Water Hardness Research Articles

Evaluation of extruded quinoa flour on dough rheology and white salted noodles quality.

White salted noodles are popular staples in Asia, but the ones with limited nutrient composition and high glycemic value still present significant concerns. This study investigated the potential of incorporating extruded quinoa flour (EQF) into wheat flour to enhance nutrient quality and reduce the starch digestibility of composite noodles. Moreover, the effect of EQF addition on the rheological properties of wheat dough and the cooking properties of composite noodles was also studied. The results showed that increasing the proportion of EQF in the composite flour led to a decrease in pasting viscosities and an increase in pasting temperatures, indicating that EQF inhibits starch gelatinization and retrogradation. The incorporation of EQF increased water absorption and softening degree while decreasing dough development time and viscoelasticity. The cooked noodles exhibited a significant reduction in water absorption, hardness, chewiness, and springiness, while an increase in cooking loss following EQF addition. Notably, noodles supplemented with EQF exhibited reduced overall starch digestibility with an increased digestion rate. Collectively, our results showed that substituting 10-20% EQF for wheat flour in noodles effectively lowered total starch digestibility and avoided high cooking loss. This study will have implications for the industrial application of quinoa as a staple food.

Influence of the β-Casein Genotype of Cow’s Milk (A1, A2) on the Quality and β-Casomorphin-7 (BCM-7) Content of a Semi-Hard Cheese During Production

Cow’s milk contains A1- and A2-β-caseins. The breakdown of A1-β-casein produces β-casomorphin-7 (BCM-7), a peptide with opioid-like properties that is associated with health aspects. In addition, A1- and A2-β-casein have different technological properties. The aim of the present study was to investigate whether cheese produced from the milk of homozygous A1A1 and A2A2 cows varies in terms of its physicochemical parameters and BCM-7 concentration. These parameters were analyzed during initial cheese processing, six weeks of ripening and 84 days of storage, including additional microbiological analyses during the storage period. The pH values of the A1A1 cheeses were higher than those of the A2A2 cheeses from the beginning of production until the starter culture bacteria were added. The yellowness values of the A1A1 cheeses were lower until the salt bath treatment. Water activity, lightness, hardness, fat, protein, NaCl and dry matter content, as well as color and microbiological parameters, were not affected by the β-casein genotype. BCM-7 concentrations were higher in the A1A1 cheeses after pressing and during ripening. We found mainly comparable quality characteristics and slightly different BCM-7 levels in the A1A1 and A2A2 cheeses. From this point of view, both varieties are equally suitable for cheese production.

Hydrogeochemical characterization of groundwater using water quality index and multivariate statistical analysis in Binji town and environs, Sokoto basin, Northwestern Nigeria

The hydrogeochemistry of groundwater from Binji community and surroundings was assessed. The main aim of the study was to characterize the groundwater in the study area through the application of indexing and statistical methods. Measured PH revealed 12 samples to be acidic and 15 samples to be alkaline with majority of the samples from dug wells having PH that indicates alkalinity. The concentration of analyzed chemical parameters in sampled water revealed the dominance of Ca over other metals detected in the groundwater, with the dominance given in the order Ca˃ Mg ˃ Na ˃ K. The anions were dominated by HCO3 in the order HCO3 ˃ Cl ˃ SO4 ˃ CO3. Ca ion exceeded the Nigerian standard for drinking water quality (NSDWQ) and the World Health Organization (WHO) set limits in one sample, Mg in 14 samples while K exceeded in four samples. HCO3 exceeded both standards in 21 samples; Total dissolved solids and electrical conductivity were above the maximum permissible limits in four samples. Five different water types were identified in the area with Ca + Mg- HCO3 dominating other types. Computed water quality index (WQI) for drinking water gave values that are within the range of 18–77.5 indicating the groundwater to be within the excellent and good classes of suitable drinking water quality. Irrigation water quality index revealed the groundwater to be suitable except for the magnesium hazard. Correlation analysis gave a moderate positive correlation that ranges from 0.632 to 0.659 between total hardness, Mg and HCO3, and that between Mg and HCO3 indicates the contribution of these elements to the hardness of water. Principal component analysis gave six components with a total variance of 76.19% with eigenvalues above 1 with the range of 1.52 – 4.26. Cluster analysis performed on the hydrogeochemical parameters demarcated four clusters based on the sources, hydrogeochemical environment, and reactions between chemical variables. Correlation between many chemical species revealed formation under a common hydrogeochemical environment. Gibb’s plot showed the sources of chemical constituents of groundwater to be dominated by precipitation source. The groundwater of the area is hard water that is fresh and safe for drinking and other domestic uses.

