Water quality & treatment : a handbook on drinking water,6th ed

Water -- Purification -- United States. Water quality. Water-supply -- United States. TECHNOLOGY & ENGINEERING -- Environmental -- Water Supply. Adsorption (Cont.): desorption and, 14.36–14.37 of DOC, 8.29–8.30 equilibrium, 14.8–14.27 equivalent background compound and, 14.23–14.26, 14.23f. external (film) resistance to transport and, 14.28 Freundlich equation for, 14.9–14.12, 14.9f., 14.10t.–14.11t. GAC and, 10.15, 14.6–14.7 GAC capacity of, 14.62 granular media, 12.7–12.9 HSDM for, 14.30–14.31, 14.31f. of humic substances on GAC, 14.27 internal (intraparticle) transport and, 14.28 iodine number in, 14.7 isotherms, 14.8–14.12, 14.9f., 14.10t.–14.11t., 14.12f. IX kinetics compared to, 12.18 kinetic parameter estimation for, 14.29–14.30 kinetics, 14.28–14.36 mass transfer zone in, 14.31–14.34, 14.32f. MIB capacity for, 14.22, 14.22f., 14.25f. micropollutant capacity in natural waters of, 14.24, 14.25f., 14.26 molasses number in, 14.7 of NOM, 14.19–14.21, 14.20f. of NOM by HMS coagulants, 8.28–8.30 NOM preloading effect on kinetic parameters of, 14.34–14.36, 14.35f.–14.36f. NOM preloading in natural waters and, 14.26–14.27, 14.26f.–14.27f. overview of, 14.2–14.4 PAC and, 14.6–14.7 of polymers, 8.13–8.15 rate-limiting step in, 14.28 residuals and, 22.54–22.62 solvent-motivated, 14.13 surface area in, 14.4 surface chemistry of, 14.13 of synthetic resins, 14.87–14.88 of THMs, 14.53 transport mechanisms in, 14.28–14.29 treatment process selection and, 5.19–5.21 water quality and, 14.3 Adsorptive media. See also Ion exchange arsenic and residuals of, 12.54–12.55 arsenic capacity of, 12.49, 12.52–12.54, 12.52f., 12.53t. arsenic removal by, 12.46–12.55, 12.47f.–12.48f., 12.48t., 12.50t.–12.51t., 12.52.f arsenic removal process of, 12.47–12.49, 12.48f., 12.48t. Advanced oxidation processes (AOPs), 5.7, 5.25, 7.23–7.29, 16.5 adOx kinetic model for, 18.29–18.30, 18.30f. for DBP precursor control, 19.29–19.30, 19.30f. steady state OH radical model for, 18.28–18.29 UV/Cl2 AOP mechanism, 18.33 UV/H2O2 AOP mechanism, 18.24, 18.25t.–18.26t., 18.27–18.32 UV/O3 AOP mechanism, 18.33 UV/TiO2 AOP mechanism, 18.34 Aeration. See also Bubble aeration corrosion control with, 20.75 DBP removal with packed towers and, 19.42, 19.42f. softening, 13.52 spray aerators, 6.56–6.60, 6.57f. surface, 6.52–6.56, 6.52f.–6.54f. Aeromonas hydrophyla, 2.8 in distribution systems, 21.16–21.17 Aesthetic concerns with color, 2.74–2.75 with hardness, 2.75 with mineralization, 2.75 with staining, 2.75 with taste and odor, 2.73–2.74 with turbidity, 2.74–2.75 water quality and, 2.2, 2.72–2.75 Air binding, 10.49 Air saturation systems, 9.70–9.72, 9.71f.–9.72f. Air scour backwash water flow rates compared to, 10.56–10.57, 10.57t. in backwashing of rapid granular bed filtration, 10.54t., 10.55–10.57 delivery systems for, 10.56 Air stripping. See also Packed towers adsorption for off-gas control in, 6.36–6.41, 6.37f.