Langelier Index Research Articles

In the southern plains of Oran, the two main aquifer formations are the Mio-Pliocene limestone and the Plio-Quaternary conglomerates. To assess the overall quality of groundwater, and highlight the factors and mechanisms controlling its chemistry, hydrogeological and hydrochemical data are studied using geographic information system (GIS), multivariate statistics (principal component analysis [PCA] and hierarchical cluster analysis [HCA]), potable water quality indices (PWQI), and irrigation water quality parameters. The results show that the Mio-Pliocene aquifers have the best groundwater, with some samples having a mineralization of <1g/L, whereas the quality of groundwater varies in the Plio-Quaternary aquifers from one location to another. The increase in groundwater concentration generally occurs from South to North, in accordance with the direction of groundwater flow towards the Sebkha of Oran. The PCA and HCA results show that groundwater is divided into two major groups. The first represents fresh to passable waters (0.5 g/L ≤ TDS ≤ 2 g/L) located predominantly in the Tessala Mountains piedmonts and around the Tafraoui-Tlelat limestone outcrops. These groundwaters have a low Langelier index (LSI ≈ 0.25) and are neither corrosive nor scaling. The second group represents slightly saline to highly saline groundwater (2.5 g/L ≤ TDS ≤ 5g/L). The slightly saline groundwaters are mostly observed around and South of Ain Larbaa in the Plio-Quaternary conglomerates. The highly saline groundwaters are only observed for 6 samples and are most likely the result of contamination. The PWQI show that only 18% of groundwater is fit for human consumption; the remaining groundwater ranges from poor (21%), very poor (38%), to unsuitable (23%). The results also show that only 60% of samples are suited for irrigation. The hydrochemical results identify geological zoning, climate aridity, and to a lesser degree anthropic activities as the major factors regulating groundwater quality via the carbonates and silicates weathering and ion exchange process.

Adrar, located in an arid desert environment in southwest Algeria, relies exclusively on groundwater from the Continental Intercalaire aquifer for its water supply. This study aims to assess the quality of this groundwater for human consumption, irrigation, and industrial use and identify the hydrogeochemical processes driving its mineralization. To achieve this, 18 wells were analyzed using conventional laboratory methods. Quality indices applied include the drinking water quality index for potability and the irrigation water quality index for agricultural suitability. Corrosion and scaling potential were evaluated using the Langelier index, Ryznar index, Larson–Skold index, Puckorius index, and aggressive index. The results indicate that 44.44% of the water is suitable for drinking, 50% is of medium quality, and 5.56% is unsuitable for drinking. For irrigation, 31.25% of wells provide good-quality water, while 68.75% are classified as doubtful. Most of the analyzed waters are corrosive, with a tendency toward scaling and CaCO3 precipitation. Hydrochemical analyses, including Piper diagrams, identified two water types: Ca–Mg–Cl (50%) and Ca–Cl (50%). Based on the Gibbs diagram, bivariate plots, and saturation indices, the groundwater’s mineralization is primarily attributed to water–rock interactions, such as the dissolution of silicate rocks, halite, and gypsum, along with cation exchange. Additionally, human activities significantly influence water chemistry. This study provides scientific foundations for sustainable groundwater resource management in Adrar, including water quality and exploitation. This work helps inform strategies for the preservation, rational use, and treatment of water, ensuring sustainable water access for domestic, agricultural, and industrial needs.

