Agricultural Waste Management Laboratory Services

The Agricultural Waste Management Laboratory is not longer accepting BMP and ATA samples as of April 15, 2010.

Substrate Characterization:

 


The Agricultural Waste Management Laboratory has the capability to characterize substrate pH, alkalinity, volatile fatty acids, COD, TS, TSS, TDS, VS, VSS, TKN, NH4, Total P, and dissolved reactive P. When a BMP or ATA is requested, sample characterization of pH, TS, VS, and COD is standardly included. Analysis of parameters in addition to those standardly included with a BMP or ATA is available upon request. Please contact us for additional information (Robert Burns, rburns@iastate.edu, 515-294-4203; Lara Moody, lmoody@iastate.edu, 515-294-7355).

Biochemical Methane Potential Assays (BMP):

 


Biochemical methane potentials were developed to determine the anaerobic degradability of a given material (Owen et al., 1979). Biochemical methane potential assays can be used to 1) determine the concentration of organics in a wastewater that can be anaerobically converted to CH4, 2) to evaluate the potential efficiency of the anaerobic process with a specific wastewater, 3) to measure residual organic material amenable to further anaerobic treatment, and 4) to test for non-biodegradables remaining after treatment (Speece, 1996). The BMPs performed by the Iowa State University Agricultural Waste Management Laboratory at are a modified version of the ISO-11734 Water quality evaluation of the ultimate anaerobic biodegradability of organic compounds in digested sludge method by measurement of biogas production.

Prior to BMP trial setup, the sample is characterized for pH, chemical oxygen demand (COD), total solids (TS), and volatile solids (VS). Then, an aliquot of the sample is placed in a serum bottle with anaerobic inoculum. The inoculum is from a source maintained in the Agricultural Waste Management Laboratory. The head space in the serum bottle is purged with nitrogen and carbon dioxide gas to establish anaerobic conditions, and the sealed serum bottle is then placed on a shaker and incubated under mesophilic (35°C) conditions for 30 days. Each assay is performed in triplicate. Biogas production and biogas methane content are measured daily. This report completed at the conclusion of the assay provides the analyzed characteristics of the substrate material, the daily and cumulative biogas and methane production, daily biogas methane content of each bottle in the assay, biogas and methane production normalized per gram of VS, and the extent of anaerobic biodegradation in the sample.

Cost and Sample Handling:
The cost of each substrate assayed in triplicate for a 30-day BMP is $500. Payment is due at the time samples are submitted for analysis. Iowa State University policy requires customers to pay in advance of any specialized testing.

Prior to shipping samples for analysis, please contact us (Robert Burns, rburns@iastate.edu, 515-294-4203; Lara Moody, lmoody@iastate.edu, 515-294-7355) to make the necessary arrangements. We will then email you an invoice so you can submit the payment at the time of sample shipping. For the assay, please express mail 2 liters of each material (substrate) to be analyzed. Do not send the samples on a Friday, as we will not receive delivery of them until the following Monday. Samples should be pre-cooled and shipped with ice in a small cooler. Ice in the shipping container should be placed in a sealable bag or frozen in a sealable container. Ship the samples to the address as indicated on the invoice. Important: Notify us by email when the sample has been sent and provide us with a tracking number in case it does not arrive at the expected time.

Anaerobic Toxicity Assays (ATA):

 


While BMP assays provide information about potential digestibility and methane production, they are not a good indicator of substrate toxicity. In BMPs, the substrate can be greatly diluted (thus reducing toxic effects), and if gas production is suppressed, it may not be noted without assaying multiple substrate concentrations together. An Anaerobic Toxicity Assay (ATA) is the method that has been developed to determine the inhibition of gas production by a given substrate. An ATA can be used to predict the likely effect of a test material on biogas production in anaerobic digesters. However, only longer tests which simulate working digesters more closely (such as a bench scale reactor) can indicate whether adaptation of the microorganisms to the substrate can occur or whether compounds likely to be adsorbed onto sludge can build up to a toxic concentration over a longer period than allowed in the ATA (ISO-13641-1, 2003). The ATAs performed by the Iowa State University Agricultural Waste Management Laboratory are a modified version of ISO-13641-1.

Prior to ATA trial setup, the sample is characterized for pH, chemical oxygen demand (COD), total solids (TS), and volatile solids (VS). Aliquots of anaerobic inoculum and a degradable substrate are assayed alone and simultaneously with a range of 7 mass concentrations of the test material. The inoculum is from a source maintained in the Agricultural Waste Management Laboratory. The head space in the serum bottle is purged with a mix on nitrogen and carbon dioxide gas to establish anaerobic conditions, and the sealed serum bottle is then placed on a shaker and incubated under mesophilic (35°C) conditions. Each of the 7 toxicity assays is performed in triplicate. Biogas production and biogas methane content are measured daily. The percentage inhibition of methane production is calculated from the amounts produced in the respective test and control bottles.