Associations between domestic hard water exposure and incident psoriasis in adults: Insights from the UK Biobank cohort study.

Although exposure to hard water is associated with various inflammatory skin conditions, the specific relationship between hard water and psoriasis has not been clearly defined. We analyzed data from 486,414 participants in the UK Biobank cohort to explore the association between domestic hard water exposure and the incidence of psoriasis. Domestic water hardness, measured in calcium carbonate concentration, was obtained in 2005 from local water providers in Wales, Scotland, and England. During a median follow-up period of approximately 14 years, a total of 4801 (1.0%) participants reported psoriasis, and we observed that for every 50mg/L increase in water hardness (as CaCO₃), there was a 3% increase in the risk of psoriasis [Hazard Ratio (HR)=1.03, 95% Confidence Interval (CI) 1.01-1.06]. Individuals exposed to very hard water (>180mg/L) exhibited a 20% increased risk of psoriasis compared to those exposed to soft water (0-60mg/L) [HR: 1.20, 95% CI: 1.07-1.34]. A positive linear relationship was observed between water hardness and the risk of psoriasis. Furthermore, the polygenic risk score indicated a synergistic effect between hard water exposure and genetic risk factors in developing psoriasis. Subgroup analysis suggested that the effect of hard water on psoriasis is more pronounced in individuals with a low polygenic risk score, women, the elderly, non-obese individuals, those of high socioeconomic status or without dyslipidemia. Residential water hardness has been identified as a significant risk factor for psoriasis in adults. Sustained efforts to reduce exposure to hard water may alleviate the psoriasis burden.

Radial basis neural network for the hard water consumption with kidney model

The “hard water” factor shows the management of water in the Nusa Tenggara Timur, which shows a higher ratio based on the ion’s minerals. The incessant use of hard water presents kidney dysfunction, which produces diabetic and vascular kinds of diseases. Therefore, it is essential to recognize the influences of hard water on kidney function. A novel design of a stochastic solver using the transfer radial basis function is provided by applying the Bayesian regularization neural network for solving the model. The kidney dysfunction mathematical system is divided into humans (susceptible, infected, recovered) and water components (magnesium, calcium). Twelve numbers of neurons with the radial basis transfer function have been used in the hidden layers for solving the model. The approach performance is remarked through the results comparison and further reducible absolute error found around [Formula: see text] to [Formula: see text] develop the scheme’s exactness. Moreover, the statistical performances including regression coefficient performances around 1 for each case of the model validate the reliability and exactness of the scheme for solving the model.

On-Site Detection of Ca and Mg in Surface Water Using Portable Laser-Induced Breakdown Spectroscopy

Ca and Mg are key constituents in surface water that are essential nutrients and vital indicators of water hardness. Rapid on-site measurement of Ca and Mg concentrations in surface water is important. However, traditional laboratory detection methods are complex and time-consuming, and on-site detection is difficult. In this study, a portable surface water detection method was developed using laser-induced breakdown spectroscopy with a miniaturized spectrometer LIBS and a liquid jet device for sample introduction. The device enables the rapid online in situ measurement of elemental concentrations in the water. The limits of detection for the rapid on-site detection of Ca and Mg in surface water were 11.58 and 2.57 mg/L, respectively. We applied this method to assess the concentrations of Ca and Mg in authentic water samples collected from rivers and ponds. The recovery rates for Ca and Mg were 90.83–101.74% and 93.43–108.74%, respectively. This method is suitable for rapid, on-site, and highly sensitive monitoring of Ca and Mg concentrations in the environment.

