Within a water sample containing microorganisms, there are two types of ATP:
Intra-cellular ATP – ATP contained within living biological cells.
Extra-cellular ATP – ATP located outside of biological cells that has been released from dead or stressed organisms.
Accurate measurement of these two types of ATP is critical to utilizing ATP-based measurements! Being able to accurately measure these different types of ATP offers the ability to assess biological health and activity, and subsequently control water and wastewater processes!
For a detailed overview of the concepts involved in each test protocol, click on the sections below:
Total ATP is the measurement of all ATP contained in the sample. Hence, this measurement includes both intra-cellular and extra-cellular ATP. The series of figures below explains how the total quantity of ATP contained within the sample is analyzed:
tATP™ is one of two analyses involved in QuenchGone21 Industrial and QuenchGone21Wastewater test protocols, along with dATP™. In most commercially-available ATP test kits, Total ATP is the only measurement offered. However, in many applications, correcting for the background of Dissolved ATP is extremely important.
Dissolved ATP is the measurement of only extra-cellular ATP. LuminUltra’s dATP method is superior to competing methods, in that it measures the total amount of extra-cellular ATP, not just free or soluble dATP. Extracellular ATP is made up of free-floating ATP, bound ATP, complexed ATP, and easily extractable ATP. The series of figures below explains how the extra-cellular ATP component contained within the sample is analyzed:
dATP™ is one of two analyses in QuenchGone21 Industrial and QuenchGone21Wastewater test protocols, along with tATP™. It provides information relating primarily to the relative health of the biomass. As biomass becomes unhealthy or dies, it releases ATP into the external environment. Therefore, higher dATP is a direct result of biomass mortality.
Cellular ATP is the measurement of only intra-cellular ATP. The series of figures below explains how the intra-cellular ATP component contained within the sample is determined:
In the Total Control test kit line, cATP™ is calculated as the difference of tATP™ and dATP™. That is:
cATP = tATP - dATP
In the Quench-Gone Aqueous and Quench-Gone Organic test kit line, cATP is measured directly by physically separating dATP from tATP contained in the sample (via filtration).
cATP provides a direct indication of living biomass energy level, or in other words, living biomass concentration. This parameter is extremely important for water applications, where the goal is to limit the amount of living biomass, and also in wastewater treatment applications, where the goal is to maintain a stable population of living biomass.
The Biomass Stress Index is a unique feature of LuminUltra’s Total Control test kit line. Because of the precision and accuracy built into our test kits, we are able to measure the true tATP™ and dATP™, providing not only a precise measure of living biomass quantity via cATP™, but also a measure of relative biomass population health through BSI™.
There is no conventional equivalent available to measure biomass health – this measurable characteristic is available only through LuminUltra! The series of figures below explains how BSI is determined:
The BSI is calculated from tATP and dATP as a ratio:
BSI (%) = dATP/tATP
Hence, the higher the dATP content of the sample relative to the tATP, the higher the BSI. High BSI values are related to stressful situations – for example, the addition of a biocide such as chlorine will impose a stress on the biomass and cause the BSI to rise. Other stresses, such as oxygen depravation, toxicity, or nutrient deficiencies will also produce high BSI values. In general, BSI is a ‘general alarm’ of the water or wastewater process, where a change in BSI signals a change in biomass quality, for better or worse.
The Active Biomass Ratio (ABR™) is an extremely important control parameter for biological wastewater treatment processes and is only available through application of LuminUltra’s test kit products. This parameter facilitates optimization of such things as bioreactor inventory, oxygen and macronutrient supplementation, reactor load balancing, and settling problems.
ABR represents the percentage of total solids in a biosolids sample that is actual living biomass. The following figures illustrate how ABR measurements are obtained:
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 organic 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 as a conversion from ATP concentration to dry biomass concentration. For more information, consult the ATP Conversion References section.
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.
How is ATP Measured? 
