2020 Progress Report: Green plasma technology for siloxane removal and landfill gas upgrade

EPA Grant Number: SU839966
Title: Green plasma technology for siloxane removal and landfill gas upgrade
Investigators: Hoque, Shamia , Berge, Nicole D , Farouk, Tanvir
Institution: University of South Carolina at Columbia
EPA Project Officer: Page, Angela
Phase: I
Project Period: October 1, 2019 through September 30, 2020 (Extended to September 30, 2021)
Project Period Covered by this Report: October 1, 2019 through September 30,2020
Project Amount: $24,992
RFA: P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet (2019) RFA Text |  Recipients Lists
Research Category: P3 Awards , P3 Challenge Area - Sustainable and Healthy Communities

Objective:

This proposal addresses the challenge of removing the trace contaminant, volatile methyl siloxanes (VMSs) in a sustainable and economic way through the design and fabrication of a non-thermal plasma (NTP) system, CLnERG (Clean, Renewed, upgraded LFG) for siloxane removal and landfill gas (LFG) upgrade to syngas (H2 + CO).  It will design a non-thermal plasma (NTP) system for siloxane removal and landfill gas (LFG) upgrade to syngas (H2 + CO).   The specific objectives are:

1.    Determine the operating parameters for complete removal of siloxane and maximum conversion of CH4 to synthesis gas (CO + 2H2).
2.    Detailed characterization of the properties and composition of the solids produced and assess influence of operating parameters.
3.    Assess economic feasibility of upscaling the process for industrial application.
4.    Educate future scientists and engineers on designing sustainable solutions emphasizing both economic feasibility and environmental health.

Progress Summary:

The proposed CLnERG (Clean, Renewed, upgraded LFG) technology is a success in terms of siloxane removal from gaseous emissions. The optimum conditions for the removal of siloxanes specifically octamethylcyclotetrasiloxane (D4, C6H18O3Si3) has been established. < 80% of D4 was removed from the gas stream maintaining for the dielectric barrier discharge, peak to peak voltage of 24 kV and at a frequency of 23kHz. The results for octamethyltrisiloxane (L3, C8H24O2Si3) are similar to D4.  The discharge was maintained for one hour. 


Gas flow rates do not significantly influence mass deposited, but exposure to plasma discharge could play a vital role. The DBD-NTP (dielectric barrier discharge-non-thermal plasma) system deposits are mainly polydimetylsiloxanes (PDMS). Smaller chains of molecules were identified in case of L3 compared to D4. The possibility of tailoring those deposits based on exposure time to the plasma discharge is currently being assessed.   
Economic feasibility studies have shown that the cost of generating a plasma discharge is offset by the extra electricity generation possible since associated operation and maintenance costs with respect to siloxane is eliminated.

Future Activities:

1)    Optimum conditions for syngas production while maintaining maximum siloxane removal. The system will be operated using a mixture of gases at different flowrates. The gases used will be helium, carbon dioxide, methane and water vapor at flowrates ranging from 300 sccm to 700sccm.   Gases will be mixed at varying ratios, and two dominant siloxanes, D4 and L3 will be tested. Plasma characteristics will be tailored as well through changing power output and pulse duration.
2)    Analysis will focus on determining the type and quantity of gas generated at the output using gas chromatography-mass spectrometry. Representative solid samples will be analyzed through SEM (scanning electron microscopy) and NMR (nuclear magnetic resonance) spectroscopy to identify if solid characteristics are correlated to plasma discharge conditions.
3)    Economic feasibility studies will be updated based on experimental results. A complete picture of the energy and revenue flow of the proposed technology will be built
4)    CLnERG prototype has been designed. The focus is now going to be on fabrication and trouble shooting.

Journal Articles:

No journal articles submitted with this report: View all 2 publications for this project

Supplemental Keywords:

Waste to value, energy recovery, waste to energy, cost benefit assessment, emission control technologies, environmental justice