Optimizing seawater purification: Ion exchange selective demineralization through single and multi-objective techniques

This study focused on optimizing a selective demineralization process for seawater purification using ion-exchange technology. Experiments were conducted in three semi-batch reactors containing cation, anion, and mixed resins. Key process parameters included temperature (25 °C–50 °C), resin depth (23–82 cm), and pH (2–12). Statistical modeling and optimization were performed using Response Surface Methodology (RSM) with a central composite design, addressing both single and multi-objective criteria. A desirability function was used to assess process performance based on multiple response variables, such as the removal of trace metals (Ca2+, Mg2+, Mn2+, Zn2+, Fe2+, Cu2+, Ba2+, Cd2+), conductivity reduction, and total dissolved solids (TDS) elimination. Ten quadratic regression models were developed to describe the relationships between input parameters and responses, achieving high R2 values (≥0.7) for most responses except Cu2+, Mn2+, and Ba2+. Multi-objective optimization highlighted TDS, conductivity, and the removal of Ca2+, Mn2+, and Mg2+ as critical targets due to their significant impact on water hardness. The optimal conditions (temperature of 43.9 °C, resin depth of 75.45 cm, and pH of 5.9) yielded a composite desirability score of 0.77. Under these conditions, the process achieved over 99% removal efficiency for key cations (Ca2+, Mg2+), significant conductivity reduction, and near-complete TDS elimination. However, Mn2+ removal efficiency reached approximately 85%, likely due to its lower diffusion coefficient and higher hydration enthalpy. The results, particularly from the multicriteria optimization combined with desirability function approaches, highlight the effectiveness of ion-exchange resins in seawater demineralization and offer a robust framework for enhancing process performance.

Boundary Lubrication with Adsorbed Anionic Surfactant Bilayers in Hard Water.

The adsorption behavior of an anionic surfactant, hydroxy alkane sulfonate with an alkyl chain length of 18 (C18HAS), from its hard water solution onto a mica surface and resulting lubrication properties were investigated. Because of the double chain-like chemical structure and aggregation behavior, C18HAS formed vesicles in hard water, which adsorbed onto a negatively charged mica surface via cation (Ca2+) bridging and then transformed into a bilayer film. The number of bilayers formed on the surface was evaluated by force curve measurements using an atomic force microscope (AFM), and the results showed a time-dependent increase of the number of adsorbed bilayers. Friction and lubrication properties were evaluated for the confined film of the C18HAS hard water solution between mica surfaces using the surface forces apparatus (SFA). When the two surfaces were brought into contact under load and sheared against each other, the lubricating film consisted of two adsorbed C18HAS bilayers whose friction coefficient μ was of the order of 10-3 or below. The detailed analysis of the friction features revealed that the slipping in the boundary film does not occur at the interface between the opposed headgroup region of the two adsorbed bilayers, which is the typical mechanism for the low friction of adsorbed phospholipid bilayers extensively studied in the literature. Instead, slipping occurs at the interface between opposed liquid-like alkyl chain tails within the adsorbed bilayers; the low friction coefficient comes from the existence of two slip planes in the boundary film.

The effect of calcium on acute sodium chloride toxicity in Daphnia species.

Chloride concentrations in freshwater are rising, with toxic effects on aquatic life. In temperate regions with cold winters, road salt used for deicing paved surfaces is a primary cause. There is evidence that water hardness can modify salt toxicity, but data are insufficient to inform policy. Because calcium is a primary ion influencing water hardness and there is widespread calcium decline in lakes, we examined the effects of varying calcium concentrations on acute salt toxicity in three Daphnia species to gain a greater understanding of the water hardness-salt toxicity relationship. We conducted 48-hr acute sodium chloride (NaCl) toxicity tests, using chloride concentrations as our metric, on neonates less than 24 hrs old in six calcium treatments: 1.5 to 128 mg/L (hardness ∼7 to 323 mgCaCO3/L). We determined the effective concentration of chloride that was lethal to 10%, 25%, and 50% of the sample populations from each iso-female line in each calcium treatment. Acute NaCl toxicity decreased as calcium concentrations increased. The relationship between NaCl toxicity and calcium concentration differed among Daphnia, such that Daphnia catawba and Daphnia pulex were more sensitive to NaCl in lower calcium treatments and less sensitive in higher calcium treatments compared to Daphnia pulicaria. Our results provide evidence that water quality guidelines are not protective enough for aquatic life in very soft water (≤3 mg Ca2+/L, 11.3 mg CaCO3/L) because most ECxx values we found for Daphnia were significantly lower than Canada's national guidelines for short-term chloride exposure. There are already many lakes with calcium concentrations below 3 mg/L, and global widespread calcium decline may put more aquatic ecosystems at risk of experiencing NaCl toxicity.

Synthetic wheat as a new source of flour quality under drought conditions: Associations with solvent retention capacity.

