Oilfield produced water (OPW) is one of the most important by-products, resulting from oil and gas exploration. The water contains a complex mixture of organic and inorganic compounds such as grease, dissolved salt, heavy metals as well as dissolved and dispersed oils, which can be toxic to the environment and public health. This article critically reviews the complex properties of OPW and various technologies for its treatment. They include the physico-chemical treatment process, biological treatment process, and physical treatment process. Their technological strengths and bottlenecks as well as strategies to mitigate their bottlenecks are elaborated. A particular focus is placed on membrane technologies. Finally, further research direction, challenges, and perspectives of treatment technologies for OPW are discussed. It is conclusively evident from 262 published studies (1965-2021) that no single treatment method is highly effective for OPW treatment as a stand-alone process however, conventional membrane-based technologies are frequently used for the treatment of OPW with the ultrafiltration (UF) process being the most used for oil rejection form OPW and oily waste water. After membrane treatment, treated effluents of the OPW could be reused for irrigation, habitant and wildlife watering, microalgae production, and livestock watering. Overall, this implies that target pollutants in the OPW samples could be removed efficiently for subsequent use, despite its complex properties. In general, it is however important to note that feed quality, desired quality of effluent, cost-effectiveness, simplicity of process are key determinants in choosing the most suitable treatment process for OPW treatment.
Owing to their high-risk factor, many attempts have been made to remove radionuclides from water. Sr2+ ions are the target of removal by synthesized hydroxyapatite in this research. A facile method for synthesizing high-surface-area hydroxyapatite by in-situ precipitation using excess diammonium phosphate solution and without any additive was developed. The highest surface area achieved using this method was 177.00 m2/g, and the synthesized hydroxyapatite was also mesoporous. The effects of different pH, temperatures, and ion concentrations during synthesis on the properties of the hydroxyapatite were assessed, and it was found that a low temperature and high pH were optimal for synthesizing high-surface-area hydroxyapatite. The maximum strontium removal capacity of 28.51 mg/g was achieved when the pH-7.5 solution was used. This performance is competitive in comparison with previously developed synthesized materials. Synthesized hydroxyapatite could effectively remove radioactive strontium from an aqueous solution for nuclear waste management.
Palm Oil Mill Effluent (POME) treatment has always been a topic of research in Malaysia. This effluent that is extremely rich in organic content needs to be properly treated to minimize environmental hazards before it is released into watercourses. The main aim of this work is to evaluate the potential of applying natural, chemically and thermally modified banana peel as sorbent for the treatment of biologically treated POME. Characteristics of these sorbents were analyzed with BET surface area and SEM. Batch adsorption studies were carried out to remove color, total suspended solids (TSS), chemical oxygen demand (COD), tannin and lignin, and biological oxygen demand (BOD) onto natural banana peel (NBP), methylated banana peel (MBP), and banana peel activated carbon (BPAC) respectively. The variables of pH, adsorbent dosage, and contact time were investigated in this study. Maximum percentage removal of color, TSS, COD, BOD, and tannin and lignin (95.96%, 100%, 100%, 97.41%, and 76.74% respectively) on BPAC were obtained at optimized pH of 2, contact time of 30 h and adsorbent dosage of 30 g/100 ml. The isotherm data were well described by the Redlich-Peterson isotherm model with correlation coefficient of more than 0.99. Kinetic of adsorption was examined by Langergren pseudo first order, pseudo second order, and second order. The pseudo second order was identified to be the governing mechanism with high correlation coefficient of more than 0.99.
This study investigates the impact of the aggregate and individual dimensions of environmental performance (EP) on financial performance (FP), based on a dataset covering the travel and tourism industry (airlines, casinos, hotels, and restaurants) across different economic regions over the period 2003-2014. The results reveal that EP positively affects the FP in the hotel industry when aggregate EP is used. When individual dimensions of EP are considered, resource reduction is found to positively (negatively) affect the performance in the hotel (airline) industry, while product innovation positively affects the performance in the restaurant industry. Hence, the trade-off effect seems to be dominant in the airline industry, and the 'heterogeneous resources and reputation-building' hypothesis is evident in both the hotel and restaurant industries. In addition, in general, the findings support the positive moderating effect of slack resources on the relationship between the individual dimensions of EP and FP in the travel and tourism industry, and, hence, are supportive of the slack resources hypothesis. These effects, however, vary depending on the travel and tourism industry under investigation.
