Corrosivity Of Water Research Articles

상수원수의 부식평가 지수 산정 프로그램 개발 및 탄산칼슘 포화지수에 의한 수돗물의 부식성 평가

In this study, we developed the program to calculate the corrosion evaluation index for examining the corrosivity of raw water. When it was applied to the Han river and Nakdong river system, sulfuric acid ion, which accelerated corrosion, was higher in Nakdong river system than Han river system while calcium and hardness, which restrained corrosion, was the same way. Summarization of the LI and CCPP calculation result by the developed corrosion evaluation model showed that water quality of Han river system had strong tendency to corrode (is strongly corrosive). Moreover, this study evaluated the corrosivity of calcium carbonate saturation index by adding the chemicals to tap water. Saturation status was maintained in the order of > NaOH > > in the case of LI and RI.

Study for Determination of Industrial Water Corrosivity in Kashan Fajre Sepahan Galvanizing Mills During 2005-2006 Iran

This research was carried out in Kashan Fajre Sepahan Galvanizing mills (KFSGM) for evaluation of water corrosivity during 2005-2006. A total of 18 samples were taken from various points of the water supply system for testing the specific parameters and calculation Langelier Index (LI), Ryznar Index (RI) and Pukorious Index (PI). This research showed that in raw water (sand filter effluent) LI were positive as well as RI and PI were lower than 7 which means that mentioned water is not corrosive. Also LI in treated water by reverse osmosis process was negative and RI and PI were higher than 7, so, this water has corrosive properties. Finally, calculated indexes indicate that according to LI, conditioned water is not corrosive but based on RI and P. this water tend to corrosivity which this findings is compatible with literature review statement. So it is recommended that, for water conditioning addition of preservative chemicals to be continued but at the same time another alternatives such as pH adjustment, air stripping and deoxygenating, control of carbonate concentration and split flow treatment should be studied.

Assessment of tap water resources quality and its potential of scale formation and corrosivity in Tafila Province, South Jordan

This paper discusses the concept of water quality and stability, describes various indices available to assess the scale formation (protective layer) and corrosivity of water and the methods of their calculation for different tap water resources in Tafila City, south Jordan. The saturation levels are calculated by Langelier saturation index (LSI), Ryznar stability index (RSI) and the calcium carbonate precipitation potential (CCPP). LSI values are negative and range from –0.39 to –1.5 while RSI values range from 8.7 to 9.8. CCPP values are negative and range from –1.77 to –16.76. Although these results indicate corrosion conditions, this image changes upon heating and evaporation of water with the release of CO 2. Water samples exhibit high concentrations of Cl –, SO 4 2– and HCO 3 – as the major anions and Ca 2+ and Mg 2+ as the major cations. Magnesium has a threshold limit of maximum CaCO 3 solubility at about 0.00424 M. Microbiological tests indicate that three of the water samples (the three springs) are polluted with total and faecal coliform bacteria. Moreover, high concentration of nitrate has been detected in one of the springs. Most of the water samples have SO 4 2–/ HCO 3 – ratio of less than 1. At least 94% of the scale composition is CaCO 3 (aragonite).

Relationship between soil organic matter lability and liming requirement in acid sandy-loam cambisols

