A process for the isolation of clavulanic acid and pharmaceutically acceptable salts thereof, such as potassium clavulanate, from the aqueous fermentation broth of a clavulanic acid-producing microorganism comprises the microfiltration of the broth without prior treatment. An incision is formed in the skin of a patient above the cervical region. Windrow height is measured as is rate of advance of the transport structure to determine a volume throughput. When a decrease in operating speed is detected, the light emitting period of each photoemitter is extended.