tributaries, received a report of a fish kill in September 2006 that stretched 20 miles
Figure 1. Price trend of crude glycerin from September 2009 to August 2011 (Source: The Jacobsen publishing company).
downstream from Moundville, Alabama. Riverkeeper found oil around the dead fish, and reported at least 24 occasions where oily material was spotted in the water near a biodiesel plant .
In July 2006, a group of golfers on the Meadow Hills Golf Course in Iowa Falls, Iowa, was startled to see dead fish and a milky colored discharge in School Creek, which runs along the course. A subsequent investigation by the Iowa Department of Natural Resources traced the discharge to a biodiesel plant and glycerin refinery. A contractor allegedly disposed of a sludge wastewater mixture from the facilities at a recycling site that seeped into the creek. The biodiesel plant entered into a partial consent order with Iowa and paid a $100,000 fine for the pollution, without admitting fault .
In October 2007, an anonymous caller reported that a tanker truck dumped “milky white goop” into Belle Fountain Ditch, one of the man-made channels that drain Missouri’s Bootheel region. Federal and state responders found decomposing glycerin and methanol generated from a biodiesel plant near Hermondale, Missouri. In January 2008, a grand jury indicated a Missouri businessman who was involved in the discharge, which killed at least 25,000 fish and wiped out the population of fat pocketbook mussel, an endangered species [26,27].
In many states, officials and opponents discussed the propensities for discharges from biodiesel plants to impact dissolved oxygen levels. Pure glycerin has a Biochemical Oxygen Demand (BOD) of nearly 1,000,000 mg/L . Recovered wash water used in biodiesel processing can have a BOD of 10,000 - 15,000 mg/L, due largely to the presence of glycerin . With such high BOD levels, discharge of wash water, when degraded by bacteria, can deplete the oxygen content in the water, causing fish and other aquatic life to die. Similar oxygen depletion problems can occur in wet soil. Moreover, crude glycerin does not have any fertilizer value, and will tie up soil nitrogen as it decomposes. For this reason there has been little interest in studying land application. Guidance for the disposal of greasy crude glycerin suggests incorporation and loading rates of about four tons per acre as appropriate to avoid choking of soils. For benign land application of glycerin, loading rates must be low, and runoff control is absolutely essential .
The Material Safety Data Sheet (MSDS) categorizes glycerin as an irritant but not necessarily a hazard for humans and animals . Glycerin itself readily degrades in the environment. However, crude glycerin from a biodiesel plant has been described as the wastebasket of the biodiesel process, since much of the oil impurities, methanol and catalyst also go into this phase. These impurities could elevate the environmental risk of crude glycerin. To reduce its environmental impact, it is desir-
Figure 2. Glycerin polluting creek. (Source: EPA report ).
Figure 3. Over 25,000 fish killed in southeastern Missouri, due to illegal dumping of crude glycerin (Source: EPA report ).
able to neutralize crude glycerin, depending upon the catalyst used in biodiesel production .
Nebraska’s Department of Environmental Quality has published a guidance document, which is considered a model in the industry. This document describes a number of factors in considering the potential for a hazardous waste determination, and provides waste management tips for biodiesel plants. High concentrations of methanol and wide variation in the pH of waste materials tilt the determination toward hazardous materials. Alabama has similar provisions in its laws and requires that all waste discharges be performed with the National Pollutant Discharge Elimination System permit from the state. In addition to fining non-complying biodiesel plants, Alabama orders them to undergo a Best Management Practices Review, and issue to the state a report ensuring future compliance. Many states and the federal EPA have declared that willful dumping/disposal of glycerin to surface water is a criminal violation of the Clean Water Act and may subject the violator to fines and criminal enforcement [26-28].
6. Concluding Remarks
In various areas around the world, including arid regions of the Western and Southwestern U.S., dust poses serious and costly air quality problems, including visibility impairment in pristine areas, and local dust nuisance issues. To solve these problems, glycerin is proposed as a potential dust suppressant. There are a number of reports and patents indicating that glycerin can be effective in dust control applications, although detailed protocols of its application and use are generally lacking. Also, standard performance metrics are not available for assessing the effectiveness of glycerin’s dust suppressant behavior.
Steady growth of the U.S. biodiesel industry continues to increase the amount of crude glycerin in the marketplace. The resulting abundance and low price of crude glycerin makes it economically attractive to apply aqueous glycerin solutions in dust suppression. However, the potential environmental impacts cannot be ignored, since damage due to irresponsible discharge of crude glycerin into rivers and wetlands has been reported in several states. Hence, there is a need to thoroughly investigate glycerin and other impurities during application in dust control, and subsequent potential impacts to the environment. Once crude glycerin is verified as an economically and environmentally sound dust suppressant, this could lower the cost of dust control, while improving the overall economics of biodiesel production.
We gratefully acknowledge financial support from the US Department of Energy (DE-EE0000600). The authors also acknowledge meaningful conversations with Dr. Chris Fritsen of the Desert Research Institute (DRI).