Water Quality Management PDF

Prepared by: Engr. Jarlie Rosario-Clemena Environmental Pollution -Any alteration in the physical, chemical or biological properties of the environment (air, water and land) which adversely affects its aesthetic quality and beneficial use. Source: DENR Administrative Order No. 34 Series of...

Prepared by: Engr. Jarlie Rosario-Clemena Environmental Pollution -Any alteration in the physical, chemical or biological properties of the environment (air, water and land) which adversely affects its aesthetic quality and beneficial use. Source: DENR Administrative Order No. 34 Series of 1990 A. Water Classification o Depends on the uses of water, namely for domestic water supply, industrial purposes, irrigation, transportation, habitat for marine life and fish, and recreation and on how the standards may contribute to the environment making the community more pleasant to live in. Water Usage and Classification Water Usage and Classification Coastal and Marine Water CHARACTERISTICS OF WASTEWATER a. Physical Characteristics 1. Color- generally an indication of the age of sewage ( e.g.fresh: grayish or septic: black) Measurement:  Visual Comparison Method Nessler Tubes – color comparison tubes containing water of different colors and assigned a color unit ranging from 1 to 70 where 1 color unit Pt = 1/2mg/L Co  Photoelectric Colorimeters a. Physical Characteristics a. Physical Characteristics a. Physical Characteristics 2. Odor – comes from the septic decomposition at organic wastes and is due to the presence of gases such as: a. Physical Characteristics Measurement:  Olfactometer  Sensory Method – panels of human subjects are initially exposed to odor free air and then sampled air which has been diluted with odor free air to give MDTOC. The number of dilutions give TON: MDTOC/TON a. Physical Characteristics  where: MDTOC = minimum detectable threshold odor concentation  TON = threshold odor number TON = vol. of sample air + vol. of fresh air volume of sample air a. Physical Characteristics 3. Turbidity – the amount of suspended matter in water/wastewater and is obtained by measuring its light scattering activity. It is also a measure of the ability of sunlight to pass through water and the ability of water to disperse different materials disposed into it. A typical clear lake has a turbidity of about 25 units while muddy water exceeds 100 units a. Physical Characteristics Measurement:  Jackson Turbidimeter – JTU ( Jackson Turbidity Unit ; 1 unit = 1mg/L silica in H₂O a. Physical Characteristics  Secchi Disk Depth – disk in which a secchi disk may still be visible to the naked eye when submerged in water. a. Physical Characteristics 4. Temperature -lowers the solubility of oxygen in water and increases the rate at which oxygen-consuming microbes attack organic waste 5. Total Solids – solid residue when water is evaporated at 103 -105 ⁰ C b. Chemical Characteristics 1. pH – a measure of the acidity or alakalinity of water 2. Calcium and Magnesium Salts - cause hardness of water and the formation of scales and deposits on pipelines and fittings if used in industry b. Chemical Characteristics 3. Nitrogen and Phosphorous – basic components of fertilizer, serves as nutrient for microbial growth in particular algae. Excessive amounts lead to algae blooms which caused eutrophication or the overabundance in the growth of algae giving water a pea soup appearance b. Chemical Characteristics 4. Trace Metals – refers to heavy metals which are toxic even in small concentrations. Biomagnification – involves the accumulation of trace metals through each species of the food chain o Mercury – easily converted into the toxic methyl mercury which cause Minamata disease which is a neurological disease characterized by trembling, inability to walk and even serious convulsions that can lead to death BIOMAGNIFICATION b. Chemical Characteristics o Cadmium – responsible for the Itai-itai (ouch ouch) disease which is an extremely painful disease that caused disintegration of the bones o Silver – causes argyria, the blue-gray discoloration of the skin and mucous membrane o Arsenic – recognized poison; carcinogenic b. Chemical Characteristics o Chromium – causes neurological disease o Lead – lead to fetal malformation, mental disability, irritability, loss of appetite and reduction of sex drive. b. Chemical Characteristics 5. Proteins – principal constituents of animal organisms and in large quantities causes extremely foul odor 6. Carbohydrates – include sugar, starches, cellulose and woof fiber sugar + bacteria ferment alcohol + CO₂ 7. Oils, Fats, Greases – prevent natural aeration reducing the use of the stream for fishing b. Chemical Characteristics 8. Surfactants – substances that cause foamimg in water 9. Phenols – cause taste problems in water particularly when the water is chlorinated 10.Pesticides and Agricultural Chemicals – have the capacity to biomagnify at certain concentrations; are carcinogenic c. Biological Characteristics Measurement: MPN 100 ml where MPN = most probable number Uses: Escherichia Coli 1. Measures of Organic Content o Dissolved Oxygen (DO) – actual quantity of free O₂ present in water c. Biological Characteristics o Theoretical Oxygen Demand (ThOD) – a measure of the amount of O₂ needed to oxidize completely an organic matter whose chemical formula is known o Biological Oxygen Demand ( BOD ) – a measure of the amount of O₂ needed by microorganisms to decompose biodegradable organics at a specified time (5days ), temperature (20⁰C) and pH 7 c. Biological Characteristics o Chemical Oxygen Demand ( COD ) – a measure of the amount of O₂ needed to ixdize organics using strong oxidizing agents (KMnO₄ or K₂Cr₂O₇) in acid media o Total Oxygen Demand ( TOD ) – organics are converted into stable and products in a Pt-catalyzed combustion chamber and is determined by monitoring the O₂ content present in the products. c. Biological Characteristics o Total Organic Carbon ( TOC ) – organic matter is oxidized in a high temperature furnace to convert C to CO₂ c. Biological Characteristics 2. Kinetics of BOD BOD t = BODu (1 – e-Kt ) where: BODu= amount of O₂ present in H₂O anytime t BODt= amount of O₂ present in H₂O at t=0 and k = deoxygenation constant , time⁻(day) c. Biological Characteristics  For polluted and wastewater k₂₀⁰ = 0.10/day  For sewage k₂₀⁰ = 0.23/day  At different temperature kT = k₂₀⁰ ϴ (T – 20) ϴ = 1.056 ( T = 20 - 30⁰C) = 1.135 (T > 30 ⁰C) = 1.047 ( T< 20⁰C) C. WASTEWATER TREATMENT METHODS Wastewater Treatment - defined as the separation of solid and liquid impurities suspended or dissolved in the carrier water.  