The most common cyanobacterium contaminating drinking water systems in southwestern Pennsylvania is Schizothrix calcicola. Lipopolysaccharides (LPS) were isolated from this species by hot phenol-water extraction. The polysaccharide moiety was composed of glucosamine, galactose, glucose, mannose, xylose, and rhamnose. The lipid A part contained beta-hydroxylauric, myristic, pentadecanoic, palmitic, beta-hydroxypalmitic, stearic, oleic, and linoleic acids. In contrast to many LPS isolated from Enterobacteriaceae, the dominant component was not beta-hydroxymyristic but beta-hydroxypalnitic acid. The LPS induced Limulus lysate gelation and Schwartzman reaction but was nontoxic to mice. The identity of LPS was verified by alkali and lysozyme treatment. The results suggest that S. calcicola is one of the principal sources of endotoxins in water systems using open finished-water reservoirs. A water-bome outbreak of gastroenteritis affected approximately 5,000 persons in Sewickley, Pa., during August 1975. Extensive microbiological and chemical analyses of specimens obtained from patients and of water samples failed to identify a causative agent. However, investigation of the Sewickley water system revealed an accumulation of Schizothrix calcicola (Cyanobacteria = Cyanophyta) in the open finished-water reservoirs (15). Even 1 month after the outbreak, the water in the reservoir with the longest detention time was still contaminated by this species (400,000 cells ml-').

The long-term effect of lime neutralized suspended iron on fathead minnow (Pimephales promelas) survival, growth, and reproduction was assessed in a flow-through environment with a modified proportional diluter. Results of 12 months of testing reveal lower survival and declining growth of fathead minnows with an increase in lime neutralized suspended iron concentration. Hatchability and growth of fathead minnows were appreciably reduced in the lowest insoluble iron concentration tested, 1.5 mg Fe/liter. Reduced hatchability was attributed to the higher percentage of smaller particles in low lime neutralized iron concentrations. A comparison of data on survival, growth, and hatchability indicates that the safe level of suspended iron for fathead minnows presumably lies between the control and 1.5 mg Fe/liter.

This study was designed to determine geographic and seasonal distribution of Giardia cysts in wastewater and sludge and their removal by sewage treatment processes. Eleven wastewater treatment plants located in cities across the United States were included in the study. Flow weighted, composite samples of raw and treated wasteWaters and sludges were collected at monthly intervals for a period of one year. The cysts were concentrated by sucrose flotation or by simple centrifugation (“direct count”) and assayed microscopically. Sucrose flotation counts of cysts in the raw sewage were extremely variable producing results ranging from 0.4% to 77.8% of the direct counts. Based on 12 consecutive months of sampling, and using the direct counts, the highest geometric mean Giardia cyst concentrations occurred at the California site (3375 cysts/L), the Florida site (3087 cysts/L) and the Vermont site (2040 cysts/L). The lowest geometric mean Giardia cyst levels were in samples from the Pennsylvania site (642 cysts/L), the Tennessee site (762 cysts/L) and the Maryland site (957 cysts/L). Cyst concentrations in raw sewage were highest in late summer, fall and early winter. Although all raw sewage samples contained cysts, only about one half of the wastewater treatment plant effluents were positive with cyst concentrations ranging up to 44 cysts/L. Based on sucrose flotation counts, the concentrations of cysts detected in the sludges ranged from 70 to 30,000 cysts/L.

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