Bioremediation of Landfill Leachate with Fungi: Autochthonous vs. Allochthonous Strains

Abstract

Autochthonous fungi from contaminated wastewater are potential successful agents bioremediation thanks to their adaptation to pollutant toxicity and to competition with other microorganisms present in wastewater treatment plant. Biological treatment by means of selected fungal strains could be a potential tool to integrate the leachate depuration process, thanks to their fungal extracellular enzymes with non-selective catalytical activity. In the present work, the treatability of two real samples (a crude landfill leachate and the effluent coming from a traditional wastewater treatment plant) was investigated in decolorization experiments with fungal biomasses. Five autochthonous fungi, Penicillium brevicompactum MUT 793, Pseudallescheria boydii MUT 721, P. boydii MUT 1269, Phanerochaete sanguinea MUT 1284, and Flammulina velutipes MUT 1275, were selected in a previous miniaturized decolorization screening. Their effectiveness in terms of decolorization, enzymatic activity (laccases and peroxidases), biomass growth and ecotoxicity removal was compared with that of five allochthonous fungal strains, Pleurotus ostreatus MUT 2976, Porostereum spadiceum MUT 1585, Trametes pubescens MUT 2400, Bjerkandera adusta MUT 3060 and B. adusta MUT 2295, selected for their well known capability to degrade recalcitrant pollutants. Moreover, the effect of biomass immobilization on polyurethane foam (PUF) cube was assessed. The best decolorization (60%) was achieved by P. spadiceum MUT 1585, P. boydii MUT 721 and MUT 1269. In the first case, the DP was achieved gradually, suggesting a biodegradation process with the involvement of peroxidases. On the contrary, the two autochthonous fungi seem to bioremediate the effluent mainly by biosorption, with the abatement of the toxicity (up to 100%). The biomass immobilization enhanced enzymatic activity, but not the DP. Moreover, it limited the biomass growth for the fast growing fungi, MUT 721 and MUT 1269. In conclusion, robust and versatile strains coming from well-characterized collections of microorganisms can obtain excellent results comparing and even exceeding the bioremediation yields of strains already adapted to pollutants.

Assessment of landfill leachate biodegradability and treatability by means of allochthonous and autochthonous biomasses

“…Moreover, as reported in previous studies, autochthonous bacteria enabled a higher amount of organic substrate to be degraded and, in particular, thatwhich is slowly biodegradable [18,25].…”

“…Biological, chemical and physical procedures have been widely used in recent years to treat leachate [7]. Among these, chemical and physical methods are the most effective, although expensive, whereas biological treatments usually represent the less expensive degradation pathway for many biodegradable organic and nitrogen containing compounds [8,9]. However, the biological processes may not deal with refractory and hazardous compounds [10].…”

“…Alternatively, if bacteria derive from another environment (allochthonous bacteria), biodegradation is possible after theyhave adapted to the new environment (acclimation). Several studies suggested that autochthonous microorganisms could be a valuable resource for bioremediation of the leachate [17,18]. Indeed, autochthonous microorganisms are necessarily tolerant of the high toxicity of the leachate and may take part in the degradation of recalcitrant molecules [19].…”

Mycoremediation of Old and Intermediate Landfill Leachates with an Ascomycete Fungal Isolate, Lambertella sp.

“…In general, it is reasonable to assume that autochthonous microorganisms would be able to biodegrade the organic fraction of the matrices of origin, more efficiently than allochthones [49]. However, most of the time, this was not observed with the aging of LFLs.…”

Screening and selection of autochthonous fungi from leachate contaminated-soil for bioremediation of different types of leachate

“…Unfortunately, most of them have serious drawbacks, such as the low capacity in removing recalcitrant compounds, the formation of toxic by-products, operational problems due to equipment damage and malfunctioning, and their limited applicability to certain contaminants that are present at high level in the landfill leachate [2,16]. In order to overcome these drawbacks, the bioremediation was introduced as an efficient and cost effective solution for removal of a wide variety of contaminants, including the ones present in landfill leachate [17,18]. Generally, the bioremediation is defined as a process that uses microorganisms or their enzymes to degrade the environmental contaminants into less toxic forms [19].…”