Biosorption of heavy metals using permeable pavement biofilms

: Quantification, optimization, modelling and sustainability evaluation

Abstract

The present critical overview document is comprised of a background, methodological approach and discussion of a portfolio of peer reviewed journal publications, on the remediation of contaminated urban runoff containing soluble heavy metals by permeable pavement living biofilms. The biosorption efficiencies of different bacterial strains for heavy metals, were evaluated using a meta-analysis technique. The experimental biosorption studies were carried out to examine the equilibrium, thermodynamics and kinetics of heavy metals removal, using permeable pavement living biofilms, incubated on a nonwoven polypropylene and polyethylene geotextile. In sustainability studies, Life Cycle Assessment and Life Cycle Costing methodologies were used to investigate the life cycle impacts of permeable pavements and compare the results to alternative drainage systems. The results of the meta-analysis study, revealed that Firmicute phyla had the highest overall (living and dead) biosorption efficiencies for heavy metals. Living bacterial biomass was more efficient in biosorption of Cu(II), Zn(II) and Pb(II) than dead biomass. High temperatures (>35 °C) were less efficient in Cu(II) and Zn(II) removal and the maximum biosorption efficiency for non-essential heavy metals occurred at short contact times (<2 h). With 20 mg L-1 initial concentration of Hg (II), living permeable pavement biofilms with incubation times of 1, 7, 14, 21 and 28 days, showed biosorption efficiencies of 55.72, 67.12, 61.37, 62.57 and 65.38%, respectively. Thermodynamic and kinetic modelling of data revealed that a physical, feasible, spontaneous and exothermic process controlled the biosorption, with a diffusion process observed in external layers of the biofilm, fitting a pseudo-second order kinetic model. Results of sustainability studies showed that permeable pavements had lower life cycle impacts on human health than kerb and gully, infiltration basin and infiltration trench systems. Transportation of materials and construction civil works had large contributions in life cycle inventories and associated environmental impacts of the drainage systems

Date of Award	9 Sept 2022
Original language	English
Awarding Institution	Coventry University
Supervisor	Steve Coupe (Supervisor) & Alan Paul Newman (Supervisor)