A circular approach for landfill leachate treatment: Chemical precipitation with biomass ash followed by bioremediation through microalgae

Catarina Viegas, Catarina Nobre, André Mota, Cândida Vilarinho, Luísa Gouveia, Margarida Gonçalves

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

The aim of this work was to study an integrated approach for landfill leachate remediation comprising chemical precipitation with biomass bottom ash as a pre-treatment to reduce color and turbidity followed by bioremediation through microalgae treatment for effluent disposal. Optimal pre-treatment conditions were determined through batch experiments and were found to be 160 g L-1 ash dose, 96 h of contact time, overhead agitation at 15 rpm and ash particle size below 500 μm. These conditions led to removal efficiencies of 74.3% for chemical oxygen demand and 98.5% for color. Large quantities of sludge containing excess biomass ash and precipitated compounds were formed during the pre-treatment. To minimize solid disposal, this sludge was tested as a raw material for cementitious and aggregate substitute in mortar formulations. Following the pre-treatment, the leachate was inoculated with six different microalgae species to evaluate their ability to grow in such a recalcitrant effluent and remediate it. After a period of 27 days biomass concentration from 0.4 to 1.2 g L-1 were achieved for the tested microalgae. Removal efficiencies were in the range of 18-62% for COD, 63-71% for N, and 15-100% for P. At the end of the treatment, algal biomass was characterized regarding protein, lipid, fatty acids, carbohydrate, and ash contents. This approach allows a low-cost remediation of these recalcitrant effluents when compared with the present options that include inverse osmosis, and the valorization of ash-rich precipitates and microalgae biomass improves the sustainability of the overall process.

Original languageEnglish
Article number105187
JournalJournal of Environmental Chemical Engineering
Volume9
Issue number3
DOIs
Publication statusPublished - Jun 2021

Keywords

  • Bottom ash
  • Landfill leachate treatment
  • Microalgae
  • Mortars
  • Precipitation
  • Wastewater treatment

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