1 / 29

ENVR 419 Chemical Equilibria of Natural Waters Fall 2010 11:00-12:15 Tu/Th

ENVR 419 Chemical Equilibria of Natural Waters Fall 2010 11:00-12:15 Tu/Th. 2. Purification of Water. Drinking Water Wastewater Contaminated Groundwater. Sources of Drinking Water. Fresh Water Ground Water Surface Water -Rivers and streams -Lakes and impoundments Brackish Water

theo
Download Presentation

ENVR 419 Chemical Equilibria of Natural Waters Fall 2010 11:00-12:15 Tu/Th

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ENVR 419 Chemical Equilibria of Natural Waters Fall 2010 11:00-12:15 Tu/Th

  2. 2. Purification of Water Drinking Water Wastewater Contaminated Groundwater

  3. Sources of Drinking Water Fresh Water Ground Water Surface Water -Rivers and streams -Lakes and impoundments Brackish Water Reclaimed Wastewater? Importance of Watershed Protection

  4. Potential Contaminants in Drinking Water Pathogenic microorganisms Bacteria (salmonella, cholera), viruses (Hepatitis A virus, poliovirus), protozoan cysts (Giardia, Cryptosporidium) Suspended particles (turbidity) Dissolved inorganic contaminants e.g. Fe, Mn, As, Cr, Cu, Pb, NO3-, ClO4- Dissolved organic contaminants e.g. taste and odor-causing organics, pesticides, pharmaceutically active compounds

  5. Objectives of Drinking Water Treatment Removal of particulate material Removal of color (natural organic material, humic substances arising from vegetative decay) Removal of taste and odor-causing substances Removal of harmful contaminants - chemical and microbial Residual protection of water during distribution - protect against microbial recontamination, corrosion

  6. Chemicals Used in Water Treatment Coagulants Aluminum, ferric salts Polymers Disinfectants Chlorine, chlorine dioxide, ozone (UV-Irradiation) Acids/Bases for pH adjustment Lime, caustic Sulfuric Acid Corrosion Control Phosphates, silicates Other Fluoride

  7. Membrane Filtration • Thin barrier or film of material that allows certain substances to pass through while rejecting other substances. Feed Water Filtered Water (Permeate)

  8. Membrane Removal Functions • Microfiltration (MF) • particles, bacteria, cysts • Ultrafiltration (UF) • viruses and colloids • Nanofiltration (NF) • viruses; natural organic matter; SOCs; hardness • Reverse Osmosis (RO) • dissolved minerals (desalination)

  9. Membrane Filtration Comparison Feed Water Particles, Giardia, Cryptosporidium Some Viruses MF DOC, Hardness UF Minerals NF RO Water

  10. Objectives of Wastewater Treatment Removal of suspended solids Removal of oxygen-demanding material CBOD (e.g. CH2O), NOD (NH3) Removal of nutrients that can promote algal growth, eutrophication Nitrogen, phosphorus Removal of toxic substances Disinfection

  11. Dissolved Oxygen Depletion(Oxygen Demand) Carbonaceous oxygen demand (CBOD) CH2O + O2 = CO2 + H2O C6H5OH + 7O2 = 6CO2 + 3H2O Nitrogenous oxygen demand (NOD) NH4+ + 2O2 = NO3- + H2O + 2H+ Chemical oxygen demand (COD) 3CH2O + 2Cr2O72- +16H+ = 3CO2 + 4Cr3+ + 11H2O

  12. Dissolved oxygen sag curve d[C]/dt = -kL[CBOD] - kN [NOD] + kH (Cs-C) where C = dissolved oxygen concentration CBOD = carbonaceous oxygen demand NOD = nitrogenous oxygen demand Cs = dissolved oxygen saturation concentration

  13. Nutrient Enrichment of Surface Waters and Eutrophication Photosynthesis CO2 + NO3- + PO43-+ H2O  Algae biomass + O2 (C106H263O110N16P) Respiration Algal biomass + O2 CO2 + NO3- + PO43- + H2O

  14. Figure 4.23 Percent removal of PPCPs by activated sludge and microfiltration processes. (The value ‘n’ represents the number of samples that were analyzed.)

  15. Figure 4.24 Removal of PPCPs by GAC adsorption. (The values shown on the figure are the logs of the octanol-water partition coefficients (log Kow) for the PPCPs indicated. The value ‘n’ represents the number of samples that were analyzed and met the quality

  16. Figure 4.27 Comparison of PPCP removal by ozonation with ozonation rate constants and PPCP structures

  17. Metal Binding Agents in Detergents • Dissolved calcium in hard waters precipitates when the pH is raised during normal laundering operations • Dissolved calcium and magnesium in hard waters precipitates the cleansing agent in detergents • Hence, detergents contain chelating agents that bind calcium • Common chelating agents – polyphosphates, NTA, EDTA, citric acid, succinic acid

  18. Groundwater Contamination NAPLs DNAPLs

  19. Groundwater Remediation Pump and treat Use of surfactants In-situ biodegradation/bioremediation Reductive dehalogenation (zerovalentFeo) Isolation

More Related