Palm oil mill effluent (POME) is a highly polluted wastewater that consists of a high organic content of 4-5% total solids; a potential renewable energy source. A waste to energy study was conducted to improve biogas production using POME as substrate by ultrasonication pretreatment at mesophilic temperatures. The effect of temperature on the specific growth rate of anaerobes and methanogenic activity was investigated. Five sets of assays were carried out at operating temperatures between 25 °C and 45 °C. Each set consisted of two experiments using identical anaerobic sequencing batch reactors (AnSBR); fed with raw POME (control) and sonicated POME, respectively. The ultrasonication was set at 16.2 min ultrasonication time and 0.88 W mL-1 ultrasonication density with substrate total solids concentration of 6% (w/v). At 25 °C, biogas production rate and organic matter removal exhibited lowest values for both reactors. The maximum organic degradation was 96% from AnSBR operated at 30 °C fed with sonicated POME and 91% from AnSBR operated at 35 °C fed with unsonicated POME. In addition, the methane yield from AnSBR operated at 30 °C was enhanced by 21.5% after ultrasonication pretreatment. A few normality tests and a t-test were carried out. Both tests indicated that the residuals of the experimental data were normality distributed with mean equals to zero. The results demonstrated that ultrasonication treatment was a promising pretreatment to positively affect the organic degradation and biogas production rates at 30-35 °C.
Chinese enterprises that conduct overseas investment projects encounter diverse challenges that emerge from political, economic, social, and environmental risks in the host countries. To better assess the overseas investment risks faced by Chinese enterprises, this study introduced and assessed novel aspects and an indicator system. Moreover, the "Technique for Order Preference by Similarity to Ideal Solution" (TOPSIS) method based on entropy weight was performed to generate a comprehensive assessment of China's foreign investment risk and natural resource potential in 63 "Belt & Road Initiative" (BRI) countries. This study aims to encourage Chinese enterprises to devise suitable overseas investment decision-making strategies concerning natural resource potential in host countries. A Geographic Information System (GIS) map was also created to assess the potential risks and opportunities for Chinese enterprises when making investment decisions in host countries. The findings indicate that the majority of countries in Central and Eastern Europe and other BRI countries such as Singapore, Malaysia, Nepal, Bhutan, Russia, Armenia, and the United Arab Emirates were the most suitable choices for Chinese enterprises engaging in overseas investment. Based on these results, Chinese enterprises could manage and execute BRI projects more effectively to minimise potential risks and maximise their investment benefits.
The ubiquitous occurrences of microplastics in the environment have raised much concern and resulted in voluminous studies related to microplastics. Studies on microplastics pollution of the marine environment have received significantly higher attention compared to those of the freshwater and terrestrial environments. With the impetus to better understand microplastics in the freshwater and terrestrial environments, this review elucidates the findings of >100 articles related to the prevalence, fates and impacts of microplastics therein and the sustainable solutions, mostly in the past 10 years. This review shows the interconnection between terrestrial and freshwater microplastics with wastewater and sewage treatment plants as the most significant contributors of environmental microplastics via sludge and effluent discharges. Microplastics in both ecosystems comprise the primary and secondary forms with the latter resulted from weathering of the former. Besides retaining in soil and infiltrating with rainwater underground, terrestrial microplastics also enter the freshwater environment. The environmental microplastics interact with the biotic and abiotic components resulting in entrainment, settlement, biofouling, degradation, fragmentation and entry into the food chain, with subsequent transfer across the food chain. The abundance of environmental microplastics is attributed to population density and urbanization though tidal cycle, storms, floods and human activities can affect their distribution. The leaching of additives from microplastics poses major health concern and sustainable solutions target at reduction of plastics use and disposal, substitution with bioplastics and wastewater treatment innovations. Further studies on classification, detection, characterization and toxicity of microplastics are necessary to permit more effective formulation of solutions.
