Acceptance at landfills and process optimization: the importance of a consistent approach. Federico Valentini

Acceptance at landfills and process optimization: the importance of a consistent approach Federico Valentini

Directive 1999/31/EC (Landfill directive) Art. 5 - Reduction with time of biodegradable waste being landfilled (as compared to 1995) a 25% within 5 years a 50% within 8 years a 65% within 15 years Art. 6 - Mandatory treatment of waste before landfilling

Directive 1999/31/EC (Landfill directive) Reduction targets can be met by mean of: Separate collection (and recycling) of biodegradables May or may not be sufficient Then, we have to treat the residual waste by: Incineration Mechanical Biological Treatment

Mechanical Biological Treatment Processing of solid wastes containing biologically degradable organic components, by means of a combination of mechanical processes (i.e., cutting, crushing, sorting) and biological degradation (aerobic/anaerobic) Outputs (and goals) of MBT can be: Refuse Derived Fuel Biogas (anaerobic process) MSW Compost Stabilized waste to be landfilled

Mechanical Biological Treatment PICHLER, 1999

Flexibility is the key word MBT can adapt itself to changing contexts: Put variable enphasys on biostabilization or on RDF production Switching from MSW compost to Quality compost when separate collection of organics is implemented (even gradually) Perugia 1986 Perugia 2000

Does MBT comply with the Landfill directive requirements? If biological treatment is one of the possible treatment than the question is: when a mechanically-biologically treated waste can be landfilled?

What pre-treatment is needed for? Art. 1 - Directive 1999/31/EC to prevent or reduce as far as possible negative effects on the environment Biogas (GHG) Leachate (DOC)

Biological treatment and leachate quality From Adani et al, 2003

Biological treatment and leachate quality From Binner, 2002

Defining the threshold and how to measure it Gas generation test

The rational for different limit values 80% reduction 90% reduction From Binner, 2002

RESPIROMETRY It s based on measurement of Oxygen consumption (or on Carbon dioxyde production) under AEROBIC CONDITIONS IT IS A DIRECT MEASUREMENT OF DEGRADATIVE ACTIVITY & CORRELATE QUITE WELL WITH BIOGAS FORMATION POTENTIAL

RESPIROMETRY/BIOGAS PRODUCTION from J. Heerenklage, R. Stegmann, ORBIT 2006

Definition of ACCEPTANCE of MBT-treated materials at landfills Germany VS < 5% (TASi = Technical Directive on Residential Waste) only incineration is suitable AT 4 < 5 mgo 2 /g d.m. (Ablagerungsverordnung, Jan 01) ( equivalency of MBT) Austria (Deponieverordnung) Italy AT 4 < 7 mgo 2 /g d.m. DRI < 1000 mgo 2 /kgvs.h

Approaches to assess reduction of biodeg waste through MBT Codified approaches: Threshold for acceptability (and biodegradability: GER, AUT) not very flexible Threshold for biodegradability, NOT for acceptability (ITA, Guidelines for Regional Plans on diversion of BMW) so far Proportionality: NO threshold, assessment of the mass balance of biodegradability LATS (UK) allows for optimised combination of strategies

On the acceptance of waste at landfills: the case of Italy COUNCIL DECISION of 19 December 2002 establishing criteria and procedures for the acceptance of waste at landfills pursuant to Article 16 of and Annex II to Directive 1999/31/EC (2003/33/EC) MINISTERO DELL'AMBIENTE E DELLA TUTELA DEL TERRITORIO DECRETO 3 agosto 2005 Definizione dei criteri di ammissibilità dei rifiuti in discarica. (GU n. 201 del 30-8-2005)

COUNCIL DECISION 2003/33/EC

DECRETO 3 agosto 2005

Some more words on respirometry

Different approaches: solid state Static or dynamic? Otpimal respiration rate Oxygen transfer as a limiting factor Adani e Tambone (1998)

Static Respiration Index (SRI) IPLA Method (Piedmont Region, 1998) P L. Paradisi 2006

DYNAMIC RESPIRATION INDEX (DRI) Metodo DIPROVE (Adani et al., 2001)

DYNAMIC RESPIRATION INDEX (DRI)

Different approaches: liquid state Specific Oxygen Uptake Rate (SOUR) (Lasaridi & Stentiford, 1998) Interface (A/D) & controller DO meters Fish tank pumps Water bath, 30 o C O 2 probe Compost suspension

Specific Oxygen Uptake Rate mg O 2 / g VS/ hr 20 15 10 5 SOUR TOD 20 0 0 10 20 30 40 50 Time (hours)

A COMPARATIVE STUDY 18 Samples 3 Mechanical Biological Treatment processes (BT) beginning (BTb), middle (BTm) and end (BTe) of process totale = 9 campioni 3 Biodrying Treatment (BS) Beginning (BSb) and end (BSe) of process Underscreen (ST) Ø< 2 cm total = 9 samples Respiration Index determination: a comparative study Adani, F., Gigliotti G., Valentini F., and Laraia R., (2003)

MBT samples 1st process 4.500 18.000 DRI - SRI (mg O2 / kg VS / h) 4.000 3.500 3.000 2.500 2.000 1.500 1.000 500 16.000 14.000 12.000 10.000 8.000 6.000 4.000 2.000 SOUR (mg O2 / kg VS / h) DRI SRI SOUR 0 BT-1-b BT-1-m BT-1-e 0

MBT samples 2nd process 6.000 16.000 DRI - SRI (mg O2 / kg VS / h) 5.000 4.000 3.000 2.000 1.000 14.000 12.000 10.000 8.000 6.000 4.000 2.000 SOUR (mg O2 / kg VS / h) DRI SRI SOUR 0 BT-2-b BT-2-m BT-2-e 0

Biodrying samples 1st process 2.000 1.800 1.600 1.400 1.200 1.000 800 600 400 200 0 BS-1-b BS-1-e 6.000 5.000 4.000 3.000 2.000 1.000 0 DRI SRI SOUR

Biodrying samples 2nd process 2.000 6.000 1.800 1.600 5.000 1.400 1.200 4.000 DRI 1.000 3.000 SRI 800 600 2.000 SOUR 400 200 1.000 0 BS-2-b BS-2-e 0

Correlation - all data (including DOCdissolved organic carbon - fractions) DRI 1 SRI 0.78* 1 DRI SRI SOUR DOC DOC SOUR 0.70* 0.55* 1 DOC h. phylic 0.46 0.23 0.69* 1 h. philic h. phobic DOC h. phobic 0.05 0.31 0.16 0.40 1

Conclusions Dynamic respiration indexes (DRI) well describe biological treatment dynamics and efficiency SRI underestimate oxygen uptake, especially in unstable materials SOUR is quick and convenient but seems to be affected by the soluble fraction of organic matter.

Grazie! f.valentini@gesenu.it