Constructed Wetlands for landfill leachate

IRIDRA Fitodepurazione per percolati di discarica

Nature-based solutions are a valid alternative for the treatment of landfill leachate. Constructed wetlands started to be use for landfill leachate treatment since the 80s, testing both horizontal subsurface flow and free water surface systems. Nowadays, the most common solution for leachate treatment adopts multistage hybrid systems downstream an equalization tank, which is usually requested to collect the variable landfill produced in function of rain events.

High removal of organic and nitrogen loads
Less discharge of leachate due to evapotraspiration effect
Restoration of area near landfills

Landfill leachates - IRIDRA's solutions

Classical constructed wetlands

  • Constructed wetlands with horizontal subsurface flow (HF)
  • Constructed wetlands with vertical subsurface flow (VF)
  • Constructed wetlands with free water surface (FWS)
  • Hybrid constructed wetlands (VF + HF, VF + VF + HF + HF + FWS)

Intensified constructed wetlands (Constructed wetlands 2.0)

  • Aerated constructed wetlands (FBA™)

Integrated low-tech solutions

  • Lagoons

Removal efficiencies

Constructed wetlands for landfill leachate treatment show good removal efficiencies, which can vary according to different sizes, hydraulic regimes, and primary treatments (Wojciechowska et a., 2010).

 percolati rendimenti cw percolato wojcie2010

Average removal efficiencies from different Polish and Sweden case studies. (Wojciechowska et a., 2010)

A good design guarantees high removal efficiencies. For instance, mean removal efficiencies registered from 7 Slovenian case studies were: BOD5 68%, COD 73%, N-NH3+ 75%, TP 73%. The CW WWTP treating the leachate from the landfill of Chunchulala in Mobile County (Alabama – USA) has shown the following average performances: TSS 97%, COD 90%, TOC 87%. The landfill of Laflèche, Eastern Ontario, treats the landfill with a CW WWTP which was monitored the first two years of operations, showing high mean removal of organic load (95%) and ammonia (99%). Satisfactory organic removal were observed also in cold climates; for instance, the CW treating the leachate from the landfill of the Municipality of Kodiak Island, in Alaska, had mean removal of 40% for COD and 36% for ammonia, high metal removal (99% for Fe and 44% for Mn), and a clear effluent. Good performances were observed also in long term monitoring, as shown by Bulc (2006), which monitored a landfill leachate treatment plant for 7 years, reporting constant removal efficiencies of 50% for COD, 59% for BOD5 and 51% for ammonia.

percolati cod bulc2006a

Influent and effluent COD concentration correlated with precipitation for 7 years of monitoring of a CW for landfill leachate. Bulc (2006)

Constructed wetlands coupled with Sequencing Batch Reactors (SBRs).

The combination of SBR and CW is one of the most promising options of integration between nature-based and technological solution for wastewater treatment (Liu et al., 2015). SBR+CW scheme was often adopted in the UK for leachate treatment. Indeed, about 80 treatment plant for with SBR+CW scheme is reported (Mulamoottil et al., 1999). One example is the landfill of Judkins Quarry (UK), reported in the following picture.

 percolati sbr cw percolato judkins quarry  web

Areal view of the SBR+CW plant for treatment of leachate from the Judkins Quarry landfill (UK).

IRIDRA progetto per Discariche Taglietto, Villadose (RO)

Taglietto landfill, Villadose (RO - Italy)

Treated person equivalent: 338 PE (referred to organic load)

Chosen Nature-based solution: VF + VF + VF + HF + HF + FWS

Peculiarity: First constructed wetland for landfill leachate in Italy

Year of realization: 2010

The Taglietto system represents the first example in Italy of landfill leachate treatment plant based on CW. A feasibility study regarding the treatment of the landifill leachate produced by landfills Taglietto 1 and Taglietto 2 was conducted on behalf of Ecogest srl in year 2005. This study has individuated the CWs as best solution for the leachate treatment. At the moment the plant is under star up and it is fed with fresh water to test the waterproofing and ensure a good plant establishing. We are waiting for the end of authorization process to begin the feeding with leachate.The treatment plant is constituted by 4 line operating in parallel, except the final stages (FWS and Pond) finalized to the post-treatment and detention of the leachate, that are constituted by one common line.Each line of the plant is constituted by:1th VSSF stage with a superficial peat layer to ensure odor remove, leachate pre-oxidation and metals precipitation;2nd and 3rd stage VSSF in series for nitrification and organic load removal;4th and 5th stage SFS-h in series for denitrification and removal of persistent organic compounds;6th stage FWS to complete the denitrification and the organic compounds removal and to enhance the evapotranspiration;A final detention pond to accumulate the effluent and enhance the evapotranspiration.The SSF beds are planted with Phragmites Australis. The FWS is planted with floating and emergent native species.To ensure an optimal protection to subsoil and groundwater, the local authorities requested a special waterproofing of the reed beds constituted by (from the bottom): Non woven geotextile40 cm clayGeotextile Clay Liner 6 mmHDPE liner 2 mmNon woven geotextile
IRIDRA progetto per Discarica di San Donato, Vinci (FI)

San Donato landfill, Vinci (FI - Italy)

Treated wastewater quantity: 8.5 m3/day

Chosen Nature-based solution: VF + VF + VF + HF + HF + FWS

Year of design: 2010

IRIDRA progetto per Discarica di Lusignan (Guyana)

Lusignan landfill (Guyana)

Treated wastewater quantity: 100 m3/day

Chosen Nature-based solution: Lagoon + FWS

Year of design: 2014

IRIDRA progetto per Transfer station per aree turistiche in espansione (Belize)

Transfer station for touristic areas (Belize)

Treated wastewater quantity: 4.9 - 5.2 m3/day

Chosen Nature-based solution: VF + HF

Peculiarity: Treatment of landfill from waste compaction in transfer stations

Year of design: 2016

Municipal Waste Landfill Leachate - A new research assigned to the IRIDRA team: a small pilot plant located on-site is starting to operate right in this spring 2014 for assessing and improving the design of the up-scaled treatment wetlands that will be applied for the condensate generated by an evaporation-condensation reactor.
IRIDRA progetto per Impianto di trattamento di rifiuti non pericolosi della Belvedere S.p.A., Peccioli (PI)

Treatment plant for not dangerous wastes of Belvedere S.p.A., Peccioli (PI - Italy)

Treated wastewater quantity: 1 m3/giorno (pilot plant)

Chosen Nature-based solution: HF

Peculiarity: Trattament of water from evaporation tower

Year of realization: 2014

Municipal Waste Landfill Leachate - A new research assigned to the IRIDRA team: a small pilot plant located on-site is starting to operate right in this spring 2014 for assessing and improving the design of the up-scaled treatment wetlands that will be applied for the condensate generated by an evaporation-condensation reactor.
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