It is evident that the presence of organic matters in soil considerably influences by its microbial oxidation to CO<sub>2</sub> the requirement for calcareous compounds as well as the necessary amelioration dose of lime to reduce incurred soil acidity as the impact of balanced buffering CO<sub>2</sub>-HCO<sub>3</sub><sup>–</sup> system, the more labile the organic matters are. If we take into consideration that the content of soil water per hectare of topsoil is, at the total weight of 6 × 10<sup>6</sup> kg, approximately, in analyzed sandy-loam soils 1.2 × 10<sup>6</sup> litre, in the given experiment soil water is just able to use up to 220 kg CaCO<sub>3</sub>/ha for the fixation of free surplus CO<sub>2</sub> to the value of equilibrium CO<sub>2</sub>, at zero elution! From this process, even 300–400 kg water-soluble Ca(HCO<sub>3</sub>)<sub>2</sub> result. Of course, the ion exchange and the buffering system of the soil have further requirements for Ca compounds. Consequently, an unambiguous conclusion is: doses of calcareous compounds cannot be calculated only with the aim of reducing soil acidity and consumption of Ca nutrient by plants as it is common in the other nutrients. In a practical experiment in watersheds of nine Šumava brooks of the total area of 78.5 km<sup>2</sup> we studied changes in the stability of soil organic matters in the soils of these brooks in relation to variations in calcium carbonate equilibriums in waters from these watersheds in 1986–2004. The loss of the least stable fraction of soil organic matters, and the associated loss of the microbial activity of soils, were found to lead to a decrease in Langelier saturation index I<sub>s</sub> in the waters, hence to a reduction in water corrosivity against CaCO<sub>3</sub>, and so to a smaller need of liming to establish the calcium carbonate equilibrium in soil solutions even though exchange and active acidity of soil increased.

The marine corrosion of structural steels in brackish and fresh waters

High-quality models are required to describe the corrosion of structural steels in marine, brackish and fresh waters and these models should, preferably, be based on a proper understanding of the corrosion processes involved. The models should then be used to interpret field data, rather than attempting to derive models empirically from field data. On this basis a multi-phase corrosion–time model has been proposed previously for mild and low alloy steels subject to immersion in ‘at-sea’ conditions. This model is reviewed and extended to brackish and fresh waters in this paper. The scientific principles show that salinity is not the critical issue for the corrosiveness of water. Instead, the critical parameters are the temperature, pH and calcium carbonate solubility when corrosion is governed by oxidation. For later corrosion, governed by anaerobic bacterial activity, the available nutrient level and rate of supply of nutrients control the observed rate of corrosion. The data available at the present time for estimating all the parameters of the new model are somewhat preliminary and new corrosion monitoring programmes will be required to augment the information and to fully characterize the corrosivity of coastal and harbour waters. However, indicative trends for the parameters, based on currently available data, are given and permit the construction of corrosion loss curves for practical applications.

Options for recarbonation, remineralisation and disinfection for desalination plants

Un-treated desalinated water produced by seawater reverse osmosis and thermal processes differ in product water salinity. The water produced by thermal distillers, is usually, characterized by very low salinity and high aggressiveness and corrosivity. Post treatment of seawater reverse osmosis permeate is discussed, with particular emphasis on carbon dioxide (CO 2), acid dosing and boron issues. A number of chemical factors influence the aggressiveness and corrosiveness of water produced by reverse osmosis and thermal distillation plants. Stabilisation of the distillate by recarbonation to a level that is non-aggressive, non-corrosive and palatable to consumers is therefore required. Langelier saturation index and Larson Indices are commonly used indicators of the aggressiveness and corrosiveness of potable water. The “quality goals” for remineralisation will depend on factors such as nature of distribution pipework materials, palatability and client preference. An important factor influencing palatability, and which can strongly influence client preference, is the total dissolved solids content of the water. Blending remineralised desalinated water with treated brackish groundwater or treated seawater are frequently the cheapest options for increasing the dissolved solids content of desalinated water, if there is a requirement to provide a total dissolved mineral content of 150 mg/l or above in the final product water. The choice between the different processes is frequently project specific and depends on issues such as: installed capital and operating costs; volume of distillate to be treated; availability, quality and cost of locally available chemicals; issues associated with carbon dioxide such as ease and quantity recoverable from thermal desalination processes, feed water pH and resultant carbon dioxide present within SWRO permeate. Additionally boron has become an important issue associated with SWRO plants, feed water pH can influence boron removal efficiency and therefore the optimum and boron removal options associated with SWRO desalination. Additionally the simplicity of the competing processes; client experiences, whether good or bad with the competing processes. Disinfection of desalinated water can be undertaken by utilising various forms of chlorine/hypochlorite, the cost of which will vary depending upon size of plant, client preference and availability of chemicals. Remineralisation can be distinguished, for the purpose of this paper, into four treatment processes: 1) chemical addition — excluding lime or limestone; 2) carbon dioxide addition followed by limestone or dolomitic dissolution; 3) carbon dioxide addition followed by lime dosing; 4) blending with a water containing high mineral content. The methods available for recarbonation and remineralisation offer varying economic and technical merits and disadvantages. The paper explores the economic and technical differences of the various processes.

