Analysis of the temporal and spatial evolution of turbidity in Tonle Sap Lake and its influencing factors.

Turbidity is a crucial indicator of water quality. The European Commission's Copernicus Land Monitoring Service Platform provides free turbidity data for large lakes to monitor global water quality of lakes. However, data were missing from April 2012 to April 2016, severely limiting the long-term analysis. Based on MODIS and turbidity data, Random Forest and XGBoost models are used to invert Tonle Sap Lake's turbidity. Random Forest outperformed the XGBoost model. Based on Random Forest model, missing data were filled in to construct long-term series data of Tonle Sap Lake turbidity (2004-2021). Trend, persistence and correlation analyses were conducted to reveal spatiotemporal characteristics and driving mechanism of turbidity. The results showed that: (1) spatially, the average annual, monthly, and seasonal turbidity was higher in the north but lower in the south, with regions of higher turbidity exhibiting more significant changes; (2) temporally, the annual turbidity mean was 53.99 NTU and showed an increasing trend. Monthly, turbidity values were higher from March to August and lower from September to February, with the highest and lowest recorded in June and November at 110.06 and 5.82 NTU, respectively. Seasonally, turbidity was higher in spring and summer compared to autumn and winter, with mean turbidity values of 84.16, 93.47, 15.33 and 23.21 NTU, respectively; (3) In terms of sustainability, the Hurst exponent for annual turbidity was 0.23, indicating a reverse trend in the near future; (4) Dam construction's impact on turbidity was not significant. Compared with natural factors (permanent wetlands, grasslands, lake surface water temperature, and remote sensing ecological index), human activities (barren or sparely vegetated, urban and built-up, croplands and population density) had a more significant impact on turbidity. Turbidity was highly correlated with cropland (r = 0.76), followed by population density (r = 0.71), and urban and built-up areas (r = 0.69).

The performance of quaternary-ammonium chitosan in wastewater treatment: The overlooked role of solubility.

Quaternary-ammonium chitosan (CT-CTA) is a popular water treatment agent, and its electropositivity and cation strength are improved compared with chitosan. The use of CT-CTA is widely advocated to remove suspended particles and organic matter from wastewater. However, the solubility of CT-CTA is an important factor affecting the performance of CT-CTA, which is a neglected problem in previous studies. In the study, CT-CTA with different solubilities were prepared by adjusting pH from 2 to 7 in preparation, and their applications were explored in wastewater. When the pH was 2, 2.5, or 3, the obtained CT-CTA was a dissolved state. The turbidity and color removal were 95 % - 98 % and 60 % - 74 %, respectively. When the pH was 4, 5, 6, or 7, the obtained CT-CTA was a solid state. The turbidity and color removal were 30 % - 63 % and 90 % - 97 %, respectively. For domestic-wastewater treatment, CT-CTA in a dissolved state removed 92 % of turbidity and 50 % of chemical oxygen demand (COD). CT-CTA in a solid state removed 86 % of turbidity and 64 % of COD with poly aluminum chloride (PAC). The results illustrated the performance of CT-CTA with different solubilities, which can broaden its application in wastewater treatment.

Calibration and validation of the HydroColor and Citclops smartphone applications for water quality monitoring.

Water quality monitoring, essential for safeguarding ecosystems and human health, has gained increasing significance as societies worldwide prioritize environmental awareness and sustainable practices. Therefore, this study evaluates the performance of two smartphone applications (APPs), HydroColor and Citclops (now EyeOnWater), in estimating water quality parameters such as turbidity, the concentration of suspended particulate matter ([SPM]), and colour. By comparing laboratory and hyperspectral sensors measurements with water quality parameters estimated from smartphone images, the study assessed the accuracy and efficiency of the transfer functions employed by these APPs. The study findings revealed varying degrees of accuracy, with HydroColor R2 values of 0.36 and 0.83 for turbidity and [SPM], respectively, while Citclops achieved an R2 value of 0.7 for colour estimation. The study identified limitations in both APPs, particularly in their applicability to different water systems. These insights underscore the importance of proper calibration and validation procedures for smartphone-based water quality monitoring APPs. Also, the findings underscore the growing significance of smartphone APPs in enabling accessible and real-time monitoring of water quality, highlighting their potential to revolutionize the democratization of environmental monitoring practices through citizen science. Ultimately, this research contributes to the advancement of smartphone-based monitoring initiatives to inform decision-making processes in environmental management, and enhancing our understanding of water quality dynamics in diverse environments.

