Knowledge related to distributions of rainfall amounts are of great importance for the design of water related structures. The greater problem facing hydrologists and engineers identifying the best distribution form for regional data. The main goal of the study is to perform regional frequency analysis of maximum daily rainfalls selected each year among daily rainfalls measured over stations in Selangor and Kuala Lumpur by using the L-moment method. Several distributions were taken into account in this study which include two-parameter normal (NOM), lognormal (LN2), three-parameter lognormal (LN3), logistic (LOG), generalized logistic (GLO), extreme value type I (EV1), generalized extreme value (GEV) and generalized Pareto (GPA) distribution. The most suitable distribution was determined according to the mean absolute deviation index (MADI), mean square deviation index (MSDI) and the L-moment ratio diagram. The result of this study showed that the GLO distribution is the most suitable distribution to fit the data of maximum daily rainfalls for stations in Selangor and Kuala Lumpur.
Fishes from five streams in Gunung Machinchang and six streams in Gunung Raya areas of Pulau Langkawi were surveyed with the aim to investigate their diversity and distribution. Fish samples were collected from 23rd to 29th November 2007. Samplings took place along the 50 m reach of each of the site using an electrofisher and scoop nets. A total of 619 individuals of fish comprising 27 species and 14 families were recorded. Sixty-six percent from the taxa listed were of the cyprinids and Puntius binotatus was the most abundant species. Carassius auratus auratus was recorded for the first time in Pulau Langkawi. Streams of the Gunung Machinchang area were dominated by secondary freshwater fish species, but in the Gunung Raya area the streams were dominated by primary freshwater fish species. The highest diversity of fish was recorded for Sg. Kubang Badak with Simpson Index Ds = 0.838 and the lowest was for Sg. Perangin with Ds = 0.450. The highest evenness index of fish species was detected for Sg. Temurun with Es = 0.684 and the lowest was for Sg. Perangin with Es = 0.299. Species overlapping between streams of the two areas was 9.6%.
Malaysia is a tropical country that is highly dependent on surface water for its raw water supply. Unfortunately, surface water is vulnerable to pollution, especially in developed and dense urban catchments. Therefore, in this study, a methodology was developed for an extensive temporal water quality index (WQI) and classification analysis, simulations of various pollutant discharge scenarios using QUAL2K software, and maps with NH3-N as the core pollutant using an integrated QUAL2K-GIS. It was found that most of the water quality stations are categorized as Class III (slightly polluted to polluted). These stations are surrounded by residential areas, industries, workshops, restaurants and wet markets that contribute to the poor water quality levels. Additionally, low WQI values were reported in 2010 owing to development and agricultural activities. However, the WQI values improved during the wet season. High concentrations of NH3-N were found in the basin, especially during dry weather conditions. Three scenarios were simulated, i.e. 10%, 50% and 70% of pollution discharge into Skudai river using a calibrated and validated QUAL2K model. Model performance was evaluated using the relative percentage difference. An inclusive graph showing the current conditions and pollution reduction scenarios with respect to the distance of Skudai river and its tributaries is developed to determine the WQI classification. Comprehensive water quality maps based on NH3-N as the core pollutant are developed using integrated QUAL2K-GIS to illustrate the overall condition of the Skudai river. High NH3-N in the Skudai River affects water treatment plant operations. Pollution control of more than 90% is required to improve the water quality classification to Class II. The methodology and analysis developed in this study can assist various stakeholders and authorities in identifying problematic areas and determining the required percentage of pollution reduction to improve the Skudai River water quality.
