epc_fa2011_lecture_2 - Water Quality Parameters Water...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Water Quality Parameters Water quality parameters are properties used as the measure of Physical water quality Chemical water quality Biological water quality *** "parallel and continuous" environmental events 1 Physical Water Quality Parameters Physical methods measure the gross water quality of ; Suspended solids (SS) Turbidity Color Taste Odor Temperature 2 Physical Water Quality Parameters Suspended Solids (SS) - 1 Suspended Solids (SS) in water consists of inorganic and organic particles and immiscible liquids (oils, greases) Inorganic Particles - soil constituents (clay, silt, metals) Organic Particles - plankton, vegetation, algae, wastes (food, animal, human) and fine organic debris 3 Physical Water Quality Parameters Suspended Solids (SS) - 2 Sources of Suspended Solids (SS) -- natural erosion with soil constituents (clay, silt, metals) -- erosion enhanced by human activity such as construction, agriculture, development, etc. -- [debris of decayed|decaying] terrestrial vegetation from natural and non-natural causes -- [debris of decayed|decaying] aquatic vegetation from natural and non-natural causes -- domestic and industrial wastewater inputs to receiving water bodies such as stream, river, lake, reservoir, estuary -- surface runoff from developed (urban, suburban) areas 4 Physical Water Quality Parameters Suspended Solids (SS) - 3 Solids = Suspended S + Colloidal S + Dissolved S Suspended Solids (SS) -- Size of SS particles is generally 1x10-3 millimeter (= 1 µm = 1 micrometer) and larger. -- Suspended solids are larger than the dissolved solids and include settleable solids. -- Suspended solids can be removed from solution by physical means such as sedimentation, filtration, or centrifugation. 5 Physical Water Quality Parameters Suspended Solids (SS) - 4 Solids = Suspended S + Colloidal S + Dissolved S Colloidal Solids -- Sizes range between 1x10-9 and 1x10-6 meter (=1x10-3 to 1 µm), generally will not settle out of solution. -- Particles small enough to pass through a filter, and particles not measured in SS test. -- Colloidal substances can be removed from solution through physical means, typically by high-force centrifugation or by use of a filter with very small pore spaces. 6 Physical Water Quality Parameters Suspended Solids (SS) - 5 Solids = Suspended S + Colloidal S + Dissolved S Dissolved Solids -- Dissolved solids are 0.001 µm or smaller. -- Dissolved solids are ones that are truly in solution, homogenously dispersed in the liquid. -- Dissolved solids can be removed from water by distillation, precipitation, adsorption, or liquid extraction method. 7 Physical Water Quality Parameters Suspended Solids (SS) - 6 8 Physical Water Quality Parameters Suspended Solids (SS) - 7 Suspended Solid (SS) Impacts on Water Quality -- May require additional pre-treatment process in the water treatment plant (WTP) if the water is used as source water supply for drinking water. -- Causes water to be "cloudy" - may affect aquatic plants (limiting light penetration and deter photosynthesis) -- Can serve as "carrier" of toxics and absorbed chemicals and disease-causing organisms, which readily cling to suspended particles -- Causes bays, reservoirs, habors to fill up with sediment -- Can stress aquatic organisms -- Aesthetic point of view 9 Physical Water Quality Parameters Suspended Solids (SS) - 8 Nutrient inputs causing undesirable sudden algae population increase Algal bloom and Eutrophication 10 Physical Water Quality Parameters Suspended Solids (SS) - 9 Measurement of Suspended Solids (SS) -- By filtration and weighing (=Gravimetric Analysis) 11 Physical Water Quality Parameters Suspended Solids (SS) - 10 Various Regulatory Approaches (applicable in design framework) Quality-based standards specifies quality of receiving body (air or water) good idea in principle hard to implement and difficult to enforce Effluent-based standards specifies quality of effluent stream not as flexible and can be over-restrictive much easier to implement and enforce Treatment-based standards specifies type of treatment required Treatment Technique (TT) in the Surface Water Treatment Rule (SWTR) is a good example. TT is a required process intended to reduce the level of a contaminant in drinking water, and often does not explicitly specify the required quality. 