp) were identified in bacterial isolates and further sequenced. The low degradation values in this study indicate that LDPE degradation is a slow, continuous and time dependent process.

Plastic pollution in Bangladesh: A review on current status emphasizing the impacts on environment and public health

Abstract: Invention of the plastics has largely been considered as a boon for the modern life due to their light weight, high strength, and versatile application while being cheaper than other alternative materials. However, with the low biodegradability, over consumption, and widespread mismanagement, plastics have now become ubiquitous in all the environmental compartments and are held responsible for causing enormous pollution to air, soil, and water bodies. Bangladesh is no different from this global scenario, though there has been a little effort to assess the amount of plastic waste and its consequence which is necessary to encounter this mounting threat effectively. Taking this into consideration, current study investigates the impacts of plastic pollution including its most threatening formmicroplastics on environment and human health in Bangladesh. The study is based on critical review of existing literatures from the global perspective. It has been found that a major percentage of the used plastic is mismanaged in Bangladesh, posing a great threat to the environment and human health. This article also put forward some recommendations to tackle this pervasive problem alongside the measures already taken by the government. Overall, this work is aimed at creating an urge among the researchers to study the plastic pollution in Bangladesh comprehensively and raising a concern among the appropriate authorities to develop policies and impose necessary actions against plastic pollution before it is too late.

The fuzzy comprehensive evaluation (FCE) and the principal component analysis (PCA) model simulation and its applications in water quality assessment of Nansi Lake Basin, China

Abstract: The Fuzzy Comprehensive Evaluation (FCE) and the Principal Component Analysis (PCA) were simulated to assess water quality of the Nansi Lake Basin, China. The membership functions were established via the Nor-Half Sinusoidal Distribution Method, and the weight was calculated via the Exceeding Standard Multiple Method. To enhance the efficiency of extracting principal pollutant, the eigenequation was solved through the Jacobi Method, and the principal components were extracted based on eigenvalue, contribution ratio, accumulating contribution ratio, principal component loading and score. Water quality classification based on “National Surface Water Environmental Quality Standards of China (GB3838-2002) was used to assess the water quality. Considering the difference of the temporal and spatial distribution in average, water quality of Level I was 28.9%, 28.1%, 25.1%, 25.6%, respectively in spring, summer, autumn, and winter, which suggested that water quality in spring and summer was better than in autumn and winter. The order of water quality was Zhaoyang Lake (Level I) > Nanyang Lake (Level I) > Dushan Lake (Level III) > Weishan Lake (Level III and IV). There were four extracted principal components that can replace the fourteen pollutant indexes for assessing water quality. According to the annual mean data of the 1 principal components, the most important pollutions were heavy metals, including As (0.933), Hg (0.931), Cd (0.929), Cr(VI) (0.926), Pb (0.925), and Cu (0.534). It is proved that the combined FCE-PCA model could provide valuable information in the water quality assessment for the Nansi Lake Basin.

Surface modification of polyethylene microplastic particles during the aqueous-phase ozonation process

Abstract: Microplastics coexist with the chemical reactive oxygen species in natural waters, however, there is still a lack to elucidate the effect of these radicals on the microplastic surficial oxidation. In this study, the ozonation of polyethylene microplastics was carried out under varying ozone dosages ranging from 4 to 7 mg/min for 60, 120 and 180 min, where its ozone uptake was iodometrically compared and surficial modification was spectroscopically analyzed using FTIR and XPS. For that, the lowest ozone uptake was 16% at 4 mg/min ozone supplied for 60 min whereas the highest was observed of 44% at 7 mg/min ozone added for 180 min. Moreover, in the FTIR analysis, carbonyl (1,600-1,800 cm) and hydroxyl (3,200-3,600 cm) indices were improved more than 20% and 13% when they were ozonized at 7 mg/min for 180 min compared to 4 mg/min for 60 min, respectively. XPS also revealed that 7 mg/min of ozone supplied for 180 min provided the highest of oxygen functionalities, but while there was no significant change in C-C bond. It can be concluded that the surficial modification of PE including formation of oxygen functionalities could be more preferably influenced by the reaction time than ozone dosages.