Synthetic hexaploid lines are proposed as high-potential germplasm for improving bread wheat by introducing new genes (biotic and abiotic stresses) lost during common wheat evolution. A panel of 99 synthetic and common wheat was studied for quality and grain-related traits and drought tolerance under two different moisture conditions (water stress and normal) during two growing seasons. Results indicated different variations for most traits suggesting that the synthetic hexaploid wheat-derived lines (SHW-DL) panel contains valuable genes for drought tolerance improvement of wheat. Drought stress reduced morphological traits and production but increased protein (Pro), rapid mix test (RMT), and solvent retention capacity (SRC) traits. Synthetic wheat lines were superior with higher grain yield, glutenin, damaged starch, available pentosane, overall water holding capacity, and gluten strength (glutenin and gliadin strength) compared to common wheat making them more suitable for bread-baking. The results showed that solvent retention capacity had a strong capacity to differentiate the quality of wheat genotypes. Correlation analysis indicated that genetic improvement for high-yielding varieties can be achieved by producing more damaged starch, higher water absorption, hardness, and lower gluten strength, and zeleny (ZEL). Selection of superior genotypes using univariate and multivariate methods will be discussed.

Identifying spatiotemporal patterns and drivers of fecal indicator bacteria in an urban lake for water quality assessment and management.

The designated uses of lakes connect individuals to the natural environment, but some can expose recreational users to pathogens associated with fecal contamination that cause waterborne illnesses. Routine monitoring of fecal indicators in surface waters helps identify and track sources of fecal contamination to protect public health. We examined fecal indicators (Escherichia coli and enterococci) and factors influencing recreational freshwater quality. We collected and analyzed water samples from an urban lake for 12 months to assess water quality. Fecal indicators were detected and enumerated using IDEXX method. E. coli and enterococci were detected in nearly 100% of all water samples, but their concentrations varied significantly among seasons and land uses. We observed high levels of E. coli and enterococci during the warmer months. The geometric means of E. coli (28.5 MPN/100mL) and enterococci (39.3 MPN/100mL) were below and above the recreational water quality standards, respectively. The concentrations of E. coli (7%) and enterococci (22%) exceeded the recommended single-sample maximum levels. Sites near urban and forested areas recorded the highest and lowest fecal indicators, respectively. Water temperature, precipitation, salinity, resistivity, DO, and hardness were significant predictors of fecal indicators. The concentrations of fecal indicators were elevated at certain times of the year, indicating the potential presence of pathogens. Overall, the measured water quality parameters of the lake were within normal ranges. This study suggests that effective lake management should focus on the warmer months and runoff from urban and open space/agricultural areas to control nonpoint source pollution.

Investigation of benthic macroinvertable fauna and some environmental variables in Sızır Waterfall (Gemerek-Sivas)

In this study, the benthic macroinvertebrate fauna of Sızır Waterfall, which is located in Sivas Province (Türkiye) and has an important place in recreational activities, and some environmental variables (velocity speed, water temperature, pH, conductivity, dissolved oxygen, total hardness of water, Ca, Mg, Cl, salinity, total amount of dissolved matter, PO4, SO4, NO2-N, NO3-N contents) that may be effective in their distribution were investigated. Also, some elements (Li, B, Na, Al, K, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Cd, Sb, Ba, Tl, Pb) and a total of 181 types of pesticides were investigated in the studied area. During the wet and dry seasons of 2022, samplings were made from a total of 3 stations: at the beginning of the waterfall (upstream), inside the waterfall (waterfall) and at the exit of the waterfall (downstream). While individuals belonging to Oligochaeta (Potamothrix sp.), Gastropoda (Physa sp.), Amphipoda (Gammarus pseudosyriacus), Ephemeroptera (Baetis sp.), Plecoptera, Trichoptera, Coleoptera, Diptera and Odonata were determined. Also the physicochemical analysis results were evaluated in terms of water quality. The physicochemical and biological data of the sampling stations were examined statistically, and based on the similarity obtained, the effects of environmental variables on the distribution of macroinvertebrates were evaluated. The relationship between physicochemical data was analyzed using Pearson Correlation Analysis.

Chronic Radium-226 Bioaccumulation and Toxicity in the Aquatic Invertebrate Daphnia magna.

