Hardness

Originally, water hardness was a measure of the ability of water to precipitate soap. It was measured by the amount of soap needed for adequate lathering and served also as an indicator of the rate of scale formation in hot water heaters and boilers. Soap is precipitated as a gray bathtub ring deposit mainly by reacting with the calcium and magnesium cations (Ca2+ and Mg2+) present, although other polyvalent cations may play a minor role. Hardness has some similarities to alkalinity. Like...

Beryllium Be CAS 7440417 Background

Beryllium is a metal found in natural deposits as ores containing other elements and in some precious stones such as emeralds and aquamarine. Beryllium is not likely to be found in natural waters above trace levels due to the insolubility of oxides and hydroxides at normal environmental pHs. It has been reported to occur in U.S. drinking water at 0.01 to 0.7 J.g L. A major use of beryllium is as an alloy hardener. Its greatest use is in making metal alloys for nuclear reactors and the aerospace...

Drinking Water Standards

Potential Health Effects from Ingestion of Water Increase in blood cholesterol, decrease in blood glucose. system problems, increased risk of cancer. Increased risk of developing benign intestinal polyps. Some people who use water containing chromium well in excess of the MCL for many years could experience allergic dermatitis. Short-term exposure gastrointestinal distress. Long-term exposure liver or kidney damage. Those with Wilson's disease should consult their doctor if their water systems...

Soil Groundwater and Subsurface Contamination

Fulvic Acid Fractions

Steps in the Typical Development of a Soil and Its Profile (Pedogenesis) 4.5 Contaminants Become Distributed in Water, Soil, and Air Air-Water Partition Coefficient Soil-Water Partition Coefficient Determining Kd Experimentally The Role of Soil Organic Matter The Octanol Water Partition Coefficient, Kow Estimating Kd Using Solubility or Kow 4.7 Mobility of Contaminants in the Subsurface Effect of Biodegradation on Effective Retardation Factor A Model for Sorption and Retardation Soil Properties...

Predicting Bond Type From Electronegativities

Intermolecular forces are electrostatic in nature. Molecules are composed of electrically charged particles (electrons and protons), and it is common for them to have regions that are predominantly charged positive or negative. Attractive forces between molecules arise when electrostatic forces attract positive regions on one molecule to negative regions on another. The strength of the attractions between molecules depends on the polarities of chemical bonds within the molecules and the...

Indicators Of Fecal Contamination Coliform And Streptococci Bacteria

Detecting and preventing fecal contamination is of prime importance for all drinking water systems and recreation water managers. Fecal wastes may contain enteric pathogens (disease-causing organisms from the intestines of warm-blooded animals) such as viruses, bacteria, and protozoans (which include Cryptosporidium and Giardia). Fecal contaminated water is a common cause of gastrointestinal illness, including diarrhea, dysentery, ulcers, fatigue, and cramps. It also may carry pathogens that...

Breakpoint Chlorination For Removing Ammonia

Chlorine Breakpoint Drinking Water

Chlorination can be used to remove dissolved ammonia and ammonium ion from wastewater by the chemical reactions NH3 + Cl2 NH2Cl + Cl- + H+. (6.6a) NH4+ + Cl2 NH2Cl + Cl- + 2 H+. (6.6b) Ammonia is converted stoichiometrically to monochloramine (NH2Cl) at a 1 to 1 molar ratio or a 5 to 1 ratio by weight of Cl2 to NH3-N. NHCl2 (dichloramine), and NCl3 (nitrogen trichloride or Suggested Maximum Parameter Levels in Water Used for Crop Irrigation total dissolved solids (TDS) mg L specific...

Drinking Water Treatment

Clean drinking water is the most important public health factor. But well over 2 billion people worldwide do not have adequate supplies of safe drinking water. Worldwide, between 15 to 20 million babies die every year from water-borne diarrheal diseases such as typhoid fever, dysentery, and cholera. Contaminated water supplies and poor sanitation cause 80 of the diseases that afflict people in the poorest countries. The development of municipal water purification in the last century has allowed...

Lead Pb CAS 7439921 Background

Lead minerals are found mostly in igneous, metamorphic and sedimentary rocks. The most abundant lead mineral is galena (PbS). Oxide, carbonate, and sulfate minerals are lanarkite (PbO), cerrusite (PbCO3), and anglesite (Pb(SO4), respectively. Commercial ores have concentrations of lead in the range 30-80 g kg. Metallic lead and the common lead minerals have very low solubility. Most environmental lead (perhaps 85 ) is associated with sediments the rest is in dissolved form. Although some lead...

Nitrogen Ammonia Nh3 Nitrite No2 And Nitrate No3

Phosphate Species

Nitrogen compounds of greatest interest to water quality are those that are biologically available as nutrients to plants or exhibit toxicity to humans or aquatic life. Atmospheric nitrogen (N2) is the primary source of all nitrogen species, but it is not directly available to plants because the N N triple bond is too strong to be broken by photosynthesis. Atmospheric nitrogen must be converted to other nitrogen compounds before it can become available as a plant nutrient. The conversion of...

Acidity And Alkalinity

Diagram Alkalinity

The alkalinity of water is its acid-neutralizing capacity. The acidity of water is its base-neutralizing capacity. Both parameters are related to the buffering capacity of water the ability to resist changes in pH when an acid or base is added . Water with high alkalinity can neutralize a large quantity of acid without large changes in pH on the other hand, water with high acidity can neutralize a large quantity of base without large changes in pH. Acidity is determined by measuring how much...

Ph And Water Quality

Scale Common Substances

Pure water always contains a small number of molecules that have dissociated into hydrogen ions H and hydroxyl ions OH , as illustrated by Equation 3.1. The water dissociation constant, Kw is defined as the product of the concentrations of H and OH- ions, expressed in moles per liter where enclosing a species in square brackets is chemical symbolism that represents the species concentration in moles per liter. Because the degree of dissociation increases with temperature, Kw is temperature...

National Recommended Water Quality Criteria

Adapted from EPA 822-Z-99-001, April 1999. Section 304 a 1 of the Clean Water Act requires the EPA to develop, publish, and revise water quality criteria so that they accurately reflect the latest scientific knowledge. These criteria are based solely on a scientific interpretation of data concerning the relation between pollutant concentrations and environmental and human health effects. Considerations of technological feasibility or economic impacts of attaining the recommended criteria are...