Fall 2009 Floating Flocs Research and Conclusion

Fall 2009 Floating Flocs Research and Conclusion

INTRODUCTION

In concurrence with the research of previous teams, 2 causes for the bubble formation phenomena were hypothesized:

1)    Supersaturation of influent water, caused by a higher dissolved gas pressure compared with the pressure in the plant. This supersaturated water could be forming bubbles of gas that remains attached to flocs, causing flotation of them at the surface level.

2)    The linear dose controllers were located at a height from the water level in the entrance tank and when alumn dosages were dropped from above, the disturbance could have been causing bubbles.

OBJECTIVES

Analyze all theories related to the formation of bubbles and develop a solution to mitigate the occurence of floating flocs which is feasible enough to be installed as a component in the Aguaclara plants in Honduras.

EXPERIMENTAL METHODS AND RESULTS

Our team worked on learning the working of the process controller and previously set-up apparatus of the floating flocs team. We eliminated the sand filter from the system (Why?). The apparatus was in need of repairs and we changed the settings of the sensors, valves pumps etc. in order to ensure they were working accurately.

One final experiment remained to be carried out before the floating flocs apparatus was discontinued. This was a Co ordinated experiment with the Plate Settler Spacing team in order to run supersaturated water through the their apparatus and determine if the bubbles (without using the sand filter) affect the working of the plate settler.

The conclusions made were that since the problem of bubbles due to the linear dose controllers was to be taken care of by designing non-linear dose controllers (that would be submerged in the water) for newer plants and because the sand filters were actually causing more damage than help, the floating flocs research was discontinued. The high priority problem faced in Honduras is that of low alkalinity water (which results in changing pH of water during alum addition) and needed due consideration. Hence our team was transformed in to the  ANC Control Team.

Floating flocs fall '09 weekly minutes