AWWA 1944-2016 Water Distribution Grades 3 & 4.pdf
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1、 #MBOL1BHFGrades 3 and in some cases, states have adopted stricter regulations or have developed regulations for additional contaminants not regulated by USEPA.This chapter discusses current and anticipated USEPA regulations and the challenges that operators face in their efforts to comply with the
2、regulations. Water system operators should consult their local and state regulatory agencies to verify applicable regulations that may be different than the federal regulations listed in this chapter. The chapter concludes with a discussion of selected contam-inants that are commonly found in water,
3、 their significance, and the methods for their removal.Types of Water SystemsThe SDWA defines a public water system (PWS) as a supply of piped water for human consumption that has at least 15 service connections, or serves 25 or more persons 60 or more days each year. By that definition, private hom
4、es, groups of homes with a single water source but having fewer than 25 residents, and sum-mer camps with their own water source that operate less than 60 days per year are not PWSs. They may, however, be subject to state or local regulations. Such systems may also be subject to state and local well
5、 construction and water quality requirements.PWSs are classified into three categories based on the type of customers served:H18546 Community PWS: a system whose customers are full- time residentsH18546 Nontransient noncommunity PWS: an entity having its own water supply, serving an average of at le
6、ast 25 persons who do not live at the location but who use the water for more than 6 months per yearH18546 Transient noncommunity PWS: an establishment having its own water sys-tem, where an average of at least 25 people per day visit and use the water occasionally or for only short periods of timeT
7、hese classifications are based on the differences in exposure to contaminants experienced by persons using the water. Most chemical contaminants are believed to potentially cause adverse health effects from long- term exposure. Short- term US Environmental Protection Agency (USEPA)A US government ag
8、ency responsible for implementing federal laws designed to protect the environment. Congress has delegated implementation of the Safe Drinking Water Act to the USEPA.2 WSO Water Distribution, Grades 3 it is an analytic method used to measure the variety of bacteria that are common in water. The lowe
9、r the concentration of bacteria in drinking water, the better maintained the water system is.HPC measures a range of bacteria that are naturally present in the environmentLegionella Zero TT Legionnaires disease, a type of pneumoniaFound naturally in water; multiplies in heating systemsTotal coliform
10、s (including fecal coliform and Escherichia coli E. coli)Zero 5.0%* Not a health threat in itself; it is used to indicate whether other potentially harmful bacteria may be present.Coliforms are naturally present in the environment as well as feces; fecal coliforms and E. coli only come from human an
11、d animal fecal waste.Turbidity N/A TT Turbidity is a measure of the cloudiness of water. It is used to indicate water quality and filtration effectiveness (e.g., whether disease-causing organisms are present). Higher turbidity levels are often associated with higher levels of disease-causing microor
12、ganisms such as viruses, parasites, and some bacteria. These organisms can cause symptoms such as nausea, cramps, diarrhea, and associated headaches.Soil runoffViruses (enteric) Zero TT Gastrointestinal illness (e.g., diarrhea, vomiting, cramps)Human and animal fecal wasteDisinfection By-productsBro
13、mate Zero 0.010 Increased risk of cancer By-product of drinking water disinfection with ozoneChlorite 0.8 1.0 Anemia; nervous system effects in infants and young childrenBy-product of drinking water disinfection chlorine dioxideHaloacetic acids (HAA5)N/A0.060 Increased risk of cancer By-product of d
14、rinking water disinfection(continued)4 WSO Water Distribution, Grades 3 increased risk of cancerBy-product of drinking water disinfectionDisinfectantsChloramines (as Cl2)MRDLG=4 MRDL=4.0 Eye/nose irritation; stomach discomfort; anemiaWater additive used to control microbesChlorine (as Cl2) MRDLG=4 M
15、RDL=4.0 Eye/nose irritation; stomach discomfortWater additive used to control microbesChlorine dioxide (as ClO2)MRDLG=0.8 MRDL=0.8 Anemia; nervous system effects in infants and young childrenWater additive used to control microbesInorganic ChemicalsAntimony 0.006 0.006 Increase in blood cholesterol;
16、 decrease in blood sugarDischarge from petroleum refineries; fire retardants; ceramics; electronics; new lead-free solderArsenic 0 0.010 as of 1/23/06Skin damage or problems with circulatory systems; possible increased risk of contracting cancerErosion of natural deposits; runoff from orchards, runo
17、ff from glass and electronics production wastesAsbestos (fiber 10 micrometers)7 million fibers per liter (MFL)7 MFL Increased risk of developing benign intestinal polypsDecay of asbestos cement in water mains; erosion of natural depositsBarium 2 2 Increase in blood pressure Discharge of drilling was
18、tes; discharge from metal refineries; erosion of natural depositsBeryllium 0.004 0.004 Intestinal lesions Discharge from metal refineries and coal-burning factories; discharge from electrical, aerospace, and defense industriesCadmium 0.005 0.005 Kidney damage Corrosion of galvanized pipes; erosion o
19、f natural deposits; discharge from metal refineries; runoff from waste batteries and paintsChromium (total) 0.1 0.1 Allergic dermatitis Discharge from steel and pulp mills; erosion of natural depositsCopper 1.3 TT; action level=1.3Short-term exposure: gastrointestinal distress; long-term exposure: l
20、iver or kidney damage; people with Wilsons disease should consult their personal doctor if the amount of copper in their water exceeds the action level.Corrosion of household plumbing systems; erosion of natural depositsUSEPA Water Regulations 5Table 1-1 List of contaminants and their MCLs (continue
21、d)ContaminantMCLG,* mg/LMCL or TT, mg/LPotential Health Effects From Ingestion of WaterSources of Contaminant in Drinking WaterCyanide (as free cyanide)0.2 0.2 Nerve damage or thyroid problemsDischarge from steel/metal factories; discharge from plastics and fertilizer factoriesFluoride 4.0 4.0 Bone
22、disease (pain and tenderness of the bones); children may get mottled teethWater additive that promotes strong teeth; erosion of natural deposits; discharge from fertilizer and aluminum factoriesLead Zero TT; action level=0.015Infants and children: Delays in physical or mental development; children c
23、ould show slight deficits in attention span and learning abilitiesAdults: Kidney problems; high blood pressureCorrosion of household plumbing systems; erosion of natural depositsMercury (inorganic)0.002 0.002 Kidney damage Erosion of natural deposits; discharge from refineries and factories; runoff
24、from landfills and croplandsNitrate (measured as nitrogen)10 10 Infants below the age of 6 months who drink water containing nitrate in excess of the MCL could become seriously ill and, if untreated, may die. Symptoms include shortness of breath and blue-baby syndrome.Runoff from fertilizer use; lea
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