The Effects of Artificial Destratification on the Water Quality and Microbial Populations of Hyrum Reservoir

Artificial destratification is being increasingly used in attempts to improve water quality and control eutrophication. Most of the artificial destratification efforts are being conducted by public water supply utilities in efforts to improve reservoir water quality for culinary purposes. At present, artificial destratification is being conducted without a complete understanding of the process or its effects on the reservoir. Whether or not artificial destratification can control algal growth and other microbial processes is a controversial question. The effect of artificial destratification on the microbial flora must be understood if it is to be used effectively as a management tool in the control of water quality. In recent years a blue-green algal bloom has developed during the summer in Hyrum Reservoir. The massive bloom of Aphanizomenon jlos-aquae presents esthetic problems to those using the reservoir for recreational purposes. These esthetic problems have reduced the use of the reservoir for swimming, water skiing, and fishing. It is believed that artificial de stratification, or the destruction of natural stratification obtained through diffused-air aeration, will improve the water quality of the reservoir

A Field Technique Measuring Virus Decay and Potential Aerosol Hazard from Wastewater Sprinkler Irrigation

The increased use of domestic wastewater for irrigation purposes has stimulated a growing practice of sprinkler irrigating from oxidation ponds and other domestic wastewaters. Aerosols generated from these sprinkler irrigation systems may contain potentially hazardous pathogens. Subsequently, the aerosols can contain infective viruses which can be carried through the air to surrounding populations. Thus, a public health hazard can be created by sprinkler irrigating domestic wastewater. This study is an investigation of a means by which the virus decay rate of viruses in aerosols and the potentials hazard of sprinkler irrigation aerosol clouds may be examined. A means of injection of a human and animal virus stimulant, MS-2 bacteriophage, is described. In addition, the factors which are known to effect the survival of viruses in aerosols are discussed. The ambient air factors that are known to effect virus survival and which are discussed include relative humidity, air temperature, solar radiation, and aerosol age. The suspending fluid factors that are known to effect virus survival and which are discussed include dissolved inorganic salt contact, dissolved organic content, filterable solids and pH. The decay rate of the aerosolized MS-2 was measured with an all-glass impinger (AGI-30) when the wind velocity and distance of the sampler from the sprinkler system, and the initial and final concentrations of aerosolized MS-2 virus were known. The aerosol hazard of a domestic wastewater sprinkler irrigation system is defined in terms of the likelihood of infective aerosol particles to be inhaled and penetrate the human lung. Thus, the aerosol hazard is a function of aerosol particle size. The aerosol particle size distribution of the infective aerosol cloud was measured wit the Andersen sampler. A high and homogeneous concentration of the virus in the wastewater was insured by using pressure differentials in the sprinkler irrigation delivery line. By injecting the MS-2 virus into the line at a constant rate along with a tracer, Bacillus subtilus var niger (Bacillus globigii) spores, the decay rate of the virus during airborne exposure to environmental factors could be determined. The decay rate was determined assuming the environmental factors had no affect on the concentration of the tracer. It was proposed that the environmental engineer, after knowing the virus decay rates under varying environmental conditions, can define buffer zones which would be required around sprinkler irrigation sites. The buffer zone would reduce the possibility of contaminating humans by prohibiting access. The usefulness of the filed technique was demonstrated and the MS-2 was found to undergo a 33.3 percent decay per minute in the dark (no solar radiation) at 33 percent relative humidity, 70.6 percent dissolved organic material, 29.4 percent dissolved inorganic salts, 30.1 mg/1 filterable solids, and 17 degree C air temperature. The aerosol cloud resulting from the spray irrigation process appeared potentially hazardous because the Andersen sampler collected 84.2 percent of the virus infective droplets in the size range that could be inhaled

Review paper: Evaluation of Techniques for Algae Removal from Wastewater Stabilization Ponds

Introduction: Approximately 90 percent of the wastewater lagoons in the United States are located in small communities of 5,000 people or less. These communities, many with an average daily wastewater flow of only 175,000 - 200,000 gallons, do not have the resources to keep man at the lagoon sites throughout the day (38). A high degree of technical knowhow is usually lacking in these communities. Often only periodic inspection or maintenance is carried out by the general municipal work force. Therefore, the development of a relatively inexpensive method that does not require sophisticated and constant operation or extensive maintenance is needed to polish these effluents. Most regulatory agencies are adopting more stringent water quality standards, enforcement of which will necessitate changes in present treatment methods and the philosophy of wastewater treatment. Small communities utilizing stabilization ponds will be affected most drastically by new standards. Because most communities utilizing ponds are relatively small and installed ponds primariliy to avoid operating costs, it is unlikely that modifications requiring significant increases in operation will be acceptable. Therefore, the most sophisticated alternatives for upgrading treatment must be excluded from a practicable solution to solids removal from stabilization pond effluent

Effect of Protein Binding on Ultrafast DNA Dynamics: Characterization of a DNA:APE1 Complex

Synthetic oligonucleotides with a fluorescent coumarin group replacing a basepair have been used in recent time-resolved Stokes-shift experiments to measure DNA dynamics on the femtosecond to nanosecond timescales. Here, we show that the APE1 endonuclease cleaves such a modified oligonucleotide at the abasic site opposite the coumarin with only a fourfold reduction in rate. In addition, a noncatalytic mutant (D210N) binds tightly to the same oligonucleotide, albeit with an 85-fold reduction in binding constant relative to a native oligonucleotide containing a guanine opposite the abasic site. Thus, the modified oligonucleotide retains substantial biological activity and serves as a useful model of native DNA. In the complex of the coumarin-containing oligonucleotide and the noncatalytic APE1, the dye's absorption spectrum is shifted relative to its spectrum in either water or within the unbound oligonucleotide. Thus the dye occupies a site within the DNA:protein complex. This result is consistent with modeling, which shows that the complex accommodates coumarin at the site of the orphaned base with little distortion of the native structure. Stokes-shift measurements of the complex show surprisingly little change in the dynamics within the 40 ps–40 ns time range