Odour Control in Wastewater Lagoons

BioEnergizer affects odours in three ways.  First by stimulating single celled planktonic algae to greater oxygen production efficiency, second by shifting bacterial populations and creating greater species diversity to out-compete odour producers, and thirdly by stimulating a population increase in purple sulphur bacteria which consume H2S.

Greater microbial diversity leads to more efficient the waste stabilization.

BioEnergizer:

– accelerates carbon oxidation in the system. As the microbes become metabolically efficient, the oxygen uptake rate decreases and the net demand for oxygen reduces. When stimulated, algae also generate more D.O.

– selects purple sulphur bacteria which require more than normal levels of trace nutrients.

– Purple sulphur and green sulphur bacteria control odours by consuming hydrogen sulphide

–  Certain enzymes in BioEnergizer (H2O-dehydrogenase) help algae cleave water molecules to form excess oxygen lifting D.O. concentrations.

The Basis of Lagoon Odour Control

Atmospheric oxygen diffuses into the surface layers of aerobic wastewater lagoons.  Atmospheric re-aeration coupled with the production of oxygen by algae creates an odour-oxidizing zone.  The thickness of the aerobic zone capable of oxidizing sulfides is determined by temperature, mixing, algae content, zooplankton, and organic load.

Hydrogen Sulphide diffusing out of the anaerobic sludge layer into this aerobic zone will be oxidized.   In the surface layers of a lagoon algae work to elevate the pH by consuming all the CO2 and then the HCO3.  At pH greater than 8.5, odours are controlled by the disassociation of hydrogen Sulphide into hydrogen and hydrosulphides.

If the oxygen concentration in water approaches zero (< 0.1 mg/l) insufficient oxygen will be present in the water phase to oxidize sulfides diffusing out of the sludge.  The critical dissolved oxygen concentration in the wastewater below which sulfate reduction can occur is .1 to 1.0 mg/l.  Above 1.0 mg/l, sulfate reduction will be eliminated because of increased redox potential and inhibition of Desulfovibrio bacteria, which produce H2S.  If there are “dead zones”, or no mixing zones in portions of the lagoon, local anaerobic conditions may occur generating sulfides.

The rate of Sulphide generation depends on the following environmental factors

Organic load
Sulphate Concentration
DO
pH
Temperature
Wave action
Retention Time
The presence of other bacteria/microbes which may demand oxygen and out-compete sulphate reducers for food:

In ponds with shallow water caps, a good strategy to control odours is to apply BioEnergizer over the entire surface of the lagoon including the no mix dead zones.