1ESM 202Understanding Water QualityParameters2Management Value of Monitoring Water Quality Parameters Human Health Sustainable management Restoration Remediation3Water Quality Parameters Dissolved Oxygen Temperature Biochemical Oxygen Demand Nutrients: N & P Minerals: Anions & Cations Trace Elements Toxic Organic Compounds Coliform Bacteria, other Microbes, Viruses Solids (TDS, SS) Alkalinity, pH Hardness Turbidity Color Taste and Odor4Dissolved Oxygen (DO)O2(gas) Æ O2(aq)IncreasingTempIncreasingSalinityHighDOLowDO6Basic Conceptsin WaterChemistry7Basic Concepts EquilibriumA + B = C + DK = [C] [D][A] [B]=ProductsReactants Thermodynamic equilibrium Reversible vs. irreversible8Basic ConceptsConcentration in aqueous or solid systems[HCO3-] = mol / L = MConvert from mol/L to g/L using the Molecular Weight (MW), g/molConcentration in gas phase: PCO2 = atm9Dissolution O2dissolution in waterO2(aq) O2(g)= 663 atm.L/mol 0.209 atm3.15 x 10-4mol/L10.07 x 10-3g/L32.00 g/mol= 0.000315 mol/L10.07 mg/L32.00 g/mol=KH,O2= [O2(aq)]PO2=10Dissolution CO2dissolution in water:CO2(aq) = CO2(g)KH= [CO2(aq)]= 26.9 atm L/molPCO211OxygenDemand12Oxygen Demand Chemical Oxygen Demand (COD) Biochemical Oxygen Demand (BOD) Nitrogenous Biochemical Oxygen Demand (NBOD)  Total Oxygen Demand (TOD)CaHbOcNdSe+ x O2a CO2+ 1/2 b H2O + d NO3-+ e SO42-How much Oxygen is needed to degrade a load of pollutant?13Chemical Oxygen Demand Quick test to determine Oxygen Demand Strong oxidizing agent in acidic medium with catalyst (silver sulfate) No info on biologically oxidizable matter IssuesSome organic matter is quite inertInterference from minerals in waterCaHbOcNdSe+ Cr2O7 2-Cr3++ a CO2+ 1/2 b H2O + d NO3-+ e SO42-14Biochemical Oxygen Demand Measures “rapidly” biologically oxidizable organic matter Usually expressed as 5-day BOD = BOD5 Depending on BOD concentration and water characteristics:DilutionEssential nutrients (N, P, K, Fe, etc.)Bacterial seed15EZ BOD¾Simply¾ Place a sample of the microbial biomass into the test bottle with the wastewater¾ Insert integrated DO probe ¾ Follow instructions that appear on the liquid crystal display (LCD)¾Test provides a quantitative prediction of BOD5 (based on correlation to BOD5) ¾ For specific plant conditions¾ Data collected in 15 to 60 minutes16Nitrogenous BOD17Nitrogenous Oxygen Demand Two-step oxidation of ammonia:Can inhibit nitrification to measure CBOD and NBOD separatelyNH4++ 3/2 O2NitrosomonasNO2-+ H2O + 2 H+NO2-+ 1/2 O2NitrosobacterNO3-NH4++ 2 O2NO3-+ H2O + 2 H+18Effect of BOD in a RiverPollutant discharge19Microorganisms20MicroorganismsE. coliused as an indicator of water quality: normal inhabitant of intestines of many animals Indicator of presence of fecal matter Total coliforms are typically reported  Cost of testing for all possible microorganism is $$$$22Coliform test Results reported as Most Probable Number (MPN) per 100 mL Incubation at moderate temperature (35 oC) for 48 hr Test does not account for normally occurring microbes which also respond to lactose New developments to deal with these issues23Sediments25Turbidity Water clarity is an indicator of drinking water quality In the field, use a Secchi disk  In lab, measure transmission of light through a standard cuvetteColloidal particles scatter light Colloidal particles may harbor pathogens, toxics (metals, pesticides), radionuclides26Turbidity27Hardness Correlated with TDS Represents total concentration of Ca and Mg, and is reported in equivalent CaCO3 Other ions (Fe2+) may also contribute Hard water leaves solid deposits (boilers, hot water pipes, heaters, fixtures) and requires more soap Hard water is less corrosive28Hardness Soft < 50 mg/L Moderate = 50 - 150 mg/L Hard = 150 - 300 mg/L Very Hard > 300 mg/L Treatment usually left to consumer (domestic, industrial, etc.) depending on needs29pH30pH What is pH?Concentration of H+Measured on a log scaleActually, an inverse log…pH = -log10([H+])pH = 7 means [H+] = 10-7mol H+/L What does it mean?31pH Natural conditionsAcidicTemperate forest soils (pH 4-6)Raindrop through clean atmosphere (pH 5-5.5)Sulfur vents (pH 2-4)AlkalineArid soils (pH 8-11)Limestone dominated soils (pH 7-9)Ocean (pH 8-8.5)32pH Human (anthropogenic) changes to pHAcid rain (deposition)Acid mine drainageDischarge of acidic or alkaline wastewaterOpen mining of limestoneCattle feedstock yards (NH3)Fossil fuel combustion33pH Why does it matter? pH controls the chemical form (species) of many compounds Low pH leads to faster dissolution (weathering) of surrounding minerals Releases potentially toxic elements Changes in biodiversityHigh pH Can increase concentration of ammonia, toxic to fish Increased precipitation of metals34Dissociation of WaterH2O + H2O = H3O++ OH-Kw =[H3O+] [OH-][H2O ] [H2O ]=[H+] [OH-] = 10-14-log10(Kw ) = pKw= 1435pH-pC DiagrampCpH[H+][OH-]pH = 6pCH+= 6[H+]= 10-6M36pH-pC DiagrampCpH[H+][OH-]pH = 8pCH+= 8[H+]= 10-8M37MacroNutrients38Macro Nutrients Common Forms of Nitrogen: Ammonia/Ammonium NH3/ NH4+ Nitric Acid/Nitrate HNO3/ NO3- Nitrous Acid/Nitrite HNO2 /NO2- Organic NitrogenPhosphate PO43-, HPO42- Ratio of Uptake of Nutrients (typical):1:16:100::PNC39DissociationAcids:HNO3+ H2O = H3O++ NO3-KHNO3=[H+] [NO3-][HNO3]= 101mol/LpKHNO3= -1.0NH3+ H2O = NH4++ OH-KNH3 =[OH-] [NH4+][NH3]= 10-9.3mol/LpKNH3= 9.3Bases:40pH-pC Diagram for