The paper studies the operation of a highly mineralized water purification system with a reverse osmosis unit for the needs of a metalworking enterprise. It identifies the reasons for the unsatisfactory operation of the water purification system and develops recommendations for its improvement based on the assessment of water quality in samples at water treatment stages and the assessment of the tendency of the feed water to form silt on reverse osmosis membranes. The work aims to develop an effective technology for purifying highly mineralized water, which contains both ammonium and iron ions, based on the study of the existing water purification system at the enterprise. Groundwater is chloride-sulphate calcium-magnesium and does not meet the requirements for drinking water in terms of turbidity, total mineralization, total hardness, ammonium, total iron, silicates, magnesium, manganese, sodium, strontium, and chlorides. Standard methods were used to determine water quality indicators at various water treatment stages. Highresolution scanning electron microscopy was used to analyze the surface of the filter material grain. The elemental composition of the filter material grain and its surface sediment were analyzed locally using energy dispersive spectrometry. The hypothetical composition of groundwater and the quality of water at various water treatment stages were investigated; the silt density index, the Langelier index, and the Gibbs energy of carbon dioxide equilibrium in the aerator were calculated; the aeration system performance was assessed. The reasons for the performance slowdown of the reverse osmosis unit and the frequent replacement of the pressure filter media were identified. The tested water supplied to the reverse osmosis unit does not meet the requirements for total hardness and total iron. The insufficiency of the specific air flow rate in the aerator was proven. Mudding of granular filter material with calcium carbonate and amorphous silicon was observed. Technical solutions are proposed to increase the efficiency of aeration-degassing and iron removal at the preliminary water purification stage before reverse osmosis. The proposed solutions will be relevant for the design and operation of process flows for complex groundwater purification.

In a desalination station, the remineralization step of osmosis water (OW) is essential to return to produced water its calco-carbonic equilibrium. For this, the use of calcite CaCO3 or lime Ca(OH)2 for water equilibrium in post-treatment processes needs the utilization of both CO2 and/or H2SO4 in osmosis water. For this reason, we describe here in detail, the effect of H2SO4 and CO2 on the remineralization process in a post-treatment desalination plant, especially with using hydrated lime Ca(OH)2 and calcite contactor (CaCO3)·In this paper, the different cases were discussed and investigated, by monitoring several indicator parameters such as pH, Ca2+ content, alkalinity, Langelier Index, etc. After the remineralization stage, we have shown that the efficiency of the remineralization process by CaCO3 or Ca(OH)2 depends on CO2 or H2SO4 content. Remineralization by CaCO3 (limestone) coupled with CO2 acidification is easy and more operator-friendly compared to the process using Ca(OH)2 (lime); it provides a clean environment for people working in the plant. In addition, the H2SO4 injection in the pretreatment stage followed by CaCO3 contact could lead to great results and correct calco-carbonic equilibrium. In the end, a comparative study of the investment cost in each process shows that the acidification of raw water with sulfuric acid (pretreatment) is the cheapest one, according to many studies. But on the other hand, the direct injection of CO2 is the easiest one to use for water balancing.

An integrated approach combining water quality indices (WQIs), multivariate data mining, and geographic information system (GIS) was employed to examine the water quality of Bheemasandra Lake, located adjacent to a sewage treatment plant (STP) in Tumakuru city, India. The analysis of 22 lake water samples, examined before and after the monsoons, revealed that the physicochemical parameters namely - electrical conductivity, biochemical oxygen demand, turbidity, total dissolved solids, ammoniacal nitrogen, nitrates, phosphates, magnesium, total hardness, total alkalinity, and calcium - exceeded the acceptable limits stipulated by national and international standards. The Canadian Council of Ministers of the Environment WQI (pre-monsoon: 25.3; post-monsoon: 33.9) and weighted arithmetic WQI (pre-monsoon: 3398; post-monsoon: 2093) designated the water as unsafe for drinking. Irrigation WQIs (sodium adsorption ratio, sodium percentage, residual sodium carbonate, magnesium hazard, permeability index, and potential salinity) implied water's suitability for irrigation. However, electrical conductivity indicated otherwise. Industrial WQIs (Larson-Skold Index, Langelier Index, Aggressive Index, and Puckorius Scaling Index) illustrated scaling propensity and the chloride sulfate mass ratio alluded galvanic corrosion potential. Hierarchical cluster analysis gathered 22 sampling points into two clusters (cluster 1: relatively lower polluted regions; cluster 2: highly polluted regions) for each season based on similarities in water features. Principal component analysis extracted four (79.07% cumulative variance) and six (87.14% cumulative variance) principal components before and after the monsoons, respectively. These components identified the primary pollution sources as urban sewage and natural lithological processes. WQI maps, created using the inverse distance weighted interpolation technique, enhanced the visualization of spatial-temporal variations. This study highlights the dire consequences of urbanization, STP pollution, and sewage management failures, necessitating that concerned authorities should implement policies and measures to curb the negative impacts on the environment and public health.

