Biogas and Leachate Treatment Experiences in Ireland

Margaret Heavey, Head of Landfill Operations

Gabriel Dennison, Technical Director

• Established 1999

• Irish owned and managed

• 600 employees in 25 locations

• Ireland’s largest waste management company

• Recycling, Composting, Residual Landfill / energy recovery

• Manages household, commercial and industrial (C&I) waste

• Operates 4 of Ireland’s 5 private non-hazardous landfills

• Industry award for National Recycler of the year 2006

Greenstar (Ireland) – who we are

Presentation Format

• Regulatory issues that affect leachate and Biogas planning

• General summary of biogas treatment technologies

• Landfill biogas – progress in Ireland

• Greenstar’s experiences - biogas

• General summary of leachate treatment technologies

• Leachate treatment in Ireland

• Greenstar’s experiences - leachate

• EU landfill directive

• Kyoto Agreement

• EPA buffer guidance restrict landfills to relatively remote locations

• Planning restrictions in proximity to significant receiving water bodies

• Failure by local authorities to close small old landfills as planned

• Planning uncertainty due to slow rate of progress with incineration plans

• Capacity constraints - Municipal Waste Water Treatment Plants

• Capacity constraints - National Electricity Grid

• Electricity prices

Biogas / Leachate - Regulatory Issues

• Landfill gas typically 50% - 75% Methane

• Utilisation guide limits >200kt, >25% organic; >4m depth; > 50% CH4

• Most common utilisation technology - internal combustion engines

• Using boilers to generate heat is also used but less common

• Landfill gas as a vehicle fuel – pilot stage research in USA

• Pre-treatment of gas – corrosive compounds- moisture content

• Waste acceptance procedures and filling methods

• Flaring of gas using Enclosed flares

Landfill Biogas Technologies

• Many small local authority landfills practise passive venting

• Most common gas technology is flaring

• Due to landfill size and remoteness only 8 landfills generate electricity

• High costs of electricity grid connection make below 1MW unviable

• Landfills < 100,000 tpa unviable due to grid costs

• 18 months to 3 years electricity grid application process duration

• High cost of upgrading electricity network over long distances

• Landfill gas planning uncertainty associated with landfill size restrictions

• Large scale landfills have better gas generation efficiencies

Biogas Technologies - Ireland

Greenstar 4.5 MW Utilisation Plant, KTK landfill

Biogas Utilisation – Greenstar experience

• KTK landfill, Co Kildare, Ireland

• 275,000 tpa ; No food or green waste

• leachate recirculation

• flaring and utilising 7,500 m3/ hr gas

• Generating 3.75 MW of electricity

• limiting factor is electricity grid

• Joint Venture Greenstar Gas Energy

• 25% owned GAS GmbH Germany

• 75% owned Greenstar

Biogas Utilisation – Greenstar experience

• June 2006, engine M1 suffered catastrophic failure after less than 1 year• Investigation of other two engines M2 and M3 showed similar symptoms• Build up of siloxane deposits on cylinder liners• Piston and liner seized leading to failure• November 2006 dewatering / chilling treatment system installed• Increased maintenance regime

Landfill Leachate – Worldwide

• MSW leachate worldwide has similar characteristics (Enviros,UK 2005)

• Climatic conditions (rainfall, temperature) affect volumes and treatment

• Discharge consent limits vary – determine level of treatment required

• Young leachate (acetogenic) is different to older (methanogenic) leachate

Leachate Treatment Technologies

• Most common treatment in Europe involves Municipal Waste Water Treatment Plants (MWWTP)

• On-site typically includes aerobic treatment to reduce BOD and NH4-N

• Discharge consent limits vary – countries /sewer discharge / surface water

• Ammonical Nitrogen removal (nitrification) can be temperature sensitive

• Nutrient removal (nitrates) may be a requirement of the regulatory authority.

• Biological denitrification, air stripping, reverse ozmosis, reed bed polishing

• Hard COD may need to be removed ( activated carbon, ozonation, UV )

• Discharge of COD subject to toxicity testing.

• Leachate evaporation technologies used in France and Finland

• Leachate discharged to sewer is likely to need methane removal

• Leachate recirculation – treatment / gas production/ volume control

Leachate Treatment – Ireland

• 3 purpose designed Leachate Treatment Plants in Ireland

• 1 extended aeration ; 1 SBR technology; 1 Biofiltration using peat.

• EPA set discharge limits on BOD, NH4-N, pH, SS

• All landfills in Ireland are currently using MWWTPs to treat their leachate

• Road transportation distances of > 20km are typical

• Local authorities do not charge themselves leachate treatment costs

• Many MWWTPs need upgrading and capacity increases

• No national policy on effluent treatment charges at MWWTPs – prices vary

• Since May 2007 MWWTPs are to be regulated by the EPA

SBR system, Arthurstown Landfill Co. Kildare

Greenstar Leachate Management

• Due to planning limitations landfills are not near receiving waters

• Recirculation of leachate to promote stabilisation and gas production

• Currently treating the small volumes for disposal at MWWTPs

• Investigating pre-treatment and centralised alternatives

• Difficult to plan long-term solution until upper tonnage limit known

• Aftercare planning – the walk away solution

• Sustainability is the key

Recommendations

• Ireland needs to close down old inefficient landfills < 50,000 tpa

• In the short-term Ireland needs to facilitate the development / expansion of existing modern landfills to a scale which will economically support bioenergy utilisation and efficient leachate management.

• Adopt findings of Eunomia (UK) 2007 report ‘Waste Policy Planning and Regulation in Ireland’ recommending MBT and landfill as an interim alternative to incineration for Ireland to meet EU landfill diversion targets

• Regulation needed to encourage the source segregation of gypsum

• Re-examine Inert Landfill limits for wastes containing sulphates

• Investment in national waste water treatment infrastructure

• Investment in national electricity grid – financial instruments

www.greenstar.ie

Thank You