Acute and sub-lethal toxicity of landfill leachate towards two macro-invertebrates Assessing the Remediation Potential of Constructed Wetlands

• Published in: Process safety and environmental protection 2005-03, Vol.83 (B2), p.184-190
• Main Authors: Bloor, M C, Banks, C J
• Format: Article
• Language: English
• Subjects: Asellus; Asellus aquaticus; Gammarus pulex; Juncus effusus
• ISSN: 0957-5820
• DOI: 10.1205/psep.03303

A specific leachate that contained 1.036 mgl super(-1) of 2-chlorobiphenyl was used in the study (255 mgl super(-1) COD and 133 mgl super(-1) BOD sub(5)). When operated on a 10 day hydraulic retention time (RT), reed beds planted with Juncus effusus removed 60% of the leachates COD, compared to 25% in unplanted beds. The constructed wetlands proved effective at reducing the level of acute toxicity to A. aquaticus and G. pulex. In untreated leachate, the LC sub(50) for A. aquaticus was 57% v/v leachate in deionized water and 5% for G. pulex. When reed beds were operated on a 1-10 day RT, the LC sub(50) for Asellus increased from 69% to below the LC sub(50) threshold. The Gammarus LC sub(50) also rose from 10% to 50%. The maximum toxicity reduction achieved by unplanted beds was 10% towards A. aquaticus and 5% for G. pulex, when operated on a 10 day RT. However, in sub-lethal concentrations of reed bed effluent (100%, 80% and 60% dilutions, obtained from planted beds on a 10 day RT), the final length of Asellus was significantly reduced, in comparison to a deionized water control. It is also speculated that chronic leachate stress may have affected the fecundity of Gammarus, however, insufficient data was collected to statistically validate this hypothesis.