Monitoring Methane Monitoring Methane Emissions from Landfill Emissions from Landfill

Leachate DischargeLeachate Discharge

EV4002EV4002Eimear O’KeeffeEimear O’KeeffePaul O’MahonyPaul O’Mahony

The Greenhouse EffectThe Greenhouse Effect Greenhouse effect is Greenhouse effect is

defined as the defined as the accumulation of energy & accumulation of energy & the overall warming of the overall warming of the atmosphere.the atmosphere.

Greenhouse gases are Greenhouse gases are those gases in the those gases in the atmosphere, both natural atmosphere, both natural & anthropogenic, that & anthropogenic, that absorb & re-emit absorb & re-emit radiation & hence trap radiation & hence trap heat in the atmosphere.heat in the atmosphere.

Fig – Illustration of the Fig – Illustration of the greenhouse Effectgreenhouse Effect

Greenhouse GasesGreenhouse Gases Greenhouse gases Greenhouse gases

are made up of H2O, are made up of H2O, CO2, CH4, N2O & CO2, CH4, N2O & other trace gases.other trace gases.

Greenhouse gases Greenhouse gases absorb more than absorb more than 90% of the infrared 90% of the infrared radiation that the radiation that the Earth emits.Earth emits.

Increasing concentrations of these greenhouse Increasing concentrations of these greenhouse gases lead to an enhanced greenhouse effect –gases lead to an enhanced greenhouse effect –i.e. increasing temperatures on Earth.i.e. increasing temperatures on Earth.

Fig – Total Greenhouse Gases for Fig – Total Greenhouse Gases for 2001 2001

Methane Gas & the Greenhouse Methane Gas & the Greenhouse EffectEffect

Methane (CHMethane (CH44) is the 2) is the 2ndnd largest largest contributor to global warming.contributor to global warming.

Its atmospheric concentration is Its atmospheric concentration is 1.7ppmv, which is much less than 1.7ppmv, which is much less than COCO22 concentration of 350ppmv. concentration of 350ppmv.

However, each molecule of CHHowever, each molecule of CH44 is 20 is 20 times more effective than each times more effective than each molecule of COmolecule of CO2 2 at trapping infrared at trapping infrared radiation.radiation.– Contributes greatly to global warmingContributes greatly to global warming

Methane Gas & the Greenhouse Methane Gas & the Greenhouse EffectEffect

Approx 60% of CHApprox 60% of CH44 emitted into the emitted into the atmosphere is anthropogenic in atmosphere is anthropogenic in source.source.

Methane atmospheric concentrations Methane atmospheric concentrations are increasing at a rate of approx 1% are increasing at a rate of approx 1% per year.per year.

Hence the reduction of CHHence the reduction of CH44 emissions emissions would have a rapid impact on would have a rapid impact on mitigating global warming.mitigating global warming.

Increase in CHIncrease in CH44 emissions over emissions over the yearsthe years

Methane in landfillsMethane in landfills A large contributor to methane A large contributor to methane

emissions to the atmosphere is the emissions to the atmosphere is the burying of waste in landfills.burying of waste in landfills.

Methane in landfills exist as a gas & Methane in landfills exist as a gas & as dissolved CHas dissolved CH44 in landfill leachate. in landfill leachate.

It is produced by decay & It is produced by decay & decomposition of organic matter in decomposition of organic matter in oxygen poor conditions.oxygen poor conditions.

Reducing CHReducing CH44 emissions from landfill emissions from landfill will decrease CHwill decrease CH44 emissions into the emissions into the atmosphere.atmosphere.

Cork City LandfillCork City Landfill This is an old landfill site & therefore doesn’t This is an old landfill site & therefore doesn’t

have a bottom liner system in place to have a bottom liner system in place to separate the rubbish & the leachate.separate the rubbish & the leachate.

