Research to Improve Compost Facility Air Emissions Permitting

Investigator: Engineered Compost Systems (ECS)

Start Date:
Feb 2021

Award Amount:

The waste management industry is increasingly caught between mandates to recycle more organics through composting and ever more stringent environmental regulations. Air emissions are a critical component in the permitting process of every large compost facility in the US. Volatile organic compound (VOC) emission factors (EFs) commonly used by regulators throughout the US to calculate the expected emissions were developed in California 10+ years ago using a random collection of source test results. One of the most widely used EF’s (SCAQMD 1133-3) is 5.71 lb VOC/ton of mix, which triggers an EPA Title V air permit designation for facilities composting as little as 35,027 tons per year of feedstocks. This EF overestimates the VOC emissions of a well-designed and operated compost facility by factors of 10 to 100. High EFs are key drivers in the cost and complexity of permitting, add requirements for expensive source tests and purchase of VOC off-sets, and cause throughput limitations and the long-hauling of organic waste. Fortunately, the composting key performance indicators (KPIs) that result in low VOC EFs are the same that result in low odor emissions and higher process efficiency and can be used to predict emissions. What is lacking is a scientifically rigorous data set that can be disseminated to regulators to increase their knowledge and give them the evidence to relax their EFs and focus on the KPIs that truly impact air emissions.

The primary objectives of this project are:

  1. Demonstrate low VOC EFs and correlate to easily measurable process KPIs
  2. Demonstrate how process design and operations determine KPIs
  3. Provide regulators, and process designers, with a technology-agnostic guideline to predict and produce low VOC EFs