Cancer incidence and asbestos in drinking water, Town of Woodstock, New York, 1980–1998

Late in 1985, asbestos contamination was discovered in the public water supply of the Town of Woodstock, Ulster County, New York. Contamination resulted from asbestos–cement pipes installed in the town water system in the mid to late 1950s and the corrosiveness of the local water. The New York State (NYS) Department of Health established the Woodstock Asbestos Exposure Registry (WAER) in 1986 to monitor rates of cancer among individuals who lived on the water supply between 1960 and 1985. Demographic, health, and residential information were collected on 2936 registrants. The follow-up period for observation of cancer was 1980–1998, consistent with the expected lag of 20–30+ years for development of asbestos-related cancers. The NYS Cancer Registry was used to ascertain cancer diagnoses. Standardized incidence ratios (SIRs) for gastrointestinal, respiratory, and total cancers were all approximately 1.00 or less and all 95% confidence intervals (CIs) included 1.00. For individual types of the gastrointestinal cancers, only the SIR for pancreatic cancer was marginally statistically significant at 2.19 (95% CI=1.00–4.16), based on a total of nine observed cases. The excess in pancreatic cancer occurred primarily among men (SIR=3.08; 95% CI=1.13–6.70) and was only slightly elevated among women (SIR=1.39; 95% CI=0.29–4.06). This association may be related to factors other than asbestos exposure such as occupation and lifestyle or to chance. No cases of mesothelioma were observed among WAER participants. There was no increase in incidence by latency or duration of residence on the water supply, but the ability to detect these trends is limited by small numbers and unknown dates of initial exposure. The general pattern of results did not demonstrate a likely link between exposure to asbestos in drinking water and cancer occurrence among participants in the WAER.

Oxidation of Stainless Steel in H<sub>2</sub>O/O<sub>2</sub> Environments – Role of Chromium Evaporation

Oxidation of Stainless Steel in H<sub>2</sub>O/O<sub>2</sub> Environments – Role of Chromium Evaporation

Technical note an evaluation of water corrosivity of the river tigris at Baghdad

A series of experiments was carried out on different samples of tap water abstracted from the Baghdad water supply network in order to observe the effect of water on supply pipes, either scale forming or corrosive. This experimental investigation on the corrosive effect of the city of Baghdad tap water showed that the water can be classified as corrosive according to the Ryznar index, while the Langelier index showed that the water has the ability to form scale on the pipes. However, personal field observation indicated that the water is corrosive to the pipes and to the network appurtenance. Other findings are reported herein.

Variability of silt grain size and planktonic foraminiferal preservation in Plio/Pleistocene sediments from the western equatorial Atlantic and Caribbean

