Intermediate Water Treatment

SKU: RVI-11521Duration: 20 Minutes

Water treatment affects all of our everyday lives, from the water we drink to the sewage we flush, from the wash water we discharge to the cooling water used in manufacturing and in buildings. This course will cover intermediate water treatment in large buildings, and is directed toward the building manager or technician. Operation and maintenance of cooling towers and boilers will be discussed, along with control of water chemistry, dissolved oxygen, solids and bacteria that can lead to scaling, corrosion and fouling of water treatment systems, along with exposure to Legionnaires' disease.

Course Details


Training Time: 20 minutes

Compatibility: Desktop, Tablet, Phone

Based on: Industry Standards and Best Practices

Languages: English

Learning Objectives

  • Explain the impact of oxygen scavengers on microbial growth
  • Describe ASHRAE 188 and how it relates to Legionella
  • Explain how to monitor system water quality
  • Differentiate between open-loop and closed-loop water systems
  • Describe best practices to ensure cooling tower efficiency

Key Questions

The following key questions are answered in this module:

What is the purpose of water treatment?
The primary purpose of water treatment in industrial systems and buildings (cooling towers, boilers, and chillers) is to reduce the costs of operating these large and often expensive pieces of equipment.

What is conductivity?
Conductivity is the reciprocal of electrical resistivity. It represents a material's ability to conduct electric current. In water, conductivity is directly related to the total dissolved solids (TDS).

How often should basic water chemistry levels be tested?
Basic water chemistry levels should be tested daily by building maintenance staff.

What are the different types of cooling water systems?
Cooling water systems come in three types: once-through, or single pass, closed-loop recirculating, and open-loop recirculating.

What are some recommendations to reducing the risk of Legionnaires' disease?
Legionella bacteria are found naturally in freshwater and can contaminate hot water tanks. Recommendations for reducing the risk of Legionnaires' disease include preventing stagnation, preventing biofilm buildup, periodically disinfecting the system, and reducing the production of aerosols.

Sample Video Transcript

Below is a transcript of the video sample provided for this module:

After pretreatment, corrosive gases such as oxygen (O2) and carbon dioxide (CO2) must still be removed from feed water to a boiler. Mechanical deaeration can remove these gases, especially oxygen, reducing them either to an acceptable level for the boiler system or to a suitable level for application of oxygen scavengers. Considering the corrosive potential of oxygen, it is best to remove all traces of oxygen from boiler feedwater. This can be done by adding chemical oxygen scavengers that react with free oxygen in the water to form harmless oxidized products. Commercially available oxygen scavengers include: • Sodium sulfite • Hydrazine • Carbohydrazide • Erythorbate • Diethylhydroxylamine • Methylethylketoxime • Hydroquinone Oxygen scavengers can also be used in cooling tower systems. Addition of oxygen scavengers will impact microbiological growth in cooling towers by: 1. Suppressing growth of aerobic bacteria, which are the fastest-growing type of bacteria. 2. Allowing growth of anaerobic bacteria, which can be corrosive to metal surfaces. Sulfate-reducing bacteria, which produce hydrogen sulfide (H2S) in water, are common in anaerobic water systems. 3. Measuring dissolved oxygen (DO) with a field meter during routine water chemistry monitoring.
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