Salt pollution reduces turbidity, dissolved organic matter, and cyanobacteria in experimental vernal pool communities.

Anthropogenic activities such as the over-application of road deicers are causing an increase in the concentration of salts in historically fresh waters. Experimental and field investigations demonstrate that freshwater salinization disrupts ecosystem functions and services, causing the death of freshwater organisms and changes to nutrient conditions. Wetland habitats are one system negatively affected by salt pollution, including ephemeral wetlands (vernal pools) that fill with salt-polluted water after snowmelt. In urbanized areas, the degradation of these ecosystems could result in irreversible ecological damage including reduced water quality and a reduction in biodiversity. To investigate the effects of freshwater salinization on vernal pool communities, we exposed soils from vernal pools to water containing no salt (control), or four concentrations of three salts standardized by chloride concentration (50 mg Cl- L-1, 100 mg Cl- L-1, 200 mg Cl- L-1, and 400 mg Cl- L-1; magnesium chloride, calcium chloride, and sodium chloride). The results of this experiment suggest that emerging zooplankton communities in vernal pools are sensitive to low concentrations of salt pollution, and that alternative salts such as magnesium chloride and calcium chloride are more toxic than sodium chloride. We did not find positive or negative changes in the abundance of eukaryotic phytoplankton but did find negative effects of salt on cyanobacteria abundance, possibly due to corresponding reductions in turbidity which might be needed as a fixation site for cyanobacteria to form heterocysts. Finally, we found that salt pollution likely caused flocculation of Dissolved Organic Matter (DOM), resulting in reduced concentrations of DOM which could alter the buffering capacity of freshwater systems, light attenuation, and the populations of planktonic heterotrophs.

Estimating turbidity concentrations in highly dynamic rivers using Sentinel-2 imagery in Google Earth Engine: Case study of the Godavari River, India.

Turbidity is an essential biogeochemical parameter for water quality management because it shapes the physical landscape and regulates ecological systems. It varies spatially and temporally across large water bodies, but monitoring based on point-source field observations remains a difficult task in developing countries due to the need for logistics and costs. In this study, we present a novel semi-analytical approach for estimating turbidity from remote sensing reflectance ( R rs ) in moderate to highly turbid waters in the lower part of the Godavari River (i.e., locations near Rajahmundry). The proposed method includes two sub-algorithms-Normalized Difference Turbidity Index (NDTI) and semi-empirical single-band turbidity ( T s ) algorithm-to retrieve spectral reflectance information corresponding to the study locations for turbidity modeling. Sentinel-2 Multi-Spectral Imager data have been used to quantify the turbidity in the Google Earth Engine (GEE) platform. The correlation analysis was observed between spectral reflectance values and in situ turbidity data using cubic polynomial regression equations. The results indicated that the T s , which uses the only red-edge wavelength, identified turbidity as the most accurate across all locations (highest R2 = 0.91, lowest RMSE = 0.003), followed by NDTI (highest R2 = 0.85, lowest RMSE = 0.05), respectively. The remote sensing data application provides a better way to monitor turbidity at large spatio-temporal scales in attaining the water quality standards of the Godavari River.

Optimization use of watermelon rind in the coagulation-flocculation process by Box Behnken design for copper, zinc, and turbidity removal.

