Water Quality Parameters Laboratory Manual PDF

EXPERIMENT 1 – WATER - Collected in a common container over CHARACTERIZATION AND DETERMINATION the sampling period OF PHYSICAL AND CHEMICAL WATER - Represent the average performance of QUALITY PARAMETERS...

EXPERIMENT 1 – WATER - Collected in a common container over CHARACTERIZATION AND DETERMINATION the sampling period OF PHYSICAL AND CHEMICAL WATER - Represent the average performance of QUALITY PARAMETERS water system during the collection period Physical and Chemical water quality parameters - Used indicator of treatment plan - Taken an measured as soon as possible performance after sample collection – on-site Indicators Water sampling and analysis - CBOD5 – five-day carbonaceous - Collection of water samples biochemical oxygen demand - Measurement of physical, chemical, and - TSS – total suspended solids biological characteristics - TN – total nitrogen - Results are compared against water quality standards to determine use and * CBOD5 – It is a measure of the amount of treatment oxygen required by microorganisms to decompose organic matter in a sample of water Water or Wastewater sampling over a five-day period at a temperature of 20°C - Grab sampling - Composite sampling Standard methods (20th edition, section 1060B) - “Collection and sampling” Grab sampling - A sample can represent only the - All of the test material is collected at composition of its source at the time and one time place of the collection - Reflects performance only at the point in - Grab samples – represent well-mixed time, if properly collected surface waters, but rarely wastewater - Allows the analysis of unstable streams for water quality evaluation parameters Residential treatment plants Unstable parameters - Widely varying flow patterns – - pH impossible to evaluate performance by - Dissolved oxygen analyzing a single grab sample of - Chlorine residual effluent - Nitrites - Receive frequent number of hydraulic - Temperature surges followed by intermittent periods of no flow Composite sampling - Composite samples – only verifiable - Collection of numerous individual indication of treatment plan discrete samples taken at regular performance, but expensive and time intervals over a period of time, usually consuming 24 hours  - Grab sample – compound degree of * Sulfides: These are compounds containing error, erroneous conclusions sulfide ions (S2-). Examples include hydrogen sulfide (H2S) and sodium sulfide (Na2S). Independent Third-party certifiers - Recognized by regulatory organizations * Carbonate compounds: These are compounds - Measure system performance in containing carbonate ions (CO32-). Examples standardized, reproducible setting include sodium carbonate (Na2CO3) and calcium carbonate (CaCO3). * RTPs frequently encounter hydraulic surges, Electrolytes which are sudden increases in flow rate. These - Compounds that dissolve into ions surges can overload the treatment system, leading to incomplete treatment and potential Distilled or deionized water effluent quality issues. Conversely, intermittent - Insulator periods of no flow can cause the treatment - Low conductivity system to become stagnant, leading to increased solids accumulation and reduced treatment Sea water efficiency. - High conductivity Conductivity - Water’s capability to pass electrical flow pH - Directly related to concentration of ions - Negative logarithm of hydrogen ion in the water concentration - More ions, more conductive - intensity of the acidic or basic character of a solution Conductive ions - 0-7 – acidic - Dissolved salts - 7-14 – alkaline - Inorganic materials: - 7 – neutral - Alkalis - Chlorides - Sulfides Turbidity - Carbonate compounds - Optical property that causes light to be scattered and absorbed, rather than * Alkalis: compounds that produce hydroxide transmitted in straight lines ions (OH-) in solution. Examples include sodium - Nephelometry – effect on the scattering hydroxide (NaOH) and potassium hydroxide light (KOH). - Nephelometer – low turbidity * Chlorides: These are compounds containing - Turbidimeter – moderate turbidity chloride ions (Cl-). Common examples include - Higher intensity of scattered lights, sodium chloride (NaCl), potassium chloride (KCl), higher turbidity and calcium chloride (CaCl2). * Turbidity is a measure of the cloudiness or EXPERIMENT 3 – DETERMINATION OF haziness of a liquid caused by suspended CHLORIDES CONTENT OF particles WATER/WASTEWATER BY ARGENTOMETRIC METHOD Temperature - How hot or cold water is Chloride - Average thermal energy of a substance - Chloride ion, CL— - Has influence on water chemistry - Major inorganic anion in waste/water - Rate of chemical reactions increases at - Salty taste – produced by chloride high temperatures concentrations – variable and dependent - High temperature – dissolve more on the chemical composition of water minerals form rocks, higher electrical conductivity 250 mg Cl— / L - Warm water – less dissolved oxygen - Detectable salty taste than cool water – may not contain - If the cation is sodium enough for the survival of different species of aquatic life 1000 mg Cl— / L - Absent salty taste - Predominant cations are Magnesium, Mg Total Dissolved Solids (TDS) and Calcium, Ca - Sum of all ion particles that are smaller than 2 microns = 0.0002 cm Chloride concentration - Includes all disassociated electrolytes - Higher in wastewater than raw water that make up salinity concentrations - Sodium chloride, NaCl – common article - Clean water – TDS = salinity of diet and passes unchanged through - Wastewater – TDS includes organic the digestive system solutes in addition to salt ions Sea coast * Salinity is a measure of the concentration of - High chloride concentrations dissolved salts in water. It is typically expressed - Leakage of salt water into the sewerage as parts per thousand (ppt) or grams of salt per system kilogram of water. - Increased