Explain with chemical equations and calculate the amount of lime and soda needed for softening 1,00,000 litres of water containing the following: HCl = 7.3 mg/L, Al 2 (SO 4) 3 = 34.2 mg/L ; MgCl 2 = 9.5 mg/L ; NaCl = 29.25 mg/L Purity of lime is 90% and that of soda 98%. Lime is also used to combat "red water" by neutralizing the . calculations, 1400 lbs/MG of lime should be used. Calculator Net acidity = potential acidity + existing acidity * The factor 1.02 is used to stoichiometrically convert units of sulfuric acid (H 2 SO 4) to units of calcium carbonate (CaCO 3) A minimum safety factor of 1.5 should be used There is also information about three lime soda water softening process alternatives (two stage excess lime water softening, split treatment, and selective calcium removal), along with calculation of the dosages needed for lime, soda ash, and carbon dioxide. cycles of concentrationbut the disadvantage is the risk of post-precipitation of lime. All these units together make the lime softener a complicated unit operation. Ecodyne can customize the basic Reactivator-Clarifier design to accommodate cold lime or warm lime operation as required for TSS hardness, alkalinity and silica removal. So the amount of water flow in each individual will be 130 / 2 =65 m3/hour. Lime softening was abandoned on the premise that the effective hardness removal did not warrant Lime Softeners. Calculation for Sizing a Water Softener. This process is used for the following purposes: Spreadsheets for Lime Soda Water Softening Calculations There are logical choices (e.g. Given the following water compositions before and after an excess lime softening, calculate the amount (in mg / L) of Lime [Ca (OH) 2)] added and the amount (in mg / L) of sludge produced (Note, sludge includes Mg (OH) 2 and CaCO 3) 2 pg. Our hot lime system is designed for treating produced water (seperated from oil emulsion). Alkalinity to be added to the water (mg/ L) = total alkalinity required (mg/ L) - (minus) alkalinity present in the water (mg/ L) much lime (the source of alkalinity) must be added. Estimate the carbonic acid concentration. CO2 + H2O = H2CO3 H2CO3 + CaCO3 = Ca (HCO3)2 Cold Lime Softening Lime softening accomplished at ambient temperatures is referred to as cold lime softening. pH Adjustment/Coagulation - Hydrated lime is widely used to adjust the pH of water to prepare it for further treatment. You just type in the numbers and the spread sheet calculates the chemical requirements. Since the amounts added are rather small it is advantageous to prepare 5% by weight lime milk by simply mixing 10g lime with 90g . 6 pg. Multiply the answer by your water hardness in grains per gallon (to convert mg/l or ppm to grains, divide by 17.1). The purity of lime is 70% and soda is BS% Ca(HCO 3) = 30.2 , Mg(HCO 3) = 20.8 ,CaCI 2 = 28.1 ,MgCl 2 = 8.78, CaSO 4 = 35, MgSO 4 = 6.7 . Lime-enhanced softening can also be used to remove arsenic from water. The chief operator at the plant reduced the lime feed to save money. Lime Softening 1 Lime Softening . Chemicals normally used are lime (calcium hydroxide, Ca(OH) . With the conversion calculators you can convert the units that are most commonly used. Volume Step 1: Enter Starting Water Profile Step 5: View Resulting Water Profile Step 3: View Mash pH Distilled water Mash pH (from chart) If your water report gives Sulfate as Sulfur (SO 4-S) such as a Ward Lab's report, multiply by that by 3 to get SO 4 Chalk The lime-softening methods above require time, special chemicals, and a pH meter to conduct successfully. Removal of CH with Lime Feed Only 6 Removal of Noncarbonate Hardness with Lime and . 9. . The warm lime softening process operates in the temperature range of 120-140F (49-60C). Example 21. cause valves to stick due to the formation of calcium carbonate crystals How does the lime-softening process work? Sodium aluminate has a special advantage as a coagulant in lime-soda softening since unlike most other coagulants it is alkaline and also contributes to the softening reactions', particularly in reducing magnesium. II.) This may be useful, because most American and British use American or British units and European use the standard metric units. Lime soda water softening is the subject of this e-book. softening can be achieved by adding lime in the form of limewater, ca (oh)2, which, in a carbonatation reaction with co2, forms calcium carbonate precipitate, reacts next with multivalent cations to remove carbonate hardness, then reacts with anions to replace the non-carbonate hardness due to multivalent cations with non-carbonate hardness due 1 pg. Cold lime softening, also known as Clark's process, is used to reduce the hardness, alkalinity, silica, and other constituents of raw water. Calculators. 