This research predicted the effectiveness of variety game design elements in enhancing the intrinsic motivation of users on energy conservation behaviour prior to its actual implementation to ensure cost-effective. Face-to-face questionnaire surveys were conducted at the five recognized Malaysian research universities and obtained a total of 1500 valid survey data. The collected data was run with Structural Equation Modeling (SEM) analysis using SmartPLS 3 software. The results predicted the positive effect of gamification on intrinsically motivate the users based on Self-Determination Theory (SDT). The identified nine core game design elements were found to be useful in satisfying users' autonomy, competence and relatedness need satisfactions specified by SDT. This research is useful to guide the campaign organizer in designing a gamified design energy-saving campaign and provide understanding on the causal relationships between game design elements and users' intrinsic motivation to engage on energy conservation. A game-like campaign environment is believed to be created to users by implementing the game design elements in energy-saving campaign, and subsequently users' intrinsic motivation to engage on energy conservation behaviour can be enhanced.
Carcinoscorpius rotundicauda and Tachypleus gigas may co-exist and share common spawning grounds elsewhere but at Balok (East Coast of Peninsular Malaysia), C. rotundicauda is an understudied species. Neglected as research candidate because of inaccessible spawning grounds, smaller size and less commercial value than T. gigas and also, difficulty to attain from the wild has made C. rotundicauda population status remaining unidentified at Balok. This standpoint drove the present attempt because anthropic activities like structure placement and mining are point-source for runoffs that load sediments into Balok River. While erosion-accretion events have altered Balok River width, the shore sediments in Balok Beach were transitioned between medium-fine and fine sand between years 2012 and 2016. Eventually by year 2016, the C. rotundicauda were depositing 5117 eggs in 91 nests from 200 to 1000 m range along this corridor facing South China Sea. From this yield, C. rotundicauda released 2880 eggs in 56 nests during the Southwest monsoon, 1254 eggs in 19 nests during the Northeast monsoon and 983 eggs in 16 nests during the Inter-monsoon seasons. Though female C. rotundicauda opted to lay their eggs in shallow burrows at lower shorelines, the absence of erosion and substantial silt and clay (>20%) deposition facilitates C. rotundicauda embryogenesis with brief periods of temperature and salinity shocks during day-time falling tides. This encourages C. rotundicauda to emerge with increasing abundance and carry out bi-monthly spawning at Balok Beach. In short, shore restoration initiatives like systematic boat docking, proper disposal of nets and waste and, periodic fish-catching operations were effectively led by the Balok fisher citizen scientist. This successful community joint-cooperation proves that citizen-led caretaking of degraded beaches offers marine life protection and are practical for coastal area management especially at areas where other oviparous animals such as turtles and crocodiles are harboured.