Mining operations in Canada, including uranium mining and milling, generate by-products containing radionuclides, including radium-226 (226Ra), a long-lived, bioaccumulative calcium (Ca2+) analog. Despite strict discharge regulations, there is limited evidence to suggest that current thresholds for 226Ra adequately protect aquatic organisms. Furthermore, Canada lacks a federal water quality guideline for 226Ra, underscoring the need for protective limits to safeguard aquatic ecosystems. Hence, this research aimed to generate data on 226Ra toxicity to the model aquatic invertebrate Daphnia magna. For this purpose, two 21-day chronic toxicity tests with D. magna were conducted, with survival and reproduction as the endpoints, as well as a reduced water hardness experiment, a multigenerational study, and a bioaccumulation assay. These experiments demonstrated that a high activity concentration (nominal 50Bq/L) of 226Ra can significantly impact the survival of D. magna. 226Ra was also found to bioaccumulate in D. magna with a BAF of 72.8. Since the Canadian Metal and Diamond Mining Effluent Regulations (MDMER) monthly mean effluent limit is currently set at 0.37Bq 226Ra /L, the limit for composite samples at 0.74Bq/L 226Ra, andthe limit for grab samples at 1.11Bq/L 226Ra, it is unlikely that toxic effects to aquatic cladocerans like D. magna from 226Ra will be observed downstream of Canadian mines and mills.

The association between domestic water hardness and kidney stone disease: a prospective cohort study from the UK Biobank.

Kidney stone disease is a common surgical disease and significant public health issue, may be influenced by environmental factors such as domestic water hardness and its related minerals. Previous studies have shown inconsistent and controversial results regarding the impact of domestic water hardness on kidney stone formation. This prospective cohort study analyzed data from 288,041 participants in the UK Biobank with no prior history of kidney stones from 2006-2024. The exposures were domestic water hardness, calcium concentration, calcium carbonate concentration, and magnesium concentration. The main outcomes were the disease status and onset time of kidney stone diseases. The confounding factors of model adjustment included age, sex, ethnicity, economic level, education level, Townsend Deprivation Index, Index of Multiple Deprivation, assessment center, body mass index, drug history influencing the metabolism of calcium and magnesium, and water intake based on the directed acyclic graph of causal hypothesis. The association between domestic water hardness and kidney stone was assessed using the Cox regression models, sensitive analyses, subgroup and interactive analyses. During the follow-up period, 3,298 participants (1.14%) developed kidney stones. In all participants, mean concentration of calcium, calcium carbonate, and magnesium was 52.61mg/L, 135.01mg/L, and 4.66mg/L, respectively. In cox regression models, higher magnesium levels (Q4,>5mg/L) in natural water use can reduce risk of kidney stones [HR and 95%CI: 0.88 (0.80-0.97) in the model 3], but no significant correlation was found in domestic water hardness, calcium concentration, and calcium carbonate concentration in the overall models. Four sensitive analyses further supported the overall results in the overall models. In subgroup analysis, hard water and calcium concentration in domestic water can increase the 18%-34% incidence risk of kidney stones in participants over 60years old and female participants; high magnesium concentration (>5mg/L) in domestic water can decrease the 10%-28% risk of kidney stones in males, participants≤45years old, and participants without renal failure. Magnesium interacted with other minerals, and its protective effects was more significant in the hard water (HR: 0.73, 95%CI: 0.61-0.87), high concentration of CaCO3 (HR: 0.62, 95%CI: 0.50-0.78) and calcium (HR: 0.48, 95%CI: 0.33-0.71) in domestic water. Our findings suggested that magnesium levels in water can decrease kidney stone risk, but in the overall population, domestic water hardness, calcium concentration, and calcium carbonate concentration have no significant impact on the formation of kidney stones. Interestingly, hard water and its calcium concentration can promote the formation risk of kidney stones in participants>60years old and females, while high magnesium concentration in domestic water can reduce the risk in males,≤45years old, and those without renal failure. The protective effects of magnesium interacted with other minerals and were more obvious in the population intake of hard water and high concentrations of CaCO3 and calcium. This study contributes to the complex understanding of environmental factors in kidney stone etiology and suggests a need for focusing on mineral-specific effects in different population and interaction with other minerals, which hope to provide some evidence of water in public health and clinical management of kidney stones.