Watermelon rinds were investigated as a bio-coagulant for treating water contaminated by metals and turbidity, owing to their biodegradability and greater environmental friendliness compared to chemical coagulants. Fourier transform infrared spectroscopy, scanning electron microscopy paired with energy dispersive X-ray analysis and X-ray diffraction characterized the watermelon rinds before and after use. A Box-Behnken experimental design optimized the most influential parameters of initial pH, coagulant dose, and particle size based on response surface methodology. This analysis revealed the experimental data fit quadratic polynomial models, achieving maximum removal efficiencies of 97.51 % for zinc, 99.88 % for copper, and 99.21 % for turbidity under optimal conditions. Statistical analysis confirmed the models effectively captured the experimental data. Analysis of variance denoted the high significance of the quadratic effects of dose and pH. Removal of metal ions Zn2+ and Cu2+ was significantly impacted by these factors. The watermelon rind powder retained its coagulation efficiency after five cycles of reuse, with removal rates of 80.04 % for Zn, 88.33 % for Cu and 86.24 % for turbidity. These results demonstrate the potential of watermelon rind as an alternative coagulant for wastewater treatment. Further testing on real industrial effluents at larger scales would help assess their feasibility for real-world applications.

Reduction of Malnutrition Related to Unsafe Water Consumption in Developing Countries: Potabilization of Surface Water and Traditional Well Water, with Plant Extracts.

The consumption of unsafe water in rural areas is a real public health problem in developing countries. This situation mainly affects children under five years of age and causes several deaths and many cases of malnutrition every year. The objective of this study was to evaluate and optimize the capacity of four local plant extracts in the potabilization of unsafe water. Thus, Moringa oleifera and Boscia senegalensis seeds, or Aloe vera and Opuntia ficus-indica mucilages were prepared in a solution and applied during a jar test as biocoagulants and bioflocculants on three raw water samples of 82.3 NTU, 549.8 NTU and 796.9 NTU. After treatment results showed that 0.9 g/L of Moringa biocoagulant or 1 g/L of Boscia biocoagulant applied with 0.4 mL of Aloe vera bioflocculant or 0.6 mL of Opuntia ficus-indica bioflocculant reduced the turbidity of each water sample to values less than 5 NTU after only 15 min of decanting. Moreover, the sanitary quality of the water treated by these different extracts showed a perfect conformity of the physicochemical and microbiological parameters with the standards of acceptability in drinking water decreed by the World Health Organization. Thus, the application of these local plant extracts has made it possible to considerably improve the quality of unsafe water in record time. Their popularization could be an alternative in the fight against malnutrition related to the consumption of unsafe water, especially in rural areas.

Detection and modeling of Staphylococcus aureus and fecal bacteria in Hawaiian coastal waters and sands.

Microbial pollution of recreational waters leads to millions of skin, respiratory, and gastrointestinal illnesses globally. Fecal indicator bacteria (FIB) are monitored to assess recreational waters but may not reflect the presence of Staphylococcus aureus, a global leader in bacterial fatalities. Since many community-acquired S. aureus skin infections are associated with high recreational water usage, this study measured and modeled S. aureus, methicillin-resistant S. aureus (MRSA), and FIB (Enterococcus spp., Clostridium perfringens) concentrations in seawater and sand at six beaches in Hilo, Hawai'i, USA, over 37 sample dates from July 2016 to February 2019 using culturing techniques. Generalized linear models predicted bacterial concentrations with physicochemical and environmental data. Beach visitors were also surveyed on their preferred activities. S. aureus and FIB concentrations were roughly 6-78 times higher at beaches with freshwater discharge than at those without. Seawater concentrations of Enterococcus spp. were positively associated with MRSA but not S. aureus. Elevated S. aureus was associated with lower tidal heights, higher freshwater discharge, onsite sewage disposal system density, and turbidity. Regular monitoring of beaches with freshwater input, utilizing real-time water quality measurements with robust modeling techniques, and raising awareness among recreational water users may mitigate exposure to S. aureus, MRSA, and FIB. PRACTITIONER POINTS: Staphylococcus aureus and fecal bacteria concentrations were higher in seawater and sand at beaches with freshwater discharge. In seawater, Enterococcus spp. positively correlated with MRSA, but not S. aureus. Freshwater discharge, OSDS density, water turbidity, and tides significantly predicted bacterial concentrations in seawater and sand. Predictive bacterial models based upon physicochemical and environmental data developed in this study are readily available for user-friendly application.

