Flocculator Tank Maintenance
Cleaning Tank
The flocculator needs to be cleaned when flocs start to build up in the tank otherwise they will affect the turbidity measurements at the end of the tank. It should be obvious from looking at the last unused section of the flocculator whether or not the tank needs cleaning. Flocs will have filled the the entire section. A pump and hose for cleaning the tank are next to the flocculator. Waste from the tank must be drained into the grit chamber next to the sedimentation tank. Waste cannot go into the sink because it clogs the sink. When cleaning is finished, water can be emptied from the hose by detaching it from the pump and elevating the end. Walking the length of the hose while elevating it should empty the entire hose. A shovel can be used to remove sludge at the bottom of the tank when the tank is completely empty.
Filling/Emptying the Tank
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The third section of the flocculator has three places for the water to exit out of the flocculator. There are two pipes capped with rubber fittings; these lead to the sedimentation tanks and should not be uncapped unless the sedimentation tanks are going to be used. There is also a vertical PVC pipe that leads back to the Water Filtration Plant's grit chamber. When this pipe is in place, and the inlet pump is on, water will fill the flocculator until it overflows the top of that pipe, which keeps it at a good level for running experiments. When the flocculator needs to be emptied, simply remove the vertical pipe (it is not glued in) and the water will drain from the bottom of the flocculation tank.
Tube Settlers
After moving them, the tube settlers are filled with air and tend to float. This can be prevented by submerging the tube settlers to fill them with water before connecting the sampling line. If they are not submerged, the tube settlers will fill very slowly. The seal between the tube settler and the turbidimeter must be air tight otherwise the turbidimeters will not fill. Check to be sure the sampling line is all the way in the bulkhead fitting if the tube settlers are not filling (push past initial resistance). Replace the tubing from the tube settlers to the turbidimeters when they are clogged or very dirty.
In order to get the tube settlers to stay at a 60 degree angle, rest the bottom end on the supporting PVC pipe of the baffle configuration against one wall of the flocculator section and the top end against the other wall of the flocculator section. This achieves approximately 60 degree angle. To keep the tube settler in place tuck the sampling line between a baffle and the wall. This is an effective way of securing the tube settlers.
Clogged tube settlers are the result of over alum dosing. Excessive alum doses result in the formation of large buoyant chemical flocs.