The prevalence of multidrug-resistant Gram-negative bacteria in aquatic environments has been a long withstanding health concern, namely extended-spectrum beta-lactamase (ESBL) producing Escherichia coli. Given increasing reports on microplastic (MP) pollution in these environments, it has become crucial to better understand the role of MP particles as transport vectors for such multidrug-resistant bacteria. In this study, an incubation experiment was designed where particles of both synthetic and natural material (HDPE, tyre wear, and wood) were sequentially incubated at multiple sites along a salinity gradient from the Lower Weser estuary (Germany) to the offshore island Helgoland (German Bight, North Sea). Following each incubation period, particle biofilms and water samples were assessed for ESBL-producing E. coli, first by the enrichment and detection of E. coli using Fluorocult® LMX Broth followed by cultivation on CHROMAgar™ ESBL media to select for ESBL-producers. Results showed that general E. coli populations were present on the surfaces of wood particles across all sites but none were found to produce ESBLs. Additionally, neither HDPE nor tyre wear particles were found to harbour any E. coli. Conversely, ESBL-producing E. coli were present in surrounding waters from all sites, 64% of which conferred resistances against up to 3 other antibiotic groups, additional to the beta-lactam resistances intrinsic to ESBL-producers. This study provides a first look into the potential of MP to harbour and transport multidrug-resistant E. coli across different environments and the approach serves as an important precursor to further studies on other potentially harmful MP-colonizing species.
Although estimating the uncertainty of models used for modelling nitrate contamination of groundwater is essential in groundwater management, it has been generally ignored. This issue motivates this research to explore the predictive uncertainty of machine-learning (ML) models in this field of study using two different residuals uncertainty methods: quantile regression (QR) and uncertainty estimation based on local errors and clustering (UNEEC). Prediction-interval coverage probability (PICP), the most important of the statistical measures of uncertainty, was used to evaluate uncertainty. Additionally, three state-of-the-art ML models including support vector machine (SVM), random forest (RF), and k-nearest neighbor (kNN) were selected to spatially model groundwater nitrate concentrations. The models were calibrated with nitrate concentrations from 80 wells (70% of the data) and then validated with nitrate concentrations from 34 wells (30% of the data). Both uncertainty and predictive performance criteria should be considered when comparing and selecting the best model. Results highlight that the kNN model is the best model because not only did it have the lowest uncertainty based on the PICP statistic in both the QR (0.94) and the UNEEC (in all clusters, 0.85-0.91) methods, but it also had predictive performance statistics (RMSE = 10.63, R2 = 0.71) that were relatively similar to RF (RMSE = 10.41, R2 = 0.72) and higher than SVM (RMSE = 13.28, R2 = 0.58). Determining the uncertainty of ML models used for spatially modelling groundwater-nitrate pollution enables managers to achieve better risk-based decision making and consequently increases the reliability and credibility of groundwater-nitrate predictions.
The rapid depletion of fossil fuels and ever-increasing environmental pollution have forced humankind to look for a renewable energy source. Microalgae, a renewable biomass source, has been proposed as a promising feedstock to generate biofuels due to their fast growth rate with high lipid content. However, literatures have indicated that sustainable production of microalgae biofuels are only viable with a highly optimized production system. In the present study, a cradle-to-gate approach was used to provide expedient insights on the effect of different cultivation systems and biomass productivity toward life cycle energy (LCEA), carbon balance (LCCO2) and economic (LCC) of microalgae biodiesel production pathways. In addition, a co-production of bioethanol from microalgae residue was proposed in order to improve the economic sustainability of the overall system. The results attained in the present work indicated that traditional microalgae biofuels processing pathways resulted to several shortcomings, such as dehydration and lipid extraction of microalgae biomass required high energy input and contributed nearly 21 to 30% and 39 to 57% of the total energy requirement, respectively. Besides, the microalgae biofuels production system also required a high capital investment, which accounted for 47 to 86% of total production costs that subsequently resulted to poor techno-economic performances. Moreover, current analysis of environmental aspects of microalgae biorefinery had revealed negative CO2 balance in producing microalgae biofuels.
The environment sustenance and preservation of global climate are known as the crucial issues of the world today. Currently, the crisis of global warming due to CO2 emission has turned into a paramount concern. To address such a concern, diverse CO2 capture and sequestration techniques (CCS) have been introduced so far. In line with this, Metal Organic Frameworks (MOFs) have been considered as the newest and most promising material for CO2 adsorption and separation. Due to their outstanding properties, this new class of porous materials a have exhibited a conspicuous potential for gas separation technologies especially for CO2 storage and separation. Thus, the present review paper is aimed to discuss the adsorption properties of CO2 on the MOFs based on the adsorption mechanisms and the design of the MOF structures. In addition, the main challenge associated with using this prominent porous material has been mentioned.
