Water Pollution Assessment and Control (ENVS 525-241) PDF

9/23/2024 ENVS 525 1 Advanced Environmental Pollution Term : 241 Assessment and Control of Water Pollution...

9/23/2024 ENVS 525 1 Advanced Environmental Pollution Term : 241 Assessment and Control of Water Pollution Dr. Bassam Tawabini September, 2024 Types of Contaminated Waters 2 ▪ Polluted Surface waters ▪ Polluted Ground water ▪ Polluted Drinking water ▪ Polluted Seawater (marine) ▪ Wastewater  Municipal (Sewage)  Industrial  Agriculture 1  9/23/2024 Water Quality 3 ❖ Water Quality describes the condition of the water, including chemical (i.e. pesticides, herbicides, heavy metals, salts, organics, nutrients…etc), physical (i.e. DO, temperature, salinity, turbidity, conductivity), and biological (i.e. bacteria, viruses, BOD…etc) characteristics, usually with respect to its suitability for a particular purpose such as drinking or swimming…etc. ❖ It is most frequently used by reference to a set of standards against which compliance, generally achieved through treatment of the water, can be assessed. ❖ The most common standards used to monitor and assess water quality convey the health of ecosystems, safety of human contact, extend of water pollution and condition of drinking water. ❖ Water quality has a significant impact on water supply and oftentimes determines supply option Water Regulations 4 (1)1972 USEPA Clean Water Act –CWA-(CFR-Title 33)-Discharge Limits for different Receiving Waters ❖ The objective of CWA is to restore and maintain the chemical, physical, and biological integrity of the US Nation’s waters ….“ (2)1974 USEPA Safe Drinking Water Act (CFR-Title 42)-Different for Different Water Use ❖ Amended in 1996 with the objective to protect the quality of drinking water in the U.S. ❖ Primary Vs Secondary DW Standards ❖ HW : Each student need to report the following water standards adopted in his own country and compare with WHO and EPA. ❖ Drinking water standards ❖ Wastewater Treatment Effluents ❖ Discharge limits to marine environment ❖ Water use for irrigation ❖ Any Industrial-related water standards a maximum contaminant level (MCL) 2  9/23/2024 Assessment of Water Pollution 5 Problem Statement (extent of contamination, type and levels) Site visit : (hydrology, hydrogeology, water use) Sampling & Analysis : Qualitative vs Quantitative Standards (limits) for the intended use Pollutants fate and transport (modeling) Remediation techniques (treatment solutions) Monitoring Assessment of water pollution-The Analytical Approach 6  Definition of Sampling Objective  Selection of Sampling Procedure  Sampling Plan: Sampling points, Sample Transport & Storage  Sample Preparation  Measurement / Determination  On-site Measurement  Lab Measurement  Data Evaluation  Conclusions and Report 3  9/23/2024 Sampling 7 ✓ Of all of the stages in the analysis, sampling is the most important ✓ The sample eventually will be a very small part of the bulk material ✓ Samples must therefore be representative A representative sample: A portion of a material taken from a consignment and selected in such a way that it possesses all of the essential characteristics of the bulk. A Grab Sample 8 ❖ A single sample collected at a particular time and place that represents the composition of the water at that time and place ❖ A Composite sample in which a series of water samples taken over a given period of time and weighted by flow rate. A sample is created by combining several distinct sub-samples 8 4  9/23/2024 Continuous Sampling / Monitoring 9 ❖ Real-time measurements to provide detail on temporal variability (variability as a function of time) ❖ Examples ❖ Water quality monitoring ❖ Industrial stack emissions (CO, NO2, SO2) ❖ Workplace monitoring (radiation exposure) ❖ Smoke detectors Sample Integrity 10 ▪ It means to maintain the original physical chemical and biological characteristics of the sample ▪ It includes proper sample collection, storage, preservation and preparation ▪ Chain of events from the process of taking a sample to the analysis is very important. ▪ Each sample should be registered (have a unique barcode) and all details recorded : the storage conditions and chain of contact. ▪ Details of samples to consider: ▪ sample properties (e.g. volatility, sensitivity to light) ▪ appropriate container (e.g. glass is not suitable for inorganic trace analyses, low molecular weight polyethylene is not suitable for hydrocarbon samples) ▪ length of holding time and preservation techniques ▪ amount of sample required to perform the analysis. 