Groundwater, a predominant reservoir of freshwater, plays a critical role in providing a sustainable potable water and water for agricultural and industry uses in the In Salah desert region of Algeria. This research collected 82 underground water samples from Albian aquifers to assess water quality and identify hydrogeochemical processes influencing mineralization. To achieve this objective, various methods were employed to evaluate water quality based on its intended uses. The drinking water quality index utilized revealed the water potability status, while the indicators of irrigation potability were employed to evaluate its quality for agricultural purposes. Additionally, an assessment of groundwater susceptibility to corrosion and scaling in an industrial context was conducted using several indices, e.g., Langelier index, Larson-Skold index, Ryznar index, chloride-sulfate mass ratio, Puckorius index, aggressiveness index, and the Revelle index. The findings of this study revealed thatthe groundwater quality for consumption fell into four categories: good (2.44%), fair (29.27%), poor (65.85%), and non-potable (2.44%). Concerning agricultural irrigation, the indexical results indicated that 15.85% of the waters exhibited adequate quality, while 84.15% were questionable for irrigation. Calculations based on various corrosion and scaling evaluation indices showed that most wells were prone to corrosion, with a tendency for calcium bicarbonate deposit formation. Furthermore, the hydrochemical study identified three water types: Na-Cl (53.66%), Ca-Mg-Cl (37.80%), and Ca-Cl (8.54%) waters. Analyses of correlation matrices, R-type clustering, factor loadings, Gibbs diagrams, scatterplots, and chloro-alkaline indices highlighted that the chemistry of the Albian groundwater is fundamentally impacted by a number of processes such as silicate weathering, evaporite dissolution, ionic exchange, and anthropogenic inputs, that played impactful role in the aquifer's water chemistry.

When performing technological calculations of water treatment units for thermal power plants (TPP) and nuclear power plants (NPP), it is necessary to determine the quality indicators of process water after the processing steps. The main difficulty is to calculate the concentrations of weak electrolytes since they are in chemical equilibrium with all forms of dissipation. Currently, for each type of processing, either simplified models or methods that solve a complex computational problem are used for calculations. It is necessary to develop a universal mathematical model that allows high accuracy to calculate the concentrations of weak electrolytes and the pH value for various types of water treatment. To develop the model the authors have applied the method of mathematical modeling of chemical-technological processes at thermal power plants and nuclear power plants. A mathematical model based on the transformed equation of electrical neutrality is proposed. It can be used to determine the equilibrium concentrations of dissociation forms of weak electrolytes (primarily water itself and carbonic acid) after various stages of water treatment. The proposed model allows, when conducting technological calculations of water treatment plants, to more accurately and universally calculate the concentrations of weak electrolytes and determine the pH value in process waters for various types of water treatment. The model can be used to determine the required doses of chemical reagents to ensure the required values of technological indicators (pH and Langelier index) in treated water.

