Evaluation of strategies to minimize ecotoxic side‐effects of sorbent‐based sediment remediation

Abstract

BACKGROUND In situ sorbent amendment for persistent organic pollutant sequestration in sediment has over the past 15 years steadily progressed from bench‐scale trials to full‐scale remediation applications. Hindering a wider technology uptake are, however, concerns about ecotoxic side‐effects of the most commonly used sorbent, activated carbon, on sensitive, sediment dwelling organisms like Lumbriculus variegatus. Using River Tyne sediment polluted with polycyclic aromatic hydrocarbons (PAHs) and L. variegatus as a case study, sorbent alternatives and magnetic sorbent‐recovery were investigated as potential engineering strategies to mitigate such ecotoxic side‐effects. The potential benefits of contacting the treated sediment with fresh River Tyne water, as would naturally occur over time in the intended applications, were studied.RESULTSMagnetic biochar was identified as an effective PAH sorbent with less ecotoxic side‐effects than magnetic activated carbon. After 85.1–100% magnetic recovery of this biochar, no ecotoxic side‐effects on L. variegatus were measurable in the treated sediment. Results show that ecotoxic effects of magnetic activated carbon can be alleviated through sorbent recovery. In contrast, contacting treated sediment repeatedly with River Tyne water had no measurable benefits.CONCLUSIONSMagnetic biochar is a promising sorbent material for the remediation of PAH polluted sediment. © 2017 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Sorption, separation and recycling of ammonium in agricultural soils: A viable application for magnetic biochar?

“…This would, therefore, minimise the economic and environmental burden generated by agrochemical production and transport, which can be significant as shown in various Life Cycle Assessments of N fertiliser use ( Charles et al, 2006 ; Hasler et al, 2015 ; Wang et al, 2007 ), while simultaneously limiting the amount of waste produced. Also, removal of magnetic biochar reduces the likelihood of negative impacts on the environment, such as ecotoxicity towards organisms that could be caused by re-release of sorbed pollutants ( Han et al, 2017 ).…”

A Combined Field and Laboratory Study on Activated Carbon-Based Thin Layer Capping in a PCB-Contaminated Boreal Lake

“… 13 The most sensitive species were found to be sediment dwelling organisms, such as for example Lumbriculus variegatus , Chironomus riparius , or Arenicola marina . 14 − 18 Observed effects in these organisms are most often reduced growth or loss in biomass, reduced emergence rate ( C. riparius ) or lowered feeding rates. Acute toxicity (mortality) has been observed in a few cases involving high doses of AC for Gammarus pulex ( 15 ) and L. variegatus.…”

“…The magnitude of these secondary effects induced by AC vary depending on the affected species and have been reviewed by Rakowska et al and Janssen and Beckingham . The most sensitive species were found to be sediment dwelling organisms, such as for example Lumbriculus variegatus, Chironomus riparius, or Arenicola marina. − Observed effects in these organisms are most often reduced growth or loss in biomass, reduced emergence rate (C. riparius) or lowered feeding rates.…”