Growth projections against set-target of renewable energy and resultant impact on emissions reduction in India

Abstract: In accordance with the Paris Climate Agreement (COP21) and Sustainable Development Goals (SDGs), India is greatly focused on deployment of renewable energy (RE) for supplementing the energy requirements of the country. The present article assesses the validity of the promises offered by RE technologies in India and its necessary action to understand the gap between setting goals and the ground situation, which can also show a pathway to other developing countries. Therefore, the long-term projection perspectives on RE growth have been made using the India Energy Security Scenario-2047. In order to achieve the set target for emissions reduction of greenhouse gases (GHGs) i.e., 1209 MT CO2e in support of SDGs to the 2005 level by 2030, three renewable growth scenarios have been tested for transitioning the Indian energy system. Accordingly, the regression analysis reveals that the most desirable growth scenario will require a steady rise of RE contribution in the overall energy mix of India by 2030 from the current ~21% to 68% of the installed capacity. In this view, the present study highlights the exploration of new alternatives in long-term energy planning, and less on one-sided scenario to achieve the emissions’ reduction target.

Evaluation of Microbially Induced Calcite Precipitation (MICP) methods on different soil types for wind erosion control

Abstract: Application methods (i.e., pouring and mixing method) of Microbially Induced Calcite Precipitation (MICP) and its effect on wind erosion were investigated on four soil types (i.e., medium sand, fine sand, loamy fine sand and loam). With mixing method, calcite precipitated evenly throughout the upper part (0 5 cm) of all the soils tested, but with pouring method, only medium sand showed even calcite distribution. The reason can be ascribed to the limited permeability of MICP-inducing solution (i.e., calcium, urea and Sporosarcina pasteurii) through loamy fine sand and loam due to their low hydraulic conductivity (i.e., < 10 cm/s). Moreover, bacterial penetrability was also reduced by calcium (i.e., 70 to 20%) in fine sand. Hence, pouring method for medium sand and mixing method for the others were applied with various MICP-inducing solution concentrations (i.e., 0.1 to 1 M of urea and calcium). When exposed to wind of 15 m/s after MICP application, 0.25 M solution in medium and fine sand, and 0.1 M solution in loamy fine sand and loam showed little or no soil loss. The results suggest that a proper application method be chosen considering soil properties that affect even calcite distribution to mitigate soil erosion.

Efficient reduction of CO 2 using a novel carbonic anhydrase producing Corynebacterium flavescens

Abstract: Emission of greenhouse gases into the atmosphere by human activities leads to global warming. To reduce the level of CO2 the bio-catalytic properties of microbial carbonic anhydrase (CA) can be exploited. The present study aimed to isolate CA producing bacteria from cow saliva. After thorough screening for CA activity in the bacterial cultures, ten isolates were selected. Out of ten bacterial isolates, T5 isolate showed the highest CA activity (83.92 U/mL) and the isolate was identified as Corynebacterium flavescens using 16s rRNA analysis. Various production parameters for the optimum production of CA were optimized. During the optimization, incubation temperature 40°C, agitation speed 120 rpm, and inoculum volume 4%v/v was found to be optimum for CA production. The optimum reaction pH, reaction time and temperature were 7, 10 min and 35°C, respectively. The crude enzyme was tested for the conversion of CO2 into the calcium carbonate (CaCO3) under controlled conditions. The CO2 conversion efficacy of crude CA was observed to be ~45 mg CaCO3/mg protein. The synthesized CaCO3 was analyzed using scanning electron microscopy and X-ray diffraction techniques for particle size, morphology and elemental structure. Calcite precipitation by bacterial CA makes it a potential candidate to be effectively employed in biomimetic CO2 sequestration.

Evaluation of physicochemical and heavy metals characteristics in surface water under anthropogenic activities using multivariate statistical methods, Garra River, Ganges Basin, India

Abstract: Water samples from twenty-six locations were collected during March 2014, to evaluate the spatial variation in the water quality of Garra River, Ganges Basin. The physicochemical and heavy metals concentration along the river water were significantly different between the natural and urbanized areas. In the case of the mainstream, the chemical oxygen demand (COD) and the biological oxygen demand (BOD5), which indicate the levels of organic pollution of the river water, were in the range of 8.1 51.4 mg/L and 5.8 – 26.9 mg/L, respectively. On the other hand, in the case of tributaries, these values were in the range of 19 – 36 mg/L and 11.2 – 20 mg/L, respectively. Multivariate statistical analysis was also carried out to discriminate sources of spatial variation of water quality. The results of principal component analysis (PCA) show the relationship between physicochemical parameters suggesting that the quality of water is mostly controlled by carbonate weathering. Dolomite is most likely to be present, which is a common source of Ca and Mg. Spatial distribution of PO4 with a high concentration in the downstream area of river (average 0.35 mg/L) suggests runoff from agricultural fields in this region as the main source.