The aim of this study is to perform a spatial complex hydrochemical analysis of groundwater quality in Bulgaria and compile a map. For this purpose, data for the chemical composition (Ca2+, Mg2+, Na+, Cl–, SO42–, NO3–, HCO3–, TDS, EC) of fresh groundwater (having shallow circulation) for the year 2015 have been summarized. These are the waters most vulnerable to incoming contaminants infiltrating from the surface and, at the same time, these are the waters of importance for the provision of potable water supply. The Groundwater Quality Index has been used to assess the water quality for domestic usage. An assessment of the potential groundwater’s corrosive activity has also been made. For this purpose, the Langelier Saturation Index and the Potential to Promote Galvanic Corrosion were determined as well. The galvanic corrosion of water in respect to lead (expressed as the chloride-sulphate mass ratio) has not been determined and mapped on the territory of Bulgaria, nor has the Langelier index for fresh groundwater. For the year of 2015, the groundwater of the territory was classified as being in acceptable (76 to 90), and good (90 to 95) condition in terms of the Groundwater Quality Index. In terms of the Langelier Saturation Index and the Potential for Galvanic Corrosion, the territory of the country can be characterized by low to moderate potential (for galvanic corrosion), and according to LSI it can be classified in three categories – potentially corrosive, indeterminate, and scale forming.

Predicting Legionella contamination in cooling towers and evaporative condensers from microbiological and physicochemical parameters.

The article presents the results of a computational and analytical study of hybrid RO–MD (Reverse Osmosis–Membrane Distillation) technologies for desalination of the Caspian Sea, providing for the production of an additional amount of desalinated water by the MD method from RO concentrates heated to 50–80°C due to waste heat of fuel combustion products in steam boilers. Two options for solving the problem of the formation of CaCO3 and CaSO4 precipitates on membranes were studied: with preliminary nanofiltration (NF) or Na-cationation (Na) of sea water, as an alternative to the use of antiscalants (AS) and acid. The negative environmental effect of most plants (eutrophication of water bodies) and their low efficiency at high concentrations of desalinated water are taken into account. The Langelier index (СаСО3) and the degree of concentrate saturation (СаSO4) were used as criteria for precipitation of deposits on the membranes. The NF and RO processes were studied using the ROSA computer program, and the MD and Na processes were studied by computer simulation of the corresponding calculation models. It was found that at a 70% permeate yield at the NF and RO stages, the possibility of calcium precipitation on the RO and MD membranes is prevented, but their precipitation on the NF membranes is predicted, which makes the use of AS forced. At the same time, additional permeate production at the MD stage from RO concentrates reaches 40% of the amount of permeate from RO stadium, and the electricity consumption in general according to the scheme is 1.88 kWh/m3. Reducing the calcium hardness of sea water to 50 µg-eq/dm3 by the Na-cationization method makes it possible to refuse both the use of AS and acidification with sulfuric acid with additional production of MD permeate – 27% relative to RO permeate. Electricity consumption rises to 2.5 kWh/m3. To use the known advantages of NF without the use of AS, a hybrid Na–NF–RO–MD scheme is proposed. It has been established that at 80% yields of NF and RO permeates, to prevent the formation of CaSO4 precipitates at all stages of treatment, it is sufficient to reduce the hardness of sea water from 16 to 5.5 m-eq/dm3, and by acidifying the softened water to exclude the formation of CaCO3 precipitates.

Keeping purpose and targeted end-users in perspective, several water quality indices have been developed over the past decades to summarily convey water quality information to decision-makers and the general public. Industrial water quality is often analyzed based on the corrosion and scaling potentials (CSPs) of water. The commonly used CSP index parameters are chloride-sulfate mass ratio, Langelier index, Larson-Skold index, aggressive index, Ryznar stability index, and Puckorius scaling index. Simultaneous application of these index parameters often classifies a sample into multiple water quality categories, thereby introducing bias in assessment anddecision-making. No previous numerical model integrated the CSP indices to provide a single, composite index value for a more unbiased interpretation of industrial water quality. Therefore, this paper proposes an integrated industrial water quality index (IIWQI) that integrates the six CSP index parameters for direct and concise assessment of industrial water resources. To achieve its aim, this research incorporated information entropy theory and soft computing techniques. The developed IIWQI was applied to water samples from southeastern Nigeria. Different classification groups were observed based on the six CSP indices. However, the IIWQI summarized the classifications of the water samples into three categories: Class 1 (28.57%, slight-medium corrosivity, significant scaling potential); Class 2 (46.43%, medium-high corrosivity, no scaling); and Class 3 (25.00%, high-very high corrosion, no scaling). Correlation analysis revealed the relationships between the physicochemical variables, CSP index parameters, IIWQI, and the entropy-based variability of the IIWQI. The spatiotemporal water quality groups were revealed by Q-mode hierarchical dendrograms. Multiple linear regression and two multilayer perceptron neural networks accurately predicted the IIWQI. The findings of this paper could help in better evaluation, interpretation, and management of industrial water quality.

