Activated Sludge

The following sections are included:

• Flocculation

• Operating Factors

  • Process control

    • Mixed liquor suspended solids

    • Sludge residence time or sludge age

    • Plant loading

    • Sludge settleability

    • Sludge activity

    • Recirculation of sludge

  • Factors affecting the process

  • Aeration methods

    • Surface aeration

    • Air diffusion

    • Testing aerators

• Modes of Operation

  • Conventional activated sludge processes

    • Plug-flow systems

    • Completely mixed systems

    • Sequencing batch reactor technology

  • Extended aeration

    • Oxidation ditches

    • Packaged plants

  • High-rate activated sludge processes

    • A–B process

  • Advanced activated sludge systems

    • ICI Deep Shaft^® process

    • Pure oxygen systems

• Sludge Problems

  • Deflocculation

  • Pin-point floc

  • Foaming

  • Filamentous bulking

  • Identifying problems

  • Non-filamentous bulking

  • Denitrification

• Ecology

  • Bacteria

  • Fungi

  • Protozoa

  • Other groups

• Nutrient Removal

  • Denitrification

  • Phosphorus removal

• Further reading