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Los retos en la gestión de residuos urbanos en una economía globalizada

Els reptes en la gestió de residus urbans en una economia globalitzada

Challenges in waste management in a globalized economy

ORGANIZADO POR: CON LA COLABORACIÓN DE:

MBT: CONSEQUENCES ON CONSTRUCTION AND OPERATION OF LANDFILLS

Kai Münnich

Leichtweiß-Institute for Hydraulic Engineering and

Water Resources

Department of Waste and Resource Management

Los retos en la gestión de residuos urbanos en una economía globalizadaEls reptes en la gestió de residus urbans en una economia globalitzada


Common practice of waste disposal….

© Now Public



MBT disposal on landfills…Practice of waste disposal in future…. !?



< 60 mm < 25 mm

Fresh waste

Why MBT?

Reduction of- risks by emissions during

landfill operation - time necessary for aftercare- effort for aftercare

Changes in construction and operation?

MBT material



Quality of MBT waste in Germany:

- Criteria in annex 3 of Landfill Ordinance (2009).

- Stability parameter:- respiration rate: ≤ 5 mg/g (DS) or- digestion rate: ≤ 20 l/kg (DS)- TOCEluate : ≤ 300 mg/l

- Utilisation parameter:- Upper calorific value: ≤ 6000 kJ/kg (DS) or- TOCsolid: ≤ 18 M. % (DS)

low concentrations in leachate

low concentrations of organics in leachate low gas emissions

material size < 40 – 60 mm



Waste disposal: no requirements in view of physical parametersbut: maximal emplacement density should be achieved less settlement less leachate higher mechanical stability longer lifespan until end of backfilling

How to determine waste density?- measurement of landfill surface (e.g. GPS)

but, settlement of old waste layers and subsoil is enclosed - sampling on landfill area

problems in sampling- proctortests

maximal size < 60 mmstatic test dynamic compaction on landfill differences?



20

30

40

50

60

70

80

90

0,5 0,6 0,7 0,8 0,9 1 1,1 1,2 1,3

Proctordensity [t/m3 DS]

Wate

r co

nte

nt

[w-%

DS

]

Bidlingmaier et al (1999)Kühle-Weidemeier (2004) Rettenberger (2005)Entenmann/Wendt (2007)Heyer et al (2008)Entenmann (2009)LWI (anaerob-aerob)LWI (aerob)

Fresh Waste 0.5 – 1.0MBT material 0.8 – 1.5

Results from proctortests:



0,50

0,60

0,70

0,80

0,90

1,00

1,10

1,20

5 10 15 20 25 30 35 40 45

Dry

de

ns

ity [

t/m

3]

MH <60

WHV <60

NH <60

Bu < 60

Water content [w-% WS]

Proctorcurve and material size



40

56

sgs engineers

Slope stability:

MBT: - screening to <60 mm reduction of reinforcing material (fibres)

from >25 M.-% to < 5 M.-% Tensile strength??

Reason: plastics are able to take uptensile forces

„grouted anchor“ forthe slope

18

3.01.0



Surface settlement:

Calculation based on the physical properties of the waste is notpossible at the moment

Total settlement:

MBT Fresh waste

primary settlement (load): 15 - 20 35 – 50 %

secondary settlement (creep, biol. processes) : < 5 15 - 30 %

Consequences for construction and operation: final surface sealing system can be installed earlier time and effort for monitoring in the closing and aftercare phase

are reduced distinctly

after total filling settlement is completed in large part

as a result of the homogeneity of MBT material large differences in settlement are not to be expected



Hydraulic properties:

Parameters important for the movement of water and the generation of leachate at the base of the landfill body:

Infiltration-rate F and saturated hydraulic conductivity k

F > k !

German recommendation: MBT-material: k = 1*10-6 – 1*10-9 m/sFresh waste: k = 1*10-3 – 1*10-6 m/s

Low permeabilities?- Surface runoff possible less leachate at the landfill base- Pore water pressure? slope stability?- higher evaporation rate less leachate



1E-09

1E-08

1E-07

1E-06

1E-05

1E-04

0,6 0,7 0,8 0,9 1 1,1 1,2

Dry density [t/m³]

Satu

rate

d h

ydr.

co

nd

uct

ivit

y [m

/s]

< 60 mm< 40 mm< 30 mm

MB

T

Fre

sh w

aste

k-values from laboratory tests



Landfill operation - emplacement technology

Engines:

For compaction: compactor?

For distribution: bulldozer/tracked loaders

pad foot roller

and vibrating smooth roller



Design of the emplacement surface:

Why ?

To avoid impoundment of surface water

soaking of the surface

impassability of the area



© Rettenberger

Design of the emplacement surface: Covering with foils?

Problems:

Generation of condense respectively impounded water underneath the foil

trafficability ?

slipping of the foil ?

Slope of the surface ( 5 %) daily rolling with smooth roller catchment and treatment of surface runoff!



Emissions from MBT landfills: Leachate volume

Leachate at the basis + surface runoff = ~ 65 % of precipitation

Leachate at the basis : surface runoff = 55 : 45 %



0

1000

2000

3000

Apr/ 10 Mai/ 10 Jul/ 10 Aug/ 10 Okt/ 10 Dez/ 10 Jan/ 11 Mrz/ 11 Mai/ 11 Jun/ 11

CO

D [

mg

/l]

F1 Basis

F1 Surfacenew waste layer

- Leachate and surface runoff must be collected- Dilution effects esp. on concentrations in surface runoff- A purification of both streams might be necessary- Increase in concentrations after emplacement of new waste layers- Concentrations much lower than in fresh wastes, typical for landfills in

the stable methane phase- Biostability is already high (BOD5/COD = 0,02 – 0,15)

Emissions from MBT landfills: Leachate quality



By MBT the gas potential is reduced of about 80 – 90 % to 10 – 45 Nm3/Mg DS The gas flux is expected to be low: low permeability of the MBT material

low temperatures in the MBT landfill

Active degassing does not make sense in technical and economical view

Methane oxidation potential:Soil layer: 2,5 – 12 l CH4/m2*hCompost substrate: 12 – 30 l CH4/m2*h

Emissions from MBT landfills: Gas

Passive system, e.g. methane oxidation layer

H2O CO2 O2

CH4CH4

CH4

Recultivation- and methane oxidation layer

> Methane flux from MBT



Water household

Stability

Gas

Operation

• less monitoring• shorter duration

Modification

• lower volume of leachate at the base• lower concentrations in leachate • collection treatment of runoff

• higher density• low settlement • flat slopes

• no active degassing and gas treatment

• changes in engines for disposal and compaction• less infrastructure• longer lifespan• less staff

Aftercare

Changes in construction and operation of MBT landfills in comparison to „traditional“ landfills



Summary:

Physical behaviour of MBT output material has to be tested before disposal

The construction (slope, engines etc.) and the operation (covering,drainage etc.) have to be adapted to the specific local conditions

Leachate from the base has still to be treated, but the volumesand concentrations are definitely lower

The low volumes of gas can be collected and treated by passivesystems

Time and effort during operation phase is increased, during theaftercare phase clearly reduced

The better the intensity of treatment (or the degree of stabilization) the smaller the effort necessary after closure of the landfill

Surface runoff has to be collected and possibly be treated



Dr.-Ing. K. Münnich

[email protected]

Thank you for your attention !

Date post:	06-Jul-2015
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