Laboratory assessment of the ecotoxic effects of sewage sludge from the Maluti-Drakensberg region on a terrestrial oligochaete species
We used the Enchytraeid Reproduction Test to evaluate the potential ecotoxic effects of sewage sludge samples on terrestrial oligochaetes in an Afromontane area. The sludge samples were collected from two wastewater treatment plants near the towns of Phuthaditjhaba and Harrismith in the Afromontane region of the eastern Free State in South Africa. Laboratory experiments revealed that although the sludge samples were not detrimental to the survival of Enchytraeus albidus (p > 0.05); they were able to significantly hinder its reproduction (p < 0.01). Through metal analyses, the sludge samples were found to belong to the relatively “best quality” pollutant class a sludge which is deemed suitable for land disposal and use as soil amendment for agricultural purposes. Herein, we point to the fact that the current South African sewage sludge disposal guidelines may not insure the protection of beneficial soil dwelling invertebrates such as oligochaetes. Our contribution also highlights the paucity of studies with an emphasis on environmental pollution in mountain areas across Africa and should signal a need for broader environmental considerations such as environmental pollution to be taken into account in the existing mountain invertebrate conservation methodologies.
KeywordsMetal toxicity Ecotoxicity Wastewater sludge Enchytraeidae Oligochaeta
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This article does not contain any studies with human participants performed by any of the authors. All applicable international, national, and/or institutional guidelines for the care and use of animals were followed.
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