Effects of fulvic acid and humic acid on aluminum speciation in drinking water

Unraveling the ecological mechanisms of Aluminum on microbial community succession in epiphytic biofilms on Vallisneria natans leaves: Novel insights from microbial interactions

The extensive use of aluminum (Al) poses an escalating ecological risk to aquatic ecosystems. The epiphytic biofilm on submerged plant leaves plays a crucial role in the regulation nutrient cycling and energy flow within aquatic environments. Here, we conducted a mesocosm experiment aimed at elucidating the impact of different Al concentrations (0, 0.6, 1.2, 2.0 mg/L) on microbial communities in epiphytic biofilms on Vallisneria natans. At 1.2 mg/L, the highest biofilms thickness (101.94 µm) was observed. Al treatment at 2.0 mg/L significantly reduced bacterial diversity, while micro-eukaryotic diversity increased. Pseudomonadota and Bacteroidota decreased, whereas Cyanobacteriota increased at 1.2 mg/L and 2.0 mg/L. At 1.2 and 2.0 mg/L. Furthermore, Al at concentrations of 1.2 and 2.0 mg/L enhanced the bacterial network complexity, while micro-eukaryotic networks showed reduced complexity. An increase in positive correlations among microbial co-occurrence patterns from 49.51% (CK) to 57.05% (2.0 mg/L) was indicative of augmented microbial cooperation under Al stress. The shift in keystone taxa with increasing Al concentration pointed to alterations in the functional dynamics of microbial communities. Additionally, Al treatments induced antioxidant responses in V. natans, elevating leaf reactive oxygen species (ROS) content. This study highlights the critical need to control appropriate concentration Al concentrations to preserve microbial diversity, sustain ecological functions, and enhance lake remediation in aquatic ecosystems.

Hazardous or Advantageous: Uncovering the Roles of Heavy Metals and Humic Substances in Shilajit (Phyto-mineral) with Emphasis on Heavy Metals Toxicity and Their Detoxification Mechanisms

Shilajit is a phyto-mineral diffusion and semi-solid matter used as traditional medicine with extraordinary health benefits. This study provides a comprehensive data on Shilajit with emphasis on heavy metal profile, associated toxicities, and metal detoxification mechanisms by humic substances present in Shilajit. Data was searched across papers and traditional books using Google Scholar, PubMed, Science Direct, Medline, SciELO, Web of Science, and Scopus as key scientific databases. Findings showed that Shilajit is distributed in almost 20 regions of the world with uses against 20 health problems as traditional medicine. With various humic substances, almost 11 biological activities were reported in Shilajit. This phyto-mineral diffusion possesses around 65 heavy metals including the toxic heavy metals like Cu, Al, Pb, As, Cd, and Hg. However, humic substances in Shilajit actively detoxify around 12 heavy metals. The recommended levels of heavy metals by WHO and FDA in herbal drugs is 0.20 and 0.30 ppm for Cd, 1 ppm for Hg, 10.00 ppm for As and Pb, 20 ppm for Cu, and 50 ppm for Zn. The levels of reported metals in Shilajit were found to be lower than the permissible limits set by WHO and FDA, except in few studies where exceeded levels were reported. Shilajit consumption without knowing permissible levels of metals is not safe and could pose serious health problems. Although the humic substances and few metals in Shilajit are beneficial in terms of chelating toxic heavy metals, the data on metal detoxification still needs to be clarified.

Suitability of Highly Polymerised Polyaluminium Chlorides (PACls) in the Treatment of Mixture of Groundwater and Surface Water

The aim of this study was to evaluate the effectiveness of the coagulation process using highly polymerised polyaluminium chlorides in reducing the level of pollution of water in a mixture of groundwater and surface water. The coagulants used were prehydrolysed polyaluminium chlorides with the trade names PAXHP908 and PAXXL1911 that had alkalinity 85% and different iron contents (<0.01% and 0.7%). The Al species distribution in the PACls (PAXXL1911 ad PAXHP908) samples were analysed by the Ferron complexation timed spectrophotometry. The content of polymer forms of aluminium (Alb) in the tested coagulants was 40%. The worse results in the removal of organic matter (TOC, DOC, UV254), iron, colour and turbidity in the coagulation process were produced by the PAXXL1911, possessing higher content of iron (0.7%). The lower usefulness of the PAXXL1911 was probably caused by the interaction of organic ligands present in the treated water and Fe(III) ions introduced into the water with the coagulant. The effectiveness of the coagulation process with the tested coagulants was also evaluated by measuring the electrokinetic potential ζ, which determines the stability of the colloidal system.

