Effect Of Water Hardness Research Articles

Effect of Washing Conditions on Cleaning Action of Linear Alkylbenzene Sulfonate in Hard Water

Abstract The effects of water hardness on textile detergency in aqueous linear dodecylbenzene sulfonate (LAS) solutions were examined under various washing conditions. Plain-woven and towel cotton fabrics and plain-woven polyester fabric were soiled with a mixture of carbon black/oleic acid. The soiled fabrics were shake-washed in the LAS solution together with the original unsoiled fabrics. Surface reflectance measurements revealed that the soil removal and redeposition decreased and increased, respectively, with increasing water hardness. The identity of the mineral species (calcium or magnesium ions) in the hard water had no notable effect on the detergency. The addition of significant amounts of extra LAS did not fully compensate the reduction in detergency in hard water. Addition of softening agents and an alkali builder to the hard water limited the reduction in detergency, but the detergency was still lower than that in the absence of hardness salts. Moreover, a high wash temperature and repeated rinse procedure did not prevent the reduction in detergency in hard water. Finally, a washing test was carried out in hard water under the conditions considered to be effective for improving the detergent quality in hard water, based on the experimental results. The LAS detergency toward the cotton fabrics under these conditions was still poorer than that in the absence of hardness salts. We concluded that using soft wash water is the best choice for maximizing the cleaning power of detergents.

Effect of water hardness on the settling characteristics of coal tailings

ABSTRACTWater hardness has an important effect on the settling characteristics of coal tailings. This article is mainly on a research of the relationship between water hardness and the settling performance of coal tailings. Samples from five coal preparation plants were used for mineralogical and water chemistry analyses by the X-ray diffraction (XRD) technique and the ion chromatograph technique, which showed that the water hardness of the recycled water was determined by the mineral composition of coal slimes. The settling tests indicated that water hardness of the sample water was closely related to mineral composition and could be used to evaluate the settling characteristics. It was shown that the increase of water hardness resulted in the increase of settling rate and the transmittance of supernatants. A gradual decrease of the slope was obtained in the curves of settling rate and transmittance. Verification tests on settling rate and transmittance of five coal samples were in agreement with the claim. The Zaozhuang and Datun samples, whose water hardness was at a high level (over 90°DH), achieved the settling rate over 19 cm/min and transmittance of supernatant over 89%. Settling rate and transmittance of the supernatant are below 12 cm/min and 41%, respectively, for the Xingtai, Shitai, and Linhuan samples, whose water hardness is below 10°DH.

Effect of Water Hardness on Efficacy of Sodium Hypochlorite Inactivation of Escherichia coli O157:H7 in Water

This study examined how the hardness of water affected the efficacy of sodium hypochlorite in inactivating Escherichia coli O157:H7 in water. Water was prepared at different degrees of total hardness (0, 50, 100, 200, 500, 1,000, 2,000, and 5,000 mg/liter CaCO3). Inactivation was assessed at different levels of free chlorine (0, 0.2, 0.5, and 1.0 ppm) at 2 to 4°C and pH 6.5. Thirty milliliters of chlorinated water was inoculated with 6 log CFU/ml of E. coli O157:H7 and allowed to mix for 3, 10, 20, or 30 s. In the absence of sodium hypochlorite, no reduction in counts of E. coli O157:H7 was observed regardless of the degree of water hardness. However, in the presence of hard water, under certain chlorine concentrations and exposure times, the reduction of E. coli O157:H7 in chlorinated hard water was significantly less than the reduction observed in chlorinated deionized water. For example, after exposure to 0.5 ppm of free chlorine for 10 s, E. coli O157:H7 counts were reduced by 4.8 ± 1.4, 2.0 ± 1.3, 1.6 ± 0.7, 0.5 ± 0.7, and 0.0 ± 0.1 log CFU/ml in water containing 0, 100, 1,000, 2,000, and 5,000 mg/liter CaCO3, respectively. With the exception of 5,000 mg/liter CaCO3, the effect of water hardness was no longer visible after 20 s of exposure to 0.5 ppm of free chlorine. Also, hard water significantly lowered the efficacy of sodium hypochlorite at 3 s of exposure to 1.0 ppm of free chlorine. But after 20 s of exposure to 1.0 ppm of free chlorine, the impact of water hardness was no longer observed. This study demonstrated that water hardness can affect the germicidal efficacy of sodium hypochlorite, and such an impact may or may not be apparent depending on the condition of the solution and the treatment time at which the observation is made. Under the conditions typically seen in commercial produce washing operations, the impact of water hardness on chlorine efficacy is likely to be insignificant compared with that of organic load.

