Food Waste and Anaerobic Digestion

It’s Farm Safety and Health Week from September 15th-21st. One factor often ignored but important to the safety and hygiene of our environment is food waste disposal. Hartford Steam Boiler insures Anaerobic Digesters (AD), equipment able to process this waste.

Food waste is generated from restaurants, grocers, academic institutions, and other places where food is handled or processed. Food products could be classified as waste for a variety of reasons, but the most likely reason is that the food is unfit for human consumption.

Instead of trucking the food-waste to the local landfill, it’s increasingly being processed at a regional AD. Here, the product is digested and recycled to produce energy and high-grade fertilizer.

What is an Anaerobic Digester?

The Anaerobic Digester is a huge tank with a rubber dome that accepts truckloads of waste. In the tank, the food waste breaks down with the help from biological enzymes and the right temperature. The digestion process acts very similarly to the way your stomach breaks down food. Though in the AD process, the methane produced is vented to a diesel engine for the generation of electricity.

Although there are food waste-specific Anaerobic Digesters, more commonly the food waste is usually a supplemental ingredient, or feedstock, to an agriculture AD. Quite often, the existing ADs in the region are built on a farm that has a primary ingestion of animal waste. The processing of animal waste is a good way for the farmer to reduce the odorous smell on the farm, while simultaneously generating electricity and heat from the engine that burns the methane fuel produced in the AD. Dairy cows are most common, but hog and poultry farms also seek the benefits of having an Anaerobic Digester.

While the waste from the animals on the farm produce feedstock quite consistently and regularly, the supplemental food waste can be seasonal. Think of a city with a football stadium that supplies food waste to the Digester. The feedstock in the AD would be quite different in the autumn versus springtime so, just like a stomach, the AD can have digestion problems. That means amounts and mixes of the various food wastes have to be known and controlled.

So remember, if there is a rubber dome on a large tank at a farm, chances are the local market’s food waste is helping that farmer generate electricity while keeping food waste out of the landfill.

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© 2019 The Hartford Steam Boiler Inspection and Insurance Company. All rights reserved. This article is for informational purposes only and is not intended to convey or constitute legal advice. HSB makes no warranties or representations as to the accuracy or completeness of the content herein. Under no circumstances shall HSB or any party involved in creating or delivering this article be liable to you for any loss or damage that results from the use of the information contained herein. Except as otherwise expressly permitted by HSB in writing, no portion of this article may be reproduced, copied, or distributed in any way. This article does not modify or invalidate any of the provisions, exclusions, terms or conditions of the applicable policy and endorsements. For specific terms and conditions, please refer to the applicable endorsement form.

Noel Skwiot

Principal Mechanical Engineer at Hartford Steam Boiler, with over 30 years in industrial equipment design and support.

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