Long-term exposure to environmentally relevant concentrations of ibuprofen and aluminum alters oxidative stress status on Danio rerio

Despite the ubiquitous presence of multiple pollutants in aqueous environments have been extensively demonstrated, the ecological impact of chemical cocktails has not been studied in depth. In recent years, environmental studies have mainly focused on the risk assessment of individual chemical substances neglecting the effects of complex mixtures even though it has been demonstrated that combined effects exerted by pollutants might represent a greater hazard to the biocenosis. The current study evaluates the effects on the oxidative stress status induced by individual forms and binary mixtures of ibuprofen (IBU) and aluminum (Al) on brain, gills, liver and gut tissues of Danio rerio after long-term exposure to environmentally relevant concentrations (0.1-11 μg L^-1 and 0.05 mg L^-1- 6 mg L^-1, respectively). Lipid peroxidation (LPO), Protein carbonyl content (PCC) and activity of Superoxide Dismutase (SOD), Catalase (CAT), and Glutathione Peroxidase (GPX) were evaluated. Moreover, concentrations of both toxicants and the metabolite 2-OH-IBU were quantified on test water and tissues. Results show that ibuprofen (IBU) and aluminum (Al) singly promote the production of radical species and alters the oxidative stress status in all evaluated tissues of zebrafish, nevertheless, higher effects were elicited by mixtures as different interactions take place.

Effects of fulvic acid size on microcystin-LR photodegradation and detoxification in the chlorine/UV process

Microcystin-LR (MC-LR), a polypeptide toxin generated by cyanobacteria, threatens the safety of drinking water supplies. In this study, fulvic acid (FA) was separated into two molecular weight (MW) ranges to evaluate the effects of FA size on MC-LR degradation in the chlorine/UV process. The rates of MC-LR degradation were significantly reduced in FA-containing water (3.7 × 10^-3 s^-1 for small MW FA; 4.3 × 10^-3 s^-1 for large MW FA) as compared with FA free water (4.9 × 10^-3 s^-1). The contributions of ClO• to MC-LR degradation were dramatically lower in small MW FA water (0.4%) than large MW FA (13.9%) and FA free water (17.4%), suggesting inhibition by lignin-like substances in FA in the transformation of Cl• to ClO• and scavenging ClO•. Monochlorination and hydroxylation occurred in the first step of the MC-LR degradation process. The accumulation of intermediate products in the chlorine/UV process indicated that small MW FA inhibited further degradation of MC-LR. Small MW FA, rather than MC-LR degradation, was the dominant factor in minimizing MC-LR cytotoxicity toward a human intestinal epithelial cell line.

Factors associated with low birthweight: a case-control study in a city of Minas Gerais

OBJECTIVE To analyze the many factors regarding socioeconomic and healthcare-related variables linked to maternal diseases and the possible impact of the environmental disaster of Mariana, given the prenatal exposure to different water sources for human consumption that were associated with low birthweight in full-term live births in the Municipal Hospital of Governador Valadares, Minas Gerais. METHODS Case-control study, carried out with live births at the Municipal Hospital of Governador Valadares, from May 2017 to July 2018. The case group consisted of full-term live births and low birthweight, and the control group consisted of full-term live births with adequate weight, matched by gender and date of birth. For each case, two controls were selected. Data collection was performed through interviews with the puerperal women, and complementary information was obtained by analyzing the prenatal card and medical records. For data analysis, logistic regression was performed. RESULTS The study included 65 live births from the case group and 130 from the control group. After the analysis was adjusted for other factors under study, we found that the higher risks of low birthweight are associated with the first childbirth (OR = 2.033; 95%CI = 1.047-3.948; p = 0.036), smoking during pregnancy (OR = 2.850; 95%CI = 1.013-8.021; p = 0.047) and consumption of water supplied by the municipalities affected by the tailings from the Fundão dam failure (RC = 2.444; 95%CI = 1.203-4.965; p = 0.013). CONCLUSIONS The variables "water consumed during pregnancy," "previous pregnancies" and "maternal smoking" were associated with low birthweight in the population studied. The importance of epidemiological studies that assess water quality and its adverse health effects is reinforced, as well as greater prenatal control of first-time pregnant women and greater support of policies against smoking, especially during pregnancy.

