A Ceriodaphnia algal uptake suppression test (CAUST) was developed for short-term toxicity screening. The test is based on the feeding behavior of C. dubia and requires as little as I hour contact time between C. dubia neonates and toxicant. Before the test, neonate digestive tracts were cleared by feeding yeast to the daphnids. Neonates were then exposed to toxicant, followed by addition of Scenedesmus subspicatus to the bioassay vessels. Daphnids were examined under bright-field microscopy for presence of algae (indicated by a green-colored digestive tract) or absence of algae. Uptake indicated no toxic effect, whereas absence of uptake indicated toxic inhibition. Median effective concentrations (ECso values) were computed based on results over a range of dosed toxicant concentrations. Results for cadmium, zinc, copper, pentachlorophenol, phenol, cyanide, and selected pesticides showed that CAUST was similar in sensitivity to the standard 48-hour C. dubia acute bioassay and was as sensitive as or more sensitive than the I-hour LQ. test and 30-minute Microtox. Water Environ.

ABSTRACf: Fermented organic wastes were investigated as electron donors for denitrification in activated sludge. Fermentation of primary domestic wastewater sludge improved denitrification rates in nonacclimated activated sludge, whereas fermentation of wastewater had no effect. In both acclimated and nonacclimated activated sludges, higher denitrification rates were obtained with fermented sludges (from domestic wastewater or swine waste) than with either methanol or acetate. Methanol was equivalent to acetate as electron donor for denitrification in acclimated sludges but supported lower denitrification rates than acetate in nonacclimated sludges. Mixing and pH were important determinants 'ofvolatile fatty acid yields from organic wastes, whereas temperature in the range of 28°C to 35°C had little influence. Waler Environ. Res .. 67, 1119(1995).