The previously proposed mechanism of bicarbonate ions decomposition by the H-mechanism (with the formation of H+ and CO32-) or OH-mechanism (with the formation of OH- and CO2) is confirmed experimentally without and with heating water up to 190oC. The change decomposition mechanism depends on hardness, alkalinity and pH. The H-mechanism is observed at higher pH values (pH decreases) and the OH-mechanism is observed at lower values (pH increases) in particular solutions.
 The developed technique is based on the measurement of changing the pH (ΔрНt) of the solution (at a fixed temperature of 15 to 25oC) after heating it to a given temperature (ranging from 40 to 190oC) and maintaining this temperature for at least 30 minutes. A decrease in the pH of the water after heating (ΔрНt>0) indicates the formation of carbonate ions and the need for additional water treatment to reduce the hardness, alkalinity or pH. The greater the ΔрНt, the greater the concentration of carbonate ions formed in water. If ΔрНt is zero then this temperature can be used as a water quality index. This temperature is 86.4oC for tap water in Kyiv (pH 7.4). Measurement of ΔрН in water meeting standards for water in German heating supply systems (pH 9.06, Hardness 45 μmol/dm3 - 5 times less than in Ukraine) shows that such water is not scale-safe (ΔрН150=0.15).
 The proposed technique will be able to replace the Langelier index (up to 90oC) and the carbonate index (up to 190oC) under the condition of systematic processing of experimental data obtained for the water of different compositions on its basis. This method can be used in addition to the expensive experimental method of dynamic tube blocking.

Introduction: Corrosion and scaling are important factors affecting drinking water quality, causing health and economic problems. This study aimed to investigate the indicators of corrosion and scaling in Rafsanjan drinking water. Materials and Methods: The present descriptive cross-sectional study was conducted in winter 2018 and spring 2019 in Rafsanjan. The 56 samples were randomly taken from the drinking water distribution and transmission networks. Physicochemical parameters, such as pH, temperature, total dissolved solids (TDS), total hardness (TH), calcium hardness (CH), electrical conductivity (EC), and alkalinity were measured. Finally, corrosion and scaling indices, including langelier index (LI), ryznar index (RI), aggressiveness index (AI), and Puckorius index (PI) were calculated and analyzed. Results: The mean temperature, pH, CH, TH, TDS, alkalinity, and EC were 17.79 ± 0.80 °C, 8.08 ± 0.11, 56.34 ± 2.72 mg/L.CaCO3, 140.86 ± 6.81 mg/L.CaCO3, 530 ± 110 mg/L, 181.21 ± 13.65 mg/L, and 840 ± 180 µs/cm, respectively. The mean corrosion and scaling indices, including LI = 0.18 ± 0.12, RI = 7.72 ± 0.14, AI = 12.09 ± 0.11, and finally PI = 7.96 ± 0.10 were obtained. Conclusion: Based on the obtained data, drinking water in the transmission and distribution network of Rafsanjan has scaling properties. Water scaling and deposition causes problems, such as blockage of water transmission and distribution pipes, reduction of flow rate and increase of pressure drop in the network, and finally increase of water facilities operation costs. Therefore, measures should be considered to control the scaling of water in this region.

