High Water Turbidity Research Articles (Page 1)

Access to clean water remains a global challenge, particularly in areas where populations rely on surface water. These water sources must be treated. Coagulation with chemicals causes environmental problems and adverse effects on human health. Natural coagulants obtained from papaya (Carica papaya) waste are presented as an alternative that is safe for human health, non-polluting, and biodegradable. The effectiveness of these natural coagulants is compared to that of aluminum sulfate using jar tests and synthetic and natural surface water, with statistical tools to model treatment processes. All coagulants have competitive results, reaching turbidity remotion levels above 90%. However, in equivalent tested ranges, natural coagulants require lower dosages and perform better with high initial water turbidity due to their polymeric bridging mechanisms and adsorption processes through the action of their functional groups, as detected by FTIR analysis. Additional testing with contaminated water from the Valsequillo dam confirms the use of these coagulants to treat water, with papaya seed coagulant yielding the best results and requiring lower doses, making it a competitive alternative. It can be concluded that papaya-based coagulants obtained from waste can be used as an eco-friendly alternative to aluminum sulfate in physicochemical treatments to purify surface water for human consumption.

Natural organic matter (NOM) in surface waters is a major challenge for drinking water treatment due to its role in the formation of disinfection byproducts (DBPs) during chlorination. This study evaluated the performance of chitosan, a biodegradable coagulant, dissolved in acetic, lactic, and L-ascorbic acids for NOM removal under three turbidity levels (403, 1220, and 5038 NTU). Jar tests were conducted using raw water from the Río Grande de Añasco (Puerto Rico), and TOC, DOC, and UV254 were measured at multiple time points. TOC removal ranged from 39.8% to 74.3%, with the highest performance observed in high-turbidity water treated with chitosan-L-ascorbic acid. DOC and UV254 reductions followed similar trends, with maximum removals of 76.4% and 76.2%, respectively. Estimated THM formation potential (THMFP) was reduced by up to 81.6%. Across all acids, flocculation efficiencies exceeded 95%. Compared to conventional aluminum-based coagulants, chitosan demonstrated comparable performance, while offering environmental benefits. These results confirm the potential of chitosan-acid systems for effective organic matter removal and DBP control, supporting their application as sustainable alternatives in drinking water treatment.

High turbidity in raw water poses a major challenge to drinking water quality and requires effective, sustainable treatment solutions. This work investigates the reduction in turbidity in raw water and the enhancement of overall drinking water quality through the coagulation–flocculation process. The performance of Pine cone extract as a bio-coagulant was evaluated using four different solvent-based extractions (PC-H2O, PC-HCl, PC-NaCl, and PC-NaOH). The effects of key operational parameters were analyzed, and jar tests were carried out to enhance the coagulation–flocculation process by identifying the optimal conditions. Experimental design was further refined using RSM based on a BBD, incorporating three factors: initial pH, coagulant dosage, and settling time, with turbidity removal efficiency as the response variable. Statistical analysis confirmed that initial pH, coagulant dosage, and settling time significantly influenced turbidity reduction at a confidence level of p-value < 0.05 for all four solvents. Among the extracts tested, PC-HCl demonstrated the highest turbidity removal efficiency. The optimal conditions achieving 78.57% turbidity reduction were a pH of 8.5, a coagulant dosage of 100 mL/L, and a settling time of 120 min. These findings highlight the significant potential of Pine cone extract as an effective, sustainable, and eco-friendly organic coagulant for raw water treatment.

Underwater wireless communications face significant challenges due to high attenuation, turbulence, and water turbidity. Traditional methods like acoustic and radio frequency (RF) communication suffer from low data rates (<100 kbps), high latency (>1 s), and limited transmission distances (<10 km).Visible Light Communication (VLC) emerges as a promising alternative, offering high-speed data transmission (up to 5 Gbps), low latency (<1 ms), and immunity to electromagnetic interference. This paper provides an in-depth review of underwater VLC, covering fundamental principles, environmental factors (scattering, absorption), and dynamic water properties. We analyze modulation techniques, including adaptive and hybrid schemes (QAM-OFDM achieving 4.92 Gbps over 1.5 m), and demonstrate their superiority over conventional methods. Practical applications—underwater exploration, autonomous vehicle control, and environmental monitoring—are discussed alongside security challenges. Key findings highlight UVLC’s ability to overcome traditional limitations, with experimental results showing 500 Mbps over 150 m using PAM4 modulation. Future research directions include integrating quantum communication and Reconfigurable Intelligent Surfaces (RISs) to further enhance performance, with simulations projecting 40% improved spectral efficiency in turbulent conditions.