緑茶の抗菌効果に及ぼす水の硬度の影響

Effect of water hardness on antibacterial activity of green tea extract was studied using tap water and mineral water. The agar medium containing green tea made with six samples of tap water or two samples of mineral water, were tested for Escherichia coli culture, and the colony forming number was compared with that on the agar medium containing each water. Increasing water hardness resulted in increasing antibacterial activity of green tea. Using the high hardness (1468 mg/L) mineral water, the ratio of colony forming number on the green tea medium to one on the water medium was 0.016, which is 43 times lower than that on the low hardness (18 mg/L) tap water. The principal component analysis based on the concentrations of mineral elements in water samples, suggested that the high concentrations of Ca and Mg in water, and low concentration of Si increased antibacterial activity of green tea. The water hardness increased the amount of (-)-epicatechin gallate, not the total amount of catechins in green tea extract. The results are discussed considering the formation of complexs with catechin with Ca and Mg and the change in antibacterial activity of green tea.

Effects of Water Hardness on Textile Detergency Performance in Aqueous Cleaning Systems.

The effects of water hardness on textile detergency in aqueous solutions were systematically investigated using four surfactants: sodium oleate (OLNa), linear dodecylbenzene sulfonate (LAS), sodium dodecyl sulfate (AS), and polyoxyethylene (10) dodecyl ether (AE). Water hardness was adjusted according to the standard procedure described in IEC 60734:2012. As expected, by adding hardness salts the surface tension of the OLNa solution increased. Surprisingly, the addition of hardness salts lowers the surface tension for the LAS and AS solutions. In the case of the AE solution, hardness salt did not affect the surface tension. A decrease in transmittance and foamability after adding hardness salts was observed for every anionic surfactant solution, indicating that anionic surfactants can combine with divalent ions to form insoluble precipitates. Detergency experiments were performed using cotton plain-woven and towel fabrics soiled with a carbon black and oleic acid mixture. One piece each of untreated and soiled fabric were stacked and placed horizontally in detergent solution with or without hardness salts. As a mechanical action of soil removal, the shaking of 190 spm was applied. Soil removal and redeposition due to washing were evaluated from changes in values of the Kubelka-Munk function for both fabrics. With increasing water hardness, soil removal decreased and redeposition increased. In order of decreasing detergency, the surfactants were as follows: LAS > OLNa ≈ AS > AE. The results indicate that precipitates, formed by reaction of LAS or AS with hardness salts, are strongly adsorbed on the water surface because of their hydrophobicity, but they have no detergency power. The field emission scanning electron microscopic observation and X-ray photoelectron spectroscopic analysis showed that Ca(LAS)2 precipitation clung to fiber surfaces, and remained on the surfaces after washing. Significant changes in the cotton fabric due to washing were observed in mechanical properties and water absorbency.

Effect of Water Hardness on Green Tea Infusions

Effect of Water Hardness on Green Tea Infusions

Effects of Water Hardness on Dyeing of Cotton Fabrics with Different Types of Reactive Dyes and Shade Percentages

This research was investigated the influence of water hardness on dyeing of cotton fabric with three types of reactive dyes (Synozol, Ramazol and Setazol). The effects of various fastness (color fastness to wash, abrasion test, Rubbing test and Perspiration test) properties of dyes were also studied and reported in this paper in details. Single color (Blue) is used for the shade of 1% and 2% and varied water hardness of 120 ppm, 70 ppm and 9 ppm respectively. The main objective of this paper was to find out the parameters of various fastness properties at different range of water hardness in the application of different types of reactive dyes. It is visualized that different amount of water hardness showed in different fastness for using three types of reactive dyes having shade of 1% and 2%. We reported that water hardness up to 9 ppm, for using three types of reactive dyes showed excellent wash fastness and it deteriorates with increasing hardness. Setazol 1% & 2%, showed highest abrasion resistance at 9 ppm water hardness compare to other dyes at higher water hardness. Rubbing test result also showed very good for 9 ppm water hardness in three reactive dyes irrespective of shade percentage. The perspiration test result is good at 9 ppm water hardness for all types of reactive dyes with all shade percentages.

