Assessment of addition of biochar to filtering mixtures for potential water pollutant removal

Abstract

Green roofs are used increasingly to alleviate peaks of water discharge into the sewage systems in urban areas. Surface runoff from roofs contain pollutants from dry and wet deposition, and green roofs offer a possibility to reduce the amounts of pollutants in the water discharged from roofs by degradation and filtering. These pollutants would otherwise enter wastewater treatments plants and ultimately end up in sewage sludge that is spread on agricultural soils. The most common substrates used in green roofs have limited capacity for filtration and sorption. Also, more sustainable alternatives are sought, due to the high carbon footprint of these materials. Biochar is a carbon-rich material produced by pyrolysis of biomass, and several types of biochar have been described as good sorbents and filter materials. Biochar is also a light and carbon negative material, which may fulfill other desired criteria for new green roof substrates. We here report on an experiment where two types of biochar, produced from olive husks at 450 °C or from forest waste at 850 ° C were mixed with volcanic rock or peat, and tested for retention capacity of phenanthrene and six heavy metals in a column experiment with unsaturated gravimetric water flow lasting for 3 weeks. The results suggest that biochar as a component in green roof substrates perform better than traditional materials, concerning retention of the tested pollutants, and that different types of biochar have different properties in this respect.Electronic supplementary materialThe online version of this article (10.1007/s11356-017-0650-6) contains supplementary material, which is available to authorized users.

Nutrient leaching in extensive green roof substrate layers with different configurations

“…Compared to PV, PVG exhibited a significant NH 4 + -N interception capacity, which may be because green zeolite has a higher affinity for NH 4 + -N in rainfall runoff than vermiculite. Alternately, it may be because the two adsorption substrates in the substrate layer have a synergistic purification effect on NH 4 + -N in rainfall runoff, which exhibits better NH 4 + -N interception effect in rainfall runoff than a single adsorption substrate (Piscitelli et al 2018). The total CLQ of NH 4 + -N for PVG and PVGP is similar because the NH 4 + -N interception in rainfall runoff is highly dependent on the substrate adsorption capacity.…”

Effective mechanisms of water purification for nitrogen-modified attapulgite, volcanic rock, and combined exogenous microorganisms

“…The relative occupied abundances of Proteobacteria offered their use in wastewater treatment, especially the bioremediation of hydrocarbon pollutants ( Romero et al, 2019 ). The volcanic rock increased the expression of Planctomycetes, decreased the expression of Proteobacteria, and a recent study showed that volcanic rock had a retention capacity of heavy metals when combined with the use of biochar ( Piscitelli et al, 2018 ).…”

Study of Adsorption Performance of Biochar for Heavy Metals Removal

“…Amin MT et al [15] used banana peel biochar as adsorption filter media for eliminating lead and copper. Piscitelli L et al [16] studied different types of biochar, this study indicated that each of volcanic rock VR, peat, and its mixtures with biochar had high efficiency to remove pollutants (heavy metals) from water and biochar was better than conventional materials. Reddy et al [17] concluded that the removal efficiencies of different heavy metals Cd, Cu, Pb, and Zn were 18, 65, 75, and 24%, respectively after passing through the biochar filter.…”