12 Physical Water Quality Parameters Suspended Solids (SS) - 11 Measure of suspended solids often made on waste streams such as influents to and effluents from the WWTP (Wastewater Treatment Plant). This is very common element in the NPDES (National Pollutant Discharge Elimination System) and correspondingly, VDPES Permit requirement. NPDES is based on the Clean Water Act (CWA) as amended in 1977, 1981 and 1987. VA Department of Environmental Quality (DEQ) handles NPDES permits in Virginia under the name of VPDES (Virginia Pollutant Discharge Elimination System). Example) $12.6 million fine to Smithfield factory (1997/1999) for polluting adjacent Pagan River [which in turn flows into the James River and ultimately into Chesapeake Bay]. This remains the largest civil penalty ever imposed under the NPDES/Clean Water Act so far. 13 Physical Water Quality Parameters Turbidity - 1 Turbidity is a measure of water clarity how much the material suspended in water decreases the passage of light through the water (by measuring degree of absorption and scattering of light passed through a sample). A turbidity measurement represents both suspended solids and colloids. Higher turbidity increases water temperatures, and also reduces the amount of light penetrating the water, which reduces photosynthesis and the production of DO (Dissolved Oxygen). When particles settle, they can blanket the stream bottom, especially in slower waters, and smother fish eggs and benthic macroinvertebrates, clog fish gills, reducing resistance to disease in fish, lowering growth rates, and affecting egg and larval development. 14 Physical Water Quality Parameters Turbidity - 2 Suspended solids include soil particles (clay, silt, and sand), algae, plankton, microbes, and other substances. These materials are 1 µm or larger in diameter size. Sources of turbidity include: ------- Soil erosion (mostly in forms of clay and silt particles) Domestic and industrial waste discharge Urban runoff Eroding stream banks Excessive algal growth Large numbers of bottom feeders (such as carp), which stir up bottom sediments (near water intakes) 15 Physical Water Quality Parameters Suspended Solids vs. Turbidity Turbidity is not a measurement of the amount of suspended solids present or the rate of sedimentation of a steam since it measures only the amount of light that is scattered by suspended particles. Measurement of Total Suspended Solids (TSS) is a more direct measure of the amount of material suspended and dissolved in water. 16 Physical Water Quality Parameters Turbidity - 3 Turbidity can be measured by using 1) Secchi Disk (8” dia) / Secchi Tube 2) Turbidimeter/Nephelometer 3) Gravimetric Methods (in laboratory) 17 Physical Water Quality Parameters Turbidity - 4 1) Secchi Disk -- The higher Secchi depth readings indicate clear water, and lower readings indicate turbid or colored water. Thus, the clearer the water, the greater the Secchi depth. -- Secchi disks are simple to use and inexpensive (Secchi disks cost about $50 and can be homemade). -- Secchi depth for typical lakes/reservoirs varies, but typically in the range of 1 m to 8 m depending on their characteristic and season. -- For example, small local lake has about 2 m. For a sewage stablization pond, about 0.2 m. -- Lake Tahoe holds the record for Secchi depth of 92 m (yup, m in meter). 18 Physical Water Quality Parameters Turbidity - 5 2) Turbidimeter/Nephelometer -- A turbidity meter (also called a Turbidimeter or a Nephelometer) is a photometric instrument that consists of a light source that illuminates a water sample and a photoelectric cell that measures the intensity of light scattered at a 90 degree angle by the particles in the sample. High light transmittance (=clearer) low turbidity Low light transmittance (=more turbid) high turbidity 19 Physical Water Quality Parameters Turbidity - 6 Nephelometric Turbidity Units (NTUs) -- A standard turbidity unit -- Turbidimeter can measure turbidity over a wide range from 0 to 1000 NTUs. - A clear mountain stream ~ 1 NTU - A large river like the Mississippi ~ 10 NTUs - Runoff ~ hundreds of NTU Turbidity is an important measure of drinking water quality (< 0.5 NTU drinking water quality regulation) and is regularly measured at water treatment plants. 