Laboratory and field studies were conducted to evaluate the importance of periphyton in western Lake Superior with special reference to the make-up and distribution of the periphyton growths and to the overall importance of productive capacity of this assemblage of organisms. The taxonomic portion of the investigation indicated that over 90% of the total number of organisms were diatoms and that the phyla to which these diatoms belonged were the Chrysophyta, the Chlorophyta, and the Cyanophyta. Predominant genera were Synedra, Achnanthes, Navicula, Cymbella, and Gomphonema. In many respects, the periphyton of Lake Superior was similar to that found in streams and there was evidence that the interrelated factors that affected periphyton growths were temperature, light intensity, depth of water, water movements, nutrient levels, and the type of substrate.

Analysis of exploratory test cores and rock chip samples has made available information necessary to the development of rational techniques for reclaiming coal mine spoil for useful purposes. By assigning an area a particular future use and analyzing the rock structure in advance of the surface mining, materials can be assembled and placed in the fill to allow the filled strip mine to revegetate and be developed into a useful area. Oxidation of pyrite materials, source of most acidity below 4.0 in mine spoils, can be controlled by: (1) using clay shales for fill; (2) controlling gain size in the fill; and (3) controlling accessibility to exchange of solutes and oxygen. In miniature lysimeters filled with 4 ft of normal, loamy (pH 6.7) soil, no acidity nor iron drained from the bottom from pyrite buried at 6 depths, from 1/2 to 36 inches, during a 24 week test period. Base exchange by the soil neutralized the acid and retained the iron.

A process (called UNOX) for treating municipal wastewater using high-purity oxygen in the activated sludge process was further evaluated at Batavia, New York in a full scale wastewater treatment plant. The present evaluation places emphasis on the production rate, filtration, and digestion characteristics of oxygenated waste activated sludge. Operation was conducted at two different system loadings over a period of three months. The filtering characteristics of waste activated sludge from an oxygenation system were investigated. Waste activated sludge was aerobically digested in 800-gallon batches using high-purity oxygen. The economics of oxygenation systems as compared with conventional diffused air aeration systems were revised from the cost estimates presented in initial work.

A field project demonstrated the feasibility of renovating secondary sewage effluent by ground water recharge with infiltration basins. Maximum loading rates were obtained. With the schedules the system could infiltrate 300-400 ft/year using a water depth of 1 ft. Grassed basins had higher infiltration rates, and a gravel covered basin had a lower infiltration rate than a bare soil basin. Essentially complete removal of BOD and fecal coliform, and significant removal of phosphorus, nitrogen and fluoride were obtained. Hydraulic properties of the aquifer were evaluated by analog from the response of piezometric heads in the ground-water system to infiltration. These properties were then used in the design of a prototype system, which would yield renovated water at an estimated total cost of about $5 per acre-foot at the pump.