Items
Subject is exactly
Water treatment plants
-
Demonstration of water cleanliness
1973-03 -
Water treatment control panel
1973-03 -
Water treatment reservoir
1973-03 -
Control levers for water purification
1973-03 -
Water treatment pool
1973-03 -
Water being purified
1973-03 -
Clean Water Sewage Treatment Plant
1973-03