20 Physical Water Quality Parameters Turbidity - 7 3) Gravimetric Methods for Turbidity (filtration and weighing) -- Used in laboratory is based on solid classification by size and volatility. TS = TDS + TSS TS (Total Solids) = residue left in drying dish after evaporating water TDS (Total Dissolved Solid) = filter sample through 1.24 µm filter TSS (Total Suspended Solids) = particles retained on filter [Note: dissolved < 10-3 µm; 10-3 µm < colloids < 1 µm] -- Total Volatile Solids (TVS) and Settleable Solids (Sett.S) by Imhoff cone measurement 21 Physical Water Quality Parameters Color - 1 -- Color is imparted by dissolved substances in water -- In natural water, organic matters from vegetative decay and metal oxides dominate -- Brown water color common in swamp waters are due to natural tannins, lignins and humics -- Color of water is regulated in wastewater discharges for aesthetics and ecological reasons -- Pulp and paper mills are major problematic industries affecting the water color -- Common use of color measurement is as an indicator of natural organic matter particularly in water treatment plants (easier/faster than measuring other physical parameters) 22 Physical Water Quality Parameters Color - 2 Measurement of Color 1) Colorimeter 2) Spectrophotometer 3) Nessler Tubes (Comparison with platinum-cobalt standards) 23 Physical Water Quality Parameters Color - 3 1) Colorimeter -- A light is shined though a sample. This light is detected by a photodiode which displays the concentration of the parameter directly. The colorimeter eliminates visual interpretation, concern about lighting, and variations in an operator’s ability to discern color (i.e., objective measurement). Measurements are expressed as parts per million (ppm) or milligrams per liter (mg/L). 24 Physical Water Quality Parameters Color - 4 2) Spectrophotometer -- Similar to the colorimeter in concept -- A monochromatic light beam passed through sample with 420 ~ 810 nanometer (nm) wavelength, light absorption of sample is recorded. 25 Physical Water Quality Parameters Color - 5 2) Nessler Tubes (Comparison with platinum-cobalt standards) -- Comparison tubes (i.e., Nessler tubes or cylinders) containing standard platinum-cobalt solutions ranging from 0 to 70 color units are used for visual measurements of the sample. 26 Physical Water Quality Parameters Taste and Odor -- Taste and odor in water are primarily caused by minerals, metals, and organic compounds. 27 Physical Water Quality Parameters Temperature - 1 Temperature is an very important water quality parameter because it strongly influences; -- Rate of chemical reactions -- Biological activity -- Circulation Temperature affects the oxygen content in the water (oxygen level becomes lower as temperature increases). Temperature also affects rises, the rate of photosynthesis by aquatic plants; the metabolic rates of aquatic organisms; and the sensitivity of organisms to toxic wastes, parasites, and waterborne diseases 28 Physical Water Quality Parameters Temperature - 2 Most organisms active between 0 and 40ºC with the maximum efficiency in their metabolisms around 35ºC. 29 Physical Water Quality Parameters Temperature - 3 Temperature and Biological Activity (Rate of Metabolism) Temperature dictates the rate at which a substance is consumed or produced by biota (organisms) As Temperature rises (in natural waters); a) rate of algal growth increases b) suspended solids increases c) concentration of organics in water increases (from algal exudate) d) water treatment plant downstream may experience elevated THM (=Trihalomethane) in treated water e) other effects - DO depletion, stress in cold water fish habitat 30 Physical Water Quality Parameters Temperature - 4 Temperature and Circulation -- Density of water changes with temperature, and the maximum density occurs at 4ºC -- Less dense water "floats" on higher density water, causes the circulation -- Higher density water "sinks" through less dense water, causes the circulation 31 Physical Water Quality Parameters Temperature - 5 Temperature and Circulation Example 1) Power plant discharge -- Less dense, warm water stays at surface, and consequently the remaining waterbody mixes much slower dues to lack of wind, waves, current, etc. Thermocline 32 Physical Water Quality Parameters Temperature - 6 Temperature