85% of that amount is added to the first sample, 100% is added to the 2nd sample and 115% is added to the 3rd sample. I also included chemical costs to make comparisons but the chemical price figures will need adjusted as they are very old. Your Ca:Mg ratio is. Calculation explanations 3.1.1. If iron is present, add 5 grains for every ppm (mg/l) of iron (iron MUST be . 10% of chemicals are to be used in excess in order to complete the . Also there are logical choices and numerous equations used in calculating chemical dosages for lime soda water softening . In this process Calcium and Magnesium ions are precipitated by the addition of lime (Ca(OH) 2) and soda . Fig -1 Water Softening 215 Solution Because the alkalinity is greater than the total hardness, all the hardness is carbonate hardness: Total hardness (mg/L) as CaCO 3 = Carbonate hardness (mg/L) as CaCO 3 105 mg/L as CaCO 3 = Carbonate hardness No noncarbonate hardness is present in this water. In both calculation methods, lime and soda ash dosages depends on carbonate and non-carbonate hardness in the water. Determination of lime and soda ash dose requirements for water softening Cold & Warm. Use calcitic lime if the Ca:Mg ratio is below 7:1. Lime softening has been proven to remove a wide variety of contaminants including tannins, arsenic, barium, lead, nickel, cadmium, chromium and other metals. It's just a simple spread sheet showing # of hydrated lime and Magox to be used with a varying alkalinty and Mg content of the raw water. As the softeners required are similar, equal flow of water will enter the two softeners. High concentration of silica causes. Spreadsheets for Lime Soda Water Softening Calculations There are logical choices (e.g. In Salbukh water treatment plant, silica. Calculations are presented for daily chemical requirements and solids production rates. The limesoda uses lime, Ca(OH) 2 and soda ash, Na 2 CO 3, to precipitate hardness from solution. In small systems, lime softening is typically practiced by adding hydrated Lime softening is the reduction of hardness by the application of hydrated lime to water to precipitate CaCO3, Mg(OH)2, or both. CALCULATIONS OF LIME AND SODA ASH CONCENTRATIONS REQUIRED FORWATER SOFTENING. Water will stop at nothing to find equilibrium.so when it's hungry for calcium, it will aggressively look for it. Problem According to Wang (), recarbonation is defined as "(a) the process of introducing carbon dioxide, CO 2, as a final stage in the lime-soda ash softening process in order to convert carbonates to bicarbonates and thereby stabilize the solution against precipitation of carbonates, (b) the diffusion of carbon dioxide gas through liquid to replace the carbon dioxide gas removed by the addition of . Be able to calculate the lime, soda ash, and carbon dioxide dosages needed for the two stage excess lime softening process, if concentrations are known or can be calculated for CO2, calcium carbonate hardness, calcium noncarbonate hardness, magnesium carbonate hardness, and magnesium noncarbonate hardness, using design values for excess . . Processing or disposal of this sludge material may be an additional cost to the process. membrane fouling in the reverse osmosis units. Determine/calculate the mg/L lime required by using a proportion that relates bicarbonate alkalinity to . 1 pg. Is Alkalinity > Hardness or is Hardness > Alkalinity) in calculating the types of hardness in a water supply source. The lime sludge bed can filter the oil in water. Profile B. Compared to lime softening and sodium chloride (NaCL) zeolite softening technologies, nanofiltration membrane softening is a less-expensive alternative. Thus the minimum calcium hardness can be achieved is about 30 mg/L as CaCO3, and the magnesium hardness is about 10 mg/L as CaCO3. concentration of raw water is about 30 ppm. The LSI is basically a way to determine if water is corrosive (negative LSI) or scale-forming (positive LSI). The normal pH of water is between 6.5-8.5. Lime sludges are dense and will tend to settle, however, it is recommended that 10 mgL-1 of an alumina coagulant be added to capture the lime fines. It also explains how cold lime softening works, and provides guidance on maintaining system reliability. treatment process necessary for softening this water is the excess lime process. Ion exchange softening is covered in Chapter 12, and membrane processes that . . Lime sludges cannot be returned to the Section 4.2 - Calculations Table of Contents Lime Softening Study Guide - January 1994 Edition pg. Note: A dose of 1 mg/L of aluminium sulphate reacts with 5.3 mg/L of alkalinity expressed as CaCO3 []Hydrated lime (Ca(OH)) is considered in the lime dosage calculations Hardness causes problems with the water such as scaling in pipes and excessive usage of soap. Options for on-site erection depending on location and site access are also available. 