The Effect of Water Hardness on Mortality of Zebrafish (Danio rerio) During Exposure to Oxytetracycline.

Marking of fish otoliths with oxytetracycline and tetracycline is a widely used method to evaluate the effectiveness of stocking operations. Available protocols for the labeling of fish specify a number of factors influencing mark quality and potential risk for fish during marking. This study investigates the influence of water hardness on mortality of freshwater fish during marking with OTC. In order to pursue this question complexation of OTC with Mg(2+) and Ca(2+) cations was measured spectrophotometrically. Furthermore, zebrafish (Danio rerio) were immersed in OTC solutions (1200 mg/L; 48 h immersion) combined with varying levels of water hardness (5.5, 15.5, 25.5, 32.5°dH). The amount of OTC-Mg-Ca-complexes was positively correlated to water hardness. Moreover, it could be demonstrated that mortality of zebrafish during marking varied as a factor of water hardness. Highest mortalities occurred at the lowest (5.5°dH) and the highest (32.5°dH) tested levels during marking with OTC.

Selective flotation of scheelite from calcite and fluorite using a collector mixture

Collector 733, a sodium soap (C12–16COONa) is widely used industrially for scheelite flotation. Low selectivity of 733 collector is always observed. In this study, a collector mixture of 733 and MES (sodium fatty acid methyl ester sulfonate) demonstrated a high selectivity for the flotation of scheelite from calcite and fluorite. An optimal mass ratio 4:1 of 733:MES was found, producing a 65.76% WO3 concentrate grade with a recovery of 66.04% from a feed material containing only 0.57% WO3. In addition, the effect of water hardness and water glass addition were studied. The results indicated that the presence of Ca2+ or Mg2+ had little effect on the adsorption of the collector mixture at the scheelite surface. Addition of water glass for depressing calcite and fluorite had no significant effect on the adsorption of the collector mixture on the scheelite surface. The advantages of this new collector mixture (733+MES) include lower cost, low dosage, high tolerance against water hardness and high selectivity, and this collector mixture has great potential for industrial application.

Effect of water hardness and pipe material on enhanced disinfection with UV light and chlorine

Limited studies have been conducted to evaluate synergistic benefits between disinfectants, although promise has been shown between ultraviolet (UV) light and chlorine-based disinfectants. This research aimed to determine drinking water quality factors that affect potential for enhanced removal of heterotrophic bacteria due to synergy between UV light and free chlorine. An additional goal was to determine the impact of pipe material on the formation of biofilm and the effectiveness of combined disinfection in controlling it. Annular reactors (ARs) containing polycarbonate or cast iron coupons were used to simulate typical drinking water distribution systems. Two experiments were conducted with untreated hard groundwater and groundwater treated with ion exchange to remove hardness, each comparing chorine alone to chlorine with UV pre-treatment. Results show that enhanced removal of heterotrophic plate count (HPC) bacteria existed with hard water when UV preceded chlorine, but synergistic benefits were not consistently observed. Under softened water conditions, no enhanced reduction or synergy was observed. Cast iron ARs supported biofilm HPC bacteria that were unaffected by any disinfection scheme regardless of source water, while bulk HPC bacteria were more resistant to disinfection in polycarbonate than cast iron ARs. Results indicate that disinfection synergy between UV and chlorine is limited in groundwater sources.

Effects of water hardness and pH on efficacy of chlorine-based sanitizers for inactivating Escherichia coli O157:H7 and Listeria monocytogenes

The effects of hardness and pH of water used to prepare electrolyzed oxidizing (EO) water and bleach solutions on the bactericidal activity of sanitizer prepared from the water were examined. EO water and bleach solutions were prepared with hard water of 0, 50, 100, and 200 mg/l as CaCO3 at pH 5, 6, 7, and 8. Increased water hardness tended to increase free chlorine and oxidation–reduction potential (ORP) and decrease pH of EO water. Chlorine levels also increased with water pH. Water hardness and pH only had minor effect on the pH of bleach solutions. Increasing hardness to 50 mg/l increased antimicrobial effect of EO water against Escherichia coli O157:H7, but reduced when water hardness further increased to 100 mg/l or higher. Water pH had no effect on EO water produced against E. coli O157:H7. Water hardness had no significant effect on bactericidal activity of EO water against Listeria monocytogenes but elevated water pH decreased bactericidal activity of EO water produced against L. monocytogenes. Bleach solution prepared using hard water at 200 mg/l or at pH 7 or higher had significant lower efficacy in inactivating E. coli O157:H7, but had no effect on the inactivation of L. monocytogenes. Results indicate that increasing the hardness or pH of water used to prepare EO water or bleach solutions will decrease the bactericidal activity of sanitizers prepared from the water.