and Circulation Example 2) Cold stream entering warmer lake -- In late fall, very dense, cold water flows deep into the lake. If pollutants present in this cold stream, they would not be detected at the surface of the lake. -- Late-Fall and Early-Spring Turnovers 33 RECAP -- Physical Water Quality Parameters Physical methods measure the gross water quality of ; Suspended solids (SS) Turbidity Color Taste Odor Temperature 34 Biological Water Quality Parameters Biological Aspects of Water Quality -- Living organisms affect DO (Dissolved Oxygen) and other physical water quality parameters -- Organisms are classified by their energy source and carbon source -- First water quality-related law (Public Health Service Act, 1912) was primarily concerning with waterborne diseases in navigable water Classifications -- Nutritional Requirements of Organisms - 1 -- To grow, microorganisms, including single-cell bacteria, must extract from the environment those substances needed for the synthesis of new cell material and for the generation of energy for cell maintenance. In general, these substances are termed nutrients. -- For the synthesis of new cell tissues, an organism must have a source of carbon and energy. In addition, elements such as nitrogen, phosphorous and trace elements including sulfur, potassium, calcium, magnesium must be available. -- Generally, organisms can be classified by their preferences in carbon source, energy source and oxygen source. Classifications -- Nutritional Requirements of Organisms - 2 Classification by Carbon source Classifications -- Nutritional Requirements of Organisms - 3 Classification by Energy source Classifications -- Nutritional Requirements of Organisms - 4 Classification by Metabolic process (for carbon + energy) Classifications -- Nutritional Requirements of Organisms - 5 Thus, we can say about an organism; Classifications -- Nutritional Requirements of Organisms - 6 Classification examples Now, you should be able to understand the characteristic of an organism if a nutritional classification is given. Biological Pathogens Pathogens are defined as organisms in water that can cause or transmit human diseases. Followings are important pathogen groups that directly affect water quality. 1) 2) 3) 4) 5) 6) Bacteria Fungi (include molds and yeasts) Algae Protozoa Worms Viruses Pathogen Groups -- Bacteria - 1 sing.: Bacterium | pl.: Bacteria Characteristics of Bacteria are: -- Mostly single-celled organisms with a simple structure, or colonial with limited coordination -- Heterotrophic or Chemosynthetic -- Predominantly causes gastrointestinal diseases -- Sizes normally range 0.1 - 10 µm. (larger than viruses) However, some spiral/filamentous shaped bacteria are bigger/longer than 100 µm. -- 3 major shapes; - rods = Bacillus (pl. bacilli) - spheres = Coccus (pl. cocci) - spirals Lactobacillus Streptococcus Vibrio Pathogen Groups -- Bacteria - 2 Characteristics of Bacteria are: (continued) -- Follows an exponential growth pattern (i.e., binary fission); 1 cell => 2 => 4 => 8 => 16 .. etc. every 20 minutes in ideal conditions. -- Typically, decline of bacteria colonies is triggered by decrease in food and/or increase in waste materials (i.e., Principle of supply and demand) -- Nitrogen/Phosphorus ratio (N/p ratio)= 12/1 - Algal bloom during summer. Algal bloom is correlated to the levels and ratios of nitrogen (N) and phosphorous (P) in the water. - Noxious algal blooms (e.g., dinoflagellates and blue-green cyanobacteria) prevention is mainly by nutrient reduction at the receiving-water buffer. (BNR in WWTP) Pathogen Groups -- Bacteria - 3 Bacteria in interest in drinking water and waterborne diseases Pathogen Groups -- Bacteria - 4 Bacteria in interest in drinking water and waterborne diseases (C’td) Pathogen Groups -- Bacteria - 5 Heterotrophic Bacteria -- Very important because they safely stabilize/decompose organic wastes Decomposers! -- Without them, the earth will be filled with wastes that never break down. Chemosynthetic Bacteria -- Two important inorganic reactions are carried out by Chemosynthetic bacteria. a) Nitrification (2-step process) b) Thiobacillus Pathogen Groups -- Bacteria - 6 rods = Bacillus / Bacilli spirals spheres = Coccus / Cocci Nitrogen fixation by Cyanobacteria -- Nitrogen fixation is a conversion process of atmospheric