Pulp Bleaching Environmental Considerations
Pulp bleaching is usually accomplished using a series of chemical treatments. The chemicals and the order in which they are used make up a “bleaching sequence.” One of the main goals of bleaching is to mitigate the environmental impact it has on the environment. This course will focus on the environmental concerns associated with pulp bleaching including water and energy use, resource conservation, air emissions, and wastewater quality.
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Learning Objectives
• Describe environmental concerns and considerations for bleaching
• Describe AOX and its environmental impacts
• Describe pulp bleaching wastewater quality concerns and typical controls
• Describe air emissions and controls
• Explain how water use is conserved in the bleach plant and why
• Identify and describe the factors that impact bleach plant energy use
Specs
| Course Level | Intermediate |
| Languages | English, Portuguese |
| Compatibility | Audio, Video |
| Based on: | Industry Standards and Best Practices |
Key Questions
What are the environmental concerns of pulp bleaching?
Energy use, water use, wood use, land use, air emissions, and toxic chemicals (AOX) in the wastewater are all environmental concerns for bleaching.
What is AOX?
They are harmful chemicals that are formed when chlorine containing chemicals are used for bleaching. AOX lasts a long time in the environment and accumulates in the food chain. Dioxins are a particularly toxic form of AOX that has been linked to cancer and other major health problems.
What environmental concerns exist besides AOX?
BOD, COD, and color are other wastewater concerns. Air emissions need to be monitored. Minimizing water use, energy use, and wood use are also important.
What environmental regulations exist to control the release of AOX and other pollutants?
The EPA established the cluster rule to regulate toxic pollutant releases to air and water from pulp mills.
How is AOX and other wastewater quality parameters such as BOD, COD, and color controlled?
Wastewater quality from a bleach plant depends on the lignin content of the pulp entering the bleach p
Sample Video Transcript
There are many different compounds that make up AOX, but some of the most toxic components are dioxins. Dioxins belong to a dangerous group of chemicals known as persistent organic pollutants that are highly toxic and last a long time in the environment. When contaminated food is consumed, dioxins are absorbed in the fat tissue of animals and humans, where they can remain for decades. Dioxin levels are highest in people because dioxin accumulates in the food chain, so the higher in the food chain, the higher the concentration. Dioxins have been linked to cancer, birth defects, and many other serious health problems. After dioxins were linked to chlorine bleaching in 1986, steps were taken to eliminate chlorine usage.
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