Experimental and neural network modeling of micellar enhanced ultrafiltration for arsenic removal from aqueous solution

Abstract: The optimization of micellar-enhanced ultrafiltration (MEUF) of arsenic (As) contaminated aqueous solution using cetylpyridinium chloride (CPC) as surfactant was studied through experimental and artificial neural network (ANN) modeling. Experimental studies were carried out by varying operational conditions such as time, pressure, molar ratio of CPC to As, concentration of As and pH of feed solution. Root mean square error (RMSE) and coefficient of determination (R) were considered as performance criterion to evaluate the predicted results of ANN model. The experimental studies provided optimum operating parameters such as pressure 1.8 bar, molar ratio of CPC to As was 5:1, As concentration 1 mM and pH 8.0 of feed solution. ANN model presented reliable results with RMSE values 0.259, 0.553 and 0.623 for training, validation and testing datasets, respectively, while R values for training, validation and testing dataset were noted as 0.962, 0.942 and 0.932, respectively. The proposed ANN model traced input-output relationship to predict As removal efficiency (RE) of MEUF process. Therefore, ANN model can be considered as a competitive, powerful and fast alternate because of its high computational speed, accuracy and economics in MEUF process optimization without doing laborious experimental work.

A review on metal organic frameworks (MOFs) modified membrane for remediation of water pollution

Abstract: Porous metal-organic frameworks (MOFs) have received wide attention on the potential application to separation of pollutants from contaminated water to produce clear water. Recently, the report on MOFs modified membrane in pollution separation is very interesting. The main focus is that adding MOFs onto the surface of the membrane can significantly improve its separation performance and anti-fouling ability. This review took the opportunity to give readers a preliminary and detailing understanding of the basic knowledge of the MOFs modified membrane used in remediation of water pollution.

Paracetamol degradation and kinetics by advanced oxidation processes (AOPs): Electro-peroxone, ozonation, goethite catalyzed electro-fenton and electro-oxidation

Abstract: The advanced oxidation of paracetamol (PCT), frequently used analgesic, promoted by electro-oxidation (EOX), goethite catalyzed electro-Fenton (GEF) with goethite, ozonation and electro-peroxone (E-peroxone) was investigated. The degradation efficiency of the processes was evaluated considering the decay of PCT versus time. All the processes showed pseudo-first order character for PCT degradation. kobs values, at optimum conditions for an individual process, were defined as 0.0022, 0.0029, 0.0870 and 0.1662 min for EOX, GEF, ozonation and E-peroxone processes, respectively. Where EOX and GEF processes showed poor degradation efficiencies, novel E-peroxone process provided complete removal of PCT. The degradation of the PCT would mostly occur by OH and molecular O3 due to the higher rate constants achieved at E-peroxone and ozonation. Conversely, with lower kobs values gained at EOX, hydroxyl radicals would not contribute noticeably to the PCT degradation. In GEF process, due to relatively lower OH production rate, lower kobs values were obtained for the degradation of PCT. The formation of reaction intermediates, aromatics and carboxylic acids, was also determined in this study.

An overview of the hydropower production potential in Bangladesh to meet the energy requirements

Abstract: Current environmental catastrophes generating from fossil fuel power generation has attracted the attention of energy planners to look for sustainable energy sources. Hydropower is one of the oldest energy sources that have been utilized all over the world to generate electricity, especially in remote areas. Being one of the most densely populated countries, the majority of power demand is fulfilled from fossil fuel. Despite having lots of rivers, Bangladesh has not explored its true potential. So, this paper presents a comprehensive review of the current hydropower potential in Bangladesh. Locations having hydropower potential is evaluated. Different technologies used for hydropower generation have been reviewed. Moreover, global hydropower potential has also been discussed in this study. Based on the economic and environmental study, it is found that small scale hydropower is most feasible in Bangladesh to provide sustainable energy. With a reasonable flow rate, 232 rivers of Bangladesh can be utilized small scale hydropower generation as well as ensuring energy security for remote people. The current study is believed to provide useful information in advancing the generation of hydropower based electricity in Bangladesh.

