connected to the funnel alongside the shadow mask. The washed funnel is coated
with black graphite which is a good electrical conductor and a non-reflective coating.
The panel mask assembly is then connected to the funnel and fixed to position.
Thereafter, the assembly is oven heated to fuse the frit joint between the panel and
funnel at the seal edges. The electron guns, which give the color used in the screen,
are combination of several assembled metal components embedded in glass parts.
The gun assembly is then fused to the neck of the funnel using high temperature
flame. After this, the tube is sealed and all the gases in it are removed using vacuum
pumps. Furthermore, the tube is coated with carbon black paint and metal band is
glued to the outside of the panel to protect the tube when subjected to voltage testing
and other specifications. Figure 4.2 summarizes the manufacturing process of
cathode ray tube.
2.4.2 Water Use
According to SIC code 36, plants 11114 and 30172 which are involved in the
manufacturing of color television picture tubes in different locations produce wastewater, approximately as large as 280,000 and 150,000 L/day, respectively. Large
volume of water is used in the manufacturing of the components under this
subcategory for washing, rinsing, and solution preparation. In the manufacturing
of receiving and transmitting tubes, water is used for backwashing, tower cooling,
and steam boiling. Water is employed in processes leading to electroplating of
anodes, cathodes, and grids and also for washing and rinsing of basic solution and
other solvents involved in the processes. Water is equally used for bath dumps and
subsequent rinsing during processes accompanying finishing.
2.4.3 Wastewater Characterization
Large amount of wastewater is generated from the production process of the
television picture tubes and other cathode ray tubes; these resulted from solution
and rinses in the electroplating process and washing off of grease, solvents, and
particles on the surface of the panel, funnels, and glass tubes. Both alkaline cleaning
and chemical etching processes and subsequent rinsing contribute to the wastewater
stream in most of the plants.
The results of the wastewater characterized in plant 11114 and plant 30172 are
presented in Tables 4.22 and 4.23, respectively.
2.4.4 Wastewater Treatment Process
Wastewater treatment technologies in this subcategory target the segments that
manufacture television picture tubes as well as steel aperture masks. These are
applied in three steps, with one complementing the other. The treatment processes
146
O. S. Amuda et al.
with black graphite which is a good electrical conductor and a non-reflective coating.
The panel mask assembly is then connected to the funnel and fixed to position.
Thereafter, the assembly is oven heated to fuse the frit joint between the panel and
funnel at the seal edges. The electron guns, which give the color used in the screen,
are combination of several assembled metal components embedded in glass parts.
The gun assembly is then fused to the neck of the funnel using high temperature
flame. After this, the tube is sealed and all the gases in it are removed using vacuum
pumps. Furthermore, the tube is coated with carbon black paint and metal band is
glued to the outside of the panel to protect the tube when subjected to voltage testing
and other specifications. Figure 4.2 summarizes the manufacturing process of
cathode ray tube.
2.4.2 Water Use
According to SIC code 36, plants 11114 and 30172 which are involved in the
manufacturing of color television picture tubes in different locations produce wastewater, approximately as large as 280,000 and 150,000 L/day, respectively. Large
volume of water is used in the manufacturing of the components under this
subcategory for washing, rinsing, and solution preparation. In the manufacturing
of receiving and transmitting tubes, water is used for backwashing, tower cooling,
and steam boiling. Water is employed in processes leading to electroplating of
anodes, cathodes, and grids and also for washing and rinsing of basic solution and
other solvents involved in the processes. Water is equally used for bath dumps and
subsequent rinsing during processes accompanying finishing.
2.4.3 Wastewater Characterization
Large amount of wastewater is generated from the production process of the
television picture tubes and other cathode ray tubes; these resulted from solution
and rinses in the electroplating process and washing off of grease, solvents, and
particles on the surface of the panel, funnels, and glass tubes. Both alkaline cleaning
and chemical etching processes and subsequent rinsing contribute to the wastewater
stream in most of the plants.
The results of the wastewater characterized in plant 11114 and plant 30172 are
presented in Tables 4.22 and 4.23, respectively.
2.4.4 Wastewater Treatment Process
Wastewater treatment technologies in this subcategory target the segments that
manufacture television picture tubes as well as steel aperture masks. These are
applied in three steps, with one complementing the other. The treatment processes
146
O. S. Amuda et al.