Introduction to Environmental Engineering Dr. Kagan ERYURUK

2 WATER QUALITY 1.Physical Water Quality Parameters 2.Chemical Water Quality Parameters 3.Biological Water Quality Parameters

3 1.Physical Water Quality Parameters Physical parameters define those characteristics of water that respond to the senses of sight, touch, taste, or smell. Temperature Color Taste and Odor Turbidity Solids fall into this category

4 Temperature: affects some of the important physical properties and characteristics of water: thermal capacity, density, specific weight, viscosity, surface tension, specific conductivity, salinity, solubility of dissolved gases and etc

5 Color; is primarily a concern of water quality for aesthetic reason. Presence of organic substances such as algae or humic compound. A quantitative assessment of the presence of potentially hazardous or toxic organic materials in water.

6 Taste and Odor; human perceptions of water quality. Human perceptions of taste includes sour (hydrochloric acid), salty (sodium chloride), sweet (sucrose), and bitter (caffeine). Organic materials discharged directly to water, such as falling leaves, runoff, etc., are sources of tastes and odor-producing compounds released during biodegradation. Turbidity; is a measure of the light-transmitting properties of water and is comprised of suspended and colloidal material. For health and aesthetic reasons.

7 Solids; The total solids content of water; the residue remaining after evaporation of the water and drying the residue to a constant weight at 103 °C to 105 °C. The organic fraction (or volatile solids content) is considered to be related to the loss of weight of the residue remaining after evaporation of the water and after ignition of the residue at a temperature of 500 °C. The inorganic (or fixed solids) remind as inert ash. Solids are classified as settleable solids, suspended solids and filterable solids.

8 2. Chemical Water Quality Parameters The chemical characteristics of natural water are a reflection of the soils and rocks with which the water has been in contact. Agricultural and urban runoff and municipal and industrial treated wastewater. Microbial and chemical transformations

9 2. Chemical Water Quality Parameters The chemical characteristics of natural water are a reflection of the soils and rocks with which the water has been in contact. Agricultural and urban runoff and municipal and industrial treated wastewater. Microbial and chemical transformations

10 Inorganic minerals; Water dissolves inorganic minerals during contact with rocks and soil because of run off. Inorganic compounds may dissociate to varying degrees, to cations and anions. Major Cations Calcium (Ca 2+ ), magnesium (Mg 2+ ), sodium (Na + ) and potassium (K + ). Calcium concentration of up to 300 mg/L or higher have been reported. Calcium concentrations of 40 to 120 mg/L are more common. Magnesium is not abundant in rocks as calcium. Sodium and potassium are commonly found as free ions. The concentration of these cations in natural water usually are low.

11 Major Anions Chloride, sulfate, carbonate, bicarbonate, fluoride and nitrate. Bicarbonate (HCO 3 - ) is the principal anion found in natural water. The sulfates anions (SO 4 2- ) are frequently found in natural water as the result of the chemical dissolution Nitrate anions (NO 3 ) are found in natural water as the result of the bacteriological oxidation of nitrogenous materials in soil.

12 pH, alkalinity, and acidity The pH is an indication for the acidity or alkalinity of a substance Alkalinity is defined as the capacity of natural water to neutralize acid added to it. Acidity is the "quantitative capacity of aqueous media to react with hydroxyl ions". Acidity indicates the corrosiveness of acidic water on steel, concrete and other materials.

13 Inorganic Indicators of Water Quality Hardness Hardness is correlated with TDS (Total dissolved solids). It represents total concentration of Ca 2+ and Mg 2+ ions, and is reported in equivalent CaCO 3. Total dissolved solids Total dissolved solids (TDS) is a measure of salt dissolved in a water sample after removal of suspended solids. TDS is residue remaining after evaporation of the water. Relationship of Hardness Concentration and Classification of Natural water

14 Inorganic Indicators of Water Quality Conductivity The conductivity measures the capacity of water to transmit electrical current. mhos/cm Sodium Adsorption Ratio (SAR) The Sodium Adsorption Ratio (SAR) is used to evaluate the hazard in irrigation waters caused by sodium (Na + ).

15 Organic Materials Carbon (C), hydrogen (H), as well as nitrogen (N) and oxygen (O). Derived from living organism as well as industrial sources. Also containing sulfur (S), phosphorus (P), fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). Organics in water can be expressed in terms total organic carbon (TOC). The TOC is the difference between total carbon (TC) and inorganic carbon (IC). Water quality parameters and typical values

16 Biological Oxygen Demand (BOD) is a measure of the amount of oxygen used by indigenous microbial population in water in response to the introduction of degradable organic material. The 5-day BOD (BOD 5 ) Related to the dissolved oxygen concentration, which is measured at zero time and after 5 days of incubation at 20 °C. If the dissolved oxygen is measured every day for five days, it can be said the BOD is the initial DO minus the final DO.

17 With dilution (using water with no BOD of its own), the BOD equation becomes:

18 Three BOD bottles were prepared with sample and dilution water, as shown in the following table. Bottle Sample (mL) Dilution Water (mL) Calculate the dilution (D) for each. Similarly, for the other two bottles, D is calculated as 200 and 400.

19 A series of BOD test were run at three different dilutions. The results were as follows: Bottle Dilution Initial DO (mg/L) Final DO (mg/L) What is the BOD? Bottle BOD (mg/L)

20 The following are the theoretical equations used to calculate the BOD. The Figure shown is used to describe the change of BOD with time. From the figure the following correlations are derived:

21 Determine the 1-day BOD and ultimate BOD for a wastewater whose 5-day 20 °C BOD is 200 mg/L. The reaction constant K= 0.23d -1 what would have been the 5-day BOD if it had been conducted at 25°C?

22 Chemical Oxygen Demand (COD) The chemical oxygen demand (COD) test of natural water yields the oxygen equivalent of the organic matter that can be oxidized by strong chemical oxidizing agent in an acidic medium. Dissolved gases The transfer of oxygen from the atmosphere to the water. Also used to strip hydrogen sulfide (H 2 S), ammonia (NH 3 ) and volatile organic compounds (VOC) from water. Solubility of gases Depends on the temperature, the type of gas or volatile compounds, and the partial pressure of the gas or volatile compounds adjacent to the water.

23 Dissolved gases The principal transfer of gas in natural water is the transfer of oxygen from the atmosphere to the water. Gas transfer is also used to strip hydrogen sulfide (H 2 S), ammonia (NH 3 ) and volatile organic compounds (VOC) from water. Solubility of gases temperature, the type of gas or volatile compounds, and the partial pressure of the gas or volatile compounds adjacent to the water.

24 where: PgPg partial pressure of gas, atm.; H Henry's law constant; XgXg equilibrium mole fraction of dissolved gas, mol/dm 3. Henry's Law Constants for Selected Gases that are Slightly Soluble in Water (James M. Montgomery, 1985) Dissolved Oxygen Many microorganisms and fish require dissolved oxygen in aquatic system.

25 Biological characteristics Carbon, hydrogen, oxygen, nitrogen, phosphorus and sulfur which are building blocks for carbohydrates, lipids, proteins, phospholipids and nucleic acid Schematic aquatic ecosystem

26 Most important biological organisms in water and wastewater are pathogens, as they transmit diseases. not native to aquatic systems and usually require an animal host for growth and reproduction. unfortunately, can be transported by water, becoming a temporary member of the aquatic community. many species of pathogens are able to survive in water and maintain their infectious capabilities for significant periods of time. include species of bacteria, viruses, protozoa, and helminths.