Cost and Sample Handling:
The cost of each substrate ATA completed in triplicate is $3500. Payment is due at the time samples are submitted for analysis. Iowa State University policy requires customers to pay in advance of any specialized testing.

Prior to shipping samples for analysis, please contact us (Robert Burns, rburns@iastate.edu, 515-294-4203; Lara Moody, lmoody@iastate.edu, 515-294-7355) to make the necessary arrangements. We will then email you an invoice so you can submit the payment at the time of sample shipping. For the assay, please express mail 2 liters of each material (substrate) to be analyzed. Do not send the samples on a Friday, as we will not receive delivery of them until the following Monday. Samples should be pre-cooled and shipped with ice in a small cooler. Ice in the shipping container should be placed in a sealable bag or frozen in a sealable container. Ship the samples to the address as indicated on the invoice. Important: Notify us by email when the sample has been sent and provide us with a tracking number in case it does not arrive at the expected time.

Bench Scale Reactor Studies:

 


During BMP assays, material being tested is diluted by other assay additives; this dilution effect can mask toxicity issues. Additionally, BMPs are a batch loaded feed limited process; while they provide critical information, they are not continuously loaded processes and as such the results may not be representative of actual continuously fed digesters. Anaerobic Toxicity Assays are used to determine the likely effect a given substrate could have on gas production, but they don’t necessarily account for the potential of bacteria acclimation to a toxicant or build up of the material in the sludge to toxic levels. Therefore, bench scale studies are often used to optimize substrate loading and other digester parameters. Bench reactors can be run in a continuous or semi-continuous mode and will not mask potential toxicity as a result of dilution. Bench reactors allow development of potential feedstock combinations on a small scale prior to use in a full scale digester. In the event of negative results due to a feed stock combination during bench, the bench scale system can easily be restarted.

If you are interested in working with our laboratory on bench scale systems, please contact us for additional information (Robert Burns, rburns@iastate.edu, 515-294-4203; Lara Moody, lmoody@iastate.edu, 515-294-7355).

Pilot Scale Process Testing:

 


After complete bench scale reactor testing, pilot scale process testing can be utilized to assess a selected process at 5-10% of full scale. This approach allows better understanding of how the selected process will operate at full scale by removing scaling issues that may be present at smaller lab scale studies. It also allows testing of the substrate and effluent handling systems that would potentially be used in a full scale process.

If you are interested in working with our laboratory on pilot scale systems, please contact us for additional information (Robert Burns, rburns@iastate.edu, 515-294-4203).

Manure and Agricultural Waste Digesters: Process Selection Studies

 


Selection of a manure or agricultural waste digester type and the associated equipment and waste handling system is key to correct functioning of a full scale digester. These selections are dependent on multiple facility and wastewater characteristics. ISU Agricultural Waste Management Lab can provide you with assistance in selecting at appropriate digester type based on the selected feedstocks for your planned digester. Substrate characterization, biochemical methane potentials, anaerobic toxicity assays, and bench scale reactor testing can all be utilized to support development of the digestion process selection study.

As a university, we can provide an un-biased opinion of your project’s options. If you are interested in working with the ISU Agricultural Waste Management Lab to develop a process selection study for your project, please contact us for additional information (Robert Burns, rburns@iastate.edu, 515-294-4203).

Manure and Agricultural Waste Digesters: Trouble Shooting

 


Agricultural waste and manure digester owners and operators may require specialized assistance if their digester experiences lower than expected biogas and CH4 yields, manure or wastewater pumping or handling difficulties, unexpected O&M requirements, poor process control, un-planned for equipment or technology failures, and/or poor digester performance. These issues can result from misunderstanding of the physical and biological processes, insufficient system management procedures, lack of information, lack of funds, and/or improperly or inappropriately installed equipment and technologies. Anaerobic digesters require large capital investments, and closure or abandonment of digester systems should not be considered lightly. Effective trouble shooting of a digester system may head off catastrophic digester failures or may be a useful step to evaluate the system before the decision is made to close a system. The full capabilities of the Iowa State University Agricultural Waste Management Lab can be utilized to assist you with you digester issues.

As a university, we can provide an un-biased opinion of your project’s issues and help you identify possible solutions for your digester. If you are interested in working with the ISU Agricultural Waste Management Lab to trouble shoot your digester, please contact us for additional information (Robert Burns, rburns@iastate.edu, 515-294-4203).