Low cost nanoparticles derived from nitrogen fertilizer industry waste for the remediation of copper contaminated soil and water

Abstract: The goal of this study was to produce a novel nano-scale material from nitrogen fertilizer industry byproduct (nNFIB) and assess its capability to remediate Cu contaminated wastewater and soil. The novel nNFIB was produced using planetary mono mill and characterized. Equilibrium and kinetics studies of Cu sorption by nNFIB were performed in batch system. The effects of a variety of factors, including pH, coexisting ions and adsorption time on Cu adsorption were investigated. Furthermore, Cu sequestration mechanism onto nNFIB was investigated using sequential extraction technique and Fourier transform infrared (FTIR) spectra before and after nNFIB adsorption. The Cu sorption equilibrium and kinetics data were successfully described by Langmuir and first-order models, respectively. The calculated maximum Cu(II) adsorption capacity (qmax) of nNFIB (100 mg g−1) was four times higher than qmax of bulk NFIB. Copper removal by nNFIB was quite fast (around 86%) in the first 5 min and gradually slowed down until achieved 100% removal at equilibrium time. The FTIR spectra and Cu fractionation data in biosolid-amended soil demonstrated that Cu sequestration in contaminated water and soil is strongly related to CaCO3 of nNFIB. The overall findings show the potential use of nNFIB as a best management practice for Cu removal from wastewater and Cu stabilization in contaminated biosolid-amended soils.

Toward greener membranes with 3D printing technology

Abstract: 3D printing has recently influenced membrane science. As a green alternative to current membrane fabrication methods, 3D printing prevents the mixing of highly toxic chemicals into water through its sustainable production. Furthermore, the risk of exposure to these toxic materials and of mechanical accidents during the fabrication is also attenuated. This type of in-situ fabrication eliminates logistic-based problems caused by transportation and packaging. Eliminating packaging and reducing transportation and precision-based waste also reduces CO2 emissions. The advantages of 3D-printed membranes are correlated with each other and promote a greener environment. In this article, we collect their contributions under the sub-titles of sustainability, risk reduction, cost-effectiveness, precision and mobility.

Progress in bioremediation of pesticide residues in the environment

Abstract: The increasing use of various pesticides (e.g., organophosphate, organochlorine, carbamates, and pyrethroid) has helped to improve agricultural productivity by minimizing the potential crop losses associated with insect attacks. Owing to their highly recalcitrant nature, most pesticides and their residues often accumulate in the environment to exert deleterious effects on human health and various ecosystems. Among a variety of remediation options, biological approaches have attracted a widespread attention for the treatment of pesticide in soil/water systems due to their environmentally benign nature. In this regard, this review article was organized to highlight the recent advancements in the application of various bioremediation approaches for the degradation/removal of pesticides from soil/water matrixes along with the catabolic capacity of microorganisms. Our discussions were expanded further to emphasize identification of specific bacterial communities/strains, such as Bacillus sp. and Pseudomonas sp. This review is expected to provide an overview of the modern biotechnological methodologies along with the associated merits and hurdles for the effective abatement of pesticides.

Photocatalytic degradation of flumequine by N-doped TiO 2 catalysts under simulated sunlight

Abstract: Flumequine (FLU) is one of the most used fluoroquinolone antibiotics in intensive aquaculture, however, it has become a typical pollutant in water environment at present due to inappropriate use. Therefore, it is necessary to develop facile techniques for efficient degradation of FLU. In this work, three N-doped TiO2 photocatalysts were synthesized for degradation of FLU. The obtained photocatalysts were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectrum and UV-Vis diffuse reflection spectra (UV-Vis-DRS). The XRD and XPS results from NH4NO3-doped catalyst (TiO2/AN) confirmed that NO3 ions were successfully incorporated into the lattice of TiO2. The TiO2/AN sample exhibited higher photocatalytic performance than other N-doped catalysts under simulated sunlight irradiation, and 100% removal efficiency of FLU was achieved after 4 hours of illumination. The photogenerated holes (h) and hydroxyl radicals (OH) are main reactive species involved in the photocatalytic degradation of FLU. Eight intermediates for photocatalytic degradation of FLU were detected and their toxicities to aquatic organisms were predicted. This study might have important implications for further research on the removal of fluoroquinolone antibiotics in wastewater.