5  9/23/2024 Sampling : Surface Water 11 Sampling Surface Water 12 ▪ Errors occur in sampling operations, due to the inherent heterogeneity of bulk matrices. ▪ Single phase liquids, following shaking or mixing, are likely to be homogeneous and thus a single sample should be sufficient for analysis. Sample is being taken away from the side of a ship to avoid metal contamination from the ▪ Sampling frpm a depth of liquid (eg: a drum or an ocean ), hull. Sample being abstracted from about it is not possible to assume that the liquid at the top is of 1m depth to avoid the surface layer in which insoluble organics can accumulate the same consistency as that down the column of liquid and thus a single sample is no longer suitable. 6  9/23/2024 Sampling Surface Water … 13 Liquids flowing in confined boundaries (i.e. pipe, rivers and canals) are subject to principles of laminar flow and as such the liquid flows faster in the centre, with almost zero flow at the edge of the pipe or the bank of the river/canal. This waterway is slow-flowing (no turbulence or mixing), Huddersfield Narrow Canal samples should be taken across the width of the canal. Turbulent flow When sampling from pipes, turbulent flow can be created by introducing a right angled Sampling point bend into the pipe, with sampling just before Laminar flow the flow returns to laminar conditions. Liquid flowing in a pipe Sampling : Marine Sampling 14 7  9/23/2024 Ground Water Sampling Techniques 15 ❖ Well Flushing (Purging) ❖ Water that stands within a monitoring well for long periods of time may become unrepresentative of formation water because chemical or biochemical change may cause water quality alterations ▪ High-Flow Sampling Technique – Research indicates that pumping 5 to 10 times the volume of a 2-in well is sufficient to remove the stagnant water ▪ Low-Flow Sampling Technique Volume of well = π r2h Monitoring parameters until stabilization Record pH, temperature, specific conductivity, and dissolved oxygen readings at the calculated intervals Stabilization is said to occur when three consecutive readings of all four parameters fall within the a certain range Ground Water Sampling Techniques… 16  Sampling Equipment  Down-Hole Collection Devices  Bailers  Suction Lift Pumps Direct Line Centrifugal Peristaltic  Electric Submersible Pumps Gas-Lift Pumps Gas Displacement Pumps Bladder Pumps Gas Driven Piston Pumps Packer Pump 8  9/23/2024 Ground Water Sample Collection 17  Sample Containers and Preservation  Complete preservation of samples is practically impossible  Preservation techniques are intended to…  Retard biological action  Retard hydrolysis of chemical compounds and complexes  Reduce volatility of constituents ❖ Preservation Techniques are Limited to… ❖ pH control ❖ Chemical addition ❖ Refrigeration or freezing http://www.youtube.com/watch?v=EY7J9yo-rlo Water Sample Collection… 18 Plastic Bottles for Inorganic Testing Glass Bottles for Organic Testing Sterilized bottles for Bacteriological Testing Sample containers for trace organic samples require special cleaning and handling considerations Sample containers for VOCs consist of screw-cap vials (25 - 125 mL) fitted with a TFE- fluorocarbon faced silicone septum – Vials are sealed in the laboratory and only opened in the field immediately prior to sample collection – Samples must be submitted headspace free (no air bubbles) and cooled to 4oC for shipment 9  9/23/2024 Ground Water Sample Collection… 19 – Exact requirements for sample volumes and the number of containers will vary from lab. to lab. and will depend on: – Type sample analysis to be performed – the concentration levels of interest – the individual laboratory protocols ▪ Sample Labeling  Sample bottles should be clearly marked with the following information in permanent ink:  Time of Sample Collection  Date of Sample Collection  Sample Identification  Sample Location  Samplers Name  Analysis(es) to be performed Water Sample Collection… 20 – Once the samples have been placed in their appropriate laboratory-supplied containers they should be placed on ice and chilled to approximately 4oC until shipped to the laboratory – Allowable sample holding times will vary depending on the compounds of concern 10  9/23/2024 Groundwater Sample Collection… 21 ❖ Quality Assurance/Quality Control (QA/QC) ❖ The starting point for any sampling and analysis program should be the development of the QA/QC Plan ❖ Major Components of QA/QC Program ❖ Documentation of control of samples through chain-of-custody forms and sign-offs ❖ Details of decontamination procedures to minimize potential for cross contamination Water Sample Collection…. 