Predicting and analysing the quality of water resources for industrial purposes using integrated data-intelligent algorithms

As a result of changes in the chemical properties of the Shatt al-Arab River, especially in the last decade, as well as the lack of rainfall and the effect of seawater intrusion into the Shatt al-Arab, this study was conducted to investigate the possible changes in the water pipelines like corrosive and scaling which Shatt al-Arab River is the source of water supply for domestic use. Domestic water samples were collected from 10 various locations in Basrah to study the water's tendency to be corrosive or form scales along the pipelines. The Langelier Index, Ryznar Index, Larson-Skold Index, and Saturation Index were used to determine the corrosivity potential of water based on physical and chemical parameters. Most domestic water sources tend to form scales based on the Langelier Saturation Index, Ryznar Index, and Saturation Index. According to the evaluation, the Langelier Index ranged from -1.71 to 1.98, Ryznar Index was between 4.45 and 10.53, Larson-Skold Index was between 1.13(rainwater) 62.70 (Dibdabba Water) and Saturation Index was ranged -1.31 to 1.24. The results indicated that the rainwater and some groundwater samples are moderately corrosive. The water of all the water resources sampled in this study ranged from balanced to mild scaling. The Larson-Skold Index, on the other hand, shows that all domestic water samples are corrosive. The corrosion and scaling potential of natural water sources collected from groundwater, river water, and rainwater has also been determined.

The aims of this study are water quality assessment for drinking and industrial usages with refer to affective factors on water chemistry in North of Quchan plain, Razavi Khorasan province. 17 groundwater samples were collected for major cations (Ca2+, Na+, Mg2+, K+) and anions (HCO3-, SO42-, Cl-) analysis. According to Piper diagram, chemical composition of water samples is 29.4% Ca-SO4, 23.5% Na-SO4, 23.5% Mg-SO4, 11.8% Na-HCO3 and 5.8% Mg-HCO3. Based on Gibbs diagram, the main controlling process of the water composition is mainly water-rock interactions (weathering), rather than evaporation and precipitation. Schoeller diagram shows that most of water samples are categorized in moderate and acceptable classes. Also, based on water quality index (WQI), 70.59 % water samples are suitable for drinking usage. Increasing in SO42- concentration reduced the water quality for drinking purposes. Langelier index (LSI) shows 82.35 % water samples are scale forming and 17.65 % are corrosive. Scale forming of the water are due to high TH induced by carbonate dissolution (of Mozdouran and Tirgan Formations). In addition, corrosive property of some water samples is due to gypsum dissolution (from Shoorigeh Formation) and increasing of sulfate concentration in the groundwater.

