Anaerobic Digester Control
The SENTRY bio-electrode sensor detects volatile fatty acids (VFA’s)
Effective control of anaerobic digesters
Real-time volatile (fatty) acids monitoring
Maintain a healthy microbial population
Real-time data for process adjustment
SENTRY is a process monitoring system with a bioelectric sensor that detects volatile fatty acids (VFAs) in anaerobic digesters. Factors such as poor mixing, inconsistent temperature and organic overloading can increase the concentration of VFAs within the reactor. SENTRY sensors mounted in the recirculation lines of digesters provide a minute-to-minute signal indicating the health of the microbial population degrading the waste.
The SENTRY signal can be used to optimize biogas production while maximizing volatile solids destruction. By integrating the signal in your process control strategy, you can produce the most value from the digestion process.
The anaerobic digestion of complex organic matter has the potential to dramatically reduce fossil fuels use and to recycle nutrients for subsequent crop production. Control of anaerobic digestors has been one of the process limitations to more widespread use of this technology. SENTRY has solved the process monitoring problem. When used as part of an advanced control strategy, SENTRY provides a unique measurement of biological activity that can be used to control pumps and valves and can simplify the design of feedstock mixtures to maximize key performance indicators.
Anaerobic Digestion Optimization
SENTRY can be used to optimize biogas production while maximizing volatile solids destruction. SENTRY’s bioelectric sensor detects volatile (fatty) acids, providing a unique measurement of biological activity that can be used to control pumps and valves and simplify the design of feedstock mixtures.
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Specification
Sensor Type: Bioelectrochemical
Measurement Type: Electron generation rate (electrical current) from biological oxidation of organic matter in solution.
Metric: SENTRY Signal (SenS), reported as consumable cBOD (or VFA in anaerobic environments). Surrogate for readily biodegradable chemical oxygen demand (rbCOD).
Measurement Performance Range: 0.1 to 25,000 mg/L rbCOD equivalent
Measurement Frequency: SENTRY signal generated each minute (1,440 values per day) Applied voltage signal generated each minute (1,440 values per day)
Sensor Control Panel
Operating Temperature: -20°C to 55°C (-4 °F to 131 °F)
Humidity: 5-90%, non condensing
Power Supply Requirements: 24 VDC, 1.1 amp max
Analog Outputs: 4-20 mA (Active); Loop resistance 500 Ohm; Update rate 20KHz, Resolution 12 Bit; Short-circuit, over-current, over-temperature, ESD, and transients protected.
Dimensions: W 0.31 x L 0.40 x D 0.13 meters
Weight: 3.3 Kg
Sensor
Storage Temperature: 1 – 4 °C (33.8 – 39.2 °F)
Operating Temperature*: 4 – 60 °C (39.2 – 140 °F)
Immersion Depth*: 25 feet (7.6 meters.), maximum
Immersion Pressure*: 75 kPa (10.8 psi), maximum
Sample pH Range*: 6.0 to 8.0 Standard Units
Water Velocity: 0.5-5 m/s (1.6 – 16.4 ft/s)
Incompatibility (within proximity to dosing point): Metal salts – based coagulants, polymers, disinfectants, prolonged exposure to air
Mounting Options: Open channer or in-pipe. Secured by 1.5” NPT threading in sensor body.
Mounting Requirements: sensor electrode must be completely and constantly submerged in water during operation.
Distance (sensor to control panel): 45 meters (150 feet), maximum.
Length: 219 mm
Diameter (measured at widest point): 49.5 mm (1.94 inches)
Scheduled Maintenance: Sensor cleaning every 90 days depending on conditions, sensor and cable inspection every 90 days, no calibration required
(*) Optimal operational ranges, application depending. Can effectively perform outside of optimal range at the discretion of a SENTRY
Client Manager or SENTRY Representative based on a review of local conditions.