Submerged macrophytes play a crucial role in the ecological restoration of aquatic environments, and enclosed plot planting technology is one of the economical and effective methods to establish submerged macrophyte communities in high-turbidity water bodies. This study focused on Vallisneria spinulosa Yan (V. spinulosa), examining the impact mechanism of planting density on the water restoration effectiveness of V. spinulosa growth systems constructed within enclosed plots, based on its growth and physiological characteristics as well as the water purification effects of its growth system. The research results indicate that low to medium planting densities (50–100 plants/m2) favor leaf elongation and expansion, as well as the growth of root diameter, surface area, and volume, while high densities (150–200 plants/m2) inhibit leaf and root growth. The content of photosynthetic pigments (chlorophyll a, chlorophyll b, and carotenoids) in V. spinulosa increased with planting density. At high densities, significant increases in superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) levels in V. spinulosa suggest enhanced antioxidant activity. High protein content at low densities indicates stronger metabolic activity. Medium planting density (100 plants/m2) had significant effects on increasing dissolved oxygen (DO), regulating pH, and reducing electrical conductivity (EC), and exhibited the optimum removal loadings for total phosphorus (TP), phosphate (PO43−-P), total nitrogen (TN), and nitrate (NO3−), achieving the average value of 0.44, 0.42, 6.94, 0.83 mg m−2 d−1. The findings of this study can provide a theoretical basis and technical support for practical ecological restoration projects involving submerged macrophytes in aquatic environments.

Autonomous Underwater Vehicles (AUVs) face persistent challenges in localization compared to their counterparts on the ground due to limitations with methods like Global Positioning System (GPS). We propose a novel system for localization, Pisces, that leverages the Angle of Arrival (AoA) and Received Signal Strength Ratio (RSSR) of robot-mounted blue LED signals. This method provides a spectrally efficient training-free solution for estimating 3D underwater positions. The system remains effective despite high water turbidity with a relatively low impact on marine life compared to similar acoustic methods. Pisces is less complex, computationally efficient, and uses less power than camera-based solutions. Pisces enables robust relative localization, especially in swarms of robots with the potential for additional applications like docking. We demonstrate high localization accuracy with a Mean Absolute Error (MAE) of 0.031 m at 0.32 m separation and 0.16 m MAE at 1 m separation. Moreover, it achieved this with minimal power consumption, utilizing only 11 mA of transmitter LED current and performing 3D localization within 10 ms for distances up to 3 m.

Water scarcity has required constant water recycling, leading to a decline in water quality, further exacerbated by high concentrations of fine particles that reduce the efficiency of solid–liquid separation systems. Inclined settlers offer a viable secondary treatment option for high-turbidity water. Effective design requires understanding of operational conditions, geometry, and suspension properties. Using OpenFOAM, computational fluid dynamics simulations were performed for a continuous inclined countercurrent conduit to assess the influence of inlet particle concentration on efficiency, exploring various Surface Overflow Rates (SOR) and inclination angles. The results show that the steady state in which the flow settles is strongly dependent on the particle concentration. For very low particle concentrations, the flow is mostly stationary with little to no resuspension of particles. Increasingly unstable regimes are observed to emerge as the inlet concentration increases, leading to increased particle resuspension. Instabilities arise from overhanging zones at the tip of the suspension, generating recirculation zones that enlarge the resuspension region and induce entrainment within the bulk suspension. Shear instabilities become noticeable at large particle concentrations, further increasing resuspension. Different regimes were identified, influenced by the SOR and the inclination angles. Additionally, a Reynolds number characterizing these systems is proposed alongside a scale analysis. The findings highlight particle concentration as a critical parameter in inclined plate settler design.

The success of aquaculture depends on the quality of its water source. The increasing practice and establishment of earthen ponds for aquaculture in close proximity to lotic water bodies has necessitated the need for the suitability assessment of their water quality. The aim of this study is to ascertain the suitability of Ogidekpe River as source of water for aquaculture practice. Water samples were collected from four (4) designated stations along the Ogidekpe River from September 2023 to February 2024 and twenty (20) physico-chemical parameters were analyzed according to standard methods. Observed concentration values were compared with the Nigerian Standard Water Quality Criteria for Fisheries. Concentrations of physico-chemical parameters were within their respective permissible limits, except for turbidity (27 – 30.6 NTU), dissolved oxygen (3.06 – 5.06 mg/L), iron (0.33 – 0.39 mg/L), chromium (0.04 – 0.08 mg/L), lead (0.01 – 0.013 mg/L) and zinc (0.21 – 0.38 mg/L) at all the stations. High water turbidity and heavy metal – iron, chromium, lead and zinc content values which exceeded the water quality criteria for fisheries, makes the river an unsuitable water source for aquaculture. Utilizing the River as source of water for aquaculture requires that water retention ponds be constructed to allow for sedimentation and treatment before use for fish culture. There is need also to identify point sources of pollution within the watershed and enforce compliance to environmental laws in order to improve the overall water quality of the river.