Most water supply systems operating in Ukraine are made of steel or cast iron, which are subject to corrosion. The Institute of Water Problems and Land Reclamation of the National Academy of Sciences of Ukraine carried out the experimental studies on the effect of an orthophosphate corrosion inhibitor on the quality of drinking water and the rate of corrosion as a result of its appliance in various doses in the water supply network. The water supply system of Obolon district of the city of Kiev was selected as the object of research. A characteristic feature of this water supply system is the use of various sources of water supply - groundwater and surface waters of the Desna and Dnieper rivers. The results of the calculation of water corrosivity carried out at the Institute based on the chemical analysis of the quality of water taken from 29 wells at the research object showed that the Langelier indices obtained using the calculation formulas for all sampling points are in the range from 0,89 to 1,77, which indicates the continuous and significant corrosive activity of water at all sampling point. The Risner index in all samples was in the range from 7.8 to 8.8, which indicates the significant pipeline corrosion. That is especially typical for the water from the well № 232, the Rizner index of which is 9.58, which indicates very intensive corrosion of the pipeline. Indicators rH2, for all samples, calculated both by F.U. Clarke and by the formula of A.I. Trufanov, indicate that the studied aquatic environment is very favorable for the vital activity of iron bacteria in general, and the pH - Eh zone of water samples indicates that there is an active vital activity of various strains: Leptothrix, Gallionella , Thiobacillus thiooxcidans or their combined activity. All the studied factors indicate that the most likely there is a complex genesis of corrosion processes in water supply networks, which combines both physicochemical and biological processes. This combination usually contributes to the processes of active secondary water pollution by the products of pipeline corrosion. Indicators rH2, for all samples, calculated by the formulas of F.U. Clark and of A.I. Trufanov, indicate that the studied aquatic environment is very favorable for the activity of iron bacteria in general, and the pH - Eh zone of water samples indicates that there is a rather high activity of different strains: Leptothrix, Gallionella, Thiobacillus thiooxcidans or their combined activity. The results of the research showed that for all ways to use of "SeaQuest Liquid" spicemen in the water of all sampling points there were no deviations from the standards of basic physicochemical parameters: the average pH of water was 7,67 ± 0.01, total water hardness was 4,3 ± 0,03, total alkalinity - 4,4 ± 0,05 mmol/dm,3 calcium content - 58,6 ± 0,7 mg/dm3, magnesium - 16,1 ± 0.2 mg/dm3, hydrocarbons - 261,4 ± 4,8 mg/dm3, manganese <0,01 mg/dm3, sulfates - 21,9 ± 1,2 mg/dm3, chlorides - 44,3 ± 1,4 mg/dm3, sodium and potassium - 44,0 ± 2,0 mg/dm3, residual chlorine - 0,35 ± 0,02 mg/dm3, ammonium - 0,2 ± 0.01 mg/dm3, permanganate oxidation - 2,3 ± 0,1 mgО2/dm3, nitrites - 0,09 ± 0,01 mg/dm3, nitrates - 1,53 ± 0,14 mg/dm3, total mineralization - 459,9 ± 15,1 mg/dm3. In some samples of water treated with “SeaQuest Liquid”, the iron content exceeded the hygienic standard (0,2 mg/dm3) and exceeded the maximum allowable level (1,0 mg/dm3). In drinking water samples, the levels of substances that are the part of "SeaQuest Liquid" specimen (polyphosphates, orthophosphates), varied at different sampling points but were within the normative values. The anticipated biological component of corrosion according to the calculated Rh2 index, was confirmed. In the presence of sulfate-reducing and thiobacteria in water, "SeaQuest Liquid" specimen increases the corrosion rate of steel by 2,9-7,2 times; subject to additional disinfection of water when treating with sodium hypochlorite, it reduces this indicator by 1,4-2,7 times. Under the action of "SeaQuest Liquid" in water treated with sodium hypochlorite, there was a decrease in the Langelier index: from -2,23 to -2,08 and from -1,79 to -1,70, indicating a decrease in its corrosive activity. In water untreated with sodium hypochlorite under the action of "SeaQuest Liquid" there was some increase in the Langelier index: from -1.80 to -1,95 and from -1,85 to -2,78; from -2,01 to -2,13, which indicates an increase in its corrosive aggressiveness.

ABSTRACT In developing regions that engage in agricultural and industrial activities, access to high-quality water for drinking, domestic, irrigation and industrial purposes is limited. In this study, comprehensive water quality assessment has been carried out to unravel the suitability of water supplies in Umunya suburb for human consumption, industrial and irrigation purposes. Water samples from spring, streams, and boreholes were analysed for physicochemical properties and heavy metals pollution. Pollution index of groundwater (PIG) was used to assess the drinking suitability of the waters whereas several indexical methods were integrated to unravel their suitability for irrigation and industrial purposes. The pH (4.61–6.53) revealed that majority of the samples are acidic. All the chemical ions were within their respective standard allowable limits, except for Fe, Pb and Ni. Generally, these heavy metals significantly impacted the water quality of the area. The PIG evaluation of the waters for drinking purpose revealed that 40% of the samples are unsuitable. However, most of the indices used for the irrigation water quality evaluation showed that majority of the samples are suitable for irrigation uses. The industrial water quality assessment indicated that the natural waters have more corrosive tendency than scaling tendency. Corrosivity and scaling indices, such as Langelier index, Larson-Skold index, chloride-sulphate mass ratio, aggressive index, Ryznar stability index, and Puckorius scaling index, unveiled that the natural waters are severely corrosive, having the tendency to damage domestic, irrigational, and industrial water distribution systems. This paper provides significant information necessary for the management and sustainability of water resources in Umunya suburb.