Synthesis and evaluation of a novel cross-linked biochar/ferric chloride hybrid material for integrated coagulation and adsorption of turbidity and humic acid from synthetic wastewater: Implications for sludge valorisation.

The deep removal of organic pollutants is challenging for coagulation technology in drinking water and wastewater treatment plants to satisfy the rising water standards. Iron (III) chloride (FeCl3) is a popular inorganic coagulant; although it has good performance in removing the turbidity (TB) in water at an alkaline medium, it cannot remove dissolved pollutants and natural organic matter such as humic acid water solution. Additionally, its hygroscopic nature complicates determining the optimal dosage for effective coagulation. Biochar (BC), a popular adsorbent with abundant functional groups, porous structure, and relatively high surface area, can adsorb adsorbates from water matrices. Therefore, combining BC with FeCl3 presents a potential solution to address the challenges associated with iron chloride. Consequently, this study focused on preparing and characterizing a novel biochar/ferric chloride-based coagulant (BC-FeCl3) for efficient removal of turbidity (TB) and natural organic matter, specifically humic acid (HA), from synthetic wastewater. The potential solution for the disposal of produced sludge was achieved by its recovering and recycling, then used in adsorption of HA from aqueous solution. The novel coagulant presented high TB and HA removal within 10 min of settling period at pH solution of 7.5. Furthermore, the recovered sludge presented a good performance in the adsorption of HA from aqueous solution. Adsorption isotherm and kinetics studies revealed that the Pseudo-second-order model best described kinetic adsorption, while the Freundlich model dominated the adsorption isotherm.

Reduction of large vessel traffic improves water quality and alters fish habitat-use throughout a large river.

Rivers are increasingly used as superhighways for the continental-scale transportation of freight goods, but the ecological impact of large vessel traffic on river ecosystems is difficult to study. Recently, the temporary maintenance closure of lock and dam systems on the Illinois Waterway (USA) brought commercial vessel traffic to a halt along the river's length, offering a rare opportunity to study the response of the ecosystem before, during, and after an extended pause of this persistent anthropogenic disturbance. We observed improvements in main- and side-channel water quality and a redistribution of fish habitat-use during a months-long, near-complete reduction of large vessel traffic. Over 3600 water quality and 1300 fish community samples indicate that large vessel traffic reduction coincided with a 33 % reduction in turbidity as well as increased use of sampling strata near vessel navigation corridors by sound-sensitive and rheophilic fishes. Gizzard shad (Dorosoma cepedianum), the most abundant species in the system, also expanded their use of these 'impact' areas. Though inland waterway transport is an economically- and climate-friendly alternative to trucking and rail for the shipment of freight, our data suggest that intense vessel traffic may have profound physical and biological impacts across a large river. Monitoring and mitigation of ecological impacts of the ongoing expansion of inland waterway transport around the world will be critical to balancing large rivers as both useful navigation corridors and functional ecosystems.

Compatibility studies of selected multichamber bag parenteral nutrition with fluconazole.

OBJECTIVE: Fluconazole (FLZ) is a drug widely used in the treatment of fungal infections including the treatment of immunocompromised patients, HIV-infected patients, and cancer patients. Critically ill patients often require the administration of drugs with parenteral nutrition (PN). The safety of this combination should be defined before the drug and PN are administered in one infusion line. This study aimed to determine the compatibility of FLZ with six selected multichamber bag parenteral nutrition. METHODS: FLZ solution for infusion was combined with PNs in appropriate proportions, considering most clinical situations resulting from different possible administration rates of the preparations. Samples were visually assessed, and pH, osmolality, turbidity, particle size (dynamic light scattering and light obscuration methods), and zeta potential were measured. These measurements were made immediately after combining the solutions and after 4 h of storage at 23 ± 1°C. RESULTS: FLZ combined with PNs did not cause changes observed visually. The turbidity of the samples was <0.4 NTU. The average particle size of the lipid emulsion was below 300 nm, and the PFAT5 parameter was ≤0.02%. The absolute value of the zeta potential of the PN + FLZ samples was higher for 5 out of 6 PN than the corresponding value for PN immediately after activation. Changes in pH and osmolality during 4 h of sample observations were within acceptable limits. CONCLUSION: Compatibility of the FLZ with six multichamber bag PN was confirmed. Hence, those preparations can be administered to patients in one infusion line using the Y-site.