It does have a leachate collection system in It does have a leachate collection system in place, which collects the leachate & sends it to place, which collects the leachate & sends it to be treated & then disposes it to the sewer.be treated & then disposes it to the sewer.

A gas collection A gas collection system is also in system is also in place, which is a place, which is a system of pipes system of pipes which collects the which collects the CH4 & transports it CH4 & transports it to the on-site power to the on-site power generation station.generation station.

Fig – cross section of a LandfillFig – cross section of a Landfill

Leachate Collection & TreatmentLeachate Collection & Treatment Leachate, which has a methane concentration of Leachate, which has a methane concentration of

5-10mg/l, is collected via a drain network, located 5-10mg/l, is collected via a drain network, located on the perimeter of the landfill & pumped into the on the perimeter of the landfill & pumped into the lagoons.lagoons.

Leachate is then sent to the conditioning plant, Leachate is then sent to the conditioning plant, via the plant balance tank, where the leachate is via the plant balance tank, where the leachate is aerated in order to drive off excess methane.aerated in order to drive off excess methane.

Methane concentrations are now reduced to Methane concentrations are now reduced to 0.2mg/l & sent to sewer via the pipe work.0.2mg/l & sent to sewer via the pipe work.

Fig - Leachate Conditioning Plant

Methane in sewersMethane in sewers

Danger of CHDanger of CH44 in sewers as a build up in sewers as a build up of CHof CH44 from leachate may create from leachate may create pockets of CHpockets of CH44 gas which may gas which may explode in the unventilated sewerexplode in the unventilated sewer

Therefore the landfills must monitor Therefore the landfills must monitor CHCH44 levels in the sewer levels in the sewer

Legislation & Leachate in EuropeLegislation & Leachate in Europe The following Legislation, which was The following Legislation, which was

enacted into the laws of each of the enacted into the laws of each of the member states is of relevance when member states is of relevance when considering leachate discharges& the considering leachate discharges& the permitting of leachate treatment plantspermitting of leachate treatment plants– The EU Landfill DirectiveThe EU Landfill Directive– The EU Groundwater DirectiveThe EU Groundwater Directive– The EU Urban Wastewater Directive-where The EU Urban Wastewater Directive-where

discharges are pre-treated before discharge to discharges are pre-treated before discharge to public sewerpublic sewer

– The EU Dangerous Substances DirectiveThe EU Dangerous Substances Directive– The EU Water Framework Directive The EU Water Framework Directive

IPC LicenceIPC Licence Each Landfill facility requires an Each Landfill facility requires an

E.P.A. Waste Licence by lawE.P.A. Waste Licence by law

Cork City Councils holds a Waste Cork City Councils holds a Waste Licence, which was issued by the Licence, which was issued by the E.P.A. E.P.A.

This Waste Licence is available to This Waste Licence is available to view on the E.P.A. website @ - view on the E.P.A. website @ - http://www.epa.ie/licences/waste_lic/http://www.epa.ie/licences/waste_lic/12-2lic.pdf12-2lic.pdf

Requirements of the Waste Requirements of the Waste LicenceLicence

Cork City Landfill are required to monitor Cork City Landfill are required to monitor its emissions to sewer, including its its emissions to sewer, including its dissolved methane levels going to sewer.dissolved methane levels going to sewer.

The emission limits for dissolved methane The emission limits for dissolved methane in leachate to sewer is 0.2mg/l, daily mean in leachate to sewer is 0.2mg/l, daily mean concentrationconcentration

The monitoring of methane emissions to The monitoring of methane emissions to sewer is required on a continuous basis sewer is required on a continuous basis and the analysis technique is by a and the analysis technique is by a dissolved methane probe or a headspace dissolved methane probe or a headspace monitormonitor

Sampling TechniquesSampling Techniques

As we can see from the above tables, the As we can see from the above tables, the EPA has placed a limit of 0.2 mg/l on the EPA has placed a limit of 0.2 mg/l on the emission limits of dissolved methane to the emission limits of dissolved methane to the sewer. sewer.