It is noted that the overwhelming majority of water supply systems operating in Ukraine are made of steel or cast iron, which are subject to corrosion. It has been established that/ one of the ways to reduce the corrosiveness of drinking water is the use of an orthopolyphosphate preparation “SeaQuest Liquid” (TU U 20.5-V 0502222-001:2017). The results of studies of the effect of the “SeaQuest Liquid” preparation on organoleptic and physicochemical indicators of drinking water are presented. It was determined that the treatment of tap drinking water with the “SeaQuest Liquid” preparation does not affect organoleptic indicators, the average levels of which practically did not undergo significant changes during 5 months of observation and were within the hygienic standards. In water samples, the levels of substances that make up the “SeaQuest Liquid” preparation (polyphosphates, orthophosphates) were within the normative values. The quality of water treated with the “SeaQuest Liquid” orthophosphate preparation, according to the main sanitary and chemical indicators, except for iron, meets the requirements of the hygienic standards DSanPiN 2.2.4.171-10. In some water samples, the iron content in water exceeded the hygienic standard (0.2 mg/dm3) and went beyond the maximum permissible level (1.0 mg/dm3). Under the action of “SeaQuest Liquid” in water treated with sodium hypochlorite, a decrease in the Langelier index was observed: from -2,23 to -2,08 and from -1,79 to -1,70, which indicates a decrease in its corrosivity. In water untreated with sodium hypochlorite under the influence of the “SeaQuest Liquid” preparation, a slight increase in the Langelier index was observed: from -1,80 to -1,95 and from -1,85 to -2,78, from -2,01 to -2,13, which indicates an increase in its corrosiveness. In the presence of sulphate-reducing and thiobacteria in water, the “SeaQuest Liquid” preparation increases the corrosion rate of steel by 2,9-7,2 times; subject to additional disinfection of water with sodium hypochlorite, it reduces this indicator by 1,4-2,7 times.

Introduction: Water quality is essential for industries because they play an important role in countries’ economic development. Groundwater is one of the most widely used resources, and when the ionic constituents were increasing higher than the allowable limit, it increases the cost of maintenance and production in the industries. Materials and Methods: In order to evaluate groundwater corrosiveness and scaling potential in Zahedan City, 29 groundwater wells and GIS-based geostatistical mapping techniques were analyzed clemically. The physicochemical parameters were invetsiagted and the most popular corrosion and scaling indices were determined as Langelier Index (LI), Aggressive Index (AI), Ryznar Index (RI), Puckorius Index (PI), and Larson–Skold Index (LS). Using ArcGIS 10.6.1 software, the zoning maps were plotted for LI, AI, RI, PI, and LS indices. Results: The results showed that total dissolved solids (TDS) and electrical conductivity (EC) values in all of the samples exceeded the World Health Organization (WHO) drinking water standard. AI values of 58.62% samples showing moderate corrosiveness, and the remaining 17 samples have a scaling nature with very less corrosivity. Based on the LI values, 55.2% of samples have a corrosive nature. Concerning RI values, 59% of the samples have a corrosive tendency. According to the PI values, the entire groundwater of this region has a significant corrosive tendency, and 96% of samples exceeded the LS > 1.2, showing a high rate of localized corrosion. Conclusion: The zoning and spatial analysis of water quality showed that water quality was treated for industrial purposes in the entire studied region.