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Anaerobic Control Analyzer

AnaSense™ is an on-line analyzer system designed specifically for monitoring anaerobic digesters, bringing the possibility of implementing new control alternatives to typical operating problems in anaerobic processes in mid to large scale digesters.

The primary process parameter that can be measured is total volatile fatty acids (VFA). VFA levels directly represent the metabolic condition of the anaerobic digester and respond quickly to stress induced changes. Other critical process parameters are: bicarbonate, alkalinity (partial and total) and optionally ammonia.


Anaerobic digesters require critical parameter monitoring in order to obtain optimal production efficiency, compliance and biogas yield. However, due to the expensive or time-consuming character of most analysis methods for anaerobic digestion, industrial digesters are usually not extensively monitored and continuous measurement of a few parameters is used, such as pH and gas flow. This is the reason why the loading rate of the digester has to be kept relatively low for safety precautions.

Keeping the loading rate low is also a consequence of the inherent risk of digester failure due to “overfeeding”. Critical parameter monitoring allows to maintain a higher process set point without the risk of calamities due to an accumulation of the fatty acids. Operators sometimes experience too late that a single batch of commercially available granular sludge can be much more expensive than the purchase of an on-line analyzer. In this respect, AnaSense™ offers a viable return on investment for AD operators.


AnaSense™ is also known as the Hach EZ7200 Series.

On-line, automatic measurements of volatile fatty acids (VFA), bicarbonate, alkalinity, pH and ammonia in one single run

Second generation design with less moving parts, simple maintenance and requiring no special analytical skills

Complete separation between electronics and wet part

Rapid results (10 – 15 min.) allow true process monitoring,protection and optimization

Dual range possibility for influent/effluent analysis

Multiplexing up to eight (8) sampling points possible

Incorporated industrial PC with AppliTek controller

Extended data communication and exchange features

Analysis method
Acid/base titration

Volatile fatty acids (total), bicarbonate, alkalinity
(total), alkalinity (partial), pH
Optional: ammonia

Standard measuring ranges
One combination, factory set:

VFA: 10 – 500 mg/L as acetate equivalent
Bicarbonate: 0-55 meq/L or 5,500 mg/L as CaCO3
Alkalinity *: 0-55 meq/L or 5,500 mg/L as CaCO3

VFA : 10 – 500 mg/L as acetate equivalent
Bicarbonate: 0-500 meq/L or 50,000 mg/L as CaCO3
Alkalinity *: 0-500 meq/L or 50,000 mg/L as CaCO3

VFA: 50 – 10,000 mg/L as acetate equivalent
Bicarbonate: 0-100 meq/L or 10,000 mg/L as CaCO3
Alkalinity *: 0-100 meq/L or 10,000 mg/L as CaCO3
*Alkalinity: as total and partial alkalinity

Standard measuring range (other)
One measuring range, factory set:
Ammonia: 2 – 3.5 g/L

Cycle time
10 – 15 minutes (depending on range)

Product type: Process analyzers, Water analyzers

Measuring technology: Titration

Type of application process: Anaerobic digestion

Industries: Food & Beverage, Pulp & Paper, Water treatment