1 / 23

Biodegradation in Landfills: Methane Production

Methane and Landfills. Aren't we recycling most of the paper that we throw away?Why are Landfills anaerobic?Methane ExperimentMeasure the methane production from various landfill components under various conditionsCompare the energy value of the methane with the energy value of the original wast

mercer
Download Presentation

Biodegradation in Landfills: Methane Production

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

    1. Biodegradation in Landfills: Methane Production

    2. Methane and Landfills Aren’t we recycling most of the paper that we throw away? Why are Landfills anaerobic? Methane Experiment Measure the methane production from various landfill components under various conditions Compare the energy value of the methane with the energy value of the original waste Issues... pH, pressure monitoring, inoculum

    3. Solid Waste Composition in 1994 as Generated (US averages)

    4. Landfills... Will continue to be the disposal option of choice Require long term monitoring ________________ ____________________________ _________________ ____________________ Why does gas production continue long term? Why is much organic matter preserved?

    5. Why are Landfills anaerobic? Why are landfills warm? (Average temperature of Fresh Kills Landfill is 29.4 °C) Follow carbon flow... Methane Production

    6. Cap System

    7. Experiment Setup

    8. pH control... High partial pressure of CO2 ? ____ pH Anaerobes require a pH between 6.5 and 7.5 Remember ANC... Volatile or Non-volatile system?

    9. How much ANC do we need?

    10. ANC Problem How much ANC is needed to maintain a neutral pH if the pressure is atmospheric and the CO2 fraction is 30%?

    11. ANC Problem If serum bottles have that much ANC what will the pH be if the CO2 pressure doubles?

    12. Inoculum We need a few good anaerobes... Where could we recruit? How do we choose inoculum size?

    13. Sample Size What happens if you put ź of a graham cracker into a 120 mL serum bottle with 60 mL of water and some inoculum and seal it? Estimate mass of carbohydrates at 4 grams Moles of carbohydrates – 30 g/mole _____ 0.133 moles C

    14. Samples for Analysis Bring 1 sample per person for methane production Ideas… ________________ ________________ ________________ ________________ ________________ ________________ ________________

    15. Pressure Sensors Transduce pressure into a voltage! Use Strain Gages Design of piezoresistive strain gages Sensor output Signal Conditioning Calibration

    16. Strain gage What happens to the resistance thru the strain gage if it is stretched in the y direction? ________________ In the x direction? ________________ Strain gage can be made of wire that is then bonded to the objected that is undergoing strain Or diffused into a crystalline silicon diaphragm (___________)

    17. Piezoresistive Diaphragms

    18. Pressure Sensor Failure High pressures – rupture crystal (beware of resulting leak!) Water hammer – High speed pressure waves (speed of sound) Result from flow transients such as rapidly shutting valves Install pressure snubber! Incompatible materials

    19. Absolute vs. Gage vs. Differential Absolute Port 2 sealed with vacuum on bottom side of silicon crystal Gage Port 2 open to atmosphere Differential Both ports connected to system

    20. Pressure Sensor Applications Many! Level monitoring of municipal water tanks Gas tank gage Various flow meter devices (orifice, Venturi) Stream gage (USGS) Instrumentation (Gas and Liquid Chromatographs)

    21. Pressure Sensor Signal Conditioning Full scale voltage output from the bridge circuit may be in the range of 10 to 100 mV. This low voltage may need amplification before being measured by a data acquisition system Limit cable length and beware of noise from power cables! Time average to reduce noise

    22. Pressure Sensor Calibration Sensor output should be linear Calibration involves determining the slope and intercept Subtract the voltage obtained under conditions of zero pressure (offset) to get an intercept of zero The slope can be determined by applying different pressures to the sensor and measuring the resulting voltages Multiply the remaining voltage by the slope

    23. Pressure Sensors Summary Based on a small change in resistance due to a change in dimension (strain gage) Commonly used to monitor industrial and environmental processes Easily monitored using data acquisition systems

    24. Pressure Complications… Pressurized serum bottle Placed in incubator and monitored Why does pressure increase initially?________________ What are the short term fluctuations?_______________________________ What are the long term fluctuations? ____________

More Related