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Be mindful of anaerobic digester safety risks

Melissa VanOrnum Published on 30 October 2015

Dairy farming is a risky business on many levels. With almost every decision, a dairyman must weigh the personal, societal, environmental and financial risks. Not to mention all the potential impacts the decisions may have on the well-being of workers, neighbours and animals.

Anaerobic digesters help minimize many of the societal and environmental risks that are inherent to a dairy operation – by greatly reducing odour, pathogens and BOD/COD levels in manure as well as reducing the likelihood of nutrient runoff.

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By providing additional revenue streams, such as increasing crop yield with the spread of digested liquid, they can help a farmer manage the volatility of the dairy industry. However, the day-to-day operation of an anaerobic digester does not come without its own risk potential.

Most of the safety risks associated with the typical day-to-day operations of an anaerobic digester are similar to the everyday safety risks found on farms. It is important that those working on or near the digester system wear appropriate personal protective equipment.

Depending on the task at hand, such equipment may include steel-toed boots, gloves, hard hats, hearing protection, safety glasses and face shields. Also, safety guards must never be removed when a tool is being used.

Slips, trips and falls are safety concerns at a digester site just as they are anywhere on a dairy. Falls are the second leading cause of injury at work, sending more workers to the hospital than any other injury. Basic solutions to prevent falls include:

1. Wear the correct footwear for conditions. (Older boots have poor traction; shoes should be slip-resistant, etc.)

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2. Clean up spills as soon as possible if not immediately.

3. Keep walkways, stairways and exits clear.

Every farmer knows that working with electricity can be hazardous, even at very low voltages. Under the right conditions, even a 30-volt circuit can carry enough current to cause severe injury or death.

An electrical shock occurs when your body comes in contact with a live electrical source such as open electrical boxes, bare wires or from equipment that is not properly grounded.

A person who has been shocked may seem to have no lasting ill effects; however, nervous system damage may not be readily apparent for hours after the event. Anyone who receives even a mild shock should immediately see a qualified physician for a medical check.

When working on a certain piece of equipment, it is important to isolate the machine by implementing lock-out, tag-out procedures to ensure safety.

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If someone is working on electrical wiring in the digester building, the best way to limit exposure for electrical shock is to turn off the main disconnect to the building. If you are unsure where or how to do this, call your utility for guidance.

Manure handling is an especially dangerous aspect of dairy farming. Whether it’s a raw manure pit or a digester, precautions should be taken to prevent unhealthy exposure to gases.

The gases of most concern are carbon monoxide, hydrogen sulfide, ammonia and methane. Proper ventilation is especially important for confined spaces or buildings.

Never go into a manure pit or confined space after someone or without proper equipment. Bottom line: If you are unsure of the environment, stay out.

Anaerobic digesters produce biogas, which on dairy farms is generally comprised of roughly 60 percent methane and 40 percent carbon dioxide, or CO2. From a fire perspective, carbon dioxide is helpful in that it acts as a natural flame retardant.

Under normal operating conditions, an anaerobic digester cannot create the necessary environment for a fire. A fire requires oxygen – an aerobic environment. Anaerobic digesters lack oxygen. Therefore, a digester fire can only occur if the state of the digester is altered.

That being said, fire is still a danger to contend with, whether it is in the digester building or elsewhere on the farm. “No Smoking Allowed” signs should be on display in multiple locations. If someone is smoking, be sure to have him or her extinguish the cigarette immediately.

In the event of a fire, locate the main disconnect and shut off the power supply to the building as well as the main gas line valve, if possible. A fire in a digester building should be fought as would any industrial fire.

While every digester operator should receive training to operate an anaerobic digester system, no special qualifications are needed for the normal daily operations. However, qualified individuals should do certain repairs and maintenance.

For example, an individual trained and certified in confined-space entry should do any repairs needed to be performed inside a confined space. Such an individual will carry a properly calibrated gas meter and respirator and will know how to monitor and assess air quality in the space.

They will also be trained to properly ventilate the space, either naturally or mechanically. Once again, if you are not certified to enter a confined space, you have no business entering one or directing someone else to enter. Leave the work to a professional.

There are hundreds of digesters currently operating in North America and with a great track record for safe operation. But all agricultural equipment has associated operating risks.

With proper training, equipment and maintenance – plus the all-important healthy dollop of common sense – risks associated with operating an anaerobic digester can effectively be mitigated.  PD

Melissa VanOrnum
  • Melissa VanOrnum

  • Marketing Manager
  • DVO, Inc.
  • Email Melissa VanOrnum

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