22 Quality Assurance/Quality Control (QA/QC)… ▪ Chain-of-Custody  Samples need to be recorded on the chain-of-custody (usually supplied by laboratory)  Sample chain-of-custody on next slide  Sampling >> Driver >> Shipping/Receiving >> Deliver >> Laboratory 11  9/23/2024 Environmental Testing 23 Types of water analysis parameters 1. Physical Parameters 2. Chemical Organic Analysis 3. Chemical Inorganic Analysis 4. Microbiological Analysis 5. Radioactive Testing Physical Water Analysis 24  Parameters  Temperature, pH, DO, Conductivity, Turbidity, Hardness, Total Suspended Solids (TSS), Total Dissolved Solids (TDS)….etc.  Mainly carried out on-site.  Instruments :  Multi water quality testing unit  pH meter  Titration  Gravimetery  Turbidity meter  UV/VIS Spectrophotometer 12  9/23/2024 Organic Water Analysis 25  Parameters  TOC/TN, COD, VOCs, SVOCs, Pesticides, PAHs, PCBs, TPH, BTEX, Alcohols, Phenols, Organic Acids & Solvents, Fuel additives, O &G…  Instruments :  Gas Chromatography (GC)  High Performance Liquid Chromatography (HPLC)  Gas Chromatography/Mass Spectrometry (GC / MS)  Total Organic Carbon (TOC) / Total Nitrogen (TN)  Fourier Transform Infra Red Spectroscopy (FTIR) Inorganic Water Analysis 26  Tests Covered:  Anions : NO2, NO3, SO4, F, Cl, I, Br, CO3, HCO3, PO4  Cations: Na, Ca, Mg, K..etc  Heavy/Trace Metals: Fe, Al, Hg, As, Cd, Ni, Pb, Cu..etc  Inorganic Species : Ammonia (NH3), Nutrient, Cyanides…etc  Instruments:  Inductively Coupled Plasma (ICP)  Ion Chromatography (IC)  Titration 13  9/23/2024 Standard Analytical Methods 27  http://www.eurofins.com/environment-testing/water-testing.aspx  USEPA Methods: https://www.epa.gov/measurements-modeling/collection- methods#2  ASTM Methods  AWWA Water and Wastewater Examination Methods Water Quality Index (WQI) 28 ❖ WQI summarizes the information from multiple water quality parameters into a single value. ❖ The objective of WQI is to turn complex water quality data into information that is understandable and usable by the public ❖ The single value (Q) can be used to compare data from several sites ❖ It can be used to look at trends over time on a single site ❖ Q-Value - indication of water quality relative to 100 of one parameter ❖ Weighting Factor - sets the relative importance of the parameter to overall water quality Q = 50 Medium Q = 25 Q = 75 Very Very Q=0 Bad Good Q = 100 14  9/23/2024 WQI Interpretation Weighting Factors Water Quality Index Range Water Quality Rating DO 0.18 90-100 Excellent pH 0.12 E. coli 0.17 70-89 Good Temp 0.11 50-69 Medium Turbidity 0.09 25-49 Bad T Phos 0.11 NO3 0.10 0-24 Very Bad BOD 0.12 Total 1.00 Water Treatment 30 15  9/23/2024 Water Treatment Requirements? 31 ❖When treating polluted water or wastewater, we should consider: ❖ The quality (characteristics) of the source ❖ The reliability / sustainability of the water sources ❖ The intended use and purpose (drinking, municipal, industrial…etc.) ❖ The level (degree) of treatment (allowable limits) ❖ The required volume/quantities of treated water ❖ Others (location, technology, safety….etc.) ❖ The Cost (land, the plant, maintenance, manpower …etc.) ❖ Water treatment can be classified into: 32 1. Water Purification for domestic use ❖ Surface water ❖ Groundwater ❖ Seawater (desalination) 2. Water Treatment for industrial use (Process Water) 3. Wastewater Treatment for disposal or recycle/reuse ❖ Municipal wastewater treatment ❖ Industrial and ❖ Agriculture wastewater treatment 16  9/23/2024 Major Contaminants In Surface Water 33 ❖ Solids: Settleable solids and non-Settleable solids. ❖ Pathogens: bacteria, viruses…etc. ❖ Sewage : BOD, COD, TOC…etc. ❖ Dissolved gases: DO, CO2, ammonia ❖ Inorganics: cyanide, fluoride, nitrate, nutrients, hardness, salts, acids, alkalinity….etc. ❖ Organics: hydrocarbons, VOCs/SOCs/NVOC, DBPs, solvents ❖ Toxic chemicals: Pesticides, PCBS ❖ Heavy (trace) metals: mercury, arsenic, lead, copper, cadmium, chromium ❖ Radiological constituents Water Treatment Methods For Settleable SS Removal 34 Sedimentation / Settling / Clarification Filtration For Non-Settleable SS Removal Coagulation / Flocculation followed by clarification For Hardness (Ca and Mg) removal Lime softening For Salt Removal (Anions and Cations) Ion exchange Membrane Filtration (Ultrafiltration and RO) Evaporation for desalting For Organic Compounds Removal (i.e. hydrocarbons, TOC) Air Stripping Adsorption Advanced Oxidation (Photo oxidation, Electrochemical , Photocatalytic Degradation..) For Bacterial Removal Disinfection 17  9/23/2024 Clarification/Sedimentation/Settling 35  It describes the way that suspended solids (SS) are separated from water.  In the water treatment industry, clarification is most often carried out by sedimentation.  Suspended solids settle out naturally from the raw water due to gravity.  The main aim of sedimentation is to remove any suspended solids that are heavier than water to reduce turbidity, and to reduce the load on the processes that follow. Coagulation and Flocculation 36 ❖ In water treatment, coagulation flocculation involves the addition of polymers (Fe and Al salts ) that clump the small, destabilized particles together into larger aggregates (flocculants) so that they can be more easily separated from the water. ❖ Chemical Coagulants ❖ Alum (Al2(SO4)3.18H2O is the traditional coagulant ❖ Ferric Chloride (FeCl3) is another coagulant ❖ Ferric Sulfate (FeSO4) ❖ Coagulation is a chemical process that involves neutralization of charge, whereas flocculation is a physical process and does not involve neutralization of charge. ❖ The coagulation-flocculation process can be used as a preliminary or intermediary step between other water or wastewater treatment processes like filtration and sedimentation. 18  9/23/2024 Filtration 37  It is any of mechanical, physical or biological operations that separate solids from fluids (liquids or gases) by adding a medium through which only the fluid can pass.  The fluid that passes through is called the filtrate. In physical filters oversize solids in the fluid are retained and in biological filters particulates are trapped and ingested and metabolites are retained and removed.  Water treatment filters:  Gravity (slow) sand filters  Pressure rapid filters Lime Softening of Water Hardness 38 Water hardness is the amount of dissolved calcium and magnesium in the water. Hard water is high in dissolved minerals, both calcium and magnesium and will reduce the chance to form foams. There are two types of water hardness : carbonate and non-carbonate water hardness Carbonate Hardness Removal  Calcium and Magnesium carbonate salts are precipitated from water through the addition of hydrated lime (Ca(OH)2). The precipitate is removed by sedimentation Ca (HCO3)2 + Ca(OH)2 2CaCO3 + 2H2O Mg (HCO3)2 + Ca(OH)2 CaCO3 + MgCO3 + 2H2O 19  9/23/2024 Lime Softening… 39 Non-Carbonate Hardness Removal  Calcium and magnesium sulfates or chlorides salts are precipitated from water through the addition of Soda Ash (Na2CO3).  Main chemical reactions are: Ca(OH)2 + MgSO4 CaSO4 + Mg(OH)2 CaSO4 + Na2CO3 CaCO3 + Na2SO4 Adsorption 40 ❖ Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface. ❖ Absorption : is a condition in which something takes in another substance. e.g., absorption of carbon dioxide by sodium hydroxide ❖ The removal of dissolved substances from solution using adsorbents such as activated carbon (GAC), activated alumina, zeolite, charcoal, synthesized / natural adsorbents (biochar) and nano-adsrobents (CNTs) ❖ Used for the removal of organic materials such VOCs. ❖ Help in removing contaminants responsible for the taste and odor. 20  9/23/2024 Ion Exchange / Demineralization 41 Impurities dissolve in water dissociate to form ions Cations = positively charged ions (Ca++, Na+, Mg++,…) Anions = negatively charged ions (Cl-, F-, SO4--, …) - ion exchange process uses resin material to: exchanges one ion for another, meaning: Holds