by industrial processes Experiment Proper: High chloride content - Harm metallic pipes and structures and Equipments plants - TDS meter - pH meter Methods in determination - Colorimeter - Argentometric Method - Conductivity meter - Mohr Method Mohr Method ions to form a red-brown precipitate of - Karl Friedrich Mohr, 1856 silver chromate (Ag2CrO4). This color - Determination of chlorides by titration change indicates the end point of the with Silver nitrate, AgNO3 titration. - Oldest titration method Argentometric Method - Potassium chromate, K2CrO4 – can EXPERIMENT 4 – DETERMINATION OF IRON indicate the end point of the silver nitrate CONTENT OF WATER/WASTEWATER BY titration of the chloride – neutral or POTASSIUM PERMANGANATE TITRIMETRIC slightly alkaline solution (7-10 in pH) METHOD - Silver chloride – precipitate quantitatively before red silver chromate is formed Iron, Fe - First element in Group VIII of the periodic * The argentometric method is a type of table volumetric analysis used to determine the - Atomic number – 26 concentration of halide ions (chloride, bromide, - Atomic weight – 55.85 and iodide) in a solution. It involves titrating the - Common valences – 2 and 3 halide solution with a standard solution of silver - Occasional valences – 1, 4, 6 nitrate (AgNO3). The end point of the titration is - Average abundance in earth's crust – detected using a suitable indicator, such as 6.22% potassium chromate (K2CrO4). - Widely used in steel and alloys - soils, Fe – 0.5 - 4.3 % Here's how the argentometric method works: - Streams, Fe – 0.7 mg/L - Groundwater, Fe – 0.1 - 10 mg/L 1. Sample preparation: The sample - Iron occurs in minerals: containing halide ions is prepared and - Hematite diluted to a known volume. - Magnetite 2. Titration: A standard solution of silver - Taconite nitrate is added to the sample solution - Pyrite dropwise. As silver ions (Ag+) are added, they react with the halide ions Solubility of Ferrous ion, Fe 2+ (Cl-, Br-, or I-) to form a precipitate of - Controlled by the carbonate silver halide (AgCl, AgBr, or AgI). concentration 3. End point detection: Potassium chromate is added to the solution as an * According to Le Châtelier's principle, if a indicator. At the end point of the system at equilibrium is subjected to a change, titration, when all the halide ions have the system will adjust itself to counteract the reacted with the silver ions, the excess change. In the case of ferrous carbonate silver ions will react with the chromate solubility:  Increased CO32- concentration: If the - Can impart objectionable tastes and concentration of carbonate ions is color to foods increased, the equilibrium will shift to the left to consume the excess carbonate United Nations Food and Agriculture ions. This results in the precipitation of Organization more ferrous carbonate, decreasing the - Irrigation waters – 5 mg/L solubility of ferrous ions. Decreased CO32- concentration: If the U.S. EPA concentration of carbonate ions is - Secondary drinking water standards decreased, the equilibrium will shift to MCL – 0.3 mg/L the right to replenish the carbonate ions. This results in the dissolution of more ferrous carbonate, increasing the solubility of ferrous ions. EXPERIMENT 6 – DETERMINATION OF NITRATES CONTENT OF WATER / Groundwater WASTEWATER BY ULTRAVIOLET - Often anoxic, low in oxygen SPECTROPHOTOMETRIC SCREENING - soluble iron is usually in the ferrous METHOD state Ferric ion, Fe 3+ Forms of nitrogen in water or wastewater - Oxidized from ferrous ion - Order of decreasing oxidation state: - Due to air exposure and addition of - Nitrate, NO3— oxidants - Nitrite, NO2— - Can hydrolyze to form red, insoluble - Ammonia, NH3 hydrated ferric oxide - Organic nitrogen - Not significantly soluble in the absence - Nitrogen gas, N2 of complex-forming ions, unless pH is - Biochemically inconvertible very low - Components of the nitrogen cycle * Ferric ions can react with water molecules to * The oxidation state of nitrogen in a compound form hydrated ferric oxide, which is a red, is determined by the number of electrons it has insoluble precipitate. This process is known as gained or lost compared to its neutral state. hydrolysis. The formation of hydrated ferric oxide - Nitrate (NO3-): +5 is often observed when a solution containing - Nitrite (NO2-): +3 ferric ions is exposed to air or when the pH of the - Nitrogen gas (N2): 0 solution is increased. - Ammonia (NH3): -3 - Organic nitrogen: Varies, but typically Elevated iron levels between -3 and +5 - Cause stains in plumbing, laundry, and cooking utensils Determination of nitrate, NO3— Correction factors for organic matter absorbance - Difficult due to the relatively complex - Established by the methods of additions procedures, and analysis of the original NO3— - High probability that interfering content by another method constituents will be present, and - Limited concentration ranges of various Sample filtration techniques - Remove possible interference from suspended particles Ultraviolet UV technique - Measures absorbance of NO3— at 220 Acidification of 1N HCL nm - Prevent interference from hydroxide or - Screening uncontaminated water, low in carbonate concentrations up to 1000 organic matter mg, CaCO3 / L Ultraviolet Spectrophotometric Method Chloride - NO3— calibration curve follows Beer’s - Has no effect on the determination law up to 11 mg N / L Measurement of UV absorption at 220 nm - Rapid determination of NO3— - Dissolved organic matter also may absorb at 220 nm - NO3— Does not absorb at 275 nm 275 nm - Second measurement - Used to correct the NO3— value Empirical correction - Related to the nature and concentration of organic matter - May vary from one water to another - Not recommended for significant correction for organic matter when absorbance is required - May be useful in monitoring NO3— levels within a water body with a constant type of organic matter