One year of monthly sampling in some lagoons of the Po Delta and a pond in the Comacchio Valleys helped fill a gap in the knowledge of the primary producers of these degraded environments, focusing on the competition between macrophytes and phytoplankton. Key water column and surface sediment parameters showed a strong association with the different primary producers, explaining the main factors influencing the dominance of one group over the other. Phytoplankton, recorded as Chlorophyll-a and Phaeophytin-a, and Chlorophyceae among the macrophytes, dominated in conditions of high water turbidity and elevated nutrient concentrations. In contrast, macrophytes, particularly Rhodophyceae, their abundance, total biomass, and number of taxa. prevailed in clear, oxygenated waters. Under optimal conditions, sensitive macroalgae and aquatic angiosperms were also present. Additionally, the current list of macroalgal taxa has been updated, highlighting the dominance of some nonindigenous species (NIS) that had not been recorded before the 2000s. Specifically, Gracilaria vermiculophylla and Ulva australis, native to the North West Pacific (Japan, Korea, China, and Vietnam) and to South Australia, as well as the Indo-West Pacific (India, South Africa, Japan, and Korea), respectively, are now the most frequent and abundant taxa in these lagoons.

Currently, traditional high turbidity water treatment technologies (coagulation–sedimentation–filtration) face issues such as non-compliant effluent quality, sediment compaction, and poor sludge discharge. Meanwhile, membrane filtration technology suffers from severe membrane fouling in high turbidity water treatment. Therefore, the development of green and low-carbon high turbidity water treatment technologies is urgently needed. This study employs microfiltration to directly filter high turbidity water, investigating turbidity, filtration methods, and transmembrane pressure difference to elucidate the mechanisms of mitigating membrane fouling in high turbidity water treatment. The results indicate that both excessively high and low influent turbidity are detrimental to high turbidity water treatment. Low turbidity fails to effectively protect the membrane, exacerbating membrane fouling, while high turbidity leads to excessive cake layer thickness, reducing membrane flux. Therefore, the optimal treatment turbidity must be determined based on the specifications of the experimental setup. In this study, the optimal treatment turbidity is 900 NTU. Under constant pressure conditions, cross-flow filtration effectively controls the thickness of the filter cake layer, mitigates membrane fouling, and maintains a high membrane flux. When the influent turbidity is 900 NTU, the membrane flux recovery rate and filtration flux are 80.14% and 0.9077 m h−1, respectively, with irreversible membrane fouling being only 0.97 × 1010 m−1. At a constant influent turbidity, higher transmembrane pressure difference increases the filtration flux but exacerbates membrane fouling. When the pressure increases from 6.67 kPa to 33.33 kPa, irreversible membrane fouling increases by 27.97%, while the filtration flux increases by 116.91%. At a pressure of 13.33 kPa, although the filtration flux is 56.83% of that at 33.33 kPa, the irreversible membrane fouling is only 62.25%. Therefore, this study identifies 13.33 kPa as the optimal transmembrane pressure difference. The Hermia model revealed that transmembrane pressure difference was the primary factor aggravating membrane fouling. Finally, through dosing FeCl3 as a coagulant for cake layer regulation, the cake layer structure formed at 15 mg per L dosage showed optimal pollutant interception and removal efficiency: humic acid (HA) removal efficiency reached 75.86% in actual water sources with 79.06% flux recovery rate; simulated feed water achieved 77.44% HA removal with 84.31% flux recovery rate. This study aims to provide reference for microfiltration processes in direct treatment of high-turbidity water.