To ensure this level is complied with, the To ensure this level is complied with, the licence specified that the leachate had to licence specified that the leachate had to be monitored by a dissolved methane be monitored by a dissolved methane probe, and the air above it had to be probe, and the air above it had to be monitored by a headspace methane monitored by a headspace methane monitor. monitor.

To comply with the licensing regulations To comply with the licensing regulations Cork city council installed these probes at Cork city council installed these probes at two locations, at the conditioning plant and two locations, at the conditioning plant and at a location before the sewer discharge at a location before the sewer discharge point.point.

These probes were obtained from ASD These probes were obtained from ASD Sensortechnik Gmbh. Sensortechnik Gmbh.

METS - an underwater methaneMETS - an underwater methanesensorsensor

Developed by Developed by Capsum Technologie Capsum Technologie GmbH for underwater monitoring GmbH for underwater monitoring of CH4 up to a depth of 2000 mof CH4 up to a depth of 2000 m

The The METS sensor is designed for METS sensor is designed for monitoring purposes at platforms, monitoring purposes at platforms, for long term time series for long term time series measurements, in oceans, rivers measurements, in oceans, rivers and lakes as well as deep-sea and and lakes as well as deep-sea and coastal areascoastal areas.

It can be deployed in shallow water It can be deployed in shallow water areas from a small boat, allowing areas from a small boat, allowing vertical or horizontal profiles. The vertical or horizontal profiles. The adaptation of this sensor to probe adaptation of this sensor to probe systems or loggers is possible systems or loggers is possible because it is quipped with because it is quipped with standard analogue outputs. standard analogue outputs.

The The sensor is based on semi-sensor is based on semi-conductor technology. The semi-conductor technology. The semi-conductor is protected from the conductor is protected from the water by a membrane, through water by a membrane, through which gases permeate.which gases permeate.

The sensor is based on The sensor is based on semiconductor technology & is semiconductor technology & is protected from water by a special protected from water by a special membrane, through which gases membrane, through which gases permeate. permeate.

The membrane, semiconductor The membrane, semiconductor and electronics are installed in a and electronics are installed in a watertight stainless steel housing. watertight stainless steel housing. The device is then connected via The device is then connected via a cable to the signal processing a cable to the signal processing and storage computer at the and storage computer at the surface. surface.

The sensor membrane consists of The sensor membrane consists of a silicone composite membrane, a silicone composite membrane, supported by a spherical layer. supported by a spherical layer. The stainless steel head of the The stainless steel head of the METS can be removed from the METS can be removed from the housing. It is built as a holder for housing. It is built as a holder for the membrane and for the the membrane and for the membrane supporting layer. membrane supporting layer.

METS - an underwater methaneMETS - an underwater methanesensorsensor

METS sensor specification:METS sensor specification: Measuring range:Measuring range:20 nmol/l to 10 20 nmol/l to 10

µmol/lµmol/lother ranges on request between 20 other ranges on request between 20 nmol/l and 1 mmol/l nmol/l and 1 mmol/l

Resolution:Resolution: at 50 nmol/l approx. 4 to at 50 nmol/l approx. 4 to 5 nmol/l5 nmol/l

Response time:Response time: 3 to 30 min, 3 to 30 min, conditionned to turbulences conditionned to turbulences

Pressure range:Pressure range: 200 bar (other 200 bar (other ranges on request) ranges on request)

Operational range:Operational range: +2 to +20°C +2 to +20°C (other ranges on request)(other ranges on request)

The sensor uses a heated semiconductor The sensor uses a heated semiconductor that responds to the presence of dissolved that responds to the presence of dissolved methane as well as other hydrocarbons. methane as well as other hydrocarbons.

The hydrocarbon molecules diffuse The hydrocarbon molecules diffuse through a special silicone membrane into through a special silicone membrane into the detector room. the detector room.

