Biofilters for mitigation of landfill methane emissions
Lead Research Organisation:
University of East Anglia
Department Name: Environmental Sciences
Abstract
The UK and Europe has a large closed landfill legacy with approximately 20,000 closed landfill sites. Methane generated in landfill is 25x more potent a greenhouse gas than CO2 so prevention of its escape to the atmosphere is a priority for the landfill industry and requires stringent operating conditions to minimise emissions and the risks to the environment.
Strumpshaw landfill site near Norwich is a disused quarry of 15 ha filled with ~1,000,000 mcubed of domestic and commercial waste. Waste gas is fed into on- site Stirling engines which manage the landfill gas through combustion and generate electricity. The migration line on site contains 15% methane which is difficult to combust and so needs to be treated to control off-site migration. The Norfolk County Council (NCC) Closed Landfill Team, led by Charles Wright, has been trialling successfully at Strumpshaw the bioxidation of landfill gas using a 58m3 biofilter composed of compost, wood chip, expanded clay and coir, buried in landfill soil, lined with an impermeable gas barrier. Bioxidation of the methane is done by pumping air and landfill gas through the biofilter. Aerobic methane oxidising bacteria (methanotrophs) naturally occurring in soils remove methane by converting it to water and CO2. This biofilter technology is specifically aimed at older closed landfills that are generating gas below the level where electricity generation becomes difficult. A key objective in this multidisciplinary Project is to assess the effectiveness of bio-oxidation as a gas management technique for landfill gas containing 5-20% methane.
To achieve this, it is imperative to understand the biology underpinning the effectiveness of the biofilter and to create a robust framework for future design and long term management of landfill methane biofilters.
Key questions:
How do methanotroph populations and activities change with depth and which are the most effective in consuming methane in the biofilter?
Answering these questions would lead to an optimal depth for the biofilter design based on the input gas.
Are physico-chemical parameters in the biofilter optimum for methanotrophs. Do they have the nutrients they need (CH4, O2, N, P, Cu, Fe)?
This informs biofilter design, to create the ideal matrix to allow gas and nutrients to percolate through and for methanotrophs to thrive.
Is moisture content correct, do seasonal differences matter; is temperature important?
These questions would answer if the biofilter can be run uncovered/uninsulated/unheated.
Methodology:
Physico-chemical parameters including moisture content, temperature, matrix permeability, trace element availability and landfill gas composition will be measured. Field analytical techniques used will include surface emissions testing equipment (FID, TDL) and downhole monitoring, and laboratory analysis will be used for collected samples for matrix and trace gas composition analysis.
Methane oxidation potential of biofilter samples will be determined using gas chromatography. Distribution and diversity of methanotrophs in the biofilter will be determined by analysis of 16S rRNA genes and genes targeting the key enzyme methane monooxygenase (pmoA, mmoX). Key active methanotrophs present in biofilter samples will be identified by stable isotope probing using 13CH4, a technique pioneered in Murrell's lab and subsequently isolated and characterised at the physiological and molecular level.
Strumpshaw landfill site near Norwich is a disused quarry of 15 ha filled with ~1,000,000 mcubed of domestic and commercial waste. Waste gas is fed into on- site Stirling engines which manage the landfill gas through combustion and generate electricity. The migration line on site contains 15% methane which is difficult to combust and so needs to be treated to control off-site migration. The Norfolk County Council (NCC) Closed Landfill Team, led by Charles Wright, has been trialling successfully at Strumpshaw the bioxidation of landfill gas using a 58m3 biofilter composed of compost, wood chip, expanded clay and coir, buried in landfill soil, lined with an impermeable gas barrier. Bioxidation of the methane is done by pumping air and landfill gas through the biofilter. Aerobic methane oxidising bacteria (methanotrophs) naturally occurring in soils remove methane by converting it to water and CO2. This biofilter technology is specifically aimed at older closed landfills that are generating gas below the level where electricity generation becomes difficult. A key objective in this multidisciplinary Project is to assess the effectiveness of bio-oxidation as a gas management technique for landfill gas containing 5-20% methane.
To achieve this, it is imperative to understand the biology underpinning the effectiveness of the biofilter and to create a robust framework for future design and long term management of landfill methane biofilters.
Key questions:
How do methanotroph populations and activities change with depth and which are the most effective in consuming methane in the biofilter?