Mechanism behind the Controlled Generation of Liquid Metal Nanoparticles by Mechanical Agitation.

The size-controlled synthesis of liquid metal nanoparticles is necessary in a variety of applications. Sonication is a common method for breaking down bulk liquid metals into small particles, yet the influence of critical factors such as liquid metal composition has remained elusive. Our study employs high-speed imaging to unravel the mechanism of liquid metal particle formation during mechanical agitation. Gallium-based liquid metals, with and without secondary metals of bismuth, indium, and tin, are analyzed to observe the effect of cavitation and surface eruption during sonication and particle release. The impact of the secondary metal inclusion is investigated on liquid metals' surface tension, solution turbidity, and size distribution of the generated particles. Our work evidences that there is an inverse relationship between the surface tension and the ability of liquid metals to be broken down by sonication. We show that even for 0.22 at. % of bismuth in gallium, the surface tension is significantly decreased from 558 to 417 mN/m (measured in Milli-Q water), resulting in an enhanced particle generation rate: 3.6 times increase in turbidity and ∼43% reduction in the size of particles for bismuth in gallium liquid alloy compared to liquid gallium for the same sonication duration. The effect of particles' size on the photocatalysis of the annealed particles is also presented to show the applicability of the process in a proof-of-concept demonstration. This work contributes to a broader understanding of the synthesis of nanoparticles, with controlled size and characteristics, via mechanical agitation of liquid metals for diverse applications.

A comprehensive dataset for the evaluation of a horizontal tubular flocculator implemented for drinking water treatment.

This article presents a set of data obtained during the evaluation of a horizontal flow tubular flocculator for the provision of drinking water in developing communities. The HFTF is presented as an alternative technology to replace conventional flocculators, allowing high efficiency in the subsequent sedimentation and filtration processes. For obtaining the data, experimental tests were carried out using lengths of 68.4 m and 97.6 m for the HFTF, these lengths were combined with flow rates of 0.25, 0.5, 0.75, 1.0 and 2.0 L/s, as well as raw water turbidities of 10, 20, 50, 100 and 200 NTU. The data set generated from measurements and observations made during experimental field tests is detailed. The resulting data set covers the main parameters that determine the quality of drinking water, such as turbidity and colour, as well as flocculation efficiency data. The data from the experimental system were compared with a conventional treatment plant that has a baffle flocculator. Likewise, data on the retention time and velocity gradient are presented that allowed the hydraulic characteristics of the HFTF are evaluated. This data set has significant potential for reuse in future research and development related to water treatment technologies in developing community settings. Detailed data has been collected on various operating conditions of the HFTF, such as different lengths, water flow rates and turbidity levels, as well as measurements of key parameters such as turbidity, colour, flocculation efficiency, retention time and velocity gradient, these Data could be used in future research and development related to water treatment technologies. Furthermore, a comparison of data from the experimental system with a conventional treatment plant provides useful insight into the relative performance of different water treatment technologies, which could be of interest to researchers, system designers and public policymakers in the field of drinking water supply in developing communities.

Effectiveness of a natural coagulant based on common mallow (Malva sylvestris) in urban wastewater treatment.

