An experimental and modelling study of selected heavy metals removal from aqueous solution using Scylla serrata as biosorbent

This study was conducted using crab shells as a biosorbent to remove Cu and Cd with different initial concentrations of 1, 5, 10, 15, and 20 mg/L in a biosorption treatment process. Crab shells were selected as biosorbents due to their abundance in the environment and ready availability as waste products from the market place. This study aimed to determine the ability of Scylla Serrata shells to remove Cu and Cd in an aqueous solution, as well as to provide a comparison of the removal rate between the two metals. The data were incorporated into hydrochemical software, PHREEQC, to investigate the chemical speciation distribution of each heavy metal. The shells of S. Serrata were found to have a significant (p<0.05) ability to remove Cu and Cd following the treatment. After six hours of treatment, the crab shells had removed 60 to 80% of both metals. However, the highest removal percentage was achieved for Cu with up to 94.7% removal rate in 5 mg/L initial Cu concentration, while 85.1% of Cd was removed in 1 mg/L initial solution, respectively. It can be concluded that the shells of S. Serrata could remove Cu and Cd better with significant results (p<0.05) in 1 and 5 mg/L initial concentrations, respectively

Feasibility study of the grinding process of grain materials

For a comparative assessment of the effectiveness of various types of grinders of grain materials, various approaches are used. As the main criterion, the correspondence of the crushed material according to the particle size distribution can be taken as an indicator of the reliability of the grinding process. A comparative assessment of rotary crushers is carried out using the technical and economic indicator Eg, which is the ratio of total costs to the implementation of a given amount of work. Under the reliability of the grinding process, we have accepted the condition that the particle size distribution will comply with the requirements for agricultural feeding animals, which is possible while maintaining a rational gap between the stator and rotor riffles. The contradiction manufacturing techniques for the experiment are divided into: option No. 1 – steel 3 (HRC 10–12), option No. 2 – steel 45 (HRC 15–17), option No. 3 – hardened steel 45 (HRC 45–50), option No. 4 – steel 45 hardened and having a thin-film coating of FPH (finish plasma hardening), microhardness of 13 GPa. If reliability of the grinding process equal to 80%, wear on the fourth option, the cost was 1,171 rubles per ton, which is 16% lower than the cost of the first version of the production of a rotor crusher equal to 1,405 rubles per ton, respectively, this all speaks of the possible use of the proposed options for various forms of ownership of agricultural enterprises

Comparison of monsoon variations over groundwater hydrochemistry changes in small Tropical Island and its repercussion on quality

Study on the spatial and temporal distribution of groundwater hydrochemistry in the small tropical islands is important as their insular character may expose the groundwater aquifer to too many sources of pollution, especially salinization. A total of 216 groundwater samples were collected from the monitoring boreholes during two different monsoon seasons; pre- and post-monsoon. As overall, data of groundwater concentration illustrated a trend of Ca > Na > Mg > K and HCO3 > Cl > SO4 dominations with the major finding of two different groundwater types. Pre-monsoon reported Na-HCO3 and Ca-HCO3 types while post-monsoon were only dominated by the Ca-HCO3 type. The statistical analysis shows the in situ parameters (Temp, pH, EC, Salinity, DO, TDS and Eh) and major ions (Ca, Mg, Na, K, HCO3, Cl and SO4) were strongly correlated with the monsoon changes (p < 0.01). From the analysis, its reveals that the seasonal changes have significantly affects the groundwater composition. While, the analytical calculations of the ionic ratio (Na vs. Cl; Cl/HCO3 vs. Cl; Ca + Mg vs. SO4 + HCO3) describes the groundwater is influenced by the cation exchanges processes, simple mixing and water–rock interaction. Saturation indices of carbonate minerals shows strong correlationship (p < 0.01) with Ca constituent indicating solubility on minerals, which led to dissolution or precipitation condition of water. Results of present study contribute to a better understanding of a complex groundwater system and the hydrochemical processes related

Influence of monsoon regime and microclimate on soil respiration in the tropical forests