nitrogen into usable nitrogen by Phylum Cyanobacteria (=Cyanobacteria). -- Without this nitrogen fixation, no natural nitrogen would be available to the entirety of food chain (including Human). -- Au contraire, over-abundance of nitrogen fixation [by Cyanobacteria] would also cause severe water quality problems such as algal blooms and eutrophication. Pathogen Groups -- Bacteria - 7 Nitrification (2-step process) Urea Ammonia Nitrate Pathogen Groups -- Bacteria - 8 Thiobacillus -- biological decay of waste solids releases hydrogen sulfide (H2S) gas -- hydrogen sulfide converted to sulfuric acid (H2SO4) by Thiobacillus at the crown of sewer pipes -- sewer crown deteriorates (or eaten up) by the corrosive sulfuric acid, sewer collapses Nitrite Pathogen Groups -- Fungi - 1 sing.: Fungus | pl.: Fungi Characteristics are: -- Generally aerobic, multicellular, heterotrophic, nonphotosynthetic, eucaryotic (=nuclear membraneenclosed nucleus) protists -- Main engine for carbon & nitrogen cycles -- Varies in size from microscopic organisms to mushroom; -- Two classes of fungi are particular interest in water quality - Myxomycetes [pronounced as 'MEEK-so-miset'] (slime fungi) - Phycomycetes [pronounced as 'FI-ko-miset'] (aquatic fungi that resemble algae) Pathogen Groups -- Fungi - 2 Characteristics are: (continued) -- Multicellular body consists of network of fine filaments (mycelium) [Myxomycetes] Circinella micosporangia [Phycomycetes] Piptocephalis micosporangia Pathogen Groups -- Fungi - 3 Characteristics are: (continued) -- Mostly saprophytes (=consume dead organic matters). In addition to various bacteria, fungi are important natural mechanisms stabilizing/decomposing organic wastes. Without fungi, the Earth will be filled with wastes that never break down. -- Important element in wastewater treatment plant processes since filamentous fungi growth does not settle well in settling tanks in wastewater treatment plants and causes operational problems and low treatment efficiency. -- Can grow and thrive in low moisture, low pH and low nitrogen Pathogen Groups -- Fungi - 4 Characteristics are: (continued) -- Reproduces by means of spores, spores are even found 50 km above the earth surface! [Phycomycetes] Cunninghamella [Phycomycetes] Cephalotrichum [Phycomycetes] Basifimbria [Phycomycetes] Ascobolus Pathogen Groups -- Algae - 1 sing.: Alga | pl.: Algae Characteristics of Algae are: -- A wide variety of photosynthetic organisms -- Aquatic, Unicellular or multicellular, photosynthetic, autotrophic, eucaryotic (=nuclear membrane-enclosed nucleus) and contains chlorophyll -- Presence of chlorophyll is the principal feature that distinguishes algae from fungi Pathogen Groups -- Algae - 2 -- Algae range in size from microscopic phytoplankton to giant marine kelp that may grow to 60 meters long. Typical sizes range between 5 µm to 100 µm. -- 30%~50% of atmospheric O2 are produced by algae -- Algal photosynthesis and respiration -- Some algal species can obtain CO2 needed for cell growth from bicarbonate presented in the water pH of the water will generally increase -- Many species of algae have been associated with taste and odor problems in finished drinking water, especially during summer (i.e., excessive growth, or algal blooms that degrades water quality) Pathogen Groups -- Algae - 3 -- Runoff from fertilized lawns and gardens, fields, pastures, feedlots and septic tanks [i.e., NPS = Nonpoint Source Pollution] will accelerate algae growth Algal bloom and Eutrophication Pathogen Groups -- Algae - 4 Three algal classes are in particular interest with water quality 1) Blue-green Algae (=Cyanobacteria) 2) Diatoms 3) Dinoflagellates (dino-fla-JEL-it) Pathogen Groups -- Algae - 5 1) Blue-green Algae (=Cyanobacteria) -- Cyanobacteria (technically a bacteria, not an algae) comprise a single class, Cyanophyceae. Cyanobacteria is often mistakenly classified as algae (i.e., Blue-green algae) because of the chloroplasts contained within the cells. -- Diverse group of cyanobacteria can exist in all settings from freshwater to terrestrial settings and from oligotrophic (low nutrient) to hypereutrophic (very high nutrient) environments, including Antarctica -- Blue-green algae occur in 80% of North American surface water resources, including ponds, lakes, reservoirs, rivers, and streams. -- Important