Matched MeSH terms: Water; Water Supply; Water Purification; Water Quality
Groundwater resources constitute the main source of clean fresh water for domestic use and it is essential for food production in the agricultural sector. Groundwater has a vital role for water supply in the Campanian Plain in Italy and hence a future sustainability of the resource is essential for the region. In the current paper novel data mining algorithms including Gaussian Process (GP) were used in a large groundwater quality database to predict nitrate (contaminant) and strontium (potential future increasing) concentrations in groundwater. The results were compared with M5P, random forest (RF) and random tree (RT) algorithms as a benchmark to test the robustness of the modeling process. The dataset includes 246 groundwater quality samples originating from different wells, municipals and agricultural. It was divided for the modeling process into two subgroups by using the 10-fold cross validation technique including 173 samples for model building (training dataset) and 73 samples for model validation (testing dataset). Different water quality variables including T, pH, EC, HCO3-, F-, Cl-, SO42-, Na+, K+, Mg2+, and Ca2+ have been used as an input to the models. At first stage, different input combinations have been constructed based on correlation coefficient and thus the optimal combination was chosen for the modeling phase. Different quantitative criteria alongside with visual comparison approach have been used for evaluating the modeling capability. Results revealed that to obtain reliable results also variables with low correlation should be considered as an input to the models together with those variables showing high correlation coefficients. According to the model evaluation criteria, GP algorithm outperforms all the other models in predicting both nitrate and strontium concentrations followed by RF, M5P and RT, respectively. Result also revealed that model's structure together with the accuracy and structure of the data can have a relevant impact on the model's results.
Matched MeSH terms: Fresh Water; Water Supply; Water Quality; Water Wells
The aim of this study was to determine the occurrence of free-living amoebae (FLA) in Peninsular Malaysia and to compare different methodologies to detect them from water samples. Water samples were collected from tap water, recreational places, water dispensers, filtered water, etc. and tested for FLA using both cultivation and polymerase chain reaction (PCR) via plating assays and centrifugation methods. Amoebae DNA was extracted using Instagene matrix and PCR was performed using genus-specific primers. Of 250 samples, 142 (56.8%) samples were positive for presence of amoebae, while 108 (43.2%) were negative. Recreational water showed higher prevalence of amoebae than tap water. PCR for the plating assays revealed the presence of Acanthamoeba in 91 (64%) samples and Naegleria in 99 (70%) of samples analysed. All samples tested were negative for B. mandrillaris. In contrast, the centrifugation method was less effective in detecting amoebae as only one sample revealed the presence of Acanthamoeba and 52 (29%) samples were positive for Naegleria. PCR assays were specific and sensitive, detecting as few as 10 cells. These findings show the vast distribution and presence of FLA in all 11 states of Peninsular Malaysia. Further studies could determine the possible presence of pathogenic species and strains of free-living amoebae in public water supplies in Malaysia.
Matched MeSH terms: Fresh Water/parasitology*; Water Supply/statistics & numerical data*
The remediation of wastewater requires treatment technologies which are robust, efficient, simple to operate and affordable such as adsorption. Lately, three-dimensional (3D) graphene based materials have attracted significant attention as effective adsorbents for wastewater treatment. The intrinsic properties of 3D graphene structure such as large surface area and interconnected porous structure can facilitate the transport of pollutants into the 3D network and provide abundant active sites for trapping the pollutants. For the synthesis of 3D graphene structure, ice-templating is commonly practiced due to its facile steps, cost effectiveness and high scalability potential. This review covers the ice-templating fabrication technique for 3D graphene based materials and their application as adsorbents in eliminating dyes and heavy metals from aqueous media. The assembly mechanisms of the ice-templating fsynthesis are comprehensively discussed. Further discussion on the fundamental principles, critical process parameters and characteristics of ice-templated 3D graphene structures is also included. A thorough review on the mechanisms for batch adsorption of dyes and heavy metals is presented based on the structures and properties of the 3D graphene materials. The review further evaluates the dynamic adsorption in packed columns and the regeneration of 3D graphene based materials.
Matched MeSH terms: Water Pollutants, Chemical/chemistry*; Water Purification/methods*
Preliminary work was carried out f o r the development of a rapid method for the detection and enumeration of enterococcal phages in natural water. Eight enterococcal phages were isolated after amplification from water obtained from 2 local ponds. These were plaque-purified and used to test the phage susceptibility of 34 strains of enterococci isolated from pristine and polluted waters. Eight strains with the widest phage susceptibility were used as hosts in a double agar layer (DAL) and a single agar layer (SAL) assay for phage enumeration without pre-assay amplification. N o phages were obtained with the DAL method with all 8 hosts. Usingthe SALmethod, 2 phages were obtained with 1 of the 2 hosts used. Phage isolation was not improved by incubation at 44.5°C. For rapid quantitative testing, the sensitivity of the assays has to be increased to enable phage isolation without the need for prior amplification. KEYWORDS: Enterococci, phage, enumeration
In this study, we investigated the conductivity enhancement of calix[8]arene-multi-walled CNTs (MWCNTs) thin film.