Science of the Total Environment recently discussed how open access and predatory journals affect the flow of scientific knowledge in an unfortunate way. Now, South Korea's Ministry of Education is intervening to establish a system that will help its researchers avoid the growing global number of fake conferences of low academic and scientific merit. Here, we discuss solutions to this problem with respect to what is needed. Particularly, a list similar to that of Beall's for predatory conferences, without restricting researchers' academic freedom.
The increased demand for solar renewable energy sources has created recent interest in the economic and technical issues related to the integration of Photovoltaic (PV) into the grid. Solar photovoltaic power generation forecasting is a crucial aspect of ensuring optimum grid control and power solar plant design. Accurate forecasting provides significant information to grid operators and power system designers in generating an optimal solar photovoltaic plant and to manage the power of demand and supply. This paper presents an extensive review on the implementation of Artificial Neural Networks (ANN) on solar power generation forecasting. The instrument used to measure the solar irradiance is analysed and discussed, specifically on studies that were published from February 1st, 2014 to February 1st, 2019. The selected papers were obtained from five major databases, namely, Direct Science, IEEE Xplore, Google Scholar, MDPI, and Scopus. The results of the review demonstrate the increased application of ANN on solar power generation forecasting. The hybrid system of ANN produces accurate results compared to individual models. The review also revealed that improvement forecasting accuracy can be achieved through proper handling and calibration of the solar irradiance instrument. This finding indicates that improvements in solar forecasting accuracy can be increased by reducing instrument errors that measure the weather parameter.
Lead-halide perovskite nanoparticles (NPs) are a new technology, and investigation of toxicity is of considerable importance due to the potential lead (Pb) release into the environment. The aim of the study was to investigate aqueous and dietary toxicity of Pb-halide perovskite NP and Pb in zebrafish Danio rerio. Perovskite NP toxicity was evaluated in zebrafish by mortality, gene expression, histopathology, and phylogenetic analysis of gut microbiota. Zebrafish larvae were exposed to five Pb-halide perovskite NPs in parallel with Pb(NO3)2 exposures, and zebrafish adults were exposed to the three perovskite NPs that caused the strongest effect and Pb(NO3)2. No median lethal concentration (LC50) was observed for zebrafish larvae exposed to up to 200 mg/L of perovskite NPs for 96 h. Mortality, metallothionein 2 (mt2) and δ-aminolevulinic acid dehydratase (ala-d) gene expression (24-h exposure) in zebrafish larvae after aqueous perovskite NPs exposures did not differ from total Pb concentration - response curves. The lack of differences in mortality and gene expression between perovskite NPs and soluble Pb after aqueous exposure suggest that toxicity from perovskite NPs can be attributed to bioavailable Pb rather than nano-specific effects. Induction of mt2 and reduction of ala-d expression levels in liver tissues showed Pb bioavailability after 2-d and 4-d dietary exposure to perovskite-spiked feeds. Changes in gut microbiota of adult zebrafish were detected after 14-d exposure to Pb-spiked food, but no changes were detected from perovskite-NP spiked food. The phylogenetic analysis identified different microbiome profiles of Pb-fed fish compared to perovskite-fed fish suggesting a different mechanism of toxicity. Exposure to Pb-halide perovskite NPs led to absorption of Pb likely from release of Pb ions rather than absorption of NPs. Pb-halide perovskite NPs can release bioavailable Pb and this needs to be considered during the development of this technology.