water quality management target for nitrogen fixation and N/p ratio (12:1) control Pathogen Groups -- Algae - 6 1) Blue-green Algae (=Cyanobacteria) (Contd) -- Blue-green algae can create highly objectable tastes and odors (particularly during summer time) in drinking water, clog filters, and deplete oxygen. -- Ozone and GAC (Granular Activated Carbon) are effective in removing cyanotoxins and taste and odor from finished drinking water. Pathogen Groups -- Algae - 7 2) Diatoms -- Cell wall contains silica dioxide, "silica shell" -- High concentration of diatoms in source water can cause water treatment operation problems (clogging of equipments and subsequent frequent cleaning requirement) -- Abrasive surfaces, used in toothpaste, scouring powder etc. Freshwater Diatoms Pathogen Groups -- Algae - 8 3) Dinofagellates (dino-fla-JEL-it) -- Present in both in fresh and salt waters -- Major photosynthesizers in the ocean -- Produce neurotoxin (exotoxins) -- Cause algal blooms during the warm months of summer in coastal areas triggered by nutrient overloading. Its rapid increase in micro-populations may appear golden or red, producing a "red tide“ (or “Mahogany/Brown tide”) that can cause production of toxins and massive dissolved oxygen depletion, subsequently fish kills. Dead-zone and Red tide phenomena in the Chesapeake Bay, James River and Elizabeth estuaries Pathogen Groups -- Algae - 9 3) Dinofagellates (dino-fla-JEL-it) (Contd) Red tide bloom at York River/ Chesapeake junction Costal red tide in southern Florida Pathogen Groups -- Algae - 10 3) Dinofagellates (dino-fla-JEL-it) (Contd) -- Seasonal Mahogany tide due to eutrophic conditions Colley Ave. Granby St. Lafayette river near Granby St. bridge, Norfolk, Aug. 28, 2007 Lower James river, near Strawberry Banks, Hampton, Aug. 28, 2007 Pathogen Groups -- Algae - 11 3) Dinofagellates (dino-fla-JEL-it) (Contd) -- Pfiesteria piscicida (fee-STEER-ee-uh pis-kuh-SEED-uh)!!! -- Pfiesteria can cause fish kills and open sores on fish in selected estuarine areas of the East Coast of the United States. (Eastern Shore, 1999; Rappahannock River, 1997) Pathogen Groups -- Protozoa - 1 sing.: Protozoan | pl.: Protozoa or Protozoans -- Any of a large group of single-celled, usually microscopic organisms such as amoebas, ciliates, flagellates, and sporozoans. -- Majority are unicellular membranes with no cell walls, aerobic or facultatively anaerobic, heterotrophs Entamoeba histolytica in feeding Common Amoeba, Arcella Pathogen Groups -- Protozoa - 2 -- Order of magnitude larger than bacteria and often consume bacteria and algae as energy sources (=heterotrophs) -- Mostly free-living in nature, although several species are parasitic -- Cause mild gastrointestinal disorders (only a few are pathogenic) -- one reason why new SDWA (Safe Drinking Water Act) requires Cryptosporidium filtration in drinking water treatment process (99% or 2-log removal) Pathogen Groups -- Protozoa - 3 Pathogenic Protozoa of interest in drinking water Pathogen Groups -- Protozoa - 4 Pathogenic Protozoa of interest (in WT) -- Giardia lamblia -- Causes intestinal disease refers to as Giardiasis, which can grow in the upper small intestine. -- Giardiasis is the most widespread of the protozoan disease occurring throughout the world. -- Symptoms varies depending on individual but include diarrhea, nausea, indigestion, flatulence, bloating, fatigue, appetite and weight loss. Unless treated properly,giardiasis can be chronic. -- Giardiasis is contracted by drinking surface water contaminated by wild animals or humans. Hikers who drink water from 'crystal clear' mountain streams often acquire the disease. --A giardiasis outbreak in 1995 in Rome, NY caused by beavers at the water supply reservoir filtration plant was built to deal with Giardia lamblia. Pathogen Groups -- Protozoa - 5 Pathogenic Protozoa of interest (in WTP) -- Cryptosporidium parvum -- Most common symptom of Cryptosporidiosis is watery diarrhea. There may also be abdominal cramps, nausea, low-grade fever, dehydration, and weight loss. -- Cryptosporidiosis is most severe and long-lasting in immunocompromised individuals such as people infected with HIV, cancer patients on chemotherapy, and transplant patients. Cryptosporidiosis can be life-threatening for the immunocompromised. -- Cryptosporidiosis can be transmitted