Novel cationic and amphoteric starch-modified coagulants for efficient treatment of relatively high turbidity and large organic matter source waters: Performance, predictive modeling and mechanism analysis

ABSTRACTHeavy metal contamination in water bodies is a pervasive and persistent environmental challenge in many parts of the world, especially in developing countries. This study investigates the use of multivariate analysis methods for monitoring variations in water quality along a spatial gradient and for the interpretation of pollution levels at different sampling sites. We assessed the water quality of the Seybouse River and identified possible sources of pollution using three complementary multivariate analysis techniques (PCA, NMDS, and K‐means clustering). The results indicate a longitudinal gradient in water quality associated with industrial and agricultural activities in the middle and lower Seybouse River. Physico‐chemical and heavy metal analyses show high water turbidity with elevated concentrations of iron and chromium. We show that the contamination stems from four different sources, which can be categorized into different pollution levels. Our results suggest that complementary multivariate methods are a robust approach to identifying and categorizing significant sources of pollution in rivers, enabling the development of future successful water quality management strategies based on water pollution levels. This study highlights the importance of monitoring water quality and taking effective measures to control and mitigate pollution from various sources to ensure the safety of the environment and human health.

Effects of pre-chlorination on ultrafiltration process in directly treating seasonal high-turbidity surface water: Membrane fouling control and shock load resisting

Production and characterization of efficient bioflocculant in high-turbidity drinking water treatment: Identification of flocculation-related genes

Reef-building corals live in close mutualism with dinoflagellate algae (family Symbiodiniaceae), which play key roles in coral physiological performance and survival. Association patterns between host species and endosymbiont algae and their significance are still not fully understood, but they seem to affect the ability of hosts to inhabit different environments and their resilience to climate change. In this work, we used next-generation sequencing of the Internal Transcribed Spacer 2 region of ribosomal DNA to determine the diversity and composition of the Symbiodiniaceae community in Pocillopora corals from Colombia, in the Eastern Tropical Pacific (ETP). We sampled 243 colonies from four localities characterized by distinct sea surface temperature, turbidity, and proximity to the coast. Two genera of Symbiodiniaceae, Durusdinium and Cladocopium were found associated with Pocillopora mitochondrial Open Reading Frame (mtORF) types. Cladocopium latusorum was highly specific to Pocillopora mtORF type 1, while C. pacificum was found exclusively associated with Pocillopora mtORF type 3. In contrast, Durusdinium glynnii was found in both Pocillopora mtORF types. Furthermore, a Cladocopium-dominated symbiont community occurred in cooler and less turbid localities, while a Durusdinium- dominated community was found in localities with high sea surface temperature and high water turbidity, irrespective of mtORF type. These results suggest that Pocillopora mtORF lineages associate with different Symbiodiniaceae genera in response to local environmental conditions. The ability to associate with a different partner under particular environmental conditions (Pocillopora-Durusdinium combination), and also maintain a specific partnership (Cladocopium species and Pocillopora mtORF types) may be key to understanding the resilience of the genus Pocillopora on ETP coral reefs.

Impact of variable hydrostatic pressure and intermittent operation on filtration performance and biofouling layer in gravity-driven membrane system for practical decentralized water supply

Remote sensing technology is widely used to obtain information on floating green tides, and thresholding methods based on indices such as the normalized difference vegetation index (NDVI) and the floating algae index (FAI) play an important role in such studies. However, as the methods are influenced by many factors, the threshold values vary greatly; in particular, the error of data extraction clearly increases in situations of high-turbidity water (HTW) (NDVI > 0). In this study, high spatial resolution, multispectral images from the Sentinel-2 MSI mission were used as the data source. It was found that the International Commission on Illumination (CIE) hue angle calculated using remotely sensed equivalent multispectral reflectance data and the RGB method is extremely effective in distinguishing floating green tides from areas of HTW. Statistical analysis of Sentinel-2 MSI images showed that the threshold value of the hue angle that can effectively eliminate the effect of HTW is 218.94°. A test demonstration of the method for identifying the floating green tide in HTW in a Sentinel-2 MSI image was carried out using the identified threshold values of NDVI > 0 and CIE hue angle < 218.94°. The demonstration showed that the method effectively eliminates misidentification caused by HTW pixels (NDVI > 0), resulting in better consistency of the identification of the floating green tide and its distribution in the true color image. The method enables rapid and accurate extraction of information on floating green tide in HTW, and offers a new solution for the monitoring and tracking of green tides in coastal areas.