Two types of calix[8]arenes were used, which were 5,11,17,23,29,35,41,47-p-tert-butyl-49,50,51,52,53,54,55,56-
oktakis[(carboxy)-pentoxy] -calix[8]arene (C[8]1) and 49,50,51,52,53,54,55,56 -octahydroxycalix[8]arene (C[8]2).
The monolayer properties of these two types of calix[8]arene on water subphase were examined. Later, the thin films
were fabricated by combining different ratios of each types of calix[8]arene with MWCNTs using spin coating deposition
technique. Then, the developed thin films were characterized using surface potential meter and four point probe. Thin
films of C[8]2 with hydroxyl groups at lower rims demonstrated higher surface potential and conductivity as compared
to the thin films of C[8]1 with upper rims of tert-butyl groups and lower rims of carboxyl groups. These results indicated
that the conductivity of calixarene thin films can be enhanced by MWCNTs through simple spin coating technique.
Active pharmaceutical ingredients (APIs) are typical endocrine disruptors found in common pharmaceuticals and personal care products, which are frequently detected in aquatic environments, especially surface water treated for drinking. However, current treatment technologies are inefficient for removing emerging endocrine disruptors, leading to the potential contamination of tap water. This study employed an optimized analytical method comprising solid-phase extraction and liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) to detect APIs in tap water in Putrajaya, Malaysia. Several therapeutic classes of pharmaceuticals and personal care products, including anti-inflammatory drugs (dexamethasone and diclofenac), antibiotics (sulfamethoxazole and triclosan), antiepileptics (primidone), antibacterial agents (ciprofloxacin), beta-blockers (propranolol), psychoactive stimulants (caffeine), and antiparasitic drugs (diazinon), were detected in the range of water pollutants. Diclofenac accounted for the highest concentration (21.39 ng/L), followed by triclosan and ciprofloxacin (9.74 ng/L and 8.69 ng/L, respectively). Caffeine was observed in all field samples with the highest distribution at 35.32%. Caffeine and triclosan exhibited significantly different distributions in household tap water (p water; however, the estimated risk was negligible (risk quotient water quality monitoring indicators for water resource conservation and water supply safety related to emerging organic contaminants; thus, API detection is important for safeguarding the environment and human health.
Matched MeSH terms: Water Pollutants, Chemical/analysis*; Drinking Water/analysis*
Electrocoagulation (ECoag) technique has shown considerable potential as an effective method in separating different types of pollutants (including inorganic pollutants) from various sources of water at a lower cost, and that is environmentally friendly. The EC method's performance depends on several significant parameters, including current density, reactor geometry, pH, operation time, the gap between electrodes, and agitation speed. There are some challenges related to the ECoag technique, for example, energy consumption, and electrode passivation as well as its implementation at a larger scale. This review highlights the recent studies published about ECoag capacity to remove inorganic pollutants (including salts), the emerging reactors, and the effect of reactor geometry designs. In addition, this paper highlights the integration of the ECoag technique with other advanced technologies such as microwave and ultrasonic to achieve higher removal efficiencies. This paper also presents a critical discussion of the major and minor reactions of the electrocoagulation technique with several significant operational parameters, emerging designs of the ECoag cell, operating conditions, and techno-economic analysis. Our review concluded that optimizing the operating parameters significantly enhanced the efficiency of the ECoag technique and reduced overall operating costs. Electrodes geometry has been recommended to minimize the passivation phenomenon, promote the conductivity of the cell, and reduce energy consumption. In this review, several challenges and gaps were identified, and insights for future development were discussed. We recommend that future studies investigate the effect of other emerging parameters like perforated and ball electrodes on the ECoag technique.