The consequence of precipitation and how environmental factors influence soil respiration remain poorly understood in the tropical forest ecosystems under a monsoon climate in Malaysia. This study was conducted in a recovering tropical lowland Dipterocarpus forest in Peninsular Malaysia, and its monthly variations were examined in association with changing precipitation. Soil respiration was measured using a continuous open flow chamber system connected to a multi gas-handling unit and an infrared gas analyser. The aim of this study was to determine the effects of the monsoon period and microclimate of the tropical region on soil respiration. The average monthly soil respiration rates were 152.79 to 528.67, 120.97 to 500.73, 106.77 to 472.89, 122.89 to 453.89 and 120.33 to 434.89 mg m⁻² h⁻¹ in the respective months from September to January. The emission rate varied across the days and months, with the highest value recorded between September and October, and then gradually decreasing from November to January. Soil temperature explained more than 90% of the soil respiration rate whereas precipitation had a major effect during the monsoon regime. Soil organic carbon (SOC), total organic carbon (TOC), soil organic carbon stock (SOCstock), forest biomass, carbon to nitrogen ratio (C/N) and soil pH were found to vary in considerable amounts, provide nutrients and the environment favourable for microorganism activities, leading to emission of soil CO₂. The low values of soil respiration rate between November and January were due not only on the amount of soil moisture and water potential but also on the intensity and frequency of precipitation. Therefore, these results indicate that the monsoon regime can significantly alter the emission of soil CO₂ and influence the microclimatic conditions and other environmental factors

Influential factors on the levels of cation exchange capacity in sediment at Langat river.

An exploratory study was carried out at 22 sampling stations along the Langat River, Selangor in order to investigate on the vitality of cation exchange capacity (CEC) in sediment (0–5 cm). Parameters such as pH, Eh, salinity, and electrical conductivity (EC) were determined. The CEC in sediment has been calculated by the determination of Ca2+, Na+, Mg2+, and K+ using the flame atomic absorption spectrophotometer, while the organic matter content in sediment was ascertained using the loss on ignition method. The characteristic of the sediment shows that pH (3.09–7.46), salinity (0.02–10.71 ppt), EC (3.39–517 μS/cm) and Eh (−16.20–253.10 mV) were substantially high in variation. This study also revealed that exchangeable Ca2+ and Mg2+ were controlled by organic matter contents, while exchangeable Na+ and K+ were influenced by salinity. Salinity was observed to play a major part in controlling all the exchangeable cations, as it gives strong significant correlations with Na+, K+, Mg2+, CEC, and organic matter at p < 0.01. The presence of seawater, clay mineralogy, and organic matter proves that it does play an important role in determining the CEC and soon relates to the pollution magnitude in the sediment

River water quality assessment using environmentric techniques : case study of Jakara River Basin.

akara River Basin has been extensively studied to assess the overall water quality and to identify the major variables responsible for water quality variations in the basin. A total of 27 sampling points were selected in the riverine network of the Upper Jakara River Basin. Water samples were collected in triplicate and analyzed for physicochemical variables. Pearson product-moment correlation analysis was conducted to evaluate the relationship of water quality parameters and revealed a significant relationship between salinity, conductivity with dissolved solids (DS) and 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), and nitrogen in form of ammonia (NH4). Partial correlation analysis (r p) results showed that there is a strong relationship between salinity and turbidity (r p = 0.930, p = 0.001) and BOD5 and COD (r p = 0.839, p = 0.001) controlling for the linear effects of conductivity and NH4, respectively. Principal component analysis and or factor analysis was used to investigate the origin of each water quality parameter in the Jakara Basin and identified three major factors explaining 68.11 % of the total variance in water quality. The major variations are related to anthropogenic activities (irrigation agricultural, construction activities, clearing of land, and domestic waste disposal) and natural processes (erosion of river bank and runoff). Discriminant analysis (DA) was applied on the dataset to maximize the similarities between group relative to within-group variance of the parameters. DA provided better results with great discriminatory ability using eight variables (DO, BOD5, COD, SS, NH4, conductivity, salinity, and DS) as the most statistically significantly responsible for surface water quality variation in the area. The present study, however, makes several noteworthy contributions to the existing knowledge on the spatial variations of surface water quality and is believed to serve as a baseline data for further studies. Future research should therefore concentrate on the investigation of temporal variations of water quality in the basin

The geoaccumulation index and enrichment factor of mercury in mangrove sediment of Port Klang, Selangor, Malaysia.

