Hardness Surface Water

Surface water had a total hardness of 105 pm as calcium carbonate, with 95 ppm calcium and 10 ppm magnesium. The remaining analysis is listed below (all species listed a ppm ion)  

As with Case 1, the RO system produces 110 gpm at 75% recovery that requires 150 gpm of feed water. 

The sodium softener selected to treat this water is a duplex, 150-gpm system with 54-inch diameter by 72-inch side sheet vessels. Each vessel contains 50ft3 of resin and the system regenerates 0.9 times per day. At a salt dosage of 15 pounds per cubic foot, the system uses about 675 pounds of salt per day, assuming a 100% operating factor. At a salt cost of 80 per ton, the total monthly cost for salt is about 820. 

Amortization of resin typically assumes a 5-year life or replacement cycle. Given two vessels with 100 ft3 of resin total, the monthly amortization is 100. 

Projections shows that calcium carbonate and calcium fluoride, with saturation indexes of 158% and 200%, respectively, are the species to be concerned with. The addition of 2.6 ppm of antiscal-ant would bring down the saturation indexes to 82% and 0% for calcium carbonate and calcium fluoride, respectively. At 4.00 per pound of antisealant, the cost for antisealant is about 19 per day, or about 570 per month. 

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For this low hardness, surface water case, the antisealant operating cost is lower than that for the softener. Again, the affect of the softener on improved membrane performance is not known and should be considered for this surface water source. 

Makeup. Makeup treatment depends extensively on the source water. Some steam systems use municipal water as a source. These systems may require dechlorination followed by reverse osmosis (qv) and ion exchange. Other systems use weUwater. In hard water areas, these systems include softening before further purification. Surface waters may require removal of suspended soHds by sedimentation (qv), coagulation, flocculation, and filtration. Calcium may be reduced by precipitation softening or lime softening. Organic contaminants can be removed by absorption on activated carbon. Details of makeup water treatment may be found in many handbooks (22—24) as well as in technical Hterature from water treatment chemical suppHers. 

Imidazolidinones. Several mono and dichloro isomers have been prepared and tested as disinfectants (157) 1-ch1oro-4,4,5,5-tetramethylimidazo1idin-2-one [58816-19-6] l,3-dichloro-4,4,5,5-tetramethylimidaZohdin-2-one [58816-20-9] (5), mp 102—104°C l-chloro-2,2,5,5-tetramethylimidazohdin-4-one [38951-95-8] mp 157—158°C and l,3-dichloro-2,2,5,5-tetramethylimidazohdin-4-one [128780-87-0] (6), mp 69—71°C (158). In water, these compounds are somewhat less stable but better disinfectants than the oxazoUdinones. They have potential for water disinfection and in hard surface cleaners. l-Bromo-3-chloro- [108602-19-3] mp 102—104°C, and 1,3-dibromo- [108602-18-2] mp 119—121°C, derivatives of 4,4,5,5-tetramethylimidazohdin-2-one have been prepared. 

Hard Surface Cleaners. Citric acid and sodium citrate are used in hard surface cleaners as an acid and chelator for dissolving hard water deposits and as a builder to increase the efficacy of the surfactants. 

Several cleaning formulations for specific uses contain unreacted polyamines. Examples include mixtures of ammonium alkylbenzenesulfonate, solvents, and PIP which give good cleaning and shine performance on mirrors and other hard surfaces without rinsing (305), and a hard-surface cleaner composed of a water-soluble vinyl acetate—vinyl alcohol copolymer, EDA, cyclohexanone [108-94-1] dimethyl sulfoxide [67-68-5] a surfactant, and water (306). TEPA, to which an average of 17 moles of ethylene oxide are added, improves the clay sod removal and sod antiredeposition properties of certain hquid laundry detergents (307). 

Sand. Ottawa sand has a low specific gravity of about 2.63. But since no additional water is required when using this additive, it is possible to use sand to increase the cement slurry specific weight. The sand has little effect on the pumpability of the cement slurry. When set the cement will form a very hard surface. Sand used as an additive can be used to increase the specific weight of a cement slurry to as high as 18 Ib/gal. 

The discharge of surface water from a site may originate from three potential sources rainwater from building(s), surface-water runoff from paved/hard standing areas and subsoil drainage (groundwater)... 

The surface water runoff from paved/hard standing areas also depends on rainfall intensity calculated from the geographical locations of the site and storm-return period. However, the return period for a site will be far higher than for a building in order to ensure prevention of persistent flooding of the site. In many instances the local authority may specify the storm-return period as the design criterion. 

A laboratory check is normally desirable to assess the amounts of organic and mineral acids present, and a check on hardness is usually necessary in any case. Hardness in water is due to dissolved salts - mainly of calcium, magnesium and iron, and occasionally of aluminum. Softening may be required if the water is extremely hard, because the salts react with the emulsifier in the soluble oil to form an insoluble scum that floats on the surface of the emulsion. The scum may not in itself be harmful, but its formation uses up some of the emulsifier and causes the emulsion to be unstable. 

Hard Very Moderately Slightly Moderately borehole soft soft hard hard water lake surface river river (chalk water water water water formation) hard borehole water containing sodium bicarb- onate Very hard under- ground water... 

Upland surface water. This is low in hardness salts having run over impervious rocks but will often be high in organic matter, i.e. fulvic and humic acids. 

Supply of MU water for a medium-pressure (450 psig) WT boiler, from a surface water source with very variable suspended solids and hardness (sugar refinery, South Africa). The process used is a. carbonate removal using hot-lime precipitation softening coupled with silica adsorption by magnesia addition b. clarification in anthracite filters and c. cation ion-exchange for the balance of hardness removal. 

A special application of a-sulfo fatty acid esters is for highly concentrated hard surface cleaners which are used after dilution in a pail of water. Normally hydrotropes are needed to increase the solubility of the surfactants in water and assure clear, homogeneous, and storage-stable products. If the LAS, which are typical surfactants in hard surface cleaners, are replaced by ester sulfonates the hydrotrope can be deleted from the formula [62]. 

The amount of lead that remains in solution in surface waters depends upon the pH of the water and the dissolved salt content. Equilibrium calculations show that at pH >5.4, the total solubility of lead is approximately 30 pg/L in hard water and approximately 500 pg/L in soft water. Sulfate ions, if present... 

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