Records of mean sortable silt and planktonic foraminiferal preservation from the Ceará Rise (western equatorial Atlantic) and from the Caribbean are presented to analyze the Pliocene (3.5–2.2 Ma) to Pleistocene (1.6–0.3 Ma) evolution of near-bottom current strength and the carbonate corrosiveness of deep water. During the mid-Pleistocene climate transition (∼1 Ma) a drastic decrease in glacial bottom current strength and an increase in carbonate corrosiveness is registered, demonstrating a substantial decrease in the glacial contribution of the Lower North Atlantic Deep Water (LNADW) to the Atlantic Ocean. Also, an increased sensitivity to eccentricity orbital forcing is registered after the MPT. By contrast, carbonate preservation increases considerably in the deep Caribbean in response to a strong and persistent stable contribution of Upper North Atlantic Deep Water (UNADW). We found evidence for the strongest and most stable circulation within the LNADW cell during the Northern Hemisphere cooling period between ∼3.2 and 2.75 Ma. This is in agreement with the ‘superconveyor model’ which postulates that the highest NADW production took place prior to ∼2.7 Ma. A considerable decrease in bottom current strength and planktonic foraminiferal preservation is observed synchronous with the first occurrence of large-scale continental ice sheets in the Northern Hemisphere. This documents the final termination of the ‘superconveyor’ at ca. 2.75 Ma. However, our data do not support a ‘superconveyor’ in the interval between 3.5 and 3.2 Ma when high-amplitude fluctuations in bottom current flow and preservation in planktonic foraminifera are observed. Because of the great sensitivity of NADW production to changes in surface water salinity, we assume that the high-amplitude fluctuations of LNADW circulation prior to ∼3.2 Ma are linked to changes in the Atlantic salinity budget. After 2.75 Ma they are primarily controlled by ice-sheet forcing. In contrast to the stepwise deterioration of planktonic foraminiferal preservation in the western deep Atlantic, a trend toward better preservation from the Pliocene to Pleistocene is observed in the deep Caribbean. This indicates a long-term increase in the contribution of UNADW to the Atlantic Ocean.

Proposal of a New Stability Index Taking Account of Corrosion Inhibiting Action of Silica and Derivation of Empirical Equations Containing the New Index for Corrosiveness and Scale Formation of Water

Proposal of a New Stability Index Taking Account of Corrosion Inhibiting Action of Silica and Derivation of Empirical Equations Containing the New Index for Corrosiveness and Scale Formation of Water

Millennial-scale changes of surface- and deep-water flow in the western tropical Atlantic linked to Northern Hemisphere high-latitude climate during the Holocene

There is increasing evidence that the preceding Holocene climate was as unstable as the last glacial period, although variations occurred at much lower amplitudes. However, low-latitude climate records that confirm this variability are sparse. Here we present a radiocarbon-dated Holocene marine record from the tropical western Atlantic. Aragonite dissolution derived from the degree of preservation of the pteropod Limacina inflata records changes in the corrosiveness of the bottom water at the core site due to the changing influence of northern versus southern water masses. The δ 18 O difference between the shallow-living planktonic foraminifera Globigerinoides sacculifer and the deep-living Globorotalia tumida is used as proxy for changes in the vertical stratification of the surface water, hence the trade wind strength at this latitude. We compared our data to high-latitude records of the North Atlantic region. A good agreement is found between the aragonite dissolution and the strength in the Island-Scotland Overflow Water, which contributes significantly to the North Atlantic Deep Water. This suggests that large-scale variations in the Atlantic thermohaline circulation occurred throughout the Holocene. Concurrently, the comparison of our Δδ 18 O with the GISP2 glaciochemical records points to global Holocene atmospheric reorganizations seen in both the tropics and high northern latitudes.

Causes and Cures of Distribution System Corrosion

The article offers an overview of corrosion in the distribution system and discusses ways of detecting corrosion, the cost of corrosion, classifying water, factors affecting corrosion, measuring corrosion rates and possible inhibitors. Color and taste and odor are telltale signs of distribution system corrosion. Costs must be counted in terms of both health and dollars. Water may be classified into three categories: scaling, neutral, and corrosive‐but water that is corrosive in the distribution system may become scaling in a consumer's home or vice versa. Factors affecting corrosion include low flow, temperature, alkalinity, hardness, dissolved oxygen, and the presence of chemicals (sulfates or chlorides) or biological agents (iron or sulfate‐reducing bacteria). The Langelier index is recommended as a means of measuring the corrosivity of water; a Baylis curve shows the relationship between pH values and alkalinity. Measuring rates of corrosion can be done using coupons or by testing the water. Corrosion may be inhibited by adjusting pH or introducing chemical inhibitors, which form a film on the inside of piping and sequester minerals or buffer water to help stabilize pH changes.