This study evaluated the effectiveness of a natural coagulant based on common mallow (Malva sylvestris) to remove turbidity in urban wastewater. A 22 factorial design was selected to determine the optimal dose and the working pH of the natural coagulant. Its potential was studied in 50.0-450 mg/L and 4.00-10.0 ranges of doses and pH, respectively. A simplex lattice mixture evaluated its effectiveness as a coagulant aid combined with aluminum sulfate (conventional coagulant). Mixture proportions 0.000-1.00 were studied for each component, finding the proportion more effective. Results showed that the coagulation treatment could be feasible since a turbidity removal efficiency of 73.7% can be achieved under optimal conditions (50.0 mg/L and pH of 10.0). Likewise, a turbidity removal of 58.9% is obtained using 250 mg/L and maintaining wastewater pH (7.45). This efficiency can be increased using 31.0% natural coagulant mixed with 69.0% aluminum sulfate at 250 mg/L without modifying the wastewater pH. This improvement was associated with the natural coagulant's high molecular weight and long-chained structure since these properties enhance settling time, floc size and strength, and low sludge production. These results support using common mallow as a natural coagulant, making its use more feasible in alkaline water pH or as a coagulant aid combined with aluminum sulfate for urban wastewater treatment. A cost of USD 370/Kg of natural coagulant was estimated, which is higher than conventional coagulants. However, a cost-effectiveness analysis of its implementation should be performed since process scaling costs could significantly reduce its price.

Effects of the Taste Substances and Metal Cations in Green Tea Infusion on the Turbidity of EGCG-Mucin Mixtures.

Astringency has an important impact on the taste quality of tea infusion, a process which occurs when polyphenols complex with salivary proteins to form an impermeable membrane. (-)-Epigallocatechin gallate (EGCG) is the main astringent compound found in green tea and mucin is the main protein present in saliva. Determining the turbidity of EGCG-mucin mixtures is an effective method to quantify the astringency intensity of EGCG solutions. In this study, the effects of taste-related, substances present during green tea infusion, on the turbidity of EGCG-mucin mixtures was investigated under the reacting conditions of a pH value of 5.0, at 37 °C, and for 30 min. The results showed that epicatechins, caffeic acid, chlorogenic acid, and gallic acid reduced the turbidity of EGCG-mucin mixtures, while rutin increased turbidity. Metal ions increased the turbidity of EGCG-mucin mixtures. These can be arranged by effectiveness as Al3+ > K+ > Mg2+ > Ca2+. Caffeine, theanine, and sodium glutamate all decreased the turbidity values of EGCG-mucin mixtures, but sucrose had a weak effect. Further experiments confirmed that the turbidity of green tea infusion-mucin mixture indicated the astringent intensity of green tea infusion, and that the turbidity was significantly correlated with the contents of tea polyphenols and EGCG.

Coagulation process for the removal of color and turbidity from wet coffee processing industry wastewater using bio-coagulant: Optimization through central composite design.

The growing problem of industrial pollution in developing countries, especially Ethiopia, has sparked serious issues about the quality of the water, particularly when it comes to the effluent from wet coffee processing industries. In response, this study investigates the potential of utilizing natural coagulants, Acanthus sennii C., Moringa stenopetala B., and Aloe vera L., either individually or in combination, for the treatment of coffee effluent. Methodologically, the study systematically varies operational parameters, including coagulant dose, pH levels, stirring speed, and stirring time, to evaluate their impact on coagulation efficiency. Experimental data undergo statistical analysis, employing ANOVA, while computational optimization techniques are employed using Design Expert software to determine optimal conditions. Notably, the blended form of the three coagulants emerges as particularly promising, yielding optimal conditions of 0.750 g/L coagulant dosage, pH 8.76, agitation speed of 80.73 rpm, and agitation time of 19.23 min. Under these optimized conditions, the blended coagulant achieves remarkable removal efficiencies, approximately 99.99% for color and 98.7% for turbidity. These findings underscore the efficiency of natural coagulants, particularly in blended form, for sustainable wastewater treatment in wet coffee processing.

Analysis of Phase Separation of EARLY FLOWERING 3.

Phase separation is an important mechanism for regulating various cellular functions. The EARLY FLOWERING 3 (ELF3) protein, an essential element of the EVENING COMPLEX (EC) involved in circadian clock regulation, has been shown to undergo phase separation. ELF3 is known to significantly influence elongation growth and flowering time regulation, and this is postulated to be due to whether the protein is in the dilute or phase-separated state. Here, we present a brief overview of methods for analyzing ELF3 phase separation in vitro, including the generation of phase diagrams as a function of pH and salt versus protein concentrations, optical microscopy, fluorescence recovery after photobleaching (FRAP), and turbidity assays.