–6.38f., 6.39t. low-profile, 6.15 sieve tray columns in, 6.15, 6.17 treatment process selection and, 5.5 types of, 6.1–6.2 of VOCs, 6.42–6.45 Biodosimetry UV test, 18.9–18.10, 18.9f. Biofilms, 21.7–21.8, 21.8f. Biofiltration, 14.42 DBP removal with, 19.40–19.41, 19.42f. Biological activated carbon, 14.42 Biological nutrient removal (BNR), 16.10–16.11, 16.10t. Bioterrorism Act (1992), 1.7 Blended phosphates, 20.44 Blue water, 20.46 BNR. See Biological nutrient removal Body feed precoat filtration and, 10.87, 10.92 precoat filtration and concentration of, 10.93–10.94, 10.94f. Boron, 2.35–2.36 Brasses, 20.53–20.54 Brine disposal in IX removal of nitrate, 12.39–12.40 locations for, 22.61–22.62 from softening plants in IX, 12.33 Brines, 22.3 Bromate, 2.66 control of, 19.40f. GAC reactions with, 14.59 ozonation and, 19.19 Bromide chlorine reactions with, 7.20 ozone reactions with, 7.28–7.29, 7.29f. THM reactions with, 19.20–19.22, 19.20f. Brominated acetic acids, 2.68–2.69 Bromine, 2.65–2.66 incorporation factor, 19.21 substitution factor, 19.21 THMs and, 19.21–19.22, 19.21f.–19.22f. Bromodichloromethane (BDCM), 2.67 Bromoform, 2.67–2.68 Bronzes, 20.53–20.54 Brownian diffusion, 8.51–8.52, 10.31, 11.42, 11.43f. Brunauer-Emmett-Teller isotherm equation, 14.4 Bubble aeration, 6.2, 6.41–6.52 ozone absorption problem for, 6.50–6.52 sample calculation for, 6.47–6.50 schematic of, 6.42f. schematic of mixed, 6.43f. schematic of single, 6.43f. tank schematic of, 6.44f. tanks in series development for, 6.44–6.45, 6.44f. Bubble-point testing, 11.35–11.36 Buffer intensity, 20.26–20.29, 20.27f.–20.28f. Bulk solution transport, 14.28 Bureau of Water Hygiene CWSS, 1.3–1.4 C × T approach (disinfection regulation), 17.39–17.41, 17.40t. Cadmium, 2.36 Cake filtration, 10.3 Calcium carbonate equilibria, 13.25–13.29, 13.28t. Calcium carbonate precipitation potential (CCPP), 20.34 Calcium hypochlorite, 7.17–7.18 basic chemistry of, 17.5–17.8 Caliciviruses, 2.11–2.12 California state regulations for IPR, 16.37–16.38 Campylobacter, 2.8–2.9 IPR and, 16.7, 16.7t. Canada, standards of, 1.32 Cancer, pesticides and risk of, 2.51–2.52 Candy tanks, 9.3, 9.3f.–9.4f. Capillary suction time test (CST test), 22.12, 22.13f., 22.13t. Carbamates, 2.55 Carbon dioxide, solubility of, 3.10–3.11 Carbon tetrachloride, 2.46–2.47 Carbonaceous resins, 14.7–14.8, 14.8 Carbonate hardness, 13.13–13.14 lime softening removing, 13.18–13.19 Carbonate saturometer, 20.35 Carbonic acid, 13.16 lime softening removing, 13.20–13.21 Carcinogenicity, 2.25–2.26 of DBPs, 2.61t.–2.63t. CIP waste. See Clean-in-place waste Clarifier sludge, 22.3 Clastogenicity, 2.25 Clean Water Act (CWA), 16.5–16.6 Clean-bed head loss, 10.36–10.38 Clean-in-place solutions, 11.91 Clean-in-place waste (CIP waste), 22.4, 22.44–22.45, 22.45t., 22.49–22.50, 22.49t. Clearwells, 4.46 Clostridium perfringens, 2.22, 17.20 Coagulants. See also HMS coagulants; Polyelectrolyte coagulants acidity of, 8.33–8.36, 834t. alum, 8.2 aluminum, 8.3 combinations of, 8.49 demand, 8.22 dosage estimations for, 8.41–8.45 effective acid content of, 8.42 electrokinetic measurements in control/ monitoring of, 8.68–8.70 jar tests for, 8.64–8.66 metal salts plus additives, 8.21 metal salts plus strong acid, 8.21 MF and, 8.2 MF/UF integration removing arsenic with, 11.61, 11.61f. polyaluminum chloride, 8.20 polyaluminum hydroxychloride, 8.20 polyiron chloride, 8.20 prehydrolyzed metal salts, 8.20–8.21 residuals and, 22.4–22.16, 22.11–22.12, 22.11f. selecting appropriate, 8.41–8.45 silica, 8.7, 8.8f., 8.48 simple metal salts, 8.20 Coagulation. See also Enhanced coagulation chemical oxidation as aid to, 7.46 DAF and, 9.56–9.58, 9.57f., 9.73–9.75, 9.74f. DBP precursor control with, 19.31, 19.32f., 19.33 definition of, 8.2–8.3 electrokinetic measurements in control/ monitoring of, 8.68–8.70 electrophoretic mobility and, 8.47, 8.47f. electrophoretic mobility in control/monitoring of, 8.68 lime softening and, 13.53, 13.69–13.70, 13.69f. MF/UF integration with, 11.58–11.60, 11.58f.