Technical noteBiological corrosion of metallic parts in underground irrigation system: study of alternative materials

Following the discovery of severe corrosion of cadmium plated steel bolts in an underground irrigation system, the corrosivity of the surrounding soil and ground water was assessed using the procedures outlined in the standard DIN 50929. This methodology predicted successfully the strongly aggressive nature of the soil from the irrigation system, which contained sulphate reducing bacteria, although the corrosivity of the ground water was low. An evaluation of alternative bolting materials was conducted using both soil from the irrigation network and soil of lower corrosivity from a university campus in Athens. This has shown that general corrosion rates for screws made from type 316 stainless steel or brass are much lower than those for ferritic steel or similar steel coated with cadmium or zinc. However, the brass and stainless steel screws both showed evidence of localised corrosion (pitting and dezincification respectively).

Extraction of polychlorinated biphenyls with water under subcritical conditions

Supercritical fluid extraction is a fast and efficient method to extract all manner of organic compounds from a wide variety of solid sample matrices. Due to the marked change in its polarity with temperature, water is an interesting alternative to carbon dioxide as the extraction fluid. By merely adjusting the temperature, selectivity can be achieved for inorganic or organic compounds and for polar or non-polar organic compounds. Many organic compounds are sufficiently soluble to be extracted under subcritical conditions and, in this way, instrumental and other problems, such as the high corrosiveness of supercritical water, can be avoided. Instrumentation for sub- and supercritical water extraction was developed and modified in several ways with the aim of simplifying the procedure while maintaingng good recoveries. Good recoveries of polychlorinated biphenyls (PCBs) spiked into sea sand and of native PCBs in a real soil sample were achieved with liquid collection. Relative to Soxhlet extraction, recoveries were higher or similar when solid-phase and liquid collection were combined. With a solid-phase trap packed with Tenax, the recovery was usually more than 85% for spiked PCBs.

Sludge quality benefits realized from drinking water stabilization

Concerns about sludge quality continue to increase as emphasis shifts from disposal to use. A frequently asked question is what effect a drinking water stabilization program will have on the metal content of wastewater sludge. Data presented in this paper clearly show that there is a direct correlation between drinking water corrosivity and some metal contents of sludge

Causes and Cures of Distribution System Corrosion

The article offers an overview of corrosion in the distribution system and discusses ways of detecting corrosion, the cost of corrosion, classifying water, factors affecting corrosion, measuring corrosion rates and possible inhibitors. Color and taste and odor are telltale signs of distribution system corrosion. Costs must be counted in terms of both health and dollars. Water may be classified into three categories: scaling, neutral, and corrosive‐but water that is corrosive in the distribution system may become scaling in a consumer's home or vice versa. Factors affecting corrosion include low flow, temperature, alkalinity, hardness, dissolved oxygen, and the presence of chemicals (sulfates or chlorides) or biological agents (iron or sulfate‐reducing bacteria). The Langelier index is recommended as a means of measuring the corrosivity of water; a Baylis curve shows the relationship between pH values and alkalinity. Measuring rates of corrosion can be done using coupons or by testing the water. Corrosion may be inhibited by adjusting pH or introducing chemical inhibitors, which form a film on the inside of piping and sequester minerals or buffer water to help stabilize pH changes.