The discharge of high levels of heavy metals into the environment is of concern due to its toxicity to aquatic life and potential human health impacts. Biofiltration systems have been used in urban environments to address nutrient contamination, but there is also evidence that such systems can be effective in reducing heavy metals concentration in stormwater. However, the accumulation pattern of heavy metals and lifespan of such systems, which are important in engineering design, have not been thoroughly explored. This study investigated the accumulation patterns of lead (Pb), copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe), which are common in urban runoff, in non-vegetated filtration columns using three different types of filter media, namely sand (S), and mixtures of sand with fly ash (sand-fly ash mix, SF), and with zeolite (sand-zeolite mix, SZ). The columns were assessed in terms of infiltration rate, the mass of heavy metals accumulation at different depths, and formation of crust layer (schmutzdecke) at the surface. The results show that most of the heavy metals accumulated at the top 5-10 cm of the filter media. However, Zn was found adsorbed to a depth of 15 cm in S and SZ columns, while Mn and Fe were present in column S throughout the entire 30 cm depth of the filter media. The presence especially of Zn, Mn, and Fe in the deeper portions of the filter media before the top 5 cm layer reached its maximum adsorption capacity, hints that transport to the deeper layers is not necessarily dependent on saturation of the upper layers for these heavy metals. SF accumulated heavy metals most at the top 5 cm of the filter media layer, and retained twice the mass of heavy metals in the crust layer, compared to S and SZ columns. SF also yielded the lowest value of infiltration rate of 31 mm/h. Considering both metals accumulation and clogging potential of the filter media, the periodic maintenance of these systems is suggested to be approximately between 1.5 and 3 years.
Polyhydroxyalkanoate (PHA) is a type of polyesters produced in the form of accumulated intracellular granules by many microorganisms. It is viewed as an environmentally friendly bioproduct due to its biodegradability and biocompatibility. The production of the PHA using oil substrates such as waste oil and plant oil, has gained considerable attention due to the high product yield and lower substrate cost. Nevertheless, the PHA fermentation using oil substrate is complicated due to the heterogenous fatty acid composition, varied bio-accessibility and possible inhibitory effect on the bacterial culture. This review presents the current state-of-the-art of PHA production from oil-based substrates. This paper firstly discusses the technical details, such as the choice of bacteria strain and fermentation conditions, characteristic of the oil substrate as well as the PHA composition and application. Finally, the paper discusses the challenges and prospects for up-scaling towards a cleaner and effective bioprocess. From the literature review, depending on the cell culture and the type of PHA produced, the oil platform can have a PHA yield of 0.2-0.8 g PHA/g oil substrate, with PHA content mostly from 40 to 90% of the cell dry weight. There is an on-going search for more effective oil-utilising PHA producers and lower cost substrate for effective PHA production. The final application of the PHA polymer influences the treatment needed during downstream processing and its economic performance. PHA with different compositions exhibits varied decomposition behaviour under different conditions, requiring further insight towards its management towards a sustainable circular economy.
Seaweeds form the second largest global aquaculture product in volume, and despite rapid growth of the sector over the last 25 years, production and quality in top producing regions is becoming increasingly limited due to disease and pest outbreaks, the spread of non-native cultivars and the degradation of genetic health due to inbreeding. Most notably, the lack of biosecurity measures leading to disease and pest outbreaks are reported to cause the most significant production losses in the seaweed industry. This study uses the Knowledge, Attitude and Practice (KAP) survey tool to quantify and compare biosecurity cross-culturally, in two major red seaweed producing countries, the Philippines and Tanzania. Both countries have significantly different political contexts and the seaweed sector sits within two very different value chains. Seaweed-based commodities from these countries, however, enters the same international market for carrageenan, a thickening agent used for a variety of products globally. This study uses the KAP survey tool to assess currently-adopted biosecurity control measures and understand how potential policy strategies could be developed on an international scale. Farmers from both producing countries have good biosecurity knowledge. In Tanzania 64% farmers scored Fair or Good, and in the Philippines this was 95%. Corresponding scores in practices were lower, 85% Poor for Tanzania, and 88% Fair for the Philippines, indicating there is a lack of resources for farmers to implement additional practices. The information gathered using the KAP tool in the context of the global seaweed industry can be used to facilitate compromise between science, policy and practice whilst taking into consideration smaller-scale regional challenges. Given the results from the seaweed industry were similar to that of smallholder agricultural sectors, it is suggested that governmental programs to incentivise biosecurity in smallholder rural agriculture could be adapted for the seaweed industry. This study also demonstrates the potential use of the KAP survey, as a tool to accurately compare biosecurity challenges faced by farmers in different aquaculture sectors globally, and to encourage alignment in international approaches to aquaculture biosecurity policies.