Components of Domestic Wastewater  Organic materials  Nitrogen  Phosphorous  Suspended solids  Pathogenic organisms (as estimated by coliforms) Wastewater Treatment Plant The typical w/w treatment plant is divided into five main areas: 1. Preliminary Treatment –removal of large solids to prevent damage to the remainder of the unit operation 2. Primary Treatment - removal of suspended solids by settling 3. Secondary Treatment – removal of the demand for oxygen  Wastewater Treatment Plant 4. Tertiary ( or advanced)treatment – a name applied to any number or polishing or clean up processes, one of which is the removal of nutrients such as Phosphorous 5. Solids Treatment and Disposal – the collection, stabiliza- tion, and subsequent dissposal of the solids removed by other processes. Wastewater Treatment. PRIMARY TREATMENT Physical Treatment Method 1. Screening – treatment used fro the removal of coarse or settleable interception Types of Screen  Racks or Bar Screen – composed of parallel bars or rods which may be hand cleaned or mechanically cleansed  Fine screens – wire or cloth mesh or perforated plate Purpose of Screening: To remove material which would (a) damage equipment (b) interfere with the satisfactory operation of a process , and (c) cause objectionable shore line conditions a. Physical Treatment Method 2. Comminutors – device that cut up solids from the screens into pieces about 0.3 cm or smaller 3. Grit Chamber – an enlarged channel where the velocity of wastewater flow is controlled to allow only the heavier solids to settle 4. Settling Tank (Sedimentation/Clarifier) – consists of cylindrical or rectangular tanks where settleable solids (raw sludge ) are removed by gravity Primary treatment:  removes 60% of the solids  removes about 30% of the demand oxygen  Removes 20% of the Phosphorus  When primary treatment is judged to be inadequate, solids, BOD, and phosphorus removal can be enhanced by the addition of chemicals such as aluminum sulfate (alum) or calcium hydroxide ( lime)  SECONDARY Treatment Chemical Treatment Methods 1. Neutralization – a chemical treatment whereby acids or bases are added to the influent wastewater in order to neutralize any acids or bases present and thus control pH. 2. Chemical Precipitation – involves the addition of chemicals for the express purpose of improving plant performance and removing specific components contained in wastewater. b. Chemical Treatment Methods  Common Precipitants  Lime – Ca(OH)₂  Ferric Chloride - FeCl₃  Soda Ash - Na₂CO₃  Ferric Sulfate - Fe₂(SO₄)₃  Alum - Al₂(SO₄).7H₂O b. Chemical Treatment Methods 3. Coagulation – an electrochemical process used in the removal of colloidal matter in wastewater through the addition of coagulating agents which reduce the electrostatic charges surrounding colloidal matter, thereby allowing natural Van der Waals forces of attraction to predominate and allowing solids to cluster. Common Coagulants o Alum- Al₂(SO₄)₃.7H₂O o Copperas - FeSO₄.7H₂O b. Chemical Treatment Methods 4. Chemical Flocculation – a physico-chemical process used in the removal of finely divided solids, a polyectrolyte is added to wastewater which can form bridges that will join together the solids. 5. Disinfection – refer to the destruction of water forms pathogens ( bacteria, viruses, amoebic cysts) for the sole purpose of preventing of transmission of disease through water. b. Chemical Treatment Methods 6. Ozonation – ozone (O₃) comes from the Greek word “ozein” which means to smell. It is a very unstable gas and a very powerful oxidant capable of oxidizing 200 – 300 times more than chlorine. It can reduce complex taste, odor and color. It has no lasting effect and is quite expensive and found to be toxic to fishes. b. Chemical Treatment Methods 7. Chlorination – addition of Cl₂ and its compounds ( Cl⁻ and HClO⁻) Chlorine when added to wastewater is broken down into: o chlorine demand of water – amount of Cl₂ that will oxidize organic matter o residual chlorine – amount of Cl₂ that will disinfect water  TERTIARY TREATMENT Biological Treatment Methods  Duplication of nature’s self purification process under contained and controlled condition  Use microorganisms to reduce the biodegradable organic matter of the wastewater by using them as food for metabolism converting the organics into harmless stable products c. Biological Treatment Methods  General Biochemical Reaction Organic Matter (CHONSP) + cells → simple compound + more cells ( soluble/bidegradable) 1. Activated Sludge Process – a continuous recrculating aerobic biochemical process that keeps cells in suspended growth 2. Trickling Filters – a fixed bed where wastewater is intermittently discharged and contacted with biological slimes that have grown in the filter media. c. Biological Treatment Methods 3. Stabilization Pond – a large shallow lagoon divided by thermal stratification into an aerobic surface and anaerobic bottom 4. Aerated Lagoon – stabilization pond provided with surface aerators 5. Anaerobic Digestion or decomposition – generally employed for treatment of organic sludges and concentrated organic industrial waste. Wastewater Treatment THANK YOU!!! Mam Jarlie