Agricultural activities have been arising along with the use of pesticides. The use of pesticides can impact not only on vector or other pest but also able to harm human health. Pesticide may leach from the irrigation of plant into the groundwater and in surface water. These waters could be sources of drinking water in a pesticides polluted area. This study aims to determine the occurrence pesticides in surface water and pesticides removal efficiency in a conventional drinking water treatment plant (DWTP) and the potential health risk to consumers. The study was conducted in Tanjung Karang, Selangor, Malaysia. Thirty river water samples and eighteen water samples from DWTP were collected. The water samples were extracted using solid phase extraction (SPE) before injected to the ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). Five hundreds and ten respondents were interviewed using questionnaires to obtain information for health risk assessments. The results showed that propiconazole had the highest mean concentration (4493.1 ng/L) while pymetrozine had the lowest mean concentration (1.3 ng/L) in river water samples. The pesticides removal efficiencies in the conventional DWTP were 77% (imidacloprid), 86% (propiconazole and buprofezin), 88% (tebuconazole) and 100% (pymetrozine, tricyclazole, chlorantraniliprole, azoxystrobin and trifloxystrobin), respectively. The hazard quotients (HQs) and hazard index (HI) for all target pesticides were <1, indicating there was no significant chronic non-carcinogenic health risk due to consumption of the drinking water. Conventional DWTP was not able to completely remove four pesticide; thus, advanced treatment systems need to be considered to safeguard the health of the community in future.
The pharmaceuticals are emergent contaminants, which can create potential threats for human health and the environment. All the pharmaceutical contaminants are becoming enormous in the environment as conventional wastewater treatment cannot be effectively implemented due to toxic and intractable action of pharmaceuticals. For this reason, the existence of pharmaceutical contaminants has brought great awareness, causing significant concern on their transformation, occurrence, risk, and fate in the environments. Electrocoagulation (EC) treatment process is effectively applied for the removal of contaminants, radionuclides, pesticides, and also harmful microorganisms. During the EC process, an electric current is employed directly, and both electrodes are dissoluted partially in the reactor under the special conditions. This electrode dissolution produces the increased concentration of cation, which is finally precipitated as hydroxides and oxides. Different anode materials usage like aluminum, stainless steel, iron, etc. are found more effective in EC operation for efficient removal of pharmaceutical contaminants. Due to the simple procedure and less costly material, EC method is extensively recognized for pharmaceutical wastewater treatment over further conventional treatment methods. The EC process has more usefulness to destabilize the pharmaceutical contaminants with the neutralization of charge and after that coagulating those contaminants to produce flocs. Thus, the review places particular emphasis on the application of EC process to remove pharmaceutical contaminants. First, the operational parameters influencing EC efficiency with the electroanalysis techniques are described. Second, in this review emerging challenges, current developments and techno-economic concerns of EC are highlighted. Finally, future recommendations and prospective on EC are envisioned.
Since 5-sulfosalicylic acid (SFA) has been increasingly released to the environment, SO4--based oxidation processes using Oxone have been considered as useful methods to eliminate SFA. As Co3O4 has been a promising material for OX activation, the four 3D Co3O4 catalysts with distinct morphologies, including Co3O4-C (with cubes), Co3O4-P (with plates), Co3O4-N (with needles) and Co3O4-F (with floral structures), are fabricated for activating OX to degrade SFA. In particular, Co3O4-F not only exhibits the highest surface area but also possesses the abundant Co2+ and more reactive surface, making Co3O4-F the most advantageous 3D Co3O4 catalyst for OX activation to degrade SFA. The mechanism of SFA by this 3D Co3O4/OX is also investigated and the corresponding SFA degradation pathway has been elucidated. The catalytic activities of Co3O4 catalysts can be correlated to physical and chemical properties which were associated with particular morphologies to provide insights into design of 3D Co3O4-based catalysts for OX-based technology to degrade emerging contaminants, such as SFA.
Interest in biodiesel research has escalated over the years due to dwindling fossil fuel reserves. The implementation of a carbon-based solid acid catalyst in biodiesel production eradicates the separation problems associated with homogeneous catalysis. However, its application in the glycerol-free interesterification process for biodiesel production is still rarely being studied in the literature. In this study, novel environmentally benign catalysts were prepared from oil palm empty fruit bunch (OPEFB) derived activated carbon (AC) which is sustainable and low cost via direct sulfonation using concentrated sulfuric acid. The effects of synthesizing variables such as carbonization and sulfonation temperatures with different holding times towards the fatty acid methyl ester (FAME) yield in interesterification reaction with oleic acid and methyl acetate were investigated in detail. It was found that the optimum carbonization temperature and duration together with sulfonation temperature and duration were 600 °C, 3 h, 100 °C and 6 h, respectively. The catalyst possessed an amorphous structure with a high total acid density of 9.0 mmol NaOH g-1 due to the well-developed porous framework structure of the carbon support. Under these optimum conditions, the OPEFB derived solid acid catalyst recorded an excellent catalytic activity of 50.5% methyl oleate yield at 100 °C after 8 h with 50:1 methyl acetate to oleic acid molar ratio and 10 wt% catalyst dosage. The heterogeneous acid catalyst derived from OPEFB had shown promising properties that made them highly suitable for cost-effective and environmental-friendly glycerol-free biodiesel production.
