Could anyone suggest how to control the yeast tank in wastewater treatment? Why foaming increases and nearly overflow when the pH reaches around 5.5?

When HCL was added into the yeast tank, foaming starts to form aggressively and gets thicken when pH drops to around 5.4-5.6. The appearance of bubbles is different to that before HCL was added....

13 January 2017 8,476 6 View