by drinking water or eating food that has been contaminated with oocysts found in the feces of livestock. -- Drinking untreated surface water or closed to livestock gazing areas (such as streams, rivers, and lakes) or swallowing a small amount of water when swimming, even in a chlorinated pool, can cause cryptosporidiosis. Pathogen Groups -- Protozoa - 6 Pathogenic Protozoa of interest (in WT) -- Cryptosporidium parvum -- Oocysts are not killed by typical household disinfectants, including bleach, but are killed at temperatures over 160ºF (hotter than most domestic hot tap water). Thorough drying in a clothes dryer will kill oocysts by desicating them. 99% Filtration requirement in SDWA -- Under current standards, bottled water is not necessarily any safer than tap water. (in term of Cryptosporidiosis) -- Biggest Cryptosporidium parvum outbreak so far occurred in Milwaukee, WI, April, 1993. Estimated 403,000 people were infected from the contaminated water supply. Pathogen Groups -- Worms - 1 -- A number of worms are of importance with respect to water quality from the standpoint of human disease. Direct exposure to human feces or animal feces generally causes worm infection. -- Worms can be easily removed in water treatment plant -- Two important worm phyla are Paltyhelminthes (=flatworms) and Aschelminthes (nematodes = roundworm) in term of WQ. Typical shape of flatworms, Cestoda class Adult tapeworms in small intestines Pathogen Groups -- Worms - 2 -- Dracunculiasis (dra-KUNK-you-LIE-uh-sis), commonly known as Guinea worm disease is caused by the nematode (=roundworm), Dracunculus medinensis in African countries and Yemen. Humans become infected by drinking unfiltered water containing copepods (small crustaceans) which are infected with Dracunculus larvae. -- Approximately one year after infection, the female worm induces a blister on the skin (generally on the distal lower extremity), which ruptures. When this lesion comes into contact with water (a contact that the patient seeks to relieve the local discomfort), the female worm emerges and releases larvae into the water. -- The larvae are ingested by a copepod and after two weeks (and two molts) have developed into infective larvae. Ingestion of the copepods closes the cycle. Adult worms are up to 3 feet long and are as wide as a spaghetti noodle. Pathogen Groups -- Viruses - 1 -- Small microorganisms, genetically more complex than bacteria. -- Requires a host (animal or human) to live (cannot synthesize new compounds by itself), i.e., obligate parasites, and it shows characteristics of life only inside living cells. -- Sturcturewise, a virus is a strand of DNA (Deoxyribonucleic Acid) or RNA (Ribonucleic Acid) within a protein coat, with few enzymes. -- Invade living cells to reproduce (generally attack the nervous system), enters the cell and leaves protein coat outside. Changes host cell metabolism by inserting its DNA into Host DNA to make more virus DNA (or RNA). -- Very host specific!! Pathogen Groups -- Viruses - 2 Major waterborne viral diseases are; Pathogen Groups -- Viruses - 3 Major waterborne viral diseas: Hepatitis A virus (HAV) -- It can be spread by an infected person who does not wash one's hand before handling food or utensils. It also can be spread on uncooked foods. -- One-third of Americans had evidence of past HAV infection (and acquired immunity). -- Symptoms include fever, nausea, diarrhea, jaundice, fatigue, abdominal pain and loss of appetite. -- On the other hand, Hepatitis B and C (HBV and HCV) are not waterborne viral diseases. (i.e., HBV ad HCV are transmitted via blood or body fluids from an infected person) Biological Pathogens Recap on important pathogen groups that directly affect water quality; 1) 2) 3) 4) 5) 6) Bacteria Fungi (include molds and yeasts) Algae Protozoa Worms Viruses Indicator Organisms -1 -- Members of two bacteria groups, Coliforms and Fecal Streptococci, are commonly used as indicators of possible water contamination (i.e., indicator organisms) because they are commonly found in human and animal feces. -- Since it is difficult, time-consuming, and expensive to test directly for the presence of a large variety of pathogens, water is usually tested for coliforms and fecal streptococci instead. -- Although they are generally not harmful themselves, they indicate the