Non-commercial and Home Biodiesel Waste
Waste Management - Solid and Hazardous Waste
The three "Rs" of resource conservation are: Reduce, Reuse and Recycle. These are the most effective ways to not generate waste. Most biodiesel plants will probably generate some quantities of waste. Some of the waste will be considered a "solid waste," subject to Subtitle D of the Resource Conservation and Recovery Act (RCRA). Such waste is regulated by state and local authorities with jurisdiction over the facility. Some of the solid waste could be "hazardous waste," subject to Subtitle C of RCRA. Hazardous waste will be regulated by the same state authorities and EPA as well. In Alaska and Iowa, only EPA regulates hazardous waste.
Exemption From Hazardous Waste Regulation
The regulations for hazardous waste provide certain exemptions for very small facilities. Household hazardous waste (HHW) is specifically exempt from hazardous waste regulations, although household waste may be regulated by local and state authorities as a solid waste. The HHW exemption applies only to households and not businesses. For a home-scale biodiesel plant to remain exempt from hazardous waste regulations, the produced biodiesel must not be sold or used in a commercial enterprise by the homeowner.
An example would be someone making biodiesel in their garage. If they used the biodiesel in their own commercial vehicle, such as a delivery truck or taxi, the facility would be subject to hazardous waste regulations. If they used it in their personal car for commuting or personal activities only, the biodiesel plant would be eligible for the HHW exemption. Not-for-profit agencies, such as churches or municipalities that operate a biodiesel plant, would not be eligible for the HHW exemption since they do not meet the definition of a household.
Businesses or not-for-profit entities that operate very small plants are likely subject to the much less stringent "conditionally exempt small quantity generator" (CESQG) hazardous waste regulations. If the facility generates less than 100 kg (220 lbs) of total combined hazardous waste per month and stores no more than 1,000 kg (2,200 lbs) of total combined hazardous waste at any one time, it qualifies for the CESQG exemptions. A CESQG must still determine if its waste is hazardous and properly dispose of it, but the paperwork, reporting, and management burden is much lighter. If your facility is a CESQG or larger, you should consult EPA Region 7's Biodiesel Production Facility Compliance Manual: Environmental Laws Applicable to Construction and Operation of Biodiesel Production Facilities (PDF) (144 pp, 6.4MB, About PDF).
Typical Hazardous Wastes at a Biodiesel Plant
Below is a list of materials commonly found at a biodiesel plant that may be hazardous. Each plant is responsible for determining if each waste stream is hazardous and managing it appropriately.
Spent Filter Media
Spent filter media such as diatomaceous earth, filter aid, and socks can be ignitable (D001). EPA has observed that spent filter media with high moisture content (from oil or biodiesel) can spontaneously combust. It is the responsibility of the facility to operate its plant in a manner that will not generate ignitable waste filter media. If the material is hazardous, the facility may manage the ignitable waste as a useful product and avoid RCRA regulation. Using the waste as a fuel is not a legitimate use under the regulations, unless the fuel is an actual product that results from the process. The facility may also dispose of the ignitable filter media as a hazardous waste at a permitted treatment, storage or disposal facility. If the waste filter media is not hazardous, the facility may manage it as a solid waste.
Waste glycerin can be ignitable (D001) or corrosive (D002), or both. Typically, waste glycerin is not a hazardous waste. However, EPA has observed that sometimes waste glycerin will contain sufficient quantities of unrecovered methanol to make the waste glycerin ignitable or enough catalyst to make it corrosive. Further refining or sale of the crude glycerin as a product will remove the material from regulation under RCRA, but could also invalidate the household hazardous waste exemption. The facility should take care if methanol levels in the glycerin are high, as it will still be a hazardous material until the ignitable characteristic is addressed. The same principle applies to corrosiveness caused by excess catalyst. It should also be noted that glycerin has a very high biochemical oxygen demand. While this does not make it a hazardous waste, it does present a threat to streams and lakes if disposed upon the land. This could also disrupt the wastewater treatment system's biological process into which the waste glycerin is disposed.
Spent or Unused Catalyst
Catalysts (and catalyst neutralizers) used in biodiesel production are acidic or caustic, thus the waste is potentially corrosive (D002). Any spent catalyst (or other waste material) with a pH greater than or equal to 12.5, or less than or equal to 2, is a hazardous waste. Like waste methanol, waste catalyst is not subject to RCRA if it is returned to the process in a closed-loop system, but it would be a hazardous waste outside a closed-loop system until it was returned to the process.
Wastewater disposed under the authority of a valid Clean Water Act (CWA) permit is not regulated under RCRA. However, if wastewater contains a listed hazardous waste or exhibits a hazardous characteristic, it must be managed as a hazardous waste until treated or disposed in the CWA-permitted process. Biodiesel wastewater could be hazardous if it has high or low pH from catalyst disposed in the wastewater, contains high concentrations of methanol that would make it ignitable, or contains other listed or characteristic wastes.
Spent or Unwanted Laboratory Chemicals
A variety of chemicals are used in laboratories. If these chemicals are listed as a hazardous waste or fail the Toxicity Characteristic Leaching Procedure (TCLP) toxicity levels at 40 Code of Federal Regulations (CFR) Section 261.24, they are a hazardous waste when disposed. Some unused chemicals destined for disposal may be P-listed (40 CFR Section 261.33) and thus "acute hazardous wastes." When calculating monthly waste generation rates, one kilogram of P-listed wastes generated during a month will make the facility a large quantity generator.
Spent Parts Washing Solvents
Many solvents are ignitable and/or F-listed (40 CFR Section 261.33). The generator should examine what solvents are used and consider using solvents that do not meet the definition of hazardous.
Aerosol cans are considered reactive hazardous waste (D003) in some jurisdictions because they can explode. To properly handle aerosol cans so they are not hazardous waste, the facility should employ a can-puncturing device that will collect the contents of the cans. The facility should then determine if the accumulated materials from the aerosol cans are hazardous. The empty punctured cans may then be recycled to recover the metal.
EPA has regulations (40 CFR Part 279) that address used oil separately from hazardous waste. Used oil may be a hazardous waste, but the used oil regulations assume the material will be handled separately from the hazardous waste and thus recycled. All used oil is assumed to fail the contaminant specifications listed in the regulation. A facility may burn its own used oil and do-it-yourself used oil in an on-site space heater. It may not burn used oil from other facilities or send its used oil to another facility to be burned, unless that facility is permitted to burn used oil or the used oil is proven to meet the specifications in 40 CFR Section 278.11. The regulations are written to encourage the recycling of used oil. For example, farmers are considered to be do-it-yourself used oil generators if they generate less than 25 gallons per month.
Universal Waste Lamps
Fluorescent lamps and some other types of lamps contain mercury and may fail the TCLP test. The facility may manage their lamps as hazardous waste or they may follow the Universal Waste regulations at 40 CFR Part 273, which are designed to promote recycling by allowing less strict regulation of the material. The lamps should be managed in labeled, dated and closed containers that are structurally sound and sent by approved transporters for recycling.
Universal Waste Batteries
Waste batteries may contain lead and other metals that would fail the TCLP test. There are Universal Waste regulations for batteries similar to the waste lamp regulations.