–11.59f. Coagulation (Cont.): ozone and, 8.49 in precipitative softening, 13.59–13.60 rapid granular bed filtration and pretreatment, 10.43–10.45, 10.44f. SCD measurements in monitoring/control of, 8.68–8.69, 8.69f. sedimentation and, 9.41–9.42 temperature’s effect on, 8.63–8.64 treatment process selection and, 5.7–5.9 Coarse-bed filtration, 9.87 COCODAF® dissolved air flotation, 9.69, 9.69f. Cold polymictic lakes, 3.34 Coliforms. See also Fecal coliforms; Total coliform in distribution systems, 21.13, 21.13t., 21.27 fermentation tube procedures and, 17.20 in GAC/PAC, 21.22 as indicators, 2.19–2.21, 17.20 membrane filter procedures and, 17.20 Coliphages, 2.21 Collimated beam, 18.8–18.9, 18.8f. Collision efficiency factor, 8.51 Colloids destabilization of, 8.14–8.15 DLVO theory of stability for, 8.7 like-charge electrostatic attraction of, 8.12 mass transport of, 11.42–11.43, 11.43f. Color aesthetic concerns with, 2.74–2.75 chemical oxidation removing, 7.42–7.43 corrosion and, 20.38 DAF removing, 5.33, 5.33f. iron corrosion and, 20.41–20.42 IX removing, 12.61–12.67, 12.63f.–12.65f. sludge production and, 22.6 Community Water System Survey (CWSS), 1.3–1.4 Compaction density, 22.14 Competitive adsorption in multisolute systems, 14.14–14.19, 14.15f., 14.18f., 14.18t.–14.19t. in natural waters, 14.21–14.26, 14.22f.–14.23f., 14.25f. Composite membranes, 11.10–11.11, 11.11f. Compound analysis, 20.71 Computational fluid dynamics (CFD), 4.24–4.26 disinfection and, 17.41 sedimentation and, 9.26, 9.88 tracer tests and, 4.25–4.26 chemical factors affecting, 20.25–20.39, 20.80–20.81 chloride causing, 20.29–20.30 color and, 20.38 color from iron and, 20.41–20.42 compound analysis for, 20.71 concentration cell, 20.10 concrete pipes and, 20.64–20.65 connections in, 20.3 control of, 20.73–20.77 copper and, 20.30, 20.77–20.78 copper and pitting, 20.50–20.52 copper and uniform, 20.46–20.50, 20.47f., 20.49f. coupon weight-loss testing for, 20.67 crevice, 20.10 dealloying, 20.7–20.8 DIC and, 20.25, 20.27f. differential oxygenation, 20.10 distribution systems and controlling, 21.48–21.49 divalent lead and, 20.54–20.59, 20.55f., 20.57f.–20.58f. duplex film inhibiting, 20.46 electrochemical rate measurements for, 20.67 electrolytic solution in, 20.3 electron microscopy methods for analyzing, 20.71 elemental spectroscopy after decomposition for analyzing, 20.69–20.70, 20.70t. engineering considerations for controlling, 20.74 erosion, 20.10 flow velocity and, 20.21 galvanic, 20.6–20.7 galvanized steel and, 20.63–20.64 graphitization and, 20.10 hardness and, 20.32–20.35 human exposure evaluations for, 20.77–20.78 hydrogen sulfide accelerating, 20.35 immersion testing for, 20.68 iron and, 20.9, 20.40–20.45 kinetics of, 20.12–20.13 Larson ratio and, 20.29 lead and, 20.54–20.63 limestone contactors controlling, 20.75 Corrosion (Cont.): LSI and, 20.33–20.34 magnesium and, 20.35 manganese and, 20.36, 20.37f. manufacturing processes and, 20.24 mass balance equation and, 20.14–20.15 materials selection for controlling, 20.73–20.74 membrane cell theory and, 20.51 metallic precipitates and, 20.35–20.38, 20.36f.