2 Water Softening 1. Ion-Exchange Softening is a common household water softening method that uses salt (sodium chloride or potassium chloride) to soften water. The block flow diagram of a typical lime softener is depicted in Fig - 1. In the lime-softening process, the pH of the water being treated is raised sufficiently to precipitate calcium carbonate and, if necessary, magnesium hydroxide. First, determine your calcium:magnesium ratio. Limitation of Soda Lime Process: Lime soda softening cannot produce a water at completely free of hardness because of the solubility (little) of CaCO3 and Mg(OH)2. Chemical requirement and product composition for lime-soda softening is usually calculated using the bar diagram method and its variations (3,5). softening process to take place. It should be stressed that the coagulant is present only to capture the lime fines and not to coagulate raw water turbidity. There might be more economical ways to soften your water without generating a mountain of lime sludge. This aids in the preparation of water for direct cooling tower makeup or as a first-stage treatment followed by ion exchange for boiler makeup or RO Reject recycle. Is Alkalinity > Hardness or is Hardness > Alkalinity) in calculating the types of hardness in a water supply source. Hot-process softening is predominantly used in industrial applications and is not discussed here. LSI between -0.30 and +0.30 is the widely accepted range, while 0.00 is perfect equilibrium. Using either flocculating and softening regime, only about half of the orig inal 260 mg/1 of hardness was removed. All Answers (4) Sodium hydroxide (NaOH) (caustic soda) may be utilized for chemical precipitation. Prices can vary, but for the following calculations, the prices used include $510/dry ton for caustic soda, $130.50/ton for quicklime as delivered and $153.10/ton for hydrated lime as . lime softening. Water treatment operators benefit from watching this DVD by better understanding what hard water is, the problems it causes in the distribution system and for consumers, and how and why . Simply enter the calcium carbonate hardness in mg/L, and then enter the magnesium hardness in mg/L. We accomplish this by using the ratio on below equation. Silica content in brackish water. Lime soda softening is the subject of this course, which includes coverage of calculating the different types of hardness in a water sample from lab analysis results, conversions among different units for hardness, information about three lime soda water softening process alternatives (two stage excess lime water softening, split treatment, and 9 pg. chemistry of lime soda process the amount of lime required in (meq/l) = carbon dioxide (meq/l) + carbonate hardness (meq/l) + magnesium ion (meq/l) + 1.25 (meq/l) the amount of soda ash required in (meq/l) = noncarbonate hardness (meq/l). Is 220 PPM hard water? Carbon dioxide and carbonate hardness (calcium and Magnesium bicarbonate) are complexed by lime. Softening was tried using lime as the sole flocculating agent and using lime with ferric sulfate as a conjunctive coagulant. Lime softening, the most widely used precipitation process, serves well to illus- trate the importance of four key variables in precipitation: (1) solubility, (2) par- ticle charge, (3) temperature, and (4) time. The FilmTec NF270 nanofiltration membrane, for example, offers low salt rejection, low energy consumption, and stable performance after repetitive cleaning. Anything over 180 PPM is considered very hard water, so if you measure hardness as 220 PPM, it's a sign that your water is hard. Use dolomitic lime if the Ca:Mg ratio is above 10:1. This article first covers how gravity clarifiers work, some of the chemicals used in clarification, proper chemical feeding procedures, and clarifier equipment designs. lime softening is to remove "hardness-causing" ions by converting them to particles. Allowing the plant to run for 22 hours, and leaving 2 spare hours for regeneration of the cation exchange resin, the output between . Percent lime Required by Specification Depth