Here’s how ActiSense delivered a real-time VFA signal that could be related to organic loading, giving operators sufficient lead time to intervene and prevent imbalance.
Client Overview
Location: Massachusetts, USA
Facility Type: 1 MW dairy farm anaerobic digestion facility
Digester Configuration: Continuous stirred-tank reactor (CSTR)
Feedstock: ~10–15% manure, balance organic food waste
Annual Throughput: ~42,400 tonnes
Energy Use: Biogas converted to electricity via CHP
Improved Digester Stability and Operational Control
ActiSense delivered a real-time VFA signal that could be related to organic loading, giving operators sufficient lead time to intervene and prevent imbalance.
Event 1 – April 2024
The facility received ~15,000 gallons of waste derived from ice-cream topping manufacturing (including fudge, caramel, and fryer oil residues).
- ActiSense detected a clear biological response
- Despite elevated VFA signals, the digester successfully assimilated the waste
- No process disruption or upset occurred
Figure 1: ActiSense web dashboard showing high VFA detected due to addition of ice cream topping waste to the digester
Event 2 – September 2024
During overnight operation, ActiSense detected an unexpected change in biological activity on the feed line.
- An operational error was identified
- Operators proactively reduced organic loading by ~25%
- A potential digester upset was avoided
These events demonstrate ActiSense’s role as an early-warning indicator, enabling corrective action before system stability is compromised.
Figure 2: ActiSense web dashboard showing an unexpected change in biological activity
Performance Outcomes
Biogas Production
Within two months of implementing ActiSense:
- Average biogas production increased by over 150%
- Output rose from ~161,000 cf/day (February 2024) to ~416,000 cf/day (August 2024)
This improvement occurred alongside improved process visibility and control, rather than through aggressive loading strategies alone.
Figure 3: Increased biogas production levels with ActiSense sensors installed
Reduced Manual Sampling
Correlation between laboratory-measured VFAs and ActiSense real-time signals confirmed the reliability of the sensor output.
As a result:
- Manual sampling frequency was reduced by up to 60%
- Operators gained faster, more actionable insight into digester health
- Decision-making shifted from reactive to proactive
Figure 4: Correlation between lab-measured VFA levels and ActiSense sensor real-time VFA levels
Economic Impact
Based on observed operational improvements:
- Upset prevention avoided downtime and recovery events, saving an estimated $25,000–$40,000 per year
- Reduced manual sampling lowered labour and laboratory costs by approximately $15,000–$20,000 per year
- Increased biogas production translated to an estimated >$100,000 annual revenue uplift, depending on energy pricing and utilisation
Key Takeaways
ActiSense provides real-time biological visibility that allows operators to detect instability early, respond with confidence, and maintain stable digestion performance under highly variable feedstock conditions.
Rather than replacing existing laboratory analysis, ActiSense complements it — enabling faster decisions, reduced operational risk, and more resilient plant performance.