Integrated Wastewater Treatment Technology: Efficiency of Lime and Eichhornia crassipes for Agricultural Irrigation

Introduction: wastewater treatment for irrigation is a pressing challenge in rural areas, especially in communities where agriculture depends on contaminated water sources. This study focused on developing a low-cost, sustainable technology tailored to the needs of vulnerable populations.Methods: the efficiency of a combined treatment using lime and water hyacinth (Eichhornia crassipes) was evaluated in Joa, Ecuador. A completely randomized experimental design was employed to assess changes in key physicochemical parameters, including electrical conductivity, hardness, pH, nitrates, and sulfates, before and after the treatments.Results: water hyacinth reduced water hardness significantly, from 218 mg/L to 154 mg/L of CaCO₃, while lime controlled pH, maintaining it near neutral (7,4) with precise dosing. Despite these improvements, the combination showed limitations in reducing nitrates and sulfates to meet local regulatory standards. Nevertheless, the treatments enhanced overall water quality, making it more suitable for agricultural purposes.Conclusions: the combined use of lime and water hyacinth represents a feasible, eco-friendly solution for treating agricultural wastewater in resource-constrained settings. While effective in improving water quality, further studies are needed to optimize the system, explore scalability, and evaluate its long-term impact on soil and crop productivity

Production of active chlorine and sodium hypochlorite in a closed electrolyser

Today, in the conditions of warfare, there is constant local pollution of the environment due to the use of explosives, fires, spillage of fuel and lubricants, etc. Every day, the danger increases when the water drainage systems of various enterprises are damaged, such as mining enterprises, facilities of the energy, metallurgy, chemical, petrochemical industries, sludge storage facilities for highly toxic waste. Next to this, there is a growing problem of highly efficient purification of water, primarily drinking water. As a result of the destruction of the Kakhovsky reservoir in 2023, the problem of disposal of mine waters, which are characterized by a high level of mineralization, a significant content of iron, manganese and other toxicants, has sharply worsened. In this case, there are no water resources for diluting mine waters before their discharge. Despite a significant number of developments in the field of water quality control and water purification technologies, a number of problems in this direction remain unresolved. Existing technologies are ineffective when the levels of mineralization and water hardness are exceeded. We are talking about the southern regions of our country and Donbas. In Mykolaiv, after the aggressor reduced the water intake on the Dnieper, the centralized water supply system supplies brackish water from the estuary. It is known that concentrated salt solutions, which are formed and are still present next to the problems described above, are practically not processed. In most cases, they are dumped into the surface reservoirs of the surrounding natural environment, which significantly worsens the state of water ecosystems of Ukraine. The situation is worsened by the fact that a significant part of mine water suitable for use, due to the problem of disposal of concentrates, is not used, but is discharged into the environment after dilution, or even without dilution and purification, since there is simply no resource for dilution in today's realities. That is why, the problem of processing concentrates of baromembrane purification with obtaining secondary useful products was the aim of the research of this work.

Water softening technologies for small and medium capacity systems

The current state of water resources is largely determined by human activities. The discharge of polluted waters into surface water bodies significantly reduces their quality and complicates direct usage. One of the main sources of increasing mineralization and hardness of surface waters is the discharge of spent regeneration solutions after ion-exchange softening, which creates a closed cycle of sodium, calcium, and magnesium chlorides. The need to reduce the intensity of this cycle and decrease environmental pollution has arisen long ago. Studying the standard soda-sodium softening method has shown its low suitability for systems with small and medium productivity due to the need for water heating and subsequent pH correction. Using phosphate anions as precipitants proved to be more effective, successfully removing calcium and magnesium ions over a wide range of temperatures and pH levels. Research has revealed that the formed solid phase in such treatment is poorly separated from the liquid. As one of the solutions to this problem, the use of anionic flocculants is proposed, which provide effective separation of the formed solid particles from the water. A technological scheme has been developed, which involves usage at the stage of preliminary water treatment for reverse osmosis systems with small and medium productivity.

