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.

Effects of ferrous ion coagulation in treating coke wastewater were examined through tests. In addition, nitrification tests using coagulated coke wastewater were carried out to evaluate the effect of ferrous ion coagulation on biological ammonium nitrogen removal. Experimental results showed that ferrous ion coagulation was very effective in terms of free cyanide (CN À ) removal. The best free CN À removal was found to be 98% at a ferrous ion dosage of 242 mg Fe 2þ L À1 . In addition, ferrous ion coagulation was also effective for the removal of turbidity. The highest turbidity removal was observed to be 88% at a ferrous ion dosage of 242 mg Fe 2þ L À1 , where the best free CN À removal was found. This indicates that the determination of optimum ferrous ion dosage for free CN À removal could be indicated by turbidity removal. Although ferrous ion coagulation caused a decrease in total alkalinity, it did not affect nitrification. In triplicate nitrification tests, the best NH 4 þ -N removal rate in nitrification was found to be 16.43 mg NH 4 þ -N L À1 h À1 in residual solution, where the highest free CN À removal was observed by coagulation tests. Consequently, it was found that, in terms of biological ammonium nitrogen removal, ferrous ion coagulation contributed to 35% enhancement compared to that of noncoagulated coke wastewater by reducing the concentration of free CN À from raw coke wastewater.