The sustainable management of natural resources requires the consideration of multiple stakeholders' perspectives and knowledge claims, in order to inform complex and possibly contentious decision-making dilemmas. Hence, a better understanding of why people in particular contexts do manage natural resources in a particular way is needed. Focusing on mangroves, highly productive tropical intertidal forests, this study's first aim is to map the diversity of subjective viewpoints among a range of stakeholders on the management of Matang Mangrove Forest in peninsular Malaysia. Secondly, this study aims to feed the reflection on the possible consequences of the diversity of perspectives for the future management of mangroves in Malaysia and beyond. The use of the semi-quantitative Q methodology allowed us to identify three main discourses on mangrove management: i. the optimization discourse, stressing the need to improve the current overall satisfactory management regime; ii. the 'change for the better' discourse, which focuses on increasingly participatory management and on ecotourism; and iii. the conservative 'business as usual' discourse. The existence of common points of connection between the discourses and their respective supporters provides opportunities for modifications of mangrove management regimes. Acknowledging this diversity of viewpoints, reflecting how different stakeholders see and talk about mangrove management, highlights the need to develop pro-active and resilient natural resource management approaches.
Greenhouse gasses have adverse effects on global warming and air pollution and need to be optimized by minimizing the contributing factors. This work analyzes the effects of economic growth and energy resources (renewable and nonrenewable) on the emissions of greenhouse gasses (GHG). A 2000-2016 panel data from 25 developing Asian countries is analyzed through a robust Random Effect (RE) approach and Hausman Taylor Regression (HTR). Findings show a positive correlation between economic growth and energy consumption, while a 1% increase in renewable energy consumption results in a 0.193% decrease in carbon emissions. Economic growth and renewable energy are positively correlated in both the short and long term, which implies a valid feedback hypothesis. The findings indicate the significant contribution of nonrenewable energy resources to greenhouse gas emissions and the positive impact of renewable resources on greenhouse gas emissions' control. Furthermore, this study highlights the potential of developing Asian economies to preserve the environment through more robust regional environmental policies and renewable energy resources. In light of this study's findings, policymakers in Asian developing economies should develop policies on Renewable Energy infrastructure (RE) to improve GDP and reduce greenhouse gas emissions.
With climate change and urbanization, flood disasters have significantly affected urban development worldwide. In this study, we developed a paradigm to assess flood economic vulnerability and risk at the urban mesoscale, focusing on urban land use. A hydrological simulation was used to evaluate flood hazards through inundation analyses, and a hazard-vulnerability matrix was applied to assess flood risk, enhancing the economic vulnerability assessment by quantifying the differing economic value and flood losses associated with different land types. The case study of Wangchengpo, Changsha, China, found average total economic losses of 126.94 USD/m2, with the highest risk in the settlement core. Residential areas had the highest flood hazard, vulnerability, and losses (61.10% of the total loss); transportation areas accounted for 27.87% of the total economic losses due to their high flooding depth. Despite low inundation, industrial land showed greater economic vulnerability due to higher overall economic value (10.52% of the total). Our findings highlight the influence of land types and industry differences on flood vulnerability and the effectiveness of land-use inclusion in urban-mesoscale analyses of spatial flood characteristics. We identify critical areas with hazard and economic vulnerability for urban land and disaster prevention management and planning, helping to offer targeted flood control strategies to enhance urban resilience.
The central composite rotatable design (CCD) of response surface methodology (RSM) was used to optimize aluminum dispersed bamboo activated carbon preparation. The independent variables selected for optimization are activating agent (AlCl3) concentration (mol/L), activation temperature (°C), and activation time (min.). The independent variable's response change was observed through the percentage adsorption efficiency of Ciprofloxacin hydrochloride (CIP) antibiotics. The maximum CIP adsorption efficiency was found to be 93.6 ± 0.36% (13.36 mg/g) for the adsorbent prepared at AlCl3 concentration 2.0 mol/L, activation temperature 900 °C, and activation time 120 min. The adsorption efficiency was recorded at the natural pH (7.9) of the adsorbent (3 g/L)-adsorbate (50 mL solution of 50 ppm) mixture. The Al-dispersed bamboo activated carbon was characterized for its surface morphology, surface elemental compositions, molecular crystallinity, surface area, pore morphology, and surface functional groups. The mechanism of adsorbent surface formation and CIP adsorption sites were explored. The characterization data and mechanism study will help in deciding possible future applications in other fields of study.