it temporarily in chemical combination Gives it up to a strong regeneration solution Demineralization 42 Remove dissolved (ionic matter) impurities (nearly 100%) from water by ion exchange Two Types of Ion Exchange Resins Used Cation Resins Remove Ca ++, Mg ++, Na + Solid-H+ + M+ (solution) >>>>> Solid-M+ + H+ (Low pH) Anion Resins Remove SO4--, Cl- Solid-OH- + A- (solution) >>>>> Solid-A- + OH- (high pH) 21  9/23/2024 Cross-Flow (Membrane ) Filtration 43 ✓ Cross-flow membrane filtration removes both salts and dissolved organic matter, using a permeable membrane that only allow water to pass through. ✓ It may include: micro filtration (MF), ultra filtration (UF), nano-filtration (NF) and Reversed Osmosis (RO). ✓ MF remove very fine particles (0.1 - 1.5 μ) or other SS. ✓ UF remove very fine particles (0.005 - 0.1 μ) or other SS ✓ NF remove very fine particles (0.0001 to 0.005 μ) or other SS 44 Source: www.thewaterman.co.za 22  9/23/2024 Removing Salts (Desalination Methods) 45 ❖ Two Major types of processes: ❖ Membrane: ❖ Reverse Osmosis (RO) (~ 60% of global desalination capacity) ❖ Forward Osmosis (FO) ❖ Electrodialysis (EDR) ❖ Thermal: ❖ Multi-Effect Distillation (MED) ❖ Multi-Stage Flash (MSF) (~26.8% of global capacity) ❖ Membrane Distillation ❖ Vapor Compression Reverse Osmosis 46 ❖ RO occurs when a pressure is applied to the side concentrated with the solute (salt) causing solvent (water) to less concentrated side of the permeable membrane thus producing fresh water. ❖ In Osmosis two solutions with different concentrations of dissolved constituents are separated by a semi-permeable membrane ❖ Typically a seawater RO plant produces 55-65 liters of fresh water per 100 liters of seawater ❖ Energy (3.5-5.0 kWH / m3 ) is used for pumping the water through the pre-filtering, semi-permeable membrane, and desalted/brine outputs ❖ Using RO stages (passes) and pre-treatment of water is needed to increase the lifetime of the RO 23  9/23/2024 Thermal Desalination Methods 49 Multi Stage Flash (MSF) ❖ MSF process accounts for 26.8% of global desalination capacity ❖ Seawater / brackish water is heated between 90-1100C and the tanks decrease in pressure at each stage to allow water to flash (quickly vaporize) ❖ The MSF process can be powered by waste heat or fossil fuels ❖ Energy is used to pump water through each stage, and making the steam steam and later condensed. ❖ Energy Consumption: ~80.6kWH of heat plus 2.5-3.5 kWH of electricity per m3 of water Advanced Oxidation 50  Advanced Oxidation Processes (abbreviation: AOPs), in a broad sense, are a set of chemical treatment procedures designed to remove organic (and sometimes inorganic) materials in water and wastewater by oxidation through reactions with hydroxyl radicals (· OH). 24  9/23/2024 Electrochemical Methods 51 Disinfection 52 ❖ It serves the purpose of killing microorganisms in the water; therefore disinfectants are often referred to as biocides. ❖ Disinfection Techniques include: ozone disinfection, chlorine disinfection and UV disinfection. ❖ Chlorine has a downside: it can react to chloramines and chlorinated chlorination hydrocarbons, which are dangerous carcinogens. By-products are THMs. ❖ Clorine dioxide (ClO2 ) penetrates the bacteria cell wall and reacts with vital amino acids in the cytoplasm of the cell to kill the organism. The by-product of this reaction is chlorite. ❖ Ozone: more effective than Cl2 for some viruses but can also form bromate UV (carcinogen). ❖ UV-radiation is also used for disinfection nowadays. No residual effect. 25  9/23/2024 Typical Surface Water Purification For Municipal Use 53 Chemical Addition Sedimentation Raw Water Filtration Fresh Surface Water Source (Lake or River) Coagulation/Flocculation Treated Water Primary Disinfection Secondary Disinfection Advanced Treatment (Ozone, Membranes, UV, GAC, Chlorine Dioxide) Source : McGuire Environmental Consultants, Inc Treatment of Water for Industrial Use ❖ Widely Used in various applications: 54 ❖ Boiler feed water (inhibit scale formation) ❖ Cooling water (inhibit corrosion) ❖ Food processing (avoid pathogens & toxic substances) ❖ Applications depend on the intended use Equipment Increase Corrosion performance Energy cost (failure) Scale Product Increase of Improper treatments of water can