likelihood/possible presence of pathogenic (disease-causing) bacteria, viruses, and protozoans that also live in human and animal digestive systems. (Coliforms are excreted in great number, 100~400 billion/person/day) -- The most commonly tested fecal bacteria indicators are Total Coliforms (TC), Fecal Coliforms (FC), Escherichia coli (=E. Coli), Fecal Streptococci (FS), and Fecal Enterococci (FE). Indicator Organisms - 2 / Total Coliforms (TC) -- Total coliforms (TC) are a group of bacteria that are widespread in nature. -- All members of the total coliform group can occur in human feces, but some can also be present in animal manure, soil, and submerged wood and in other places outside the human body. -- For drinking water, total coliforms are the standard test because their presence indicates contamination in the water supply. A petri dish showing the "golden-green sheen" colonies typical of total coliform colonies. Indicator Organisms - 3 / Fecal Coliforms (FC) -- Fecal coliforms, a subset of total coliform bacteria, are more fecalspecific in origin. (compared to TC) -- For recreational water quality, FC was the primary bacteria indicator until relatively recently, when EPA began recommending E. coli and enterococci as better indicators of health risk from water contact. -- Fecal coliforms are still being used in many states, including Virginia, as the indicator bacteria for assessing ambient water quality. A petri dish showing the blue colonies typical of fecal coliform bacteria. Indicator Organisms - 4 / E. coli (EC) -- E. coli is a species of fecal coliform bacteria that is specific to fecal material from human and other warm-blooded animals. -- EPA recommends E. coli as the best indicator of health risk from water contact in recreational waters; A petri dish showing the "golden-yellow sheen" colonies typical of E. coli colonies. Indicator Organisms - 5 / Fecal streptococci (FS) -- Fecal streptococci generally occur in the digestive systems of humans and other warm-blooded animals. -- Fecal streptococci are monitored together with fecal coliforms and a ratio of fecal coliforms to streptococci (FC/FS) is calculated to determine whether the contamination was of human or non-human origin. FC/FS > 4 FC/FS < 1 FC/FS ~ 1-4 Human contamination Animal contamination Unknown A petri dish showing the “small milky beads" colonies typical of Fecal streptococci colonies. Indicator Organisms - 6 / Fecal Enterococci (FE) -- Enterococci are a subgroup within the fecal streptococcus group. Enterococci are distinguished by their ability to survive in salt water. -- Enterococci are typically more human-specific than the larger fecal streptococcus group. -- EPA recommends enterococci as the best indicator of health risk in salt water used for recreation. The red colonies on the plate are enterococcus bacteria. Indicator Organisms - 7 / VA WQS Commonwealth of Virginia Water Quality Standard (WQS), August 2009:: Bacteria Standards (9 VAC 25-260-170.A) in VPDES Permits -- E.coli and enterococci bacteria per 100 mL of effluent water shall not exceed Geometric Mean Fresh water by E. coli (N/100 mL) Saltwater and Transition Zone by F. enterococci (N/100 mL) * Geometric Mean = Single Sample Max. 126 235 35 104 Indicator Organisms - 8 -- Measurement Methods - 1 -- Four EPA accepted methods of Coliform Measurement are; 1) 2) 3) 4) Multiple Tube Fermentation (MTF) Membrane Filter (MF) Minimal Media ONPG-MUG test (Colilert system) Presence-absence coliform test (P-A) -- Membrane Filter (MF) method is most frequently used by engineers for its 'quick and easy' characteristic. Indicator Organisms - 8 -- Measurement Methods - 2 Membrane Filter (MF) method 1) Water sample is passed through a filter (0.45 µm filter) 2) Place filter in petri dish with medium (i.e., broth) 3) Filter and broth are inverted and are placed in an incubator allowing coliforms to grow 4) Count coliform colonies (CFU = Colony Forming Unit), where 1 cell = 1 colony 5) Concentration will be estimated based on volume and dilution level of the sample filtered (CFU/mL) CFU/ mL = (CFU per plate/Aliquot) * Dilution factor Example) If you have counted 85 colonies and you use 2 mL of the water for MF test, and your dilution factor is 102 Coliforms concentration = (85/2) x 102 = 4250 cfu/mL ...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online