Viegas, CatarinaNobre, CatarinaMota, AndréVilarinho, CândidaGouveia, LuisaGonçalves, Maria Margarida2021-11-232021-11-232021-06Viegas, Catarina... [et.al.] - A circular approach for landfill leachate treatment: chemical precipitation with biomass ash followed by bioremediation through microalgae. In: Journal of Environmental Chemical Engineering, 2021, Vol. 9 (3), article nº 105187http://hdl.handle.net/10400.9/3615ABSTRACT: 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 mu m. 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.engMicroalgaeLandfillWastewater treatmentBioremediationjournal article10.1016/j.jece.2021.1051872213-3437