societe Active Biomass Ratio - ABR™

The Active Biomass Ratio (ABRT) is an extremely important control parameter for biological wastewater treatment processes, and is only available through application of LuminUltra's test kit products. Having this parameter facilitates maintenance and optimization of such things as bioreactor inventory, supplement oxygen delivery and macronutrients, reactor load balancing, and settlability troubleshooting.

ABR states the percentage of total solids in a biosolids sample that is actual living biomass. The following series of figures depicts the purpose of the ABR measurement:

In any water sample, there is a hierarchy of measurements that are used to estimate biomass concentrations, each measurement more specific than the one prior:

MLSS

Mixed Liquor Suspended Solids. This is a measurement of the Total Suspended Solids (TSS) concentration contained in the bioreactor, and includes all suspended solids contained in the sample.

MLVSS

Mixed Liquor Volatile Suspended Solids. This is a measurement of the Volatile Suspended Solids (VSS) concentration contained in the bioreactor, including living biomass, dead biomass, and inert organics solids.

cATP™

Cellular ATP. This is a measurement of the intra-cellular ATP contained in the sample. It provides information pertaining to the concentration of living biomass. This measurement is only available through LuminUltra.

The ABR is calculated as the ratio of living biomass concentration to the total solids concentration:

ABR (%) = (cATP™ (ng/mL) * 0,5) / MLSS (mg/L)

The factor of 0.5 has been established by various researchers in the field of microbiology as a conversion from ATP concentration to dry biomass concentration. The conversion is arrived at as follows:

  1. Research states that 1 ng ATP corresponds to 250 mg Biomass Carbon.
  2. References also state that dry biomass is 50% carbon.
  3. Therefore, 1 ng ATP = 250 mg Biomass Carbon / 0.5 = 500 mg Dry Biomass

    - ATP units are measured in ng/mL = µg/L
    - Need to convert to mg/L; 1 mg = 1000 µg
    - Therefore, 1000 µg ATP = 500 mg Dry Biomass
    - 1 µg ATP = 0.5 mg Dry Biomass

  4. 1 ng/mL ATP = 0.5 mg/L Dry Biomass

Having this parameter allows the operator to measure and subsequently make efforts to control the living activity of biosolids contained in the bioreactor. For a variety of factors, including reduced competition, elimination of wasteful aerobic digestion, and improved mass transfer operations, it is highly beneficial to maximize ABR for a biological treatment process. ABR can also be used to distinguish the source of carry-over in clarifier upsets or other sedimentation processes.