Answering these questions would lead to an optimal depth for the biofilter design based on the input gas.
Are physico-chemical parameters in the biofilter optimum for methanotrophs. Do they have the nutrients they need (CH4, O2, N, P, Cu, Fe)?
This informs biofilter design, to create the ideal matrix to allow gas and nutrients to percolate through and for methanotrophs to thrive.
Is moisture content correct, do seasonal differences matter; is temperature important?
These questions would answer if the biofilter can be run uncovered/uninsulated/unheated.
Methodology:
Physico-chemical parameters including moisture content, temperature, matrix permeability, trace element availability and landfill gas composition will be measured. Field analytical techniques used will include surface emissions testing equipment (FID, TDL) and downhole monitoring, and laboratory analysis will be used for collected samples for matrix and trace gas composition analysis.
Methane oxidation potential of biofilter samples will be determined using gas chromatography. Distribution and diversity of methanotrophs in the biofilter will be determined by analysis of 16S rRNA genes and genes targeting the key enzyme methane monooxygenase (pmoA, mmoX). Key active methanotrophs present in biofilter samples will be identified by stable isotope probing using 13CH4, a technique pioneered in Murrell's lab and subsequently isolated and characterised at the physiological and molecular level.
People |
ORCID iD |
| John Murrell (Primary Supervisor) | |
| David Pearce (Student) |
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| NE/R00742X/1 | 01/10/2017 | 30/09/2022 | |||
| 1941737 | Studentship | NE/R00742X/1 | 01/10/2017 | 30/09/2021 | David Pearce |
| Description | There have been many discoveries made through this NERC funded research. The region and temperature within the landfill methane biofilter where most methane removal occurs has been determined. The total bacterial community present in the biofilter soil has been characterised and the particular bacteria (methanotroph) responsible for the majority of methane removal in the biofilter identified. A representative of this type of bacteria has been isolated for genome sequencing to discover genetic and metabolic inventory (what is the organism capable of doing/tolerating) and for further study of growth characteristics as well as temperature and pH tolerance. Environmental factors affecting efficiency of methane removal in the biofilter during operation have been identified, as have those with no significant effect. |
| Exploitation Route | The outcomes of this funding could be used in the future design and operation of landfill methane biofilters. Understanding where methane removal is occurring in the biofilter could be used as a guide towards making a smaller and cheaper biofilter with the same methane removal capabilities. Comparing the tolerances of the methanotroph isolate with the effects of environmental variables on biofilter methane removal could indicate whether limitations are due to the organisms or biofilter design. The knowledge gained regarding the effects of different environmental variables on biofilter methane removal efficiency will be invaluable in directing operating parameters for the biofilter. The implementation of these outcomes would likely be carried out by government bodies responsible for closed landfills such as Norfolk County Council and other landfill site operators. |
| Sectors | Environment,Government, Democracy and Justice |
| Title | Biofilter soil metagenomes |
| Description | Biofilter matrix metagenomes assembled after high-throughput sequencing of DNA extracted from the biofilter. |
| Type Of Material | Database/Collection of data |
| Year Produced | 2020 |
| Provided To Others? | No |
| Impact | Partial genome reconstruction of several biofilter methanotrophs - giving information on genetic/metabolic capabilities of these species without requiring their isolation. |
| Description | Industrial CASE Partnership with Norfolk County Council closed landfill team |
| Organisation | Norfolk County Council |
| Country | United Kingdom |
| Sector | Public |
| PI Contribution | Research into bacterial methanotrophs responsible for methane oxidation in the Strumpshaw landfill methane biofilter (County Council operated). Identificatuion of key players in methane turnover and isolation of a representative methanotroph. Further study into the effects of changing physico-chemical parameters on biofilter methane oxidation efficiency. |
| Collaborator Contribution | CASE partner provides access to their site as well as appropriate PPE and health and safety training, additionally have provided required pieces of equipment such as a gas and temperature probe and gas/temperature analysers as well as transport to and from site. CASE partner also sponsored my attendance at industry conference "Landfill aftercare (LANDSS) forum". CASE partner will also provide £2,500 in direct funding (awaiting confirmation of receipt) |
| Impact | All outcomes have been supported by this partnership - as they are built from studying material/biological samples taken from the Norfolk County Council's landfill methane biofilter. |
| Start Year | 2017 |