Mangrove areas are important to the ecosystem. One of its crucial functions is as a sink of pollutants, especially metal ions. However, the accumulation of metals in mangrove sediment can generate negative impacts on plant growth, microbial activity, and soil fertility. Apart from that, the severity of the impact is highly influenced by the type of metal found in the sediment and the quality of sediment itself. One of the metals that have adverse effects on the environment is mercury. The objectives of this study are to determine the concentration and distribution of mercury and to assess the enrichment of mercury in Port Klang mangrove sediment by using geoaccumulation index and enrichment factor. Sediment samples were collected from 30 sampling points that cover Langat River and Klang River estuaries, Lumut Straits, Pulau Klang, and Pulau Indah. During sampling, water parameters such as pH, salinity, electrical conductivity, and total dissolved solids were measured in situ, whereas the total mercury in sediment samples was determined at the laboratory using inductively coupled plasma mass spectrometry. In this study, mercury was found to be concentrated along Lumut Strait especially in the mixing zone near the confluence of Langat River and at the jetty to Pulau Ketam. The geoaccumulation index and enrichment factor (calculated using logarithmized data of the reference element) found that three stations were enriched with mercury. In addition, geoaccumulation index was also observed to be more objective compared to enrichment factor whose results were influenced by the concentration of reference element used

Surface water quality contamination source apportionment and physicochemical characterization at the upper section of the Jakara Basin, Nigeria.

The present study investigates the surface water quality of three important tributaries of Jakara Basin, northwestern Nigeria to provide an overview of the relationship and sources of physicochemical and biological parameters. A total of 405 water samples were collected from 27 sampling points and analyzed for 13 parameters: dissolved oxygen (DO), 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), suspended solids (SS), pH, ammonia-nitrogen (NH3NL), dissolved solids (DS), total solids (TS), nitrates (NO3), chloride (Cl), phosphates (PO4), Escherichia coli (E. coli) and fecal coliform bacteria (FCB). Pearson’s product–moment correlation matrix and principal component analysis (PCA) were used to distinguish the main pollution sources in the basin. Four varimax components were extracted from PCA, which explained 84.86, 83.60, and 78.69 % of the variation in the surface water quality for Jakara, Tsakama, and Gama-Kwari Rivers, respectively. Strong positive loading included BOD5, COD, NH3NL, E. coli, and FCB with negative loading on DO attribute to a domestic waste water pollution source. One-way ANOVA revealed that there was no significant difference in the mean of the three water bodies (p > 0.05). It is therefore recommended that the government should be more effective in controlling the point source of pollution in the area

Pharmaceutical pollution of the world's rivers

Environmental exposure to active pharmaceutical ingredients (APIs) can have negative effects on the health of ecosystems and humans. While numerous studies have monitored APIs in rivers, these employ different analytical methods, measure different APIs, and have ignored many of the countries of the world. This makes it difficult to quantify the scale of the problem from a global perspective. Furthermore, comparison of the existing data, generated for different studies/regions/continents, is challenging due to the vast differences between the analytical methodologies employed. Here, we present a global-scale study of API pollution in 258 of the world's rivers, representing the environmental influence of 471.4 million people across 137 geographic regions. Samples were obtained from 1,052 locations in 104 countries (representing all continents and 36 countries not previously studied for API contamination) and analyzed for 61 APIs. Highest cumulative API concentrations were observed in sub-Saharan Africa, south Asia, and South America. The most contaminated sites were in low- to middle-income countries and were associated with areas with poor wastewater and waste management infrastructure and pharmaceutical manufacturing. The most frequently detected APIs were carbamazepine, metformin, and caffeine (a compound also arising from lifestyle use), which were detected at over half of the sites monitored. Concentrations of at least one API at 25.7% of the sampling sites were greater than concentrations considered safe for aquatic organisms, or which are of concern in terms of selection for antimicrobial resistance. Therefore, pharmaceutical pollution poses a global threat to environmental and human health, as well as to delivery of the United Nations Sustainable Development Goals