This review article explores utilization of banana waste (fruit peels, pseudo-stem, trunks, and leaves) as precursor materials to produce an adsorbent, and its application against environmental pollutants such as heavy metals, dyes, organic pollutants, pesticides, and various other gaseous pollutants. In recent past, quite a good number of research articles have been published on the utilization of low-cost adsorbents derived from biomass wastes. The literature survey on banana waste derived adsorbents shown that due to the abundance of banana waste worldwide, it also considered as low-cost adsorbents with promising future application against various environmental pollutants. Furthermore, raw banana biomass can be chemically modified to prepare efficient adsorbent as per requirement; chemical surface functional group modification may enhance the multiple uses of the adsorbent with industrial standard. It was evident from a literature survey that banana waste derived adsorbents have significant removal efficiency against various pollutants. Most of the published articles on banana waste derived adsorbents have been discussed critically, and the conclusion is drawn based on the results reported. Some results with poorly performed experiments were also discussed and pointed out their lacking in reporting. Based on literature survey, the future research prospect on banana wastes has a significant impact on upcoming research strategy.
Advanced oxidation process involves production of hydroxyl radical for industrial wastewater treatment. This method is based on the irradiation of UV light to photocatalysts such as TiO2 and ZnO for photodegradation of pollutant. UV light is used for irradiation in photocatalytic process because TiO2 has a high band gap energy which is around 3.2 eV. There can be shift adsorption to visible light by reducing the band gap energy to below 3.2 eV. Doped catalyst is one of the means to reduce band gap energy. Different methods are used for doped catalyst which uses transition metals and titanium dioxide. The band gap energy of three types of transition metals Fe, Cd and Co after being doped with TiO2, are around 2.88 ev, 2.97ev and 2.96 ev, respectively which are all below TiO2 energy. Some of the transition metals change the energy level to below 3.2 eV and the adsorption shifts to visible light for degradation of industrial pollutant after being doped with titanium dioxide. This paper aims at providing a deep insight into advanced oxidation processes, photocatalysts and their applications in wastewater treatment, doping processes and the effects of operational factors on photocatalytic degradation.
Globally, many studies on machine learning (ML)-based flood susceptibility modeling have been carried out in recent years. While majority of those models produce reasonably accurate flood predictions, the outcomes are subject to uncertainty since flood susceptibility models (FSMs) may produce varying spatial predictions. However, there have not been many attempts to address these uncertainties because identifying spatial agreement in flood projections is a complex process. This study presents a framework for reducing spatial disagreement among four standalone and hybridized ML-based FSMs: random forest (RF), k-nearest neighbor (KNN), multilayer perceptron (MLP), and hybridized genetic algorithm-gaussian radial basis function-support vector regression (GA-RBF-SVR). Besides, an optimized model was developed combining the outcomes of those four models. The southwest coastal region of Bangladesh was selected as the case area. A comparable percentage of flood potential area (approximately 60% of the total land areas) was produced by all ML-based models. Despite achieving high prediction accuracy, spatial discrepancy in the model outcomes was observed, with pixel-wise correlation coefficients across different models ranging from 0.62 to 0.91. The optimized model exhibited high prediction accuracy and improved spatial agreement by reducing the number of classification errors. The framework presented in this study might aid in the formulation of risk-based development plans and enhancement of current early warning systems.