cause formation contamination pumping cost Reduced heat Reduced water Product transfer flow deterioration 26  9/23/2024 Treatment of Water for Industrial Use.. 55 Water impurities associated with the some of industrial problems: Scaling of heat transfer surfaces by salts (CacO3) of hardness ions, silica, or metallic oxides. Corrosion by DO, carbon dioxide and water, acids, Caustic embitterment due to high alkalinity Fouling by organics (microorganisms) and suspended solids Treatment of water for industrial use… 56 Treatment Types ▪ External treatment: for Removal of TSS, TDS, hardness & Dissolved gases ▪ Aeration ▪ Filtration ▪ Clarification ▪ Internal treatment: ▪ Reaction of dissolved oxygen with Hydrazine or sulfite (oxygen scavengers) to inhibit corrosion ▪ Addition of inhibitors to prevent corrosion ▪ Addition of chelating agents to react with dissolved Ca2+ and prevent of calcium deposit (scale inhibition) ▪ Addition of precipitants, such as phosphate used for calcium removal (scale inhibition) ▪ Treatment with dispersants to inhibit scale ▪ Adjustment of pH ▪ Disinfection for food processing uses or to prevent bacterial growth in cooling water 27  9/23/2024 Industrial (Steam Generation) Water Treatment Plant 57 Groundwater Pollution 58 ❖ Types of Contaminants ❖ Inorganic ❖ Ammonia ❖ Nitrate/nitrite ❖ Heavy metals (As, Pb, Zn, Cd, Cr, Hg..etc) ❖ Organic ❖ Pesticides ❖ Gasoline Additives: MTBE ❖ Petroleum hydrocarbons: BTEX, Phenols, Cresol ❖ Chlorinated Organics (PCE, TCE, DCE, VC, PCBs..etc) ❖ Biological ❖ Bacteria ❖ Viruses 28  9/23/2024 Groundwater Treatment (Remediation) 59  A rapidly changing and dynamic industry.  Emerging new technologies  Remediation strategies include:  Complete Source Removal (Excavation)  Source or Plume Containment (barriers, hydraulic control)  Mass Reduction Methods  Bioremediation  Volatilization  Oxidation/Reduction  Natural Attenuation http://widit.knu.ac.kr/epa/ebtpages/treatreatmenttechnologies.html Groundwater Treatment… 60 ❖ Pretreatment studies ❖ Identify contaminants and their characteristics of transport behavior ❖ Identify the characteristics of aquifer geology (factors of GW flow, porosity, permeability, physical dimensions, structure,…) ❖ Determine the hydrologic characteristics of polluted aquifer (flow direction, flow rates, discharge and recharge conditions…) ❖ Select possible treatment strategies and methods ❖ There is may be a need to drill monitoring and treatment wells. 29  9/23/2024 G.W. Treatment Technologies 61 I. Pump and Treat Technology (Ex-situ) A. Physico-chemical Processes: Air stripping Coagulation & precipitation Flotation & Filtration Thermal Treatment Ion Exchange Adsorption by Activated Carbon Membrane Treatment (RO) Chemical Oxidation B. Biological Processes: Activated Sludge System SBR and RBC Systems Fluidized bed reactors Ex-Situ : Physico-Chemical Processes 62 Air Stripping  Air stripping : A process of moving air through contaminated water in an above-ground treatment system.  Air stripping removes VOCs which are easily evaporate with low boiling point.  Air strippers are usually packed towers or tray towers operated with countercurrent flow that removes particles from the water into the air.  Water that reaches the bottom of the system is typically considered treated to certain extent.  Many of compounds stripped are hazardous air pollutants, so air exiting a stripper require emissions control. 30  9/23/2024 Air Stripping… 63 Limitations and Concerns  Air strippers transfer contaminants from water to air.  No destruction of the contaminant and the risks of emitting pollutants into the air must be carefully evaluated.  the air stream (or off-gas) is treated before it is emitted to the atmosphere.  Algae, fungi, bacteria, and fine particles may foul the equipment, requiring pretreatment or periodic column cleaning.  Air stripping is effective only for water contaminated with VOC or semi-volatile concentrations with a Henry's Law constant greater than 0.01. Ex-Situ : Physico-Chemical Processes 64 Dissolved Air Flotation  Is a process that clarifies waters by the removal of suspended matter such as oil or solids. The removal is achieved by dissolving air in the water or wastewater under pressure and then releasing the air at atmospheric pressure in a flotation tank basin.  