Aluminum distribution heterogeneity and relationship with nitrogen, phosphorus and humic acid content in the eutrophic lake sediment

Increasing amount of aluminum (Al) gets into aquatic ecosystem through anthropogenic activity, but the knowledge about Al migration and relationships with sediments possessing different physico-chemical properties in eutrophic lakes is limited. Here, the Al migration rule and relationships with sediment nutritions in the Hangzhou West Lake, China was investigated, where a certain amount of residual Al-salts can enter because of the pre-treatment of the Qiantang River diversion project every day. Results revealed the obvious spatial distribution heterogeneity of Al in sediment vertical direction and horizontal direction following water flow. The Al content in sediment ranged 0.463-1.154 g kg^-1 in Maojiabu Lake, and ranged 9.862-40.442 g kg^-1 in Xiaonanhu Lake. Higher Al content distributed in upper layer sediment in lake with more disturbance. Total nitrogen (TN) contents were higher 0.917-3.387 mg g^-1 and 0.627-0.786 mg g^-1 in upper layer sediment than that in lower layer in Maojiabu Lake and Xiaonanhu Lake, respectively. Total phosphorus (TP) content ranged 0.779-2.580 mg g^-1, in which IP and Fe/Al-P contributed 24.9-80.8% and 17.0-51.6%, respectively. Correlations between Al content with nutrition, humic acid (HA) etc. of sediment regionally varied in Maojiabu and Xiaonanhu Lake. Spatial distribution of Al-salt in eutrophic lakes closely related with the physico-chemical characteristics of nutrients, humus, human disturbance and water division parameters. Results provides new insight into Al-salts migration and references for Al-risk evaluating in eutrophic lakes.

Enhanced algae removal by Ti-based coagulant: comparison with conventional Al- and Fe-based coagulants

The water eutrophication caused by cyanobacteria seasonally proliferates, which is a hot potato to be resolved for water treatment plants. This study firstly investigated coagulation performance of titanium tetrachloride (TiCl₄) for Microcystis aeruginosa synthetic water treatment. Results show complete algal cell removal by TiCl₄ coagulation without damage to cell membrane integrity even under harsh conditions; 60 mg/L TiCl₄ was effective in removing the microcystins up to 85%. Furthermore, besides having stronger UV₂₅₄ removal capability and the higher removal of fluorescent substances over Al- and Fe-based coagulants, TiCl₄ coagulant required more compact coagulation and sedimentation tanks due to its significantly improved floc growth and sedimentation speed. Meanwhile, its' short hydraulic retention time avoided algal cell breakage and subsequent algal organic matter release. Microcystin concentrations were kept at a low level during sludge storage period, indicating that the TiCl₄ flocs could prevent algal cells from natural lysis. To facilitate water recycling without secondary contamination, the algae-containing sludge after TiCl₄ coagulation ought to be disposed within 12 days at 20 °C and 8 days at 35 °C.

Overview of the Relationship Between Aluminum Exposure and Health of Human Being

Aluminum is a type of ubiquitously existing naturally and widely used metal in our world. It is combined with other elements and forms different compounds. In different pH and due to other conditions, it can be released into ions of different valence states. Our century is an "aluminum age"; aluminum is used in many fields of our daily life, such as vaccine adjuvant, antacids, food additives, skin care products, cosmetics, and cooking wares, and may be as elements or contaminants appeared in a lot of foods, including infant formulae, milk products, juice, wine, sea foods, and tea. It also appears in drinking water due to the water treatment process, or naturally coming from weathering rocks and soils, or released from rocks and soils caused by pollution-induced acid rain. Due to good physical and chemical property, aluminum is being tremendously utilized in many industries. In a lot of production and process procedures, aluminum particulates are seriously exposed by workers. Many factors, such as silicon, citrate, iron, calcium, fluoride, etc., can affect absorption of aluminum in human body. Human being ingests aluminum through the respiratory and digestive system and skin. Aluminum can affect our health, especially impair central nervous system. The important damage is cognitive impairment in Al-exposed peoples, Alzheimer's disease and other neurodegenerative disorders have been related with aluminum exposure, and aluminum has been proposed as etiology.

Influence on the generation of disinfection byproducts in a tannic acid solution by aluminum ions

Aluminum (Al) commonly exists in natural waters, and its salts are often used as coagulants in drinking water treatment. Therefore, associated with the security of drinking water, functions of Al ions (Al³⁺) on generation of disinfection byproducts (DBPs) should not be ignored. This study focuses on DBPs and the carcinogenic factor of chlorinated water samples after the addition of Al³⁺ with different Al³⁺/initial tannic acid molar ratios. The results imply that Al³⁺ acts as a promoter of haloacetic acids (HAAs) and an inhibitor of trihalomethanes (THMs) when tannic acid is selected as model compound of natural organic matter during chlorination. Depending on the results of size exclusion chromatography and ultraviolet spectrophotometer, an equilibrium system can be assumed between hydrolysis and flocculation in tannic acid solution with Al³⁺. Furthermore, influences on the equilibrium system for Al³⁺ addition may result in various effects on generation and distribution ratios of THMs and HAAs during chlorination. Finally, according to the analyses of a fluorescence spectrophotometer, it is demonstrated that the presence of Al³⁺ helps to increase precursors of DBPs (humic acid-like organics) and then improve the generation of DBPs.