Complete degradation of azo dye has always been a challenge due to the refractory nature of azo dye. An innovative hybrid system, constructed wetland-microbial fuel cell (CW-MFC) was developed for simultaneous azo dye remediation and energy recovery. This study investigated the effect of circuit connection and the influence of azo dye molecular structures on the degradation rate of azo dye and bioelectricity generation. The closed circuit system exhibited higher chemical oxygen demand (COD) removal and decolourisation efficiencies compared to the open circuit system. The wastewater treatment performances of different operating systems were ranked in the decreasing order of CW-MFC (R1 planted-closed circuit) > MFC (R2 plant-free-closed circuit) > CW (R1 planted-open circuit) > bioreactor (R2 plant-free-open circuit). The highest decolourisation rate was achieved by Acid Red 18 (AR18), 96%, followed by Acid Orange 7 (AO7), 67% and Congo Red (CR), 60%. The voltage outputs of the three azo dyes were ranked in the decreasing order of AR18 > AO7 > CR. The results disclosed that the decolourisation performance was significantly influenced by the azo dye structure and the moieties at the proximity of azo bond; the naphthol type azo dye with a lower number of azo bond and more electron-withdrawing groups could cause azo bond to be more electrophilic and more reductive for decolourisation. Moreover, the degradation pathway of AR18, AO7 and CR were elucidated based on the respective dye intermediate products identified through UV-Vis spectrophotometry, high-performance liquid chromatography (HPLC), and gas chromatograph-mass spectrometer (GC-MS) analyses. The CW-MFC system demonstrated high capability of decolouring azo dyes at the anaerobic anodic region and further mineralising dye intermediates at the aerobic cathodic region to less harmful or non-toxic products.
Tropical peatland degradation due to oil palm plantation development has reduced peat's ability to naturally regulate floods. In turn, more severe and frequent flooding on peatlands could seriously impair plantation productivity. Understanding the roles of peatland ecosystems in regulating floods has become essential given the continued pressure on land resources, especially in Southeast Asia. However, the limited knowledge on this topic has resulted in the oversimplifications of the relationships between floods, commercial plantations and peatland sustainability, creating major disagreement among policymakers at different levels in governments, companies, NGOs and society. Hence, this study identifies whether flood policies are integrated within peatland management through a qualitative policy analysis of publicly available papers, government reports, and other official documents that discuss flooding, and/or more in general, hydrology in peatlands. Document analysis was then triangulated with data obtained from several semi-structured discussions. The analysis indicates that the industry on peatlands and the peatland's environmental sustainability could be threatened by increased flooding. We show that, in spite of this, flood policies in SE Asian countries like Malaysia and Indonesia have not been well-integrated into peatland management. We also discuss how the countries could move forward to overcome this problem.
The Southeast Asian (SEA) region is no stranger to forest fires - the region has been suffering from severe air pollution (known locally as 'haze') as a result of these fires, for decades. The fires in SEA region are caused by a combination of natural (the El Niño weather pattern) and manmade (slash-and-burn and land clearing for plantations) factors. These fires cause the emissions of toxic aerosols and pollutants that can affect millions of people in the region. Thus, this study aims to identify the impact of the SEA haze on the Southern region of the Malaysian Peninsula and Borneo region of East Malaysia using the entire air quality observation data at surface level in 2015. Overall, the concentration of PM10 was about two-fold higher during the haze period compared to non-haze period. The concentrations of CO, flux of CO and flux of BC were aligned with PM10 during the entire observation period. The wind field and cluster of trajectory indicated that the Southern Malaysian Peninsula and Borneo were influenced mainly from the wildfires and the combustion of peat soil in the Indonesian Borneo. This study finds that wildfires from Borneo impacted the Southern Malaysian Borneo more seriously than that from Sumatra region.