The adsorption of the hydrocarbons on The adsorption of the hydrocarbons on the active layer leads to electron the active layer leads to electron exchange with oxygen and thus to exchange with oxygen and thus to modification of the resistance, which the modification of the resistance, which the electronic transduces into a voltage. electronic transduces into a voltage.

The chosen membrane polymer is The chosen membrane polymer is specialised for methane detection. specialised for methane detection. Silicone has a high permeability for the Silicone has a high permeability for the gas and it is very resistant to fouling. gas and it is very resistant to fouling.

In this sensor the membrane is used as a In this sensor the membrane is used as a phase separation between the liquid and phase separation between the liquid and the gas detection room. the gas detection room.

The transition of the gas out of the water / The transition of the gas out of the water / leachate takes place via diffusion through leachate takes place via diffusion through the membrane. the membrane.

Sensor PerformanceSensor Performance In previously conducted experiments the In previously conducted experiments the

sensor gave some indication of enhanced sensor gave some indication of enhanced methane concentrations, but was limited by a methane concentrations, but was limited by a slow relaxation of the output when the slow relaxation of the output when the ambient dissolved methane concentration ambient dissolved methane concentration changes. changes.

The sensor was deployed on CTD casts during The sensor was deployed on CTD casts during ATLANTIS and SONNE operations during ATLANTIS and SONNE operations during TECFLUX, (Bohrman et al. 2000). TECFLUX, (Bohrman et al. 2000).

The sensor was found to exhibit slow response The sensor was found to exhibit slow response to changing concentrations, but it does to changing concentrations, but it does respond at some level. respond at some level.

The findings of this journal were that in order The findings of this journal were that in order for the sensor to be deployed on a wide scale, for the sensor to be deployed on a wide scale, improved response time is essentialimproved response time is essential

The diagram on the right, indicates the The diagram on the right, indicates the results of a 36 day trial in a sewage results of a 36 day trial in a sewage water treatment plant. The top left water treatment plant. The top left sample is the reference membrane. Top sample is the reference membrane. Top right is an antifouling membrane type 1, right is an antifouling membrane type 1, 1010m. Bottom left is antifouling m. Bottom left is antifouling membrane type 2, 10 membrane type 2, 10 m. Bottom right is m. Bottom right is antifouling membrane type 3, 100 antifouling membrane type 3, 100 m. m.

Sensor PerformanceSensor Performance At present there are sensors deployed at the balance tank, the discharge At present there are sensors deployed at the balance tank, the discharge

tank and at a point before the sewer is discharged into the water. tank and at a point before the sewer is discharged into the water. The sampling process using the sensor technology has been plagued by The sampling process using the sensor technology has been plagued by

problems and has proved to be an extremely costly venture, with up to problems and has proved to be an extremely costly venture, with up to 50,00 Euro already being spent on installation and maintenance. 50,00 Euro already being spent on installation and maintenance.

The major problem associated with this form of monitoring is that biofilm The major problem associated with this form of monitoring is that biofilm growth from the leachate reduces the passage of gas into the probe. growth from the leachate reduces the passage of gas into the probe.

This biofilm layer consists of small living organisms along with tiny This biofilm layer consists of small living organisms along with tiny particles, which slow the diffusion process and can even block it particles, which slow the diffusion process and can even block it completely. completely.

In previous studies the biofilm layer has even been found to produce In previous studies the biofilm layer has even been found to produce methane, which leads to excessive readings. Capsum has recognised this methane, which leads to excessive readings. Capsum has recognised this as a significant problem and is researching ways of optimising as a significant problem and is researching ways of optimising performance. performance.

Graph illustrating Graph illustrating the effects of the the effects of the membranemembrane

Cork City Landfill Sampling Cork City Landfill Sampling ProceduresProcedures

Despite the apparent success of the antifouling membrane as seen Despite the apparent success of the antifouling membrane as seen in the previous slide, Cork City council has had serious problems with in the previous slide, Cork City council has had serious problems with the accuracy of their sensor readings. the accuracy of their sensor readings.