–20.37f. microbiologically influenced, 20.8–20.10 mixed-potential theory and, 20.13 Nernst equation and, 20.4–20.5 NOM and, 20.8–20.9, 20.38 nonprotective scales and, 20.11 optical microscopic techniques for analyzing, 20.71 ORP and, 20.30, 20.31f., 20.32 orthophosphate and, 20.38, 20.43, 20.48–20.49, 20.49f. oxygen and, 20.32 particulate lead and, 20.54 pH and, 20.38–20.39, 20.43, 20.46–20.47 photomicroscopy techniques for analyzing, 20.71 physical factors affecting, 20.20–20.24 physical inspect of, 20.66 pinhole leak and, 20.4 pipe linings, coating and paints for controlling, 20.76–20.77 pipe rig systems for, 20.67–20.68 on pipe surfaces, 20.11–20.12 of pipes in distribution systems, 21.26 pitting, 20.7–20.10, 20.7f., 20.50–20.52 planned interval tests for, 20.67 polyphosphates and, 20.39, 20.43–20.44 potential-pH diagrams (Pourbaix diagrams) and, 20.18–20.20, 20.19f.–20.20f. protective scales and, 20.11 rate measurements of, 20.66–20.67 secondary effects of control measures for, 20.75–20.76 selective leaching in, 20.7–20.8 siderite model of, 20.41 silicates and, 20.39, 20.44–20.45 solubility diagrams for, 20.13–20.18, 20.16f.–20.18f. statistical testing criteria for, 20.79–20.80 stray current, 20.10 sulfate causing, 20.9, 20.29–20.30, 20.48 TDS and, 20. wet chemical procedures for analyzing, 20.71 XAFS/XANES for identifying, 20.73 x-ray diffraction for, 20.72–20.73, 20.73f. x-ray fluorescence spectrometry for analyzing, 20.70–20.71 zinc and, 20.35 County Sanitation Districts of Los Angeles County, 16.29–16.30 Coupon weight-loss testing, 20.67 Crevice corrosion, 20.10 Critical control points (CCPs), 16.19–16.21 Cross-connections, 21.29, 21.60–21.63, 21.62t. Cryptosporidium, 2.15–2.16, 10.41, 17.20 backwashing and recycling of, 10.69 DAF and removal of, 9.81–9.83, 9.82f.–9.83f. DE filtration removing, 10.8 filtration and removal of, 10.5–10.8, 10.6t. IPR and, 16.7–16.8, 16.7t. membrane processes removing, 11.33–11.34, 11.33f. MF/UF removing, 11.33–11.34, 11.33f. Milwaukee outbreak of, 2.3 as ovoid particles, 8.3–8.4 precoat filtration removing, 10.88–10.89 pressure filtration removing, 10.8 rapid granular bed filtration and, 10.22 in SFBW, 22.42 SSF removing, 5.12, 10.8, 10.78–10.79 CST test. See Capillary suction time test Cumulative age distribution, in tracer tests, 4.4, 4.5f., 4.6, 4.7f., 4.8, 4.12f. Cuprosolvency, 20.6 Cuprous oxide, 20.51 CWA. See Clean Water Act CWSS. See Community Water System Survey Cyanobacteria, 2.18–2.19 Cyanotoxins chemical oxidation of, 7.45 PAC removing, 14.84 Cyclospora, 2.17 2,4-D. See 2,4-Dichlorophenoxyacetic acid Dacthal, 2.54 DAF. See Dissolved air flotation DALYs. See Disability-adjusted life years Dan Region, Israel (SAT system), 15.28 Darcy-Weisbach equation, 10.13, 10.37 Dayton, Ohio’s magnesium-carbonate process, 13.51–13.52 DBCM. See Dibromochloromethane DBCP. See 1,2-Dibromo-3-chloropropane DBPs. See Disinfection by-products DCA. See Dichloroacetic acid DE filtration. See Diatomaceous earth filtration Dealloying, 20.7–20.8 Dechlorination, 17.33 Decolorizing index, 14.7 Department of Homeland Security (DHS), 1.7 Depth filtration, 10.3 Desorption, 14.36–14.37 