Physical and Chemical Processes for Advanced Wastewater Treatment

Transcription

1 Chapter 16 Physical and Chemical Processes for Advanced Wastewater Treatment 1.0 PROCESS SELECTION CONSIDERATIONS SECONDARY EFFLUENT FILTRATION Background Goals Applications Process Flow Diagram Design Considerations Secondary Effluent Characteristics Filtered Effluent Quality Characteristics Filtration Removal Mechanisms Filter Medium Properties Backwash Requirements Site Requirements Hydraulic Requirements Filter Controls and Appurtenances Pretreatment/Use of Filtration (Chemical) Aids Design Optimization Protective Structures Typical Design Deficiencies Technology Types Depth Filtration Granular Media Filtration Granular Media Selection and Characteristics Granular Medium Filtration Technology Types Compressible Medium Filtration Disc Filtration Fully Submerged Disc Filters Partially Submerged Disc Filters Other Emerging Disc Filters 16-66

2 3.0 ACTIVATED CARBON ADSORPTION Process Description Application Tertiary Treatment Chemical Design Considerations Wastewater Quality Carbon Characteristics Types of Carbon Adsorption Units Upflow Columns Downflow Columns Fixed and Expanded Beds Countercurrent Adsorption Unit Sizing Backwashing Valve and Piping Requirements Instrumentation Control of Biological Activity Carbon Transport Carbon Regeneration Carbon Dewatering Regeneration Furnace CHEMICAL TREATMENT Phosphorus Precipitation Phosphorus Removal Methods Precipitants Lime Alum Sodium Aluminate Ferric Chloride Solids Considerations ph Adjustment Neutralization of Acidity Lime Alkalies Sodium Alkalies Neutralization of Alkalinity Sulfuric Acid Hydrochloric Acid

3 Acid System Design Considerations Rapid Mixing Impeller Mixers Turbine Mixers Propeller Mixers Other Mixing Devices Fluid Regimes Design Considerations Power Requirements Laboratory Scale-Up Batch and Continuous Systems Hydraulic Retention Time Vessel Geometry High- and Low-Speed Mixers Propeller and Turbine Mixers Mixer Mounting Top-Entering Turbines and Side-Entering Propeller Mixers Single-Propeller and Multipropeller Mixers Chemical Feed Systems Dry Feed Solution Feed MEMBRANE PROCESSES Process Description Low-Pressure Membranes: Microfiltration and Ultrafiltration High-Pressure Membranes: Nanofiltration and Reverse Osmosis Electrical Current-Driven Membranes Nanocomposite-Membrane Processes Forward Osmosis Membrane Bioreactor Autotrophic Membrane-Biofilm Reactor (MBfR) Process Objectives Pretreatment Scale Control Acid Addition Scale-Inhibitor Addition Softening with a Strong Acid Cation Exchange Resin Lime Softening

4 Preventive Cleaning Adjusting Operating Variables Colloidal Fouling Prevention Media Filtration Inline Filtration Coagulation/Flocculation Cross-Flow Microfiltration/Ultrafiltration Biological Fouling Prevention Chlorination Dechlorination Sodium Metabisulfite Chloramination Shock Treatment Microfiltration/Ultrafiltration Ozone Ultraviolet Irradiation Advanced Oxidation Membrane Systems Membrane Module Configuration Membrane Separation by Microfiltration or Ultrafiltration Reverse Osmosis Reject/Brine Disposal Requirements Disposal to Surface Water Deep-Well Injection Evaporation Ponds Evaporation to Dryness and Crystallization Local Brine Management (Brine Lines) Blending with Other Streams Brine Recovery Reverse Osmosis AIR STRIPPING FOR AMMONIA REMOVAL Process Description Design Considerations Tower Packing Loading Air-to-Water Ratio Temperature AMMONIA REMOVAL BY BREAKPOINT CHLORINATION Process Theory

5 7.2 Design Considerations EFFLUENT REOXYGENATION Cascade Reoxygenation Mechanical/Diffused Air Reoxygenation Relationship to Other Unit Processes References and Design Procedures REFERENCES