in Inches Soil Density Total Pounds Applied per Square Yard (This field will be populated automatically) Hence, the net flow per softener is 65 m3/hour. Lime-soda ash softening is assumed to be capable of reducing calcium and magnesium to empirically determined 11practical limits11 of 0.6 - 0.8 meq/1 and 0.2 meq/1, respectively. Figure 1: Soda lime water softening process. In small systems, lime softening is typically practiced by adding Sketch a drawing of a typical lime softening facility, identifying processes and points of chemical addition in the appropriate order for each of the following: 1. the two stage excess lime softening process, if concentrations are known or can be calculated for CO2, calcium carbonate hardness, calcium noncarbonate hardness, magnesium carbonate hardness, and magnesium noncarbonate hardness, using design values for excess lime concentration and lower limit of residual magnesium hardness. Enter the calcium (Ca) and magnesium (Mg) values from your soil test report. after softening, the water will have high ph and contain the excess lime and the magnesium hydroxide Cold lime softening uses chemical precipitation with lime and other chemicals to reduce a water s hardness and, in some cases, to enhance clarification before filtration. 7 pg. LIME CALCULATORS By Percent of Lime, Depth, Soil Density and Total Square Yards of Project INSTRUCTIONS: FILL IN PERCENT OF LIME, DEPTH, DRY WEIGHT OF SOIL AND SQUARE YARDS. 3 3 61 1 1 [ ] 305 6.1 10 / 50 1000 61 HCO . Multiply the number of people in your family times 70 (gallons of water used per day, national average). Straight lime e use lime softening extensively in certain areas of Florida and have been for over 70 years. Produced specifically for water treatment operator training, this new video illustrates and explains lime softening processes, chemistry, and feed calculations. We normally tolerate a final total hardness on the . Reducing the pH of the lime-softened water to under 8.6 through aeration or acid addition is desirable. Calculations are presented for daily chemical requirements and solids production rates. Enter ppm Ca. THE REST IS AUTOMATIC. Hardness in water is due to the presence of divalent cations, primarily calcium and magnesium, in that water. The second plant's Effective use of coagulants helps remove silica in the softening process. Program pre-calculations49 Calculate CO 2 . due to its advantages: produces less sludge than lime, or lime-soda ash processes. Lime softening produces large volumes of a mixture of calcium carbonate and magnesium hydroxide in a very finely divided white precipitate which may also contain some organic matter flocculated out of the raw water. During lime softening process calcium and magnesium are precipitated. A lime softener is actually a reactor, a precipitator and a clarifier. The normal pH of water is between 6.5-8.5. Enter ppm Mg. The chemicals increase the pH of the water so that calcium carbonate, lime, leaves the solution and crystallizes on the fine sand in the form of rock-hard balls, the pellets. 9 pg. In the lime-softening process, the pH of the water being treated is raised sufficiently to precipitate calcium carbonate and, if necessary, magnesium hydroxide. There is also information about three lime soda water softening process alternatives (two stage excess lime water softening, split treatment, and selective calcium removal), along with calculation of the dosages needed for lime, soda ash, and carbon dioxide. Supply water and chemicals (caustic soda, lime wash or sodium carbonate) are injected into the bottom of the reactor and mixed intensively. criteria for softening facilities. Click "calculate", and the calculator will return the total hardness in mg/L of CaCo3. Lime is used to remove carbonate harness, and both . Softening James Norberg Follow this and additional works at:https://commons.und.edu/theses . In many communities lime softening processes do . With these calculators you can calculate Anglo-American units to the standards units (SI-units). A. Therefore, they are more effectively removed by warm lime softening than by cold lime softening. How does the lime-softening process work? How clarifiers work Calculate how much lime and soda ash are required to soften a raw water with a total hardness = 215 mg/L (as CaCO_{3}) or 2.15 10^{3} . Revise if necessary. The lime softening reaction is relatively slow, and will continue downstream of the clarifier, exceeding the solubility of calcium carbonate in the clarified water. Calculate Lime Dosage Requirement in Sedimentation Process.