Turbidity, Solids & EC of Polluted Water PDF

Turbidity, Solids & Electrical conductivity of Water Lesson 1 Learning outcome By the end of this lecture you will learn:- 1. The principle of Water Turbidity, Solids & EC test 2. The importance of these test in water/wastewater treatment process 3. Lab tests w...

Turbidity, Solids & Electrical conductivity of Water Lesson 1 Learning outcome By the end of this lecture you will learn:- 1. The principle of Water Turbidity, Solids & EC test 2. The importance of these test in water/wastewater treatment process 3. Lab tests with their Flowchart 4. Some calculation 5. Standard permissible level of these pollutant in water/wastewater  Turbidit y Turbidity is a visible indicator of the presence of “solids” in a water sample. Water containing suspended matter that interferes with the passage of light through the water or in which visual depth is restricted is turbid. Cause of water turbidity: Suspended materials (Inorganic (clay, silt) and mostly organic matter)  Why we do not want turbid water? 1. Aesthetics 2. Difficult and expensive to treat 3. Poor filterability Turbidity & Disinfection  SOLIDS In environmental chemistry of water, solids are measured in: Drinking water Polluted water Domestic and industrial wastewater Sludges produced in treatment processes SOLIDS  SOLIDS Total Solids Total solids are the matter left behind after drying of the water sample at 103-105 °C OR Total solids are the residue remaining upon evaporation of water sample (All matter except water) Including Metal salts, inorganic salts, organic material, insoluble salts, soluble salts, etc. Evaporating dish  Total Solids There are two ways that solid materials may be classified 1. Suspended solids and dissolved solids 2. Volatile solids and fixed solids  Suspended vs Dissolved Total suspended solids are the part of the sample that may be caught with a 0.45 µm filter Total dissolved solids are the part of the sample that will pass through the filter In drinking water: – Mostly dissolved solids include inorganic salts and dissolved organics – Range: 20-1000 mg/L For drinking water use, dissolved solids < 500 mg/L is most desirable Standard recommended max. value 1000 mg/L  Desiccator While the filters or crucibles cool to room temperature, Desiccator is used to prevent errors in weighing of filters or crucibles by providing a 0% humidity atmosphere  Volatile vs Fixed Total volatile solids is the portion of the sample lost after the sample has been heated to 550 °C – It is an approximation of the organic material present. Total fixed solids is the portion that still remains after heating. – It is an approximation of the mineral matter present Environmental Significance  Calculations A= weight of the filter paper, g B= weight of filter paper + residue dried at 105 °C C= weight of filter paper + residue upon ignition at 550 °C  Volatile and Fixed Solids Solids determination in domestic, industrial wastes and sludges → Measure of organic matter. Controlled temperature → prevent decomposition and volatilization of inorganic substances Ignition at 550 °C → Lowest temperature at which organic matter oxidizes and inorganic salts are stable  Volatile and Fixed Solids Ignition at 550 °C → Pyrolysis of organic matters Combustion procedure is used in which organic matter is converted to gaseous CO2 and water  Volatile and Fixed Solids At 550 °C decomposition of inorganic salts is minimized Separation of volatile and fixed solids are conducted in muffle furnace CaCO3 is a major component of inorganic salt decomposes in 825 °C Most inorganic salts stay stable, exception: MgCO3  Settleable Solids settleable Solids will settle because of the influence of gravity Only the coarser suspended solids with specific gravity greater than the specific gravity of water will settle Determined by using Imhoff cone 1 h of settling time is required Unit: ml/L It is Important to determine the need for sedimentation in the Water/wastewater treatment plants  Solids in industrial wastewaters Include a wide variety of materials → all solids tests may be important Settleable solids test → important to determine if primary sedimentation tank is required. Application of solids analysis in Environmental engineering  Example Given the following data: Weight of a dish = 48.6212 g. 100 mL of sample is placed in a dish and evaporated. Weight of the dish and dry solids = 48.6432 g. The dish is then placed in a 550°C furnace, then cooled. Weight = 48.6300 g. Find the total, fixed, and volatile solids (expressed as mg/L). Answer  Lab procedures for TS, TSS and TDS 1. Total Solids (TS) Measurement Purpose: To determine the amount of all solids (both suspended and dissolved) present in a water sample. Procedure: 1. Sample Collection: - Collect a representative sample of water (generally about 100 mL). 