Effect of Water Hardness on the Scum Formed during Soup Stock Preparation

Effect of Water Hardness on the Scum Formed during Soup Stock Preparation

Effect of Water Hardness on the Boiled Beef, Chicken and Potato

Effect of Water Hardness on the Boiled Beef, Chicken and Potato

Effect of water hardness on peracetic acid toxicity to zebrafish, Danio rerio, embryos

The use of peracetic acid (PAA) in aquaculture has been suggested as an alternative therapeutic agent. Few data are available concerning fish toxicity by PAA or factors that modify this toxicity. The aim of this study was to investigate the influence of water hardness on the acute toxicity of PAA products to embryos of zebrafish (Danio rerio). Embryos were exposed to PAA ranging from 0 to 9 mg/L in low-hardness (1.4 dH or 25 mg/L hardness as CaCO3), medium-hardness (14 dH or 250 mg/L hardness as CaCO3) and high-hardness (140 dH or 2,500 mg/L hardness as CaCO3) waters. The lowest LC50 value was 2.24 mg/L PAA in the low-hardness water, and the highest LC50 value was 7.14 mg/L PAA in the high-hardness water. Toxicity of PAA to embryos was found to be negatively correlated with water hardness. The pH decreased with increasing concentrations of PAA, and the test waters were observed to become more acidic in low hardness. In conclusion, aquaculturists using PAA should pay attention to water hardness to avoid acidosis.

Effects of water hardness on selective flocculation of diasporic bauxite

The effect of electrolyte on settling behavior of kaolinite was studied. Effects of hard water on selective flocculation of diasporic bauxite was tested and the measures were taken to eliminate the effects of Ca2+ and Mg2+ in hard water. The results indicated that, not only the concentration of electrolyte ions but also the ionic valence of the electrolyte ions affects the settling behavior of kaolinite; hard water significantly affects its selective flocculation owing to Ca2+ and Mg2+; general dispersants could not eliminate the effects of Ca2+ and Mg2+. Self-made softening agent in our lab could weaken or eliminate the effects of hard water on flocculation processes. The results of molecular dynamics simulation show that softening agent molecules could restrict Ca2+ and prevent them from playing their roles, so as to eliminate the effects. The continuous pilot experiment results of bauxite flocculation were even better than those obtained in laboratory.

Interactions between domestic water hardness, infant swimming and atopy in the development of childhood eczema

AimRecent studies suggest that domestic water hardness and swimming in chlorinated pools may increase the prevalence of childhood eczema. The combined influence of these two factors as well as their interaction with atopic status has not been investigated. MethodsWe conducted a cross-sectional study on 358 children aged 5–6 years (54% of boys) in 30 kindergarten schools. Parents completed a questionnaire about the child's health, chlorinated pool attendance and potential confounders. Data about tap water quality were provided by water companies. Atopy was defined as a sensitization to at least one aeroallergen or as a medication for allergy. The effect of water hardness and infant swimming practice were assessed by multivariate logistic models. In addition, the effects of these risk factors combined with atopy were evaluated using two measures of biological interaction: the attributable proportion of interaction (AP) and the synergy index (S). AP>0 and S>1 indicate biological interaction between the two risk factors. ResultsWater hardness was linearly associated to the prevalence of eczema whereas the relationship of eczema with infant swimming was not linear. We observed a biological interaction between hard water (>150mg/L CaCO3L−1) and atopic status that increases the prevalence of eczema with an odds ratio (OR) of 3.30 and a 95% confidence interval (CI) of 1.34–8.15 (AP, 0.41; 95% CI 0.15–0.66 and S, 2.4; 95% CI 0.96–6.01). Infant swimming practice combined with atopy also increased the prevalence of eczema (OR, 2.72; 95% CI 1.29–5.74) although none of the interaction measures was significant. However, when water hardness and infant swimming were combined, there was no further increase of the eczema prevalence due to some form of antagonistic interaction between these two factors (AP, −0.56; 95% CI −1.12 to −0.01 and S, 0.54; 95% CI 0.33–0.87). ConclusionsOur study shows that exposure to hard water and infant swimming interact with atopic status to increase the prevalence of childhood eczema. A breaching of the epidermal barrier by detergents or salts in hard water and by chlorine-based oxidants in swimming pool water might explain these interactions.