Developmental toxicity, 2.25 Dewatering lagoons, 22.25 DHS. See Department of Homeland Security Diatomaceous earth filtration (DE filtration), 10.91. See also Precoat filtration Cryptosporidium and Giardia lamblia removal by, 10.8 Diazinon, 2.55 1,2-Dibromo-3-chloropropane (DBCP), 2.55–2.56 Dibromochloromethane (DBCM), 2.67 DIC. See Dissolved inorganic carbon Dichloroacetic acid (DCA), 2.68 Dichlorobenzenes, 2.47 1,2-Dichloroethane, 2.47 1,1-Dichloroethylene, 2.47–2.48 1,2-Dichloroethylenes, 2.48 Dichloromethane, 2.48 2,4-Dichlorophenoxyacetic acid (2,4-D), 2.54 Differential oxygenation corrosion, 20.10 Differential settling, 8.52 Diffuse layers, 8.8–8.11, 8.9f.–8.10f. Diffused aeration. See Bubble aeration Dimensionless dispersion number, 17.38 Dimictic lakes, 3.35–3.36 Direct filtration, 10.4, 22.3 advantages of, 10.70 disadvantages of, 10.70–10.71 effluent turbidity in, 10.73 filtration rates for, 10.73–10.74 in Las Vegas, 10.73 Los Angeles plant for, 10.73 pretreatment for, 10.72–10.73 source waters for, 10.71–10.72 secondary disinfection in, 21.49, 21.50f. 21.50f. stressed organisms in, 21.14 sulfur in, 21.21 TEVA for, 21.42 treatment process selection and, 5.25–5.27, 21.21–21.22 trench work in, 21.64 UDF in, 21.52–21.53 USEPA regulation requirements for, 21.35–21.36, 21.35t.–21.36t. VBNC bacteria in, 21.14, 21.15t. water age control in, 21, 21.51–21.52, 53t. water main installation and repair for, 21.63–21.65 water quality and design practices of, 21.46–21.47 water quality in, 5.25–5.27 water quality models for, 21.44–21.45, 21.44f. water quality parameter measurements in, 21.36–21.38 water security in, 21.41–21.42 waterborne disease outbreaks and, 21.2–21.4 Diuron, 2.54 Divalent lead corrosion, 20.54–20.59, 20.55f., 20.57f.–20.58f. DLVO theory of colloid stability, 8.7 DNA, 18.11, 18.11f. DOC. See Dissolved organic carbon DOM. See Dissolved organic matter Dose-response relationship, 2.23–2.24 DPR. See Direct potable reuse Drag force, 9.5–9.7, 9.6f. Drinking water advisories (DWAs), 1.18–1.19 Drinking water equivalent level (DWEL), 2.29 Drinking water standards. See Standards Drinking Water State Revolving Fund (DWSRF), 1.28–1.29 Driving force, 11.21–11.22, 11.22t. Dune infiltration, 15.8–15.9 in Leiduin, the Netherlands, 15.26–15.27 Duplex film, 20.46 Düsseldorf, Germany (RBF system), 15.25–15.26 DWAs. See Drinking water advisories DWEL. See Drinking water equivalent level DWSRF. See Drinking Water State Revolving Fund ED. See Electrodialysis EDB. See Ethylene dibromide EDR. See Electrodialysis reversal Effluent organic matter (EfOM), 14.3 EfOM. See Effluent organic matter Electrical resistance, 3.56–3.57 Electrochemical potentials, 7.2–7.4, 7.3t. Electrochemical rate measurements (corrosion), 20.67 Electrodialysis (ED), 5.16 cast membrane sheets in, 11.23, 11.24f. cell, 11.23–11.24, 11.23f. cell pairs, 11.24, 11.25f. mass transport in, 11.50–11.53 membrane stacks in, 11.24, 11.26, 11.26f. MF/UF integration with, 11.59–11.60, 11.59f. modules in, 11.24, 11.26, 11.26f. pilot plant testing for, 11.95–11.96 process of, 11.22, 11.22f. use of, 11.4, 11.8 Electrodialysis reversal (EDR), 11.2 mass transport in, 11.51–11.53, 11.53f.