The released air forms tiny bubbles which adhere to the suspended matter causing the suspended matter to float to the surface of the water where it may then be removed by a skimming device. 31  9/23/2024 65 G.W. Treatment Technologies 66 II. In-Situ Remediation Technologies 1. Volatilization (Air sparging, Soil Vapor Extraction) 2. Bioremediation 3. In situ Chemical Oxidation (ISCO) 4. Other processes Electron-beam Irradiation bio-venting natural attenuation Electrochemical thermal processes…etc. 32  9/23/2024 Air Sparging/Soil Vapor Extraction (AS/SVE) 67  Used for the treatment of saturated soils and GW contaminated by VOCs like petroleum hydrocarbons which is a widespread problem for the ground water and soil health.  Air is injected to the subsurface water and vapors are extracted by surface pumps to control the volatile air pollutants. Air Sparging/Soil Vapor Extraction (AS/SVE) 68 Advantages Disadvantages Cannot be used if free product exists (i.e., free product Readily available equipment; easy installation. must be removed prior to air sparging). Implemented with minimal disturbance to site Cannot be used for treatment of confined aquifers. operations. Short treatment times (usually less than 1 to 3 years Stratified soils may cause air sparging to be ineffective. under optimal conditions). Air sparging maybe less costly than aboveground Some interactions among complex chemical, physical, treatment systems. and biological processes are not well understood. Requires no removal, treatment, storage, or discharge Lack of field and laboratory data to support design considerations for groundwater. considerations. Can enhance removal by SVE. Potential for inducing migration of constituents. Requires detailed pilot testing and monitoring to ensure vapor control and limit migration. 33  9/23/2024 Bioremediation 69  Involves the use of organisms to remove or neutralize pollutants from a contaminated water.  Bioremediation may occur on its own (natural attenuation or intrinsic bioremediation) or may only effectively occur through the addition of fertilizers, oxygen, etc., that help in enhancing the growth of the pollution-eating microbes within the medium (bio-stimulation) Phytoremediation 70  Phytoremediation basically refers to the use of plants and associated soil microbes to reduce the concentrations or toxic effects of contaminants in the environment.  Phytoremediation is widely accepted as a cost-effective environmental restoration technology. 34  9/23/2024 In situ-Chemical Oxidation (ISCO) 71  A form of advanced oxidation processes (technology) : is an environmental remediation technique used for soil and/or groundwater to reduce the concentrations of targeted environmental contaminants to acceptable levels.  ISCO is accomplished by injecting or otherwise introducing strong chemical oxidizers (permanganate, persulfate, hydrogen peroxide and ozone) directly into the contaminated medium to destroy chemical contaminants in place.  It can be used to remediate a variety of organic compounds, including some that are resistant to natural degradation. Wastewater Treatment 72 35  9/23/2024 Industrial Wastewater Treatment 73 ❖ Processes varies based on the industry type and wastewater generated. ❖ Basically it include: ❖ Removal of organic wastes by: ❖ Biological treatment ❖ Adsorption by activated carbon (AC) ❖ Chemical process: neutralization, precipitation & oxidation/reduction…etc. ❖ Physical process: density separation, filtration, flotation, revers Osmosis, ultrafiltration ❖ Synthetic resins to remove pollutants solutes in wastewater: Industrial Wastewater (PW) Treatment Plant 74 36  9/23/2024 Municipal Wastewater (Sewage) Treatment 75 ❖ Wastewater treatment and reuse system o Centralized Water treatment plant for towns and urban cities o Decentralized Septic system— rural residential areas o Innovated ways for recycling and reclaiming waste water o New technologies for innovative waste water treatment Wastewater Treatment Objectives 76 ❖ Protect Public Health ❖ Prevent exposure to disease-causing microbes ❖ Prevent Chemical and biological contamination of drinking water ❖ Protect the Environment ❖ Remove lowering the DO levels in water streams due to DO-consuming pollutants ❖ Remove excess (nitrate