Effect of water hardness on surface tension and dilational visco-elasticity of sodium dodecyl sulphate solutions

The complementary drop and bubble profile analysis and maximum bubble pressure tensiometry are used to measure the dynamic surface tension of aqueous SDS solutions in the presence of hardness salts (CaCl2 and MgCl2 in the ratio of 2:1 at concentrations of 6 and 40FH). The presence of hardness salts results in an essential increase of the SDS adsorption activity, which indicates the formation of Ca(DS)2 and Mg(DS)2 in the SDS solutions. The surface tension isotherms of SDS in presence of Ca(DS)2 and Mg(DS)2 are described using the generalised Frumkin model.The presence of hardness salts accelerates the ageing of SDS solutions as compared with the addition of 0.01M NaCl due to a faster hydrolysis and hence formation of dodecanol. These results are used to estimate the possible concentration of dodecanol in the studied SDS solutions.The buoyant bubble profile method with harmonic surface oscillations is used to measure the dilational rheology of SDS solutions in presence of hardness salts in the frequency range between 0.005Hz and 0.2Hz. The visco-elasticity modulus in the presence of hardness salts is higher as compared with its values in the presence of 0.01M NaCl additions. The ageing of SDS solutions leads to an essential increase of the visco-elastic modulus.

Metal sorption by peat and algae treated peat: Kinetics and factors affecting the process

The article presents a new approach that can be used for the purification of water contaminated by heavy metals. The treatment of peat with microalgae showed to be an effective way of increasing metal uptake by peat. Metal sorption was studied for a multimetal solution containing Cu, Cd, Ni, Zn, Cd, and Pb. Cu and Pb were found to be the metals having the highest affinity to peat. Water hardness has a strong effect on the uptake of borderline metals (Cd, Ni, Zn, Cd) from a solution. The use of algae for peat treatment resulted in less time to reach an equilibrium (24 h vs. 72 h for pure peat), and the effect of water hardness (Ca 2+) on metal uptake was considerably reduced. Both peat and algal-treated peat were able to take up metals from rather acidic solutions (pH 3.0). pH had less influence on the metal uptake compared with water hardness. The affinity of heavy metals to peat was the following: Pb > Cu > Ni > Cd > Zn > Co. It slightly changed to Pb > Cu > Ni > Cd ≈ Co ≈ Zn when the combined sorbent, peat treated with microalga, was applied.

Effects of water hardness and Cu and Zn on LC50 in Gambusia holbrooki

The aim of this study was to determine by static bioassay whether water hardness affects the toxicity of Zn and Cu to a fish, Gambusia holbrooki Girard, 1859. The acute toxicity of selected heavy metals to G. holbrooki was determined in soft, hard and very hard water (25, 125 and 350 mg L−1 as CaCO3). Results showed that water hardness had a significant effect on Cu and on Zn toxicity on fish. Toxicity of Cu and of Zn increased with decreasing water hardness. The 96 hours LC50 values for G. holbrooki were higher in the hard and very hard water compared with soft water. Water hardness had a much smaller effect upon the acute toxicity of Cu than that of Zn. It was observed that the 96 hours LC50 for Cu at the soft, hard and very hard water was found to be 0.017, 0.17 and 0.65 mg L−1, respectively, while the 96 hours LC50 for Zn at the soft, hard and very hard water was found to be 0.46, 48.1 and 121.6 mg L−1, respectively.

Effect of Water Hardness and Dissolved‐Solid Concentration on Hatching Success and Egg Size in Bighead Carp

AbstractBighead carp Hypophthalmichthys nobilis is an Asian species that has been introduced to the United States and is regarded as a highly undesirable invader. Soft water has been said to cause the bursting of Asian carp eggs and thus has been suggested as a factor that would limit the spread of this species. To evaluate this, we subjected fertilized eggs of bighead carp to waters with a wide range of hardness and dissolved‐solid concentrations. Hatching rate and egg size were not significantly affected by the different water qualities. These results, combined with the low hardness (28–84 mg/L) of the Yangtze River (the primary natal habitat of Hypophthalmichthys spp.), suggest that managers and those performing risk assessments for the establishment of Hypophthalmichthys spp. should be cautious about treating low hardness and dissolved‐solid concentrations as limiting factors.