What is Live Core Drilling? Non-Invasive Sampling for Anaerobic Digesters
Live core drilling is a specialist technique used to extract samples from anaerobic digesters while they remain in full operation. Unlike traditional sampling methods that often require shutting down the system or opening manways, this process allows operators to take accurate, representative samples without interrupting biogas production.
Why does this matter? Anaerobic digesters are sensitive environments where any disruption can upset microbial balance, reduce gas output, and even cause costly downtime. Live core drilling avoids these issues, helping operators maintain efficiency and safety while gaining the insights they need.
In this article, we’ll explore what live core drilling is, how it works, and why it has become an essential tool for AD plant operators and engineers.
What is Live Core Drilling?
Live core drilling is a controlled method of removing a cylindrical sample—or “core”—of digestate material from an anaerobic digester that is actively operating. The term “live” refers to the fact that the process takes place without shutting down the digester or disturbing its biological activity.
This technique plays a crucial role in the anaerobic digestion process because it allows plant operators to analyse what’s happening inside the digester in real time. It’s considered non-invasive because it doesn’t compromise the digester’s integrity or introduce oxygen, which would harm the anaerobic microbes responsible for biogas production. Instead, the process is designed to keep the system sealed, safe, and fully operational throughout.
How Does Live Core Drilling Work?
Live core drilling relies on specialist equipment and carefully planned procedures to ensure safety and accuracy:
Specialist Equipment
A hollow, cylindrical drill—known as a core drill—is used to penetrate the digester wall and extract a sample. These drills are designed for this purpose, ensuring a secure fit and controlled cutting process.
Maintaining System Integrity
A gas-tight seal is critical during drilling. This seal prevents the escape of biogas and stops oxygen from entering the system, both of which could disrupt the anaerobic process or create safety hazards.
A Non-Disruptive Process
Unlike traditional methods that may require emptying or depressurising the tank, live core drilling allows samples to be collected without exposing the digestate to air. The digester continues running as normal, meaning no downtime, no contamination, and no risk to performance.
Why Non-Invasive Sampling Matters
Process Monitoring
Accurate data is the foundation of an efficient anaerobic digestion process. Operators regularly monitor parameters such as pH, volatile fatty acids, solids content, and FOS/TAC ratios to maintain a stable system and optimise biogas yield. Live core drilling provides access to the digester’s contents without disturbing its operation, giving engineers the information they need to keep performance on track.
Representative Results
Traditional sampling methods often involve drawing material from ports or manways, which usually only captures liquid from the surface or near the walls. This can lead to misleading results because digesters are stratified—conditions can vary significantly from the top layer to the bottom. Live core drilling solves this by retrieving a vertical core sample that represents multiple layers, providing a more accurate picture of what’s happening inside the tank.
Safety and Efficiency
Taking a digester offline for sampling is not only time-consuming but can also create hazards for staff, such as exposure to harmful gases or confined space entry. Live core drilling eliminates these risks by maintaining sealed conditions throughout the process, ensuring the safety of operators while avoiding costly downtime.
Key Applications in Anaerobic Digestion
Sampling for Analysis
Core samples collected during live drilling are used for chemical and microbiological testing. These insights help operators understand feedstock breakdown, nutrient levels, and microbial health, all of which are crucial for consistent biogas production.
Troubleshooting Issues
When performance drops or unexpected conditions arise, live core drilling allows targeted investigation. Engineers can assess stratification, detect scum layers or sediment build-up, and even identify foreign materials—all without draining the digester.
Installing Equipment
Beyond sampling, live core drilling creates safe entry points for adding new components like sensors, pipework, or mixing systems. These upgrades can be completed without emptying or depressurising the tank, saving significant time and resources.
Optimising Performance
By enabling regular, representative sampling, live core drilling supports ongoing process optimisation and research. It helps plant operators make informed adjustments, improving efficiency and resilience in the long term.
Techniques and Safety Protocols
Live core drilling is a highly controlled process, carried out under strict safety measures to protect both personnel and plant operations:
Gas-Tight Seals and ATEX Compliance
Specialised equipment ensures that no biogas escapes and no oxygen enters the system. All tools and procedures adhere to ATEX standards for explosive atmospheres.PPE and Hazard Awareness
Operators wear specialised personal protective equipment and follow protocols for working around hazardous gases such as methane and hydrogen sulphide.Targeted Depth Drilling
Drilling can be directed at specific layers—surface, mid-depth, or near the tank floor—depending on what data is needed. This flexibility allows precise analysis of stratification or sludge accumulation.Trained Specialists Only
Due to the complexity and risks involved, live core drilling is performed exclusively by qualified professionals with experience in anaerobic digestion systems and strict adherence to safety regulations.
Alternative Non-Invasive Monitoring Methods
While live core drilling is one of the most effective ways to gather representative samples, other non-invasive methods are emerging to complement it:
NMR (Nuclear Magnetic Resonance)
NMR technology allows for rapid, non-destructive analysis of organic waste samples. It helps assess gas production potential and key chemical properties without removing material from the digester.Ultrasonic Techniques and Process Analytical Technologies (PAT)
These tools can measure the digester’s internal conditions—including solid, liquid, and gas phases—through the tank wall. They provide real-time insights without breaching the system, making them valuable for continuous monitoring.
Although these methods are promising, they often work best when paired with physical sampling through live core drilling, which offers detailed data and flexibility.
Benefits of Live Core Drilling
No Downtime – Sampling and installations are completed without interrupting the digester’s operation.
Accurate, Representative Samples – Accessing multiple layers provides reliable insights for process control.
Enhanced Safety – Eliminates confined space entry and minimises exposure to hazardous gases.
Operational Efficiency – Supports troubleshooting, equipment upgrades, and ongoing optimisation without costly delays.
Conclusion
Live core drilling has become an essential tool for anaerobic digestion plants. By offering accurate, representative samples without downtime or disruption, it helps operators optimise performance, troubleshoot problems, and keep their systems safe and efficient.
If you’re looking to improve your plant’s reliability and output, consider incorporating live core drilling into your maintenance and monitoring strategy.
Ready to give your digester performance a boost?
Live core drilling is the safest, most efficient way to get accurate data without interrupting your plant’s operation.
Get in touch with our expert team today to learn more about our live core drilling services and how we can help optimise your anaerobic digestion process.