Deposition behavior of residual aluminum in drinking water distribution system: Effect of aluminum speciation

Finished drinking water usually contains some residual aluminum. The deposition of residual aluminum in distribution systems and potential release back to the drinking water could significantly influence the water quality at consumer taps. A preliminary analysis of aluminum content in cast iron pipe corrosion scales and loose deposits demonstrated that aluminum deposition on distribution pipe surfaces could be excessive for water treated by aluminum coagulants including polyaluminum chloride (PACl). In this work, the deposition features of different aluminum species in PACl were investigated by simulated coil-pipe test, batch reactor test and quartz crystal microbalance with dissipation monitoring. The deposition amount of non-polymeric aluminum species was the least, and its deposition layer was soft and hydrated, which indicated the possible formation of amorphous Al(OH)3. Al13 had the highest deposition tendency, and the deposition layer was rigid and much less hydrated, which indicated that the deposited aluminum might possess regular structure and self-aggregation of Al13 could be the main deposition mechanism. While for Al30, its deposition was relatively slower and deposited aluminum amount was relatively less compared with Al13. However, the total deposited mass of Al30 was much higher than that of Al13, which was attributed to the deposition of particulate aluminum matters with much higher hydration state. Compared with stationary condition, stirring could significantly enhance the deposition process, while the effect of pH on deposition was relatively weak in the near neutral range of 6.7 to 8.7.

Cationic polyacrylamide as coagulant aid with titanium tetrachloride for low molecule organic matter removal

This is the first attempt to use cationic polyacrylamide (PAM) as coagulant aid with titanium tetrachloride (TiCl4) to improve the coagulation performance and floc properties. Coagulation-flocculation treatment was applied to simulated water (with fulvic acid (FA) as model organic matter) for both coagulation behavior investigation and floc characterization. The effect of PAM on floc reformation properties after cyclic breakage/regrowth was also investigated. Ultrafiltration experiments were performed to investigate the influence of PAM aided TiCl4 coagulation on the membrane fouling. The results showed that organic removal was enhanced by PAM addition at low TiCl4 doses. Floc growth rate and floc size were significantly affected by dosing sequence. TiCl4-PAM significantly improved the floc strength factors (Sf) and recovery factors (Rf). The dosing sequence of TiCl4 and PAM significantly influenced the floc structure. Characterization of the flocculated sludge indicated that TiO2 with anatase structure and high photocatalytic activity could be obtained from the TiCl4-PAM flocculated sludge.

Polyaluminium chloride as an alternative to alum for the direct filtration of drinking water

The efficiency of various polyaluminium chloride coagulants (PACls) was compared to the efficiency of aluminium sulfate (alum) in the coagulation-flocculation process preceding direct filtration in drinking water treatment. The comparative study consisted of two separate yet complementary series of experiments: the first series included short (5-7 h) and long (24 h) filter runs conducted at a pilot filtration plant equipped with large filter columns that simulated full-scale filters. Partially treated surface water from the Sea of Galilee, characterized by very low turbidity (-1 NTU), was used. In the second series of experiments, speciation of aluminium in situ was investigated using the ferron assay method. Results from the pilot-scale study indicate that most PACls were as or more efficient a coagulant as alum for direct filtration of surface water without requiring acid addition for pH adjustment and subsequent base addition for re-stabilizing the water. Consequently, cost analysis of the chemicals needed for the process showed that treatment with PACl would be significantly less costly than treatment with alum. The aluminium speciation experiments revealed that the performance of the coagulant is more influenced by the species present during the coagulation process than those present in the original reagents.

Effect of OH-/Al3+ and Si/Al molar ratios on the coagulation performance and residual Al speciation during surface water treatment with poly-aluminum-silicate-chloride (PASiC)

Coagulation performance, mechanism of poly-aluminum-silicate-chloride (PASiC) and residual Al speciation in the effluent with respect to a specific surface water treatment in China were comprehensively investigated in this study. The impact of OH(-)/Al(3+) and Si/Al molar ratios on the coagulation performance, mechanism and residual Al speciation of PASiC in surface water treatment was discussed as a function of coagulant dosage. It was intended to provide an insight into the relationship between coagulation performance and residual Al. Experimental results revealed that when OH(-)/Al(3+) molar ratio = 2.00 and Si/Al molar ratio = 0.0500 in PASiC coagulant, PASiC exhibited beneficial coagulation property and relatively lower content of residual Al. Surface bridging and entrapment was more effective compared with charge neutralization during the specific surface water treatment. The majority of residual Al in the effluent existed in the form of insoluble suspended or particulate Al. Dissolved organically bound Al was almost the major speciation in dissolved Al and dissolved inorganically bound monomeric Al was the only component in dissolved monomeric Al. Al in PASiC remained abundant at lower dosages and residual Al concentration could be effectively reduced at the dosages of 12.0-15.0mg/L as Al.