Mouthguard-Type Wearable Sensor for Monitoring Salivary Turbidity to Assess Oral Hygiene.

Salivary turbidity is a promising indicator for evaluating oral hygiene. This study proposed a wearable mouthguard-type sensor for continuous and unconstrained measurement of salivary turbidity. The sensor evaluated turbidity by measuring the light transmittance of saliva with an LED and a phototransistor sealed inside a double-layered mouthguard. The sensor was also embedded with a Bluetooth wireless module, enabling the wireless measurement of turbidity. The mouthguard materials (polyethylene terephthalate-glycol and ethylene-vinyl acetate) and the wavelength of the LED (405 nm) were experimentally determined to achieve high sensitivity in salivary turbidity measurement. The turbidity quantification characteristic of the proposed sensor was evaluated using a turbidity standard solution, and the sensor was capable of turbidity quantification over a wide dynamic range of 1-4000 FTU (formazine turbidity unit), including reported salivary turbidity (400-800 FTU). In vitro turbidity measurement using a saliva sample showed 553 FTU, which is equivalent to the same sample measured with a spectrophotometer (576 FTU). Moreover, in vivo experiments also showed results equivalent to that measured with a spectrophotometer, and wireless measurement of salivary turbidity was realized using the mouthguard-type sensor. Based on these results, the proposed mouthguard-type sensor has promising potential for the unconstrained continuous evaluation of oral hygiene.

Development and techno-economic analysis of Grewia biopolymer-based dual coagulant system for wastewater treatment at pilot scale.

Use of Grewia biopolymer as a natural coagulant aid was explored in a dual-coagulant system (conventional coagulant + biopolymer) for wastewater treatment. Such use not only improved turbidity removal efficiency over a wide pH range (5-9) but also helped reducing the concentration demand of inorganic coagulants by 25-50 %. Response surface methodology was employed for investigating the interaction between factors (initial pH, coagulant, and biopolymer concentration) affecting coagulation/flocculation of aqueous laterite suspension, and process optimization for more than 80 % turbidity removal in the desired final pH range (6-7). Mechanisms potentially involved in coagulation/flocculation using biopolymer was elucidated. Techno-economic assessment indicated the feasibility of pilot-scale production of the biopolymer and its use in wastewater treatment. This study demonstrates that Grewia biopolymer has the potential to be used as a coagulant aid and will help researchers select appropriate markets for further cost reduction and successful implementation of biopolymer-based wastewater treatment.

Estimation of suspended sediment balance of a small catchment in Southwestern Nigeria.

Human use index caused by population pressure in Opa catchment Ile Ife, Southwestern Nigeria, has resulted in catchment denudation, accelerated erosion, and sediment delivery into a man-made (1978) reservoir (Opa) in the catchment. This study is aimed at evaluating the suspended sediment balance of Opa reservoir with a view to ascertain the annual siltation rate. River discharges, water levels, suspended sediment concentrations/yield, and flow velocities were monitored, and data collected from all the tributaries of the Opa reservoir and the spillway (outlet) in the period 2017-2018. Water samples collected were subjected to gravimetric analysis, and the results utilized to obtain sediment rating curves and to compute the suspended sediment balance. Suspended sediment inflow from the six sub-catchments ranged from 8.49 to 29.05tons/ha, with a total inflow of 1146.50tons/ha into the reservoir during the hydrological year. The corresponding outflow through the spillway was 615.70tons/ha. 530.80tons/ha was sequestered in the reservoir, equivalent to an estimate of 46% suspended sediment deposited in the reservoir. The high sediment yield in Opa reservoir is due to the dredging and clearing of the river channels in the catchment of any impediment thereby enhancing sediment delivery into the reservoir. Sediment loads were higher in the rainy season suggesting catchment erosion as the main factor responsible for the sediment yield into the reservoir. The study concluded that the positive suspended sediment balance suggests sediment sequestration with an increasing tendency for accelerated elimination of the wetland in the face of poor environmental management and enhanced human activities.