Potential of Carica papaya peels as effective biocatalyst in the optimized parametric transesterification of used vegetable oil

Abstract: This study investigates the effectiveness of a base heterogenous catalyst derived from waste Carica papaya peels in the transesterification of used vegetable oil (UVO). The calcined Carica papaya peels (CCPP) were characterised using scanning electron microscope-energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The EDX result indicated that the ash contains various minerals with potassium (K) as the main active element in remove for the charge of the high catalytic activity. Response surface methodology (RSM) based on the Box Behnken design (BBD) was used to optimise and investigate the effect of the critical process parameters which include: the reaction time (50 – 70 min), catalyst loading (2.5 – 4.5 wt%) and methanol-to-oil molar ratio (9:1 – 15:1). The optimal reaction condition for the transesterification process was found to be catalyst loading of 3.5 wt%, methanol/oil molar ratio of 12:1, process reaction time of 60 min at constant reaction temperature of 65 C which resulted in the maximum biodiesel yield of 97.5 wt%. The quality of the produced biodiesel was in agreement with ASTM standards. The catalyst was reused up to three times with minimal decrease in the catalytic activity in the biodiesel conversion. The study demonstrates the potential of waste biomass feedstocks in the production of sustainable biodiesel fuel.

Analysis of disaster resilience of urban planning facilities on urban flooding vulnerability

Abstract: Rainfall continues to increase due to the influence of global warming and is resulting in an increase in flood damage. The purpose of this study is to propose an approach for reducing urban flood damage and improving urban resilience. Urban flooding vulnerability analysis used land use and building characteristics as evaluation indicators. Disaster resilience analysis of urban planning facilities focused on urban and spatial aspects. The results of these analyses were overlapped to analyze whether urban planning facilities were properly located in areas vulnerable to urban flooding. The result of mapping the two results showed that there are some urban planning facilities with low resilience in the Red Zone, the central commercial area of Changwon, which has the highest vulnerability. This zone should have the appropriate placement of high-resilience facilities, such as disaster prevention facilities and space facilities. This study proposes a method to minimize flood damage in urban space. This system can cope with and systematically manage flood damage by increasing disaster resilience through appropriate land use planning and site selection for urban planning facilities.

Thermal energy consumption and its conservation for a cement production unit

Abstract: The manufacturing of cement is an energy-intensive industrial process which requires huge amount of heat to be supplied at a higher value of temperature. In this paper, use of the thermal energy at different sections of clinker manufacturing in cement industry, losses and thermal energy savings have been reviewed and presented. A detailed analysis of pre heater, kiln & clinker cooler was done and possible approaches of heat recovery from major losses have been discussed for technological opportunities to maximize use of waste heat recovery. The amount of CO2 emission reduction has been presented along with the payback period for energy saving measures. The energy efficiency during clinker formation was 58.67%. Unidentified losses of 5.74% were observed for the system. The energy of 16.34% was conserved by using the waste heat recovery system for electricity generation and 1.15% was conserved by using the pyro jet burner and gunning castable of 250 mm as per our design data for the cement production unit. Overall, 75.17% of heat was utilized during the process and 24.83% was lost through stack and other activities.

Urbanization effects on surface air temperature trends in Thailand during 1970-2019

Abstract: Continued urban expansion undergone in the last decades has converted many weather stations in Thailand into suburban and urban setting. Based on homogenized data during 1970-2019, therefore, this study examines urbanization effects on mean surface air temperature (Tmean) trends in Thailand. Analysis shows that urban-type stations register the strongest warming trends while rural-type stations exhibit the smallest trends. Across Thailand, annual urban-warming contribution exhibits a wide range (< 5% to 77%), probably manifesting the Urban Heat Island (UHI) differences from city to city resulting from the varied urban characteristics and climatic background. Country-wide average urban warming contribution shows a significant increasing trend of 0.15 C per decade, accounting for 40.5% of the overall warming. This evidence indicates that urban expansion has great influence on surface warming, and the urban-warming bias contributes large fraction of rising temperature trends in Thailand. The increasing trend of annual Tmean for Thailand as a whole after adjusting urban-warming bias is brought down to the same rate as the annual global mean temperature trend, reflecting a national baseline signal driven by large-scale anthropogenic-induced climate change. Our results provide a scientific reference for policy makers and urban planners to mitigate substantial fraction of the UHI warming.