Matched MeSH terms: Water Pollutants, Chemical*; Water Purification*
The suitability and efficacy of three-dimensional (3D) graphene, including its derivatives, have garnered widespread attention towards the development of novel, sustainable materials with ecological amenability. This is especially relevant towards its utilization as adsorbents of wastewater contaminants, such as heavy metals, dyes, and oil, which could be majorly attributed to its noteworthy physicochemical features, particularly elevated chemical and mechanical robustness, advanced permeability, as well as large specific surface area. In this review, we emphasize on the adsorptive elimination of oil particles from contaminated water. Specifically, we assess and collate recent literature on the conceptualization and designing stages of 3D graphene-based adsorbents (3DGBAs) towards oil adsorption, including their applications in either batch or continuous modes. In addition, we analytically evaluate the adsorption mechanism, including sorption sites, physical properties, surface chemistry of 3DGBA and interactions between the adsorbent and adsorbate involving the adsorptive removal of oil, as well as numerous effects of adsorption conditions on the adsorption performance, i.e. pH, temperature, initial concentration of oil contaminants and adsorbent dosage. Furthermore, we focus on the equilibrium isotherms and kinetic studies, in order to comprehend the oil elimination procedures. Lastly, we designate encouraging avenues and recommendations for a perpetual research thrust, and outline the associated future prospects and perspectives.
The gravity of the impending threats posed by microplastics (MPs) pollution in the environment cannot be over-emphasized. Several research studies continue to stress how important it is to curb the proliferation of these small plastic particles with different physical and chemical properties, especially in aquatic environments. While several works on how to monitor, detect and remove MPs from the aquatic environment have been published, there is still a lack of explicit regulatory framework for mitigation of MPs globally. A critical review that summarizes recent advances in MPs research and emphasizes the need for regulatory frameworks devoted to MPs is presented in this paper. These frameworks suggested in this paper may be useful for reducing the proliferation of MPs in the environment. Based on all reviewed studies related to MPs research, we discussed the occurrence of MPs by identifying the major types and sources of MPs in water bodies; examined the recent ways of detecting, monitoring, and measuring MPs routinely to minimize projected risks; and proposed recommendations for consensus regulatory actions that will be effective for MPs mitigation.
The worsening water scarcity has imposed a significant stress on food production in many parts of the world. This stress becomes more critical when countries seek self-sufficiency. A literature review shows that food self-sufficiency has not been assessed as the main factor in determining the optimal cultivation patterns. However, food self-sufficiency is one of the main policies of these countries and requires the most attention and concentration. Previous works have focused on the virtual water trade to meet regional food demand and to calculate trade flows. The potential of the trade network can be exploited to improve the cropping pattern to ensure food and water security. To this end, and based on the research gaps mentioned, this study develops a method to link intra-country trade networks, food security, and total water footprints (WFs) to improve food security. The method is applied in Iran, a water-scarce country. The study shows that 781 × 106 m3 of water could be saved by creating a trade network. Results of the balanced trade network are input to a multi-objective optimization model to improve cropping patterns based on the objectives of achieving food security and preventing water crises. The method provides 400 management scenarios to improve cropping patterns considering 51 main crops in Iran. Results show a range of improvements in food security (19-45%) and a decrease in WFs (2-3%). The selected scenario for Iran would reduce the blue water footprint by 1207 × 106 m3, and reduce the cropland area by 19 × 103 ha. This methodology allows decision makers to develop policies that achieve food security under limited water resources in arid and semi-arid regions.