Analysis of the ecological and hydrochemical state of lake akkel in the conditions of foothill of dagestan

Water pollution is one of the most serious environmental problems. Industrial waste, agricultural fertilizers and domestic wastewater enter to water bodies, leading to the death of aquatic organisms and deterioration of the quality of drinking water. Particularly dangerous are heavy metals and pesticides, which can accumulate in living organisms, causing chronic diseases and genetic mutations. Solving of these problems requires an integrated approach. It is necessary to develop and implement water purification technologies, improve wastewater collection and processing systems, and introduce methods of the rational use of water in agriculture and industry. This work is based on our own materials, obtained during research es, conducted on Lake Akkel and its tributaries. Oz. Akkel has fresh water and is located in the eastern part of the Buinaksky district. From the data presented it is clear, that water samples, taken in different sites, may differ. For example, a noticeable excess of the concentration of nitrate ion was noted in samples, taken from areas 4 and 5. In other areas no excess on this indicator was observed. On hydrocarbonate ion water samples in points 1, 4-6 had overestimated values. Sample 6 had a particularly noticeable excess of sodium and magnesium cations, exceeding the maximum permissible values in 14 and 54 times, respectively. Water hardness was too high (153,0) at point N. 6. The conducted studies showed, that the water in the studied reservoir is characterized by favorable hydrochemical regime, with the exception of water hardness, a significant excess of which, according to many authors, can negatively effect on the reproduction of aquatic organisms, living in this reservoir. In addition, most aquatic plants are also sensitive to water hardness and prefer softer water environments.

Evaluation of water hardness treatment methods using sodium hydroxide and their impact on water quality

Hard water is an environmental and technical challenge caused by high concentrations of calcium (Ca²⁺) and magnesium (Mg²⁺) ions, leading to scale formation that affects the efficiency of household and industrial appliances and increases maintenance and treatment costs. Additionally, hard water can pose health risks and reduce its quality for daily use. This study aims to evaluate the effectiveness of different doses of sodium hydroxide (NaOH) in treating water hardness and improving water quality by reducing total hardness (TH) and adjusting the physicochemical properties of water. Three main dosages were tested: the first dosage (5 g/L of NaOH), which assessed the basic effectiveness of sodium hydroxide; the second dosage (2.5 g/L of NaOH and 2.5 g/L of Na₂CO₃ with HCl and acid), aimed at balancing hardness reduction with mineral retention; and the optimized dosages (10, 20, and 30 mg/L of NaOH), which proved to be the most effective and balanced. The optimized doses successfully reduced total hardness to levels compliant with Algerian standards while maintaining calcium and magnesium concentrations within acceptable ranges. Furthermore, electrical conductivity (EC) remained within safe limits without significant increases, ensuring the water did not become oversaturated with dissolved salts. The slight increase in sodium (Na⁺) concentration also remained within permissible levels, enhancing the water's suitability for drinking and other uses. Based on these results, the optimized NaOH dosages are the optimal solution for water hardness treatment, achieving a balance between reducing hardness and ensuring water quality in compliance with local standards.

Towards the standardization of Hydra vulgaris bioassay for toxicity assessments of liquid samples.

The Hydra vulgaris bioassay is recognized as sensitive invertebrate test species for toxicity assessment of real-life environmental mixtures for enforcement and monitoring investigations. The purpose of this study was to characterize the intra-laboratory variability, study the influence of environmental variables (temperature, luminosity, inter-individual and day of analysis) on ZnSO4 toxicity, a reference model toxicant for hydra. The sublethal (effect concentration for 50 % of hydra-EC50) and lethal (lethal concentration for 50 % of hydra-LC50) were determined based on characteristic morphological changes for this species. The influence of water hardness, ammonia and dissolved oxygen for over 50 real-life environmental liquid mixtures (effluents and leachates) were examined and compared with rainbow trout and Daphnia magna acute lethality tests. A control chart for Zn was developed from over 40 trials yielding an 96 h LC50 of 0.7 mg/L (0.66-0.77 95 % confidence interval-CI) and EC50 of 0.19 mg/L (0.17-0.21 95 % CI). The influence of 8 different analysts, the trial days and luminosity did not significantly influence the LC50 and EC50. Only higher temperature significantly decreased the toxicity of ZnSO4 within 15-30 °C range. The hydra bioassay was then practiced on more than 50 real-life effluents/leachates and compared with the 96 h rainbow trout and 48 h Daphnia magna survival tests. The data revealed that water hardness, dissolved oxygen and ammonia were not significantly correlated with either the LC50 or EC50 values. Moreover, the hydra LC50 data predictive (rank correlation of 0.6) the rainbow trout LC50 with the absence of false negatives. The hydra data were at least as if not more sensitive than the rainbow trout LC50 making it a relevant alternative method to reduce fish use for screening potentially toxic environmental mixtures.