–11.54f. pilot plant testing for, 11.95–11.96 uses of, 11.4, 11.8 Electrolytic flotation, 9.46 Electrolytic solution, 20.3 Electromagnetic spectrum, 18.4, 18.4f. Electromotive force (EMF), 3.15–3.16 Electron microscopy, 20.71 Electroneutrality, 3.5–3.6 Electrophoretic mobility coagulation and, 8.47, 8.47f. coagulation control/monitoring and measurements of, 8.68 jar test interpretations for, 6.69–6.70, 6.70f Vyredox method, 15.10 Warm monomictic lakes, 3.35 Warm polymictic lakes, 3.35 Wastewater, 3.68–3.69 backwashing management of, 10.68–10.69 DAF of, 9.46 pathogens in, 17.21 surface aeration and, 6.52 upflow filter treatment for, 10.15–10.16 Water age, 21.51–21.52, 21.53t. Water dissociation, 3.3–3.4 Water properties physical, 3.3 polar nature, 3.2 Water quality adsorption and, 14.3 aesthetic concerns with, 2.2 concentrations measuring, 3.4 distribution system design practices and, 21.46–21.47 distribution system models for, 21.44–21.45, 21.44f. in distribution systems, 5.25–5.27 distribution systems, measuring parameters for, 21.36–21.38 health concerns with, 2.2–2.3 indicators of, 2.19–2.23 IX removal of nitrate and effects of, 12.35, 12.36f., 12.37 in lakes and reservoirs, 3.36, 3.37t.–3.38t., 3.38–3.39 natural treatment systems and improvements in, 15.15–15.19 NOM effects on, 3.58, 3.58t. on-line monitoring for, 21.37–21.38 particles importance to, 3.42–3.43 sampling techniques for, 21.36–21.37 Water quality (Cont.): sedimentation and seasonal, 9.40 in SSF of source water, 10.82–10.83 treatment process selection, source water considerations with, 5.2–5.4 UV transmission and effects of, 18.14–18.15 Water Replenishment District of Southern California, 16.29 Water Research Foundation, 1.6 Water reuse, 3.68. See also Direct potable reuse; Indirect potable reuse BNR in, 16.10–16.11, 16.10t. phosphorus in, 16.11 Water security, 21.41–21.42 Water supplies, hardness classification for, 13.16, 13.16t. Water treatment conversion factors, C.3t. Water treatment residuals. See Residuals Waterborne disease. See also Cryptosporidium; Escherichia coli; Giardia lamblia; Legionella; Salmonella; Shigella distribution systems and outbreaks of, 21.2–21.4 Legionella outbreaks and, 21.3–21.4, 21.3f. microorganisms and, 2.3, 2.4t. outbreaks, 2.3, 2.4t., 2.5, 2.11–2.12 reporting, 2.5 United States outbreaks of, 21.2f.–21.3f. in water main repairs and installations, 21.32–21.34, 21.33t., 21.63–21.65 Water’s physical properties, D.1t. Watersheds, protection of, 3.70 Weak-acid cation exchange resins, 12.5–12.6, 12.12–12.13 adsorption rates of, 12.18–12.19 Weak-base anion exchange resins, 12.6–12.7, 12.12–12.13 adsorption rates of, 12.18–12.19 Western Corridor Project, Queensland, Australia, 16.28–16.29 Western Corridor Recycled Water Project, Queensland, Australia, 16.41 Wet chemical procedures, 20.71 White water blanket, 9.51, 9.54 WHO. See World Health Organization Windhoek’s Goreangab Reclamation Plant, Namibia, 16.32–16.33 World Health Organization (WHO) DALYs established by, 16.18 standards of, 1.33 XAFS. See X-ray absorption fine structure XANES. See X-ray absorption near-edge spectroscopy X-ray absorption fine structure (XAFS), 20.73 X-ray absorption near-edge spectroscopy (XANES), 20.73 X-ray diffraction, 20.72–20.73, 20.73f. X-ray fluorescence spectrometry, 20.70–20.71 X-ray photoelectron spectroscopy, 20.44 Xylene, 2.45–2.46 Yellow water, 20.41 Yersinia enterocolitica, 2.8 Zeolites, 14.8 high-silica, 14.89 Zinc, 20.35