and phosphate) that cause excessive growth of algae>>>> Eutrophication ❖ Remove suspended solids or sediments in streams (turbidity increase) ❖ Prevent the release of toxic chemicals into fresh water resources 37  9/23/2024 Municipal Waste Water Treatment 77 Wastewater treatment and reuse system Decentralized Septic system— rural residential areas Centralized Water treatment for towns and urban cities Innovated ways for recycling and reclaiming waste water New technologies for innovative waste water treatment Centralized Treatment System 78 Wastewater Treatment Plant 38  9/23/2024 Decentralized Treatment Systems 79 Cluster Design On-Site Wastewater Treatment (Septic Systems) Large Community Systems Decentralized Waste streams (Septic System) 80 Parameter Concentration Percent (mg/L) Reduction BOD5 200 - 290 40 – 50 % TSS (by gravity) 200 - 290 50 – 70 % Nitrogen 35 – 100 20 – 30 % Phosphorus 18 – 30 30 % Fecal coliforms (#/L) 108 – 1010 ? BOD5 – Biochemical Oxygen Demand; TSS – Total Suspended Solids 39  9/23/2024 Onsite Disposal Systems Drain Fields 81 Discharge system in which wastewater is treated as it flows down grass-covered slopes. Soils must have low permeability to minimize percolation. Natural Wastewater Disposal Systems 82 Constructed Wetlands Plant/Soil/Organisms System Microorganisms and plants – absorb nutrients, breakdown organic compounds Soil – filter out metals Plants - removes nutrients Discharge system where Non-discharge system where treated wastewater treated by plant/soil water infiltrates or evaporates. system then discharged to stream. 40  9/23/2024 Wastewater (Sewage) 83 Treatment Plants (STPs) Treated Wastewater Sludge or Bio-solids What are the main components of the STP? 84  Large Debris Removal: screened and sent to a landfilled  Grit Removal: collected and sent to a landfill  Biological Treatment: microbes use organic matter to grow  Clarifiers: remove floating oil & grease and biosolids  Biosolids: Treated and stabilized sludge containing microbe cells 41  9/23/2024 Sewage Treatment 85 ❖ Physical treatment (primary treatment): removes 60% of SS and 30 - 40% of O2 demanding waste (BOD). ❖ Biological treatment (secondary treatment): removes 90% of dissolved & biodegradable O2 demanding organic waste (BOD) ❖ Tertiary Treatment : Nitrification-De- nitrification for ammonia removal. Levels of Treatment 86 ❖ Primary Treatment ❖ removal by physical separation of grit & large objects (material to landfill for disposal) ❖ Secondary Treatment ❖ Aerobic microbiological process (sludge) ❖ organic matter + O2 → CO2 + NH3 + H2O ❖ NH3 → NO3- (nitrification) aquatic nutrient ❖ lowers suspended solids content (into sludge) 42  9/23/2024 Tertiary (advanced) Sewage Treatment… 87 ❖ Advanced or Tertiary Treatment: series of specialized chemical and physical process that remove specific pollutants (typically nitrates and phosphates) left in water after primary and secondary treatment. ❖ Chemicals additions ❖ De-nitrification: Anaerobic microbiological process with a different microbe where O2 is toxic (more sludge) NO3- → N2 (escapes to air) ❖ Phosphate Removal; PO4-3 if not removed in sludge in secondary process PO4-3 + Al+3 → AlPO4 (s) (into sludge) ❖ Aeration to strip N2 and re-oxygenate (add DO) ❖ Advanced Oxidation (AOPs) ❖ Membrane technology ❖ Adsorption by GAC ❖ Disinfection Other Biological Processes… Membrane Biological Reactor (MBR) 88 ❖ The membrane bioreactor is an alternative to activated sludge in which water is withdrawn through a membrane filter ❖ Membrane Bioreactors combine conventional biological treatment (e.g. activated sludge) processes with membrane filtration to provide an advanced level of organic and suspended solids removal. ❖ When designed accordingly, these systems can also provide an advanced level of nutrient removal. ❖ No clarifies are needed 43  9/23/2024 Municipal Sewage Treatment 89 Effectiveness of primary, secondary, & tertiary sewage treatment Discharge of Treated Wastewater Effluent and Sludge 90  Effluent back to stream or discharged to sea or reuse for irrigation after  a final activated carbon filtration and  chlorination/de-chlorination  Sludge – very nutrient rich  applied directly to land as fertilizer  incinerated (good fuel after drying)  compost 44  9/23/2024 91 45