Ecotoxicological effect of sludge from a poultry processing center on the earthworm (Eisenia fetida) and corn (Zea mays)

Abstract

The objective of this research was to evaluate the ecotoxicological effect of dissolved air flotation (DAF) sludge from a poultry processing plant on earthworms (Eisenia fetida) and corn seeds (Zea mays) using bioassays. The physicochemical characterization of the DAF sludge and the soil used in the bioassays was performed. In the earthworm bioassay, seven doses of DAF sludge (1.56% to 6.25%) plus a control were used, and in the corn seed phytotoxicity bioassay, six doses of DAF sludge (6.25% to 21.88%) plus a control were used. The LD50 (median lethal dose) for DAF sludge on earthworms was 5.21%, and earthworm weight increased after 7 days of exposure, then decreased after 14 days of exposure. It was observed that cocoons formed at low doses of DAF sludge, and that there was a correlation between earthworm mortality (%) and pH and electrical conductivity. The ID50 (median inhibition dose) for corn seed germination was 11.1% DAF sludge. At 21 days, significant differences in the percentage of DAF sludge necrosis occurred, starting at 15.63%. A decrease in height, wet weight, dry weight, and number of leaves of Z. mays was observed as the DAF sludge dose increased, and finally, there was an association between corn seed germination and pH, and no association with electrical conductivity.