Domestic Wastewater - Treatment and Disposal

In Domestic Wastewater - Treatment and Disposal, you'll learn ...

• Preliminary, primary, secondary (biological) and advanced (tertiary) wastewater treatment processes
• Wastewater effluent disinfection and disposal methods
• Sludge treatment and disposal methods

Overview

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Credit: 4 PDH

Length: 66 pages

The treatment of domestic wastewater includes conversion of raw wastewater into an acceptable final effluent, and disposing of the solids removed in the process. Wastewater treatment processes may be classified as “preliminary”, “primary”, “secondary” (biological) or “advanced” (tertiary).

The purpose of preliminary treatment is to remove deleterious materials which would damage equipment, interfere with the satisfactory operation of a process or equipment, or cause objectionable shore-line conditions.

Primary treatment consists of settling the wastewater in a sedimentation tank. Primary treatment can usually be expected to remove 50 to 60% suspended solids and 25 to 35% BOD. Secondary treatment using conventional biological processes may remove up to 90% of suspended solids and 75 to 90% BOD. Advanced (tertiary) treatment may be expected to remove over 95% of both BOD and suspended solids, in addition to reducing some undesirable chemicals.

Prior to disposing of the effluent, it is subjected to disinfection by injecting chlorine or ozone into the effluent or exposing the effluent to ultra-violet rays. The effluent disposal methods in use are: discharge to streams and rivers, land disposal to irrigate certain crops, deep well injection, and submarine outfalls extending into the ocean.

Sludge is collected and subjected to the following treatment prior to disposal: thickening (either gravity or flotation), digestion (aerobic or anaerobic), and dewatering using sand beds or equipment such as vacuum filters or centrifuges. Dewatered sludge is disposed of on land, processed as compost and sold to farmers, deposited in sanitary landfills, or incinerated.

In this course, you’ll learn the various physical, chemical, and biological processes to remove contaminants and produce an environmentally safe fluid waste stream (or treated effluent) and a solid waste (or treated sludge) suitable for disposal or reuse. Numerical examples with solutions are provided for better understanding of the material.

Learning Objectives

Upon completion of this course, participants will be able to:

• Describe preliminary treatment units, including screens, grit chambers, scum- and grease-removal arrangements, and flow-equalization facilities.
• Explain particle-settling concepts and the design of primary sedimentation facilities for removing suspended solids and BOD.
• Describe the theory and design of secondary biological treatment processes, including trickling filters, activated-sludge plants, oxidation ditches, and stabilization ponds.
• Explain the need for advanced treatment and describe its design features.
• Compare methods for disinfecting and disposing of treated effluent.
• Describe procedures and methods for sludge treatment and disposal.

Certificate of Completion

You will be able to immediately print a certificate of completion after passing a multiple-choice quiz consisting of 20 questions. PDH credits are not awarded until the course is completed and quiz is passed.