Patent ID: 6461510
Filing Date: 2002-10-08
Classification: B01D,C02F,Y02A,Y02W

Abstract:
A process for the treatment of at least one liquid to aerobically biodegrade at least one compound contained in the liquid by contacting the liquid with at least one aerobic microorganism, whereby the at least one aerobic microorganism or at least one enzyme produced by the at least one aerobic microorganism aerobically biodegrades the at least one compound, the process comprising of a biodegradation operation which is conducted in a biodegradation vessel and a simultaneous gas recirculation operation which is conducted in a gas recirculation line attached to the biodegradation vessel and comprising:(a) feeding the liquid into the biodegradation vessel which contains the at least one aerobic microorganism and a recirculating process gas phase containing oxygen, wherein the recirculating process gas phase within the biodegradation vessel and within the gas recirculation line is closed to the ambient atmosphere exterior to the process and is not mixed with the ambient atmosphere exterior to the process during substantially the entire process operation except during operation (e); (b) contacting the liquid with the at least one aerobic microorganism or the at least one enzyme produced by the at least one aerobic microorganism to thereby cause aerobic biodegradation of the at least one compound so that the amount of the at least one compound in the liquid is decreased; (c) recirculating the process gas phase through the biodegradation vessel, out of the biodegradation vessel, and back through the biodegradation vessel by means of the recirculation line to form a closed-loop flow of the process gas phase through the process such that the process gas phase within the process remains closed to the ambient atmosphere exterior to the process and is not mixed with the ambient atmosphere exterior to the process during substantially the entire process operation, except during operation (e), to thereby intimately contact the process gas phase with the liquid and the at least one aerobic microorganism and/or the at least one enzyme to provide oxygen to the at least one aerobic microorganism and/or to the at least one enzyme for aerobic biodegradation, said aerobic biodegradation causing depletion of oxygen and causing the process gas phase to reach oxygen concentrations substantially lower than normal ambient atmospheric concentrations during substantially the entire process operation except during operation (e); (d) removing the liquid containing the at least one compound at a desired lower concentration of the at least one compound; (e) opening the process to the ambient atmosphere exterior to the process for specific minimal periods of the process operation and at specific minimal frequencies relative to the entire process operation, said opening of the process to the ambient atmosphere exterior to the process occurring for minimum periods of time and at minimum frequencies only sufficient to add air or other oxygen containing gas to the process in minimum amounts only sufficient to sustain the at least one aerobic microorganism when the process gas phase is closed to the ambient atmosphere exterior to the process during substantially the entire process operation.