Injection-Water Quality

"The objective of any water-injection operation is to inject water into the reservoir rock without plugging or permeability reduction from particulates, dispersed oil, scale formation, bacterial growth, or clay swelling." Introduction Ideally, injection water should enter the reservoir free of suspended solids or oil. It should also be compatible with the reservoir rock and fluids and would be sterile and non-scaling. The objective of any water-injection operation is to inject water into the reservoir rock without plugging or permeability reduction from particulates, dispersed oil, scale formation, bacterial growth, or clay swelling. In addition, souring of sweet reservoirs by sulfate-reducing bacteria should be prevented if possible. How Good Must Water Quality Be? Actually, the question posed by most producers is, how bad can water quality be without causing any significant problems? The methods by which people arrive at an answer to this question are both curious and diverse. In many injection projects, experience is the sole guide, and little, if any, technical investigation precedes design of the injection system. Those who wish to apply the best available technology should precede system design with a careful study of the water to be injected and the characteristics of the formation rock and fluids. Characterization of the Water and the Formation Injection Water. The water must be carefully sampled and characterized to assess the likely problem areas. The following measurements are considered essential. Chemical Composition. Knowledge of the chemical composition of the water is required to calculate scaling tendencies and to determine the likelihood of clay swelling. Certain parameters, such as pH, must be measured on site immediately after sampling. Dissolved Gases. The amounts of dissolved oxygen, carbon dioxide, and hydrogen sulfide should be known to anticipate the types of corrosion. Corrosivity. On-site corrosion-rate measurements are necessary to quantity the water corrosivity. Bacteria. Any bacteria in the water should be identified and their population estimated. Sulfate-reducing bacteria are of particular interest. Suspended Solids. The amount and composition of the suspended solids are primary indicators of water quality. The particle-size distribution can also be determined for surface waters and waters from water-supply wells. Particle-size measurements in produced waters have little meaning because particle-size-measurement instruments cannot distinguish between solid particles and oil droplets. Oil Content. Dispersed oil can decrease injectivity, especially when combined with suspended solids, such as iron sulfide. Also, emulsion blocks can form in injection wells. Injection Formation. The injection formation is often characterized simply by its permeability. Pore-size distributions, however, may also be useful in the determination of injection-water standards. Knowledge of the composition and distribution of clays in sandstone reservoirs is desirable to assess potential clay swelling and migration problems. Water-Treatment Objectives Once the water and the rock have been characterized, the difficult task of deciding how much water processing is required to create a nonplugging water begins. Suspended Solids and Oil. Methods to estimate the quantity and size distribution of suspended solids that can be tolerated in an oil-free water abound. Most methods attempt to correlate the suspended-solids concentration, particle-size distribution, or water-quality measurements with the formation permeability or pore-size distribution. Unfortunately, there is no consensus as to which method provides the most dependable estimate, and petroleum engineers are left with a bewildering array of choices. When produced water is injected, the water contains both solids and oil. Attempts to estimate acceptable levels of suspended solids and oil with theoretical models have not been successful to date. Empirical correlations currently offer the best hope.

A review of chlorine-induced corrosion in underground mines and coal preparation plants

Chlorine is a harmful constituent in coals because, above a concentration of 0.1 or 0.2 weight percent, it causes rather costly corrosive attack on metals used in boilers, combustion devices, piping, and other hardware. In coal preparation plants, due to recycling of the water, very high concentrations of chloride, an extremely corrosive agent, are observed. The process water corrosivity has a deleterious effect on the equipment thus necessitating expenditures on replacement and costly repairs. Due to agitation of solids and enhanced dissolved oxygen concentration, materials degradation occurs via an erosion-corrosion mechanism in many parts of the plants. It is observed that process water is almost as corrosive as seawater because of the high concentration of chloride and other ions. Analyses of a number of degraded metal samples from coal mines and preparation plants indicate the presence of chloride ions in the corrosion products. A number of recommendations for the control of materials degradations and strategies for materials selection are proposed.

Influence of pollutants (nitrate anions) on the corrosivity of sea water

Abstract In the estuaries called “rias”; of the N.W. of Spain, the corrosivity of the sea water has been tested using a low carbon steel as the test piece. The results show corrosion rates much higher than the ones found for the same area out to sea. The increase of the iron corrosion rate can be interpreted on the basis of the presence of pollutants like nitrate that can act as depolarizers of the cathodic reaction in the corrosion process.