Because of this grab samples are presently being taken once a Because of this grab samples are presently being taken once a month, although this is not sufficient to satisfy the EPA licence month, although this is not sufficient to satisfy the EPA licence requirement for a continuous monitoring process. Staff members requirement for a continuous monitoring process. Staff members have found this requirement impossible to meet using the sensor have found this requirement impossible to meet using the sensor device. device.

Saturated methane in air gives maximum readings of 25 mg/l, Saturated methane in air gives maximum readings of 25 mg/l, however the sensor has recorded values of up to 200 mg/l. Because however the sensor has recorded values of up to 200 mg/l. Because of these results the staff resorted to the grab sampling technique. of these results the staff resorted to the grab sampling technique.

The The samples taken from the balance tank, discharge tank and sewer samples taken from the balance tank, discharge tank and sewer samples are placed in a small voc vial which is fully sealed and taken samples are placed in a small voc vial which is fully sealed and taken back to lab for analysis A.S.A.P. back to lab for analysis A.S.A.P.

A syringe is then used to extract the gas from the headspace of the A syringe is then used to extract the gas from the headspace of the vial and this is then injected into a G.C. vial and this is then injected into a G.C.

A standard is also prepared for comparison. A bottle of methane gas A standard is also prepared for comparison. A bottle of methane gas is used to saturate a water sample i.e. 25 mg/l. A known volume is is used to saturate a water sample i.e. 25 mg/l. A known volume is extracted from the headspace in this vial and this is also injected extracted from the headspace in this vial and this is also injected into the G.C. into the G.C.

The analysis results in a plot whereby area relates to concentration The analysis results in a plot whereby area relates to concentration for both the standard and the site samples. for both the standard and the site samples.

Sample of results – March 2004Sample of results – March 2004

Conclusion: Conclusion: The results for the outlet sewer for dissolved The results for the outlet sewer for dissolved methane are within the licence limit. methane are within the licence limit.

Note the differing results between the grab samples and the Note the differing results between the grab samples and the Capsum Probe. Capsum Probe.

LocationLocation Dissolved Dissolved Methane Methane (Alcontrol (Alcontrol geochem) geochem)

mg/lmg/l

Dissolved Dissolved Methane Methane

(CCC) mg/l(CCC) mg/l

pHpH ConductivitConductivity ms/cmy ms/cm

Scada Scada reading reading

HeadspaceHeadspace

Capsum Capsum Probe Probe

readingreadingmg/lmg/l

InletInlet 2.582.58 5.35.3 7.987.98 4.3004.300 ------ ------

FHS TankFHS Tank 0.0030.003 0.350.35 8.208.20 4.2504.250 0%0%(0ppm)(0ppm)

0.080.08

Outlet Outlet SewerSewer

0.0190.019 0.200.20 8.308.30 3.5703.570 1.45%1.45%(725ppm)(725ppm)

1.451.45

License License Discharge Discharge

LimitLimit

0.20.2 0.200.20

Fig - Capsum ProbeFig - Capsum Probe

Sampling procedure Sampling procedure suggestionssuggestions

Composite SamplingComposite Sampling– Time proportional Time proportional – 24hr Flow Proportion24hr Flow Proportion

Continuous G.C.Continuous G.C.

The use of an Antifouling MembraneThe use of an Antifouling Membrane

Composite SamplingComposite Sampling The grab sampling technique that is presently in The grab sampling technique that is presently in

operation only occurs once a month, and as operation only occurs once a month, and as previously mentioned, involves simply taking a previously mentioned, involves simply taking a sample and analysing it as soon as possible. This sample and analysing it as soon as possible. This technique could be improved by taking composite technique could be improved by taking composite samples. These can be split into two forms, Time samples. These can be split into two forms, Time proportional and 24 hour flow proportional. proportional and 24 hour flow proportional.

