SYMPOSIA PAPER Published: 01 January 1991

Higher Plants (Common Duckweed, Lettuce, and Rice) for Effluent Toxicity Assessment


The objective of this study was to evaluate effluent toxicity using phytotoxicity tests. Samples including receiving water, treated effluent, and pretreated industrial wastewaters were collected from three Illinoisian sanitary districts. These samples were tested as is, using duckweed, lettuce, and rice. The treated effluents from the three sources were not toxic in all tests. A pretreated industrial sample from a metal processing plant showed 98% inhibitory effect on duckweed. The same sample was not toxic to lettuce and rice germination. A sample from a transportation industry was toxic using duckweed, lettuce, and rice tests, having inhibitory effects of 45, 13, and 39%, in that order. A sample from a dairy plant was extremely toxic. The sample as received caused inhibitory effects of 100, 87, and 100%, in the same order of three species. The IC50 value and 95% confidence limit for this sample was 50% and 47 to 53% effluent concentration, respectively, using the duckweed toxicity test method.

Author Information

Wang, W
Illinois State Water Survey, Peoria, IL
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Developed by Committee: E47
Pages: 68–76
DOI: 10.1520/STP19504S
ISBN-EB: 978-0-8031-5173-4
ISBN-13: 978-0-8031-1422-7