water suitable for recycling into the plant. The results of the effectiveness of such
treatment process are given in Table 4.19. All the three steps of treatment are
applicable to wastewater generated in the manufacture of tungsten filaments
resulting from the dissolution of the filament mandrel. Steps involving collection
and contract removal have been found suitable for the treatment of wastewater
resulting from the acid cleaning process of quartz mercury vapor lamps during its
production. General treatment technologies involved in each step for each segment
are summarized in Table 4.20.
Denotes water flow path
Calcium Salts
Anions
Ammonium
Bifluoride
Calcium
hydroxide
Nitric Acid
Filteration
Washing
Filtration
Recrystallization
Precipitation
Drying
Filteration
Drying
Calcium Carbonate and
Calcium Phosphate
Wet Scrubber
Wet scrubber
Calcium Fluoride
Precipitation
Milling & blending
Washing
Firing
Filteration
Screening & Blending
Product
Wet Scrubber
Drying
Fig. 4.1 Lamp phosphor process. (Source: [6])
4 Electrical and Electronic Wastes Treatment
139