Turbidity, as a key indicator of water quality linked to underwater light attenuation, is crucial for evaluating water quality. Control in high-turbidity water environments plays a critical role in navigable rivers. For this purpose, our study proposed a framework for analyzing the spatio-temporal variation of turbidity and its driving factors in a navigable and turbid river using in situ measurement data, satellite data, socioeconomic data, a power index function model, and correlation analysis. The results show that the proposed model is feasible for quantitative turbidity monitoring of the Xitiaoxi River. Its upstream turbidity is lower than downstream, with seasonal averages for spring, summer, autumn, and winter of 93.9, 111.3, 113.5, and 120.9 NTU, respectively. Furthermore, the turbidity in the middle and lower reaches of the Xitiaoxi River continuously increased before 2005 and began to decline after 2005 due to the policy of mining moratorium. This trend is especially noticeable at monitoring points along the main stream of the Xitiaoxi River, such as downstream of the Xitiaoxi River (S1), Gangkou station (S2), middle reaches of the Xitiaoxi River (S4), Hengtangcun station (S6), upper stream of the Xitiaoxi River (S7), and Huxi River (S8). Mining and shipping have significantly contributed to the turbidity of the target river. This framework offers a practical approach for assessing the environmental impacts of both natural and anthropogenic factors, thereby providing valuable insights for river management practices.

The temporal variability of fish habitat utilization is poorly understood in tropical deltaic systems due to high water turbidity, which limits visual censuses, and to the lack of long-term data incorporating climate variability events. We aimed to assess the influence of body size and El Niño Southern Oscillation (ENSO) variability on the cross-habitat utilization rate of 14 fish species of commercial relevance in the Ciénaga Grande de Santa Marta (CGSM). We estimated the utilization of mangroves and coastal lagoons based on relative catch frequencies from encircling gillnets used within a long-term catch monitoring program, and then tested for significant changes in each species' habitat utilization as a function of body size and climate variability. Six species showed a high dependence on mangroves and four on coastal lagoons for most body size classes (including juveniles) and ENSO conditions. One species (Elops smithi) showed a high utilization of mangroves in some ENSO phases and body size classes, while three species showed a high utilization of both mangroves and coastal lagoons. Mangrove utilization by six species (Megalops atlanticus, E. smithi, Centropomus undecimalis, Mugil incilis, Mugil liza, and Ariopsis canteri) increased in larger body sizes at low depths, which usually occurs under dry ENSO conditions, when predatory risk is higher in coastal lagoons. Another species (Caquetaia kraussi) increased its mangrove utilization from the body size at which its feeding habits change. Mangroves and coastal lagoons are important nurseries and habitats for adults of the main commercial fish species in the CGSM. Seascape habitats and fringe/riverine mangroves must be conserved in tropical deltas to promote not only nurseries but also fish lifecycles.

In order to improve dispersibility, polymerization characteristics, chemical stability, and magnetic flocculation performance, magnetic Fe3O4 is often assembled with multifarious polymers to realize a functionalization process. Herein, a typical three-dimensional configuration of hyperbranched amino acid polymer (HAAP) was employed to assemble it with Fe3O4, in which we obtained three-dimensional hyperbranched magnetic amino acid composites (Fe3O4@HAAP). The characterization of the Fe3O4@HAAP composites was analyzed, for instance, their size, morphology, structure, configuration, chemical composition, charged characteristics, and magnetic properties. The magnetic flocculation of kaolin suspensions was conducted under different Fe3O4@HAAP dosages, pHs, and kaolin concentrations. The embedded assembly of HAAP with Fe3O4 was constructed by the N-O bond according to an X-ray photoelectron energy spectrum (XPS) analysis. The characteristic peaks of -OH (3420 cm-1), C=O (1728 cm-1), Fe-O (563 cm-1), and N-H (1622 cm-1) were observed in the Fourier transform infrared spectrometer (FTIR) spectra of Fe3O4@HAAP successfully. In a field emission scanning electron microscope (FE-SEM) observation, Fe3O4@HAAP exhibited a lotus-leaf-like morphological structure. A vibrating sample magnetometer (VSM) showed that Fe3O4@HAAP had a relatively low magnetization (Ms) and magnetic induction (Mr); nevertheless, the ferromagnetic Fe3O4@HAAP could also quickly respond to an external magnetic field. The isoelectric point of Fe3O4@HAAP was at 8.5. Fe3O4@HAAP could not only achieve a 98.5% removal efficiency of kaolin suspensions, but could also overcome the obstacles induced by high-concentration suspensions (4500 NTU), high pHs, and low fields. The results showed that the magnetic flocculation of kaolin with Fe3O4@HAAP was a rapid process with a 91.96% removal efficiency at 0.25 h. In an interaction energy analysis, both the UDLVO and UEDLVO showed electrostatic repulsion between the kaolin particles in the condition of a flocculation distance of <30 nm, and this changed to electrostatic attraction when the separation distance was >30 nm. As Fe3O4@ HAAP was employed, kaolin particles could cross the energy barrier more easily; thus, the fine flocs and particles were destabilized and aggregated further. Rapid magnetic separation was realized under the action of an external magnetic field.