Landfill leachate treatment by a combination of a multiple plant hybrid constructed wetland system with a solar photoFenton process in a raceway pond reactor

The sustainable and green treatment of landfill leachate (LL), produced by municipal solid waste, represents one of the most relevant challenges in the integrated waste management systems. Accordingly, in this work a green solution was investigated by coupling an innovative hybrid constructed wetland (HCW) to a solar photo-Fenton (SPF) process. A multiple layers HCW pilot plant including different medium substrates (sand, solid compost and carriers) and plant species (Phragmites australis, Arundo donax and A. plinii) was designed. The HCW was func-tionalised with compost tea solution to simultaneously provide high nutrient content for plants and increase the microorganism biodiversity. Process efficiency was investigated using different real LLs (young and mature) in terms of chemical oxygen demand (COD), nitrogen compounds, chlorides and metals. Removals in the range 75-95% were observed for all the parameters after ten days of leachate recirculation in the pilot plant. Subse-quently, the SPF process was carried out in a raceway pond reactor (RPR) as polishing step, significantly improving COD removal (further 49%). HCW combined with SPF in RPR would allow to meet the corresponding limits according to the final use/fate of the effluent by modulating the main parameters of the process.

Automated summary

The sustainable treatment of landfill leachate poses a significant challenge. This study investigates a green solution by combining a hybrid constructed wetland with a solar photo-Fenton process. A multi-layered wetland pilot plant was designed, incorporating different substrates and plant species. The wetland was functionalized with compost tea solution to provide nutrients for plants and enhance microbial biodiversity. The efficiency of the process was evaluated using real landfill leachate, with removal rates of 75-95% observed for various parameters. Further polishing of the effluent was achieved through the solar photo-Fenton process, resulting in an additional 49% COD removal. The combined system allows for meeting the required limits by adjusting the process parameters according to the final use of the effluent.