Municipal wastewaters toxicity assessment using higher plants and invertebrates

Prie žurnalo pritvirtintas priedas CDThe toxicity of municipal wastewater was evaluated using the bioassays with aquatic invertebrates and terrestrial higher plants. Toxicity tests were performed on samples of untreated wastewater. Wastewater toxicity was assessed using seed germination and short-term early seedling growth test of lettuce (Lactuca sativa L.) and the acute microcrustaceans Thamnocephalus platyurus (24 h) assay. Undiluted wastewater was severely toxic to T.platyurus and led to death of all exposed organisms. Twofold decrease of wastewater concentration in solution (from 100 % to 50 %) led to sharp transition between extremely toxic to medium toxic to tested organisms in four and more times diluted wastewater died only 10-20 % of total exposed T. platyurus. The measured endpoints in higher plants test were seed germination, root length, shoot height and total biomass. Raw sewage severely inhibited the root growth of lettuce, but twice or more times diluted wastewater exhibited no adverse effects or even started to stimulate the growth. The growth of shoots and total biomass were stimulated due to exposure to undiluted or diluted wastewater. Stimulation effect was determined by sufficiently high concentrations of nutrientsAplinkotyros katedraGamtos mokslų fakultetasVytauto Didžiojo universiteta