Matched MeSH terms: Water Supply*; Water Resources*
The presence of microplastics (MP) and nanoplastics (NP) in the environment poses significant hazards towards microorganisms, humans, animals and plants. This paper is focused on recent literature studies and patents discussing the removal process of these plastic pollutants. Microplastics and nanoplastics can be quantified by counting, weighing, absorbance and turbidity and can be further analyzed using scanning electron microscopy (SEM), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, surface-enhanced Raman spectroscopy and Raman tweezers. Mitigation methods reported are categorized depending on the removal characteristics: (i) Filtration and separation method: Filtration and separation, electrospun nanofiber membrane, constructed wetlands; (ii) Capture and surface attachment method: coagulation, flocculation and sedimentation (CFS), electrocoagulation, adsorption, magnetization, micromachines, superhydrophobic materials and microorganism aggregation; and (iii) Degradation method: photocatalytic degradation, microorganism degradation and thermal degradation; where removal efficiency between 58 and 100% were reported. As these methods are significantly distinctive, the parameters which affect the MP/NP removal performance e.g., pH, type of plastics, presence of interfering chemicals or ions, surface charges etc. are also discussed. 42 granted international patents related to microplastics and nanoplastics removal are also reviewed where the majority of these patents are focused on separation or filtration devices. These devices are efficient for microplastics up to 20 μm but may be ineffective for nanoplastics or fibrous plastics. Several patents were found to focus on methods similar to literature studies e.g., magnetization, CFS, biofilm and microorganism aggregation; with the addition of another method: thermal degradation.
The spatio-temporal variability of water quality associated with anthropogenic activities was studied for the Bertam River and its main tributaries within the Bertam Catchment, Cameron Highlands, Malaysia. A number of physico-chemical parameters of collected samples were analyzed to evaluate their spatio-temporal variability. Nonparametric statistical analysis showed significant temporal and spatial differences (p < 0.05) in most of the parameters across the catchment. Parameters except dissolved oxygen and chemical oxygen demand displayed higher values in rainy season. The higher concentration of total suspended solids was caused by massive soil erosion and sedimentation. Seasonal variations in contaminant concentrations are largely affected by precipitation and anthropogenic influences. Untreated domestic wastewater discharge as well as agricultural runoff significantly influenced the water quality. Poor agricultural practices and development activities at slope areas also affected the water quality within the catchment. The analytical results provided a basis for protection of river environments and ecological restoration in mountainous Bertam Catchment.
Matched MeSH terms: Water Pollutants, Chemical/analysis*; Water Quality*
Pharmaceutical pollutants substantially affect the environment; thus, their treatments have been the focus of many studies. In this article, the fixed-bed adsorption of pharmaceuticals on various adsorbents was reviewed. The experimental breakthrough curves of these pollutants under various flow rates, inlet concentrations, and bed heights were examined. Fixed-bed data in terms of saturation uptakes, breakthrough time, and the length of the mass transfer zone were included. The three most popular breakthrough models, namely, Adams-Bohart, Thomas, and Yoon-Nelson, were also reviewed for the correlation of breakthrough curve data along with the evaluation of model parameters. Compared with the Adams-Bohart model, the Thomas and Yoon-Nelson more effectively predicted the breakthrough data for the studied pollutants.
Matched MeSH terms: Water Pollutants, Chemical/analysis*; Water Purification/methods*
Fruit wastes constituting up to half of total fruit weight represent a large pool of untapped resources for isolation of starch with diverse applications. In this work, the possibility of isolating starch from tropical fruit wastes and its extended application as a natural coagulant was elucidated. Amongst the 12 various parts of fruit wastes selected, only jackfruit seeds contained more than 50% of total starch content. Using alkaline extraction procedures, starch has been successfully isolated from local jackfruit seeds with a yield of approximately 18%. Bell-shaped starch granules were observed under SEM with a granule size ranging from 1.1 to 41.6 μm. Detailed starch characteristics were performed to provide a comparison between the isolated seed starch and also conventional starches. Among them, chemical properties such as the content of starch, amylose, amylopectin and the corresponding molecular weights are some of the key characteristics which governed their performance as natural coagulants. The potential use of isolated seed starch as an aid was then demonstrated in both suspensions of kaolin (model synthetic system) and Chlorella sp. microalga (real-time application) with plausible outcomes. At optimized starch dosage of 60 mg/L, the overall turbidity removal in kaolin was enhanced by at least 25% at a fixed alum dosage of 2.1 mg/L. Positive turbidity and COD removals were also observed in the treatment of Chlorella suspensions. Starches which served as bridging agents aided in the linkage of neighbouring microflocs and subsequently, forming macroflocs through a secondary coagulation mechanism: adsorption and bridging.
Matched MeSH terms: Water/analysis; Water Purification/methods*