Time ProportionalTime Proportional:: Take samples every hour for Take samples every hour for a period of 24 hours, no dependence on flow rate. a period of 24 hours, no dependence on flow rate.

24 Hour Flow Proportional24 Hour Flow Proportional:: Measure the flow Measure the flow rate, e.g. if 10 m3/hr then take 10 ml of sample. If rate, e.g. if 10 m3/hr then take 10 ml of sample. If 5 m3/hr take 5 ml of sample. These are also 5 m3/hr take 5 ml of sample. These are also taken over a 24 hour period. taken over a 24 hour period.

The samples would be analysed by G.C. in the The samples would be analysed by G.C. in the same way as the grab samples, however they same way as the grab samples, however they would result in a more accurate representation of would result in a more accurate representation of the dissolved methane values. the dissolved methane values.

Continuous G.C.Continuous G.C.

If the composite sampling techniques If the composite sampling techniques are still insufficient to satisfy the EPA are still insufficient to satisfy the EPA the final suggestion would be to the final suggestion would be to install an automatic G.C. on site. install an automatic G.C. on site.

This would be very expensive, This would be very expensive, approximately 20,000 Euro, however approximately 20,000 Euro, however in lieu of what had already been in lieu of what had already been spent it would be a very wise spent it would be a very wise investment if the EPA would accept investment if the EPA would accept this sampling method. this sampling method.

The use of Antifouling MembraneThe use of Antifouling Membrane

If the EPA will not accept the continuous G.C. If the EPA will not accept the continuous G.C. method of monitoring, the landfill staff will have method of monitoring, the landfill staff will have to examine the use of Antifouling membranes.to examine the use of Antifouling membranes.

Test results from Capsum have shown these to be Test results from Capsum have shown these to be very successful. very successful.

Due to the material being analysed this seems to Due to the material being analysed this seems to be a very important aspect of the probe which be a very important aspect of the probe which appears to have been overlooked by the staff. appears to have been overlooked by the staff.

If this proves problematic, a weekly cleaning If this proves problematic, a weekly cleaning system will have to be implemented, whereby a system will have to be implemented, whereby a staff member will go to each location and clean staff member will go to each location and clean each sensor manually, thus ensuring the sensors each sensor manually, thus ensuring the sensors can function accurately for continuous can function accurately for continuous monitoring. monitoring.

ConclusionsConclusions Due to the well publicised Greenhouse Due to the well publicised Greenhouse

effect of methane, & its highly flammable effect of methane, & its highly flammable & explosive nature, it is essential that a & explosive nature, it is essential that a continuous monitoring programme of continuous monitoring programme of methane in landfill leachate is methane in landfill leachate is implemented effectively.implemented effectively.

In conclusion: Our research suggests that In conclusion: Our research suggests that the addition of an Antifouling Membrane the addition of an Antifouling Membrane would be the most suitable way of would be the most suitable way of achieving the EPA licence demands for the achieving the EPA licence demands for the continuous monitoring of dissolved continuous monitoring of dissolved methane in landfill leachate.methane in landfill leachate.

ReferencesReferences www.epa.ie/licences/waste_lic/12-2lic.pdfwww.epa.ie/licences/waste_lic/12-2lic.pdf www.capsum.de/capsum_online/anti.htmlwww.capsum.de/capsum_online/anti.html www.corkcitycouncil.iewww.corkcitycouncil.ie www.leachate.co.uk/html/all_about_leachawww.leachate.co.uk/html/all_about_leacha

te.htmlte.html http://members.aol.com/profchm/gina.htmlhttp://members.aol.com/profchm/gina.html www.climatechange.gc.ca/english/climate_www.climatechange.gc.ca/english/climate_

change/earth.aspchange/earth.asp www.metrokc.gov/dnr/kidsweb/images/lanwww.metrokc.gov/dnr/kidsweb/images/lan

dfill_diagram.gifdfill_diagram.gif