This paper empirically investigates the effect of carbon emissions on sovereign risk? To answer this question, we use fixed effects model by using annual data from G7 advanced economies, which includes Canada, France, Germany, Italy, Japan, UK and USA, for the period from 1996 to 2014. We employ a novel extreme value theory to measure sovereign risk. The results indicate that climate change (carbon emissions) are likely to increase sovereign risk significantly. We also expand our analysis to some specific sectors, as some of the sectors emit more carbon than others. Specifically, we take top three polluting sectors namely: transportation, electricity and industry and show that they are more likely to increase the sovereign risk. Our results are robust to change in risk measures, estimation in differences and dynamic version of econometric models. Therefore, we have robust consideration that the carbon emissions significantly explain the sovereign risk.
The year 2020 marks a crucial deadline for signatories to the Convention on Biological Diversity (CBD), the most important global agreement for biodiversity conservation, which requires nations to meet conservation targets. Managers and decision-makers need a better understanding of the policy systems established to meet conservation targets in order to inform post-2020 CBD policy implementation. This paper compares two policy systems for implementing marine protected areas (MPAs) which protect a threatened source of biodiversity, coral reefs. Comparing a centralized policy system, with power emanating from ministries (Malaysia), with a decentralized policy system, with power concentrated in subnational government (Indonesia), provides insights. Policy process literature is used to build on the already substantial interdisciplinary literature on MPAs, drawing novel insights into policy-makers and how they determine policy problems, shape policy options, and are influenced by political events. Findings are that the tropics-wide coral bleaching event in 2015-2016 fundamentally changed the way managers perceived the problems that biodiversity conservation policy solves. Managers are beginning to prioritize policy responses to climate stressors with the same urgency as historically important stressors like overfishing, implementing responses at starkly different power centers within policy systems. Non-governmental organizations (NGOs), subnational governments, and the private sector are implementing innovative policy responses in the decentralized system, while the same actors in the centralized system face constraints because of its rigid policy framework. Understanding where starkly different power centers, and related dynamism, fall within policy systems allows for more effective reforms and investments for the next iteration of the CBD.
This study investigated the engine performance and emission characteristics of biodiesel blends with combined Graphene oxide nanoplatelets (GNPs) and 10% v/v dimethyl carbonate (DMC) as fuel additives as well as analysed the tribological characteristics of those blends. 10% by volume DMC was mixed with 30% palm oil biodiesel blends with diesel. Three different concentrations (40, 80 and 120 ppm) of GNPs were added to these blends via the ultrasonication process to prepare the nanofuels. Sodium dodecyl sulphate (SDS) surfactant was added to improve the stability of these blends. GNPs were characterised using Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FTIR), while the viscosity of nanofuels was investigated by rheometer. UV-spectrometry was used to determine the stability of these nanoplatelets. A ratio of 1:4 GNP: SDS was found to produce maximum stability in biodiesel. Performance and emissions characteristics of these nanofuels have been investigated in a four-stroke compression ignition engine. The maximum reduction in BSFC of 5.05% and the maximum BTE of 22.80% was for B30GNP40DMC10 compared to all other tested blends. A reduction in HC (25%) and CO (4.41%) were observed for B30DMC10, while a reduction in NOx of 3.65% was observed for B30GNP40DMC10. The diesel-biodiesel fuel blends with the addition of GNP exhibited a promising reduction in the average coefficient of friction 15.05%, 8.68% and 3.61% for 120, 80 and 40 ppm concentrations compared to B30. Thus, combined GNP and DMC showed excellent potential for utilisation in diesel engine operation.
In recent years, water resources management has become more complicated and controversial due to the impacts of various factors affecting hydrological systems. System Dynamics (SD) has in turn become increasingly popular due to its advantages as a tool for dealing with such complex systems. However, SD also has some limitations. This review contains a comprehensive survey of the existing literature on SD as a potential method to deal with the complexity of system integrated modeling, with a particular focus on the application of SD to the integrated modeling of water resources systems. It discusses the limitations of SD in these contexts, and highlights a number of studies which have applied a combination of SD and other methods to overcome these limitations. Finally, our study makes a number of recommendations for future modifications in the application of SD methods in order to enhance their performance.