Method and system for treating wastewater and sludges by optimizing sCO2 for anaerobic autotrophic microbes

A method of treating wastewater for biochemical oxygen demand (BOD) and nitrogen removal comprising:

• a. flowing wastewater effluent through a first aeration basin;
• b. optimizing CO2 content of the effluent;
• c. flowing at least a portion of the optimized CO2 effluent into a second aeration basin;
• d. flowing the optimized CO2 effluent from steps (b) and (c) into an anaerobic reactor;
• e. flowing the optimized CO2 effluent from the anaerobic reactor into a secondary clarifier;
• and
• f. recycling at least a portion of wastewater in the secondary clarifier by channeling the wastewater into the first aeration basin.

A method of treating wastewater for BOD, nitrogen and phosphorous removal comprising:

• a. flowing a volume of wastewater through a primary clarifier;
• b. optimizing CO2 content of primary effluent exiting the primary clarifier;
• c. flowing the primary effluent having optimized CO2 into an anaerobic basin for phosphorous release;
• d. flowing effluent from step (c) to an aerobic basin to remove BOD;
• e. adding nitrite to the effluent from step (d);
• f. flowing the effluent from step (e) into a second anaerobic basin;
• g. flowing the effluent from step (f) into a secondary clarifier;
• and
• h. recycling at least a portion of wastewater in the secondary clarifier to provide return activated sludge to the first anaerobic basin.

A method of treating wastewater for BOD, nitrogen and phosphorous removal comprising:

• a. flowing a volume of wastewater through a primary clarifier wherein phosphorous is removed by allowing the wastewater to occupy the primary clarifier for a sufficient hydraulic residence time (HRT);
• b. optimizing CO2 content of at least a portion of primary effluent exiting the primary clarifier;
• c. flowing effluent from steps (a) and (b) to an aerobic basin to remove BOD;
• d. adding nitrite to the effluent from step (c);
• e. flowing the effluent from step (d) into an anaerobic basin;
• f. flowing the effluent from step (e) into a secondary clarifier;
• and
• g. recycling at least a portion of wastewater in the secondary clarifier to provide return activated sludge to the primary clarifier.

A wastewater treatment system comprising:

• an aerobic treatment zone;
• an anaerobic treatment zone wherein the anaerobic treatment zone is positioned downstream from the aerobic treatment zone;
• and
• a CO2 stripping zone wherein the CO2 stripping zone is positioned between the aerobic and anaerobic treatment zones.

A wastewater treatment system comprising:

• a CO2 stripping zone;
• at least one anaerobic treatment zone wherein the anaerobic treatment zone is positioned downstream from the CO2 stripping zone;
• and
• an aerobic treatment zone wherein the aerobic treatment zone is positioned between the CO2 stripping zone and the at least one anaerobic treatment zone.

An anaerobic digestion system comprising:

• at least one anaerobic digester having a biogas headspace;
• and
• CO2 stripping equipment positioned adjacent the biogas headspace of the at least one anaerobic digester;
• whereby biogas contained in the biogas headspace is cycled through the CO2 stripping equipment and re-enters the biogas headspace with lower CO2 concentration.

A method of treating sludge comprising:

• flowing sludge through at least one anaerobic digester having a biogas headspace;
• cycling headspace biogas from the biogas headspace through CO2 stripping equipment to lower CO2 levels in the headspace biogas;
• and
• flowing the lower CO2 biogas back into the biogas headspace of the at least one anaerobic digester;
• whereby the lower CO2 headspace biogas encourages the growth of autotrophic anaerobic microbes.

A method of increasing the specific growth rate of anaerobic, autotrophic microbes in a wastewater treatment system comprising:

• optimizing soluble CO2 further comprising:
• establishing an optimal control value for the soluble CO2 concentration for wastewater;
• measuring the concentration of gaseous CO2 for the wastewater wherein the gaseous CO2 concentration is in equilibrium with reactor contents;
• comparing the measured concentration of gaseous CO2 against the optimal control value;
• and
• adjusting the measured concentration of gaseous CO2 to match the optimal soluble CO2 control value;
• whereby optimizing the soluble CO2 increases the specific growth rate of the bacteria.