2. Preparation of Sample: - Homogenize the sample by mixing it thoroughly. 3. Weighing the Crucible: - Take a pre-cleaned and dried glass or porcelain crucible. - Weigh it using an analytical balance. Record the initial weight. 4. Evaporation: - Pour a measured volume of the water sample (typically 50-100 mL) into the crucible. - Place the crucible in a drying oven at 103-105°C until all water has evaporated (usually 1-2 hours). 5. Cooling and Weighing: - Remove the crucible and allow it to cool in a desiccator to prevent moisture absorption. - Weigh the crucible again and record the weight. 6. Calculation: - The difference between the initial and final weight of the crucible gives the total solids in the sample. - Use formula to calculate the total solids: 2. Total Suspended Solids (TSS) Measurement Purpose: To measure the solid particles suspended in water that are not dissolved. Procedure: 1. Sample Collection: - Collect a representative sample of water (about 100 mL). 2. Preparation of Filter Paper: - Take a pre-weighed filter paper (usually Whatman GF/C or GF/F). - Record the weight of the dry filter paper. 3. Filtration: - Filter the water sample through the pre-weighed filter paper using a vacuum filtration apparatus. - Ensure all the suspended particles are collected on the filter paper. 4. Drying: - Dry the filter paper in an oven at 103-105°C for about 1 hour until all water is evaporated. 5. Cooling and Weighing: - Allow the filter paper to cool in a desiccator and then weigh it again. 6. Calculation: - The difference between the initial and final weight of the filter paper gives the total suspended solids. - Use the formula 3. Total Dissolved Solids (TDS) Measurement Purpose: To determine the amount of dissolved substances in water after removal of suspended solids. Procedure: 1. Sample Filtration: - Filter the water sample through a pre-washed and dried filter paper (same as used in TSS procedure) to remove all suspended solids. 2. Weighing the Crucible: - Take a clean, pre-dried glass or porcelain crucible and weigh it. Record the initial weight. 3. Evaporation: - Pour the filtered water (usually 50-100 mL) into the crucible. - Place the crucible in a drying oven at 180°C until all the water evaporates. 4. Cooling and Weighing: - After complete drying, allow the crucible to cool in a desiccator. - Weigh the crucible and record the final weight. 5. Calculation: - The difference between the initial and final weight of the crucible gives the total dissolved solids. - Use the formula  Conductivity Conductivity is an indication of the quantity of ions contained in a solution to determine if the sample can carry an electrical current via the movement of ions. Conductivity depends on the presence of ions and temperature of the water body.  What are the EC units? Conductivity is commonly reported in micromhos per centimeter (μmho/cm). In the International System of Units (SI), conductivity is reported as millisiemens per meter (mS/m) What are typical Conductivity values in nature?  Conductivity and Total Dissolved Solids Estimate total dissolved solids (mg/L) in a sample by multiplying conductivity (in micromhos per centimeter) by an empirical factor This factor may vary from 0.55 to 0.9, depending on the soluble components of the water and on the temperature of measurement. There is a linear relationship between conductivity and total dissolved solids in dilute systems lets protect our environment  References M. Islam, N. George, J. Zhu, and N. Chowdhury, “Impact of carbon to nitrogen ratio on nutrient removal in a liquid-solid circulating fluidized bed bioreactor (LSCFB),” Process Biochemistry, vol. 44, no. 5, pp. 578–583, 2009. View at Publisher · View at Google Scholar · View at Scopus A. Stare, D. Vrečko, N. Hvala, and S. Strmčnik, “Comparison of control strategies for nitrogen removal in an activated sludge process in terms of operating costs: a simulation study,” Water Research, vol. 41, no. 9, pp. 2004–2014, 2007. View at Publisher · View at Google Scholar · View at Scopus S. Jeyanayagam, “True confessions of the biological nutrient removal process,” Florida Water Resources Journal, pp. 37–46, 2005. T. Datta, L. Racz, S. M. Kotay, and R. 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