The evaluation of the importance of having accurate and representative stations in a network for river water quality monitoring is always a matter of concern. The minimal budget and time demands of water quality monitoring programme may appear very attractive, especially when dealing with large-scale river watersheds. This article proposes an improved methodology for optimising water quality monitoring network for present and forthcoming monitoring of water quality under a case study of the Selangor River watershed in Malaysia, where different monitoring networks are being used by water management authorities. Knowing that the lack of financial resources in developing countries like Malaysia is one of the reasons for inadequate monitoring network density, to identify an optimised network for cost-efficiency benefits in this study, a geo-statistical technique coupled Kendall's W was first applied to analyse the performance of each monitoring station in the existing networks under the monitored water quality parameters. Second, the present and future changes in non-point pollution sources were simulated using the integrated Cellular Automata and Markov chain model (CA-Markov). Third, Station Potential Pollution Score (SPPS) determined based on Analytic Hierarchy Process (AHP) was used to weight each station under the changes of non-point pollution sources for 2015, 2024, and 2033 prior to prioritisation. Finally, according to the Kendall's W test on kriging results, the weights of non-point sources from the AHP evaluation and fuzzy membership functions, six most efficient sampling stations were identified to build a robust network for the present and future monitoring of water quality status in the Selangor River watershed. This study proposes a useful approach to the pertinent agencies and management authority concerned to establish appropriate methods for developing an efficient water quality monitoring network for tropical rivers.
Increasing trade cooperation under the Belt and Road (B&R) Initiative has promoted economic development and intensified the water scarcity risk transmission between China and countries along the route (B&R countries). Local water scarcity risk (LWSR, the potential direct production losses induced by local water scarcity) can transcend geographical boundaries through global supply chains and influence production activities in downstream economies. To understand the vulnerability of the Initiative to water scarcity, we investigated the impacts of LWSR in China and B&R countries on each other's economies during 2001-2013, using a global environmentally extended multi-regional input-output model. Results reveal that more than 80% of China's trade-related water scarcity risk imports (TWSR imports, the vulnerability to foreign water scarcity risk through imports) originates from B&R countries. The share of TWSR from China in total imports of B&R countries has steadily increased. In particular, India, Thailand, Iran, Pakistan and Kazakhstan have the largest TWSR exports (LWSR in each nation transmitted to other nations through its exports) to China, while South Korea, Thailand, Malaysia, Singapore and Indonesia have the largest imports from China. Water scarcity to their Agriculture sectors is responsible for TWSR transmission between them. Our study can contribute to the policy-making of governments and firms involved in mitigating the supply chain wide water scarcity risk. It also reveals the need for nations to collectively manage water resources to achieve sustainable development.
Pharmaceuticals in aquatic environment have raised wide attention in recent years due to their potential adverse effects and bioaccumulation in biota. China has been a major producer and consumer of pharmaceuticals, however, the potential human health risk of these chemicals is yet to be determined in China. In this study, we evaluated available exposure data for twenty pharmaceuticals in surface waters from Chinese five major river basins (the Yangtze, Haihe, Pearl, Songliao, and Yellow River Basins), and human health risk assessment was performed. Based on the concentration data and risk data, we conducted research on the source, cause, and control measures of the pharmaceuticals. The twenty pharmaceuticals were found to be ubiquitous in China with median concentrations between 0.09 and 304 ng/L. The estimated daily intake of pharmaceuticals from drinking water and eating fish was calculated. The intake via drinking water was significantly lower than that via eating fish. The risk quotients via water intake and fish consumption ranged from 0 to 17.2, with estrogen and sulfapyridine highest among the twenty pharmaceuticals. High risks of exposure were mainly in North China, including the Haihe and Songliao River Basins. This is the first analysis in Chinese major river basins that has filled the gaps in the research on the human health risks of pharmaceuticals. The results of the study provide basic information of pharmaceutical intake from drinking water and eating fish in China and provide insights into the risk management guidance of pharmaceuticals, and will facilitate the optimization of health advisories and policy making.