The Resuspension of Flocculent Solids in Sedimentation Basins

The phenomenon of resuspension has been considered to be an important factor in the imperfect behavior of sedimentation basins receiving suspensions containing flocculent solids. Resuspension is the entrainment into the flow of particles that have once settled to the floor of the basin. This investigation has been undertaken to study the resuspension phenomenon and to find ways in which its harmful effects can be reduced. Resuspension has been found extremely difficult to isolate and define scientifically because many other factors produce the same overall effect upon the settling tank. Furthermore it is practically necessary to identify individual particles in order to know whether a particular one found in suspension in the downstream portion of a settling tank had earlier been settled out and resting on the floor. Laboratory studies on settling tank behavior were conducted on a glass-walled "scour flume" 1.27 ft wide by 14 ft long with depth adjustable from 0.5 to 2.0 ft (see Fig. 1.1). In order to simulate certain aspects of the behavior of full-scale settling tanks the laboratory flume was fitted with moving flight scrapers similar to those installed in primary sewage settling tanks. For some of the later tests the flume was fitted with 14 probes that made it possible to sample the tank contents at practically any point of five cross sections along the length of the flume. Most of the studies on the laboratory flume utilized a discrete suspension of gilsonite {s. g. 1.04) particles or a flocculent suspension of ferric chloride and bentonite clay particles. Tests for critical velocity required for entrainment of particles from a smooth bed showed that fine light particles are more easily lifted from the bed than was previously supposed. With scrapers moving upstream, the critical velocity for two sizes of gilsonite tested was found to vary between 10.5 and 14.5 times the particle settling velocity. Field and laboratory studies on one scheme proposed to improve the performance of settling tanks - a series of transverse sloping baffles installed throughout the main body of a rectangular settling tank - both indicate that baffling a tank is not the answer. Tests on full-scale settling tanks of a sewage treatment plant showed that conventional measures of settling tank performance are meaningless when the suspension entering the tank is flocculent (as is sewage). Newer measures of performance are proposed, which show promise in evaluating the behavior of settling tanks receiving flocculent suspensions

Notes on the 1973 Summer Study Program in Geophysical Fluid Dynamics at the Woods Hole Oceanographic Institution

Nonlinear wave interactions formed the theme of the fifteenth summer program in Geophysical Fluid Dynamics at the Woods Hole Oceanographic Institution. Owen Phillips was our principal lecturer on this subject, He chose to emphasize interactions among small numbers of discrete wave modes, including both internal and surface gravity waves in his discussions. His lectures provided a stimulating introduction to this important subject. Phillips' lectures were supplemented by a lecture by William Simmons on experiments with interacting internal waves, and a lecture by Carl Wunsch on internal waves in the ocean. Later in the summer, Wunsch gave us a lecture series on practical time-series analysis.We thank the National Science Foundation for their continuing support

Notes on the 1976 Summer Study Program in Geophysical Fluid Dynamics at the Woods Hole Oceanographic Institution

Originally issued as Reference no. 76-81Global climatology was the principal theme of the eighteenth summer program in Geophysical Fluid Dynamics at the Woods Hole Oceanographic Institution. This single volume contains course lectures, abstracts of seminars and lectures by summer fellows. As in previous years, the summer fellows were responsible for preparing a first draft of the course lectures on the principal theme. In most cases, the lecturer has been able to re-work the material further. The course lecturers, all of whom contributed so much to the program, are Richard S. Lindzen, Wallace S. Broecker, Abraham H. Oort, John Imbrie, Thomas Vonder Haar, Gerald R. North, Claes Rooth, Gene E. Birchfield, and Richard C. Somerville. The abstracted seminars cover a broad range of topics, including a one week symposium on planetary and benthic boundary layers. Much valuable material is referred to in these abstracts. The major creative products of the summer are the lectures of the ten fellows. These lectures have not been edited or reviewed in the manner appropriate for published papers, and should be regarded as unpublished manuscripts. Readers who would like to quote or use the material should write directly to the authors . As in previous years, much of the ultimate value of this summer's activities is likely to appear as published papers during the next year or two. In this sense, the material in this volume is simply a report of an ongoing research effort. We all express our thanks to the National Science Foundation, which provided the bulk of the financial support, the Office of Naval Research, which supported the Boundary Layer Symposium and some of the staff participation, and to Mary C. Thayer, who managed the program and prepared this volume

Cassini Imaging Science: Initial Results on Saturn's Atmosphere

The Cassini Imaging Science Subsystem (ISS) began observing Saturn in early February 2004. From analysis of cloud motions through early October 2004, we report vertical wind shear in Saturn's equatorial jet and a maximum wind speed of ∼375 meters per second, a value that differs from both Hubble Space Telescope and Voyager values. We also report a particularly active narrow southern mid-latitude region in which dark ovals are observed both to merge with each other and to arise from the eruptions of large, bright storms. Bright storm eruptions are correlated with Saturn's electrostatic discharges, which are thought to originate from lightning

Participants’ Perceptions Following Disaster Response

Academy and University students responded and provided disaster relief following hurricanes Florence and Michael. Students gave of their time, energy, and talents to provide food, water, and debris removal to hurricane victims. Learn how participants perceptions changed following hurricane disaster relief efforts

Cost of Farm Crops

The present bulletin is an inquiry into the Cost of Farm Crops, as produced at the State Experiment Station, under the following conditions: 1. The crops were treated substantially as upon the farms ordinarily found in our state. 2. The labor was all charged against the fields at the uniform rate of 15 cents an hour for each man and team, or at the rate of $3 per day of ten hours. 3. Substitute the farmer anywhere in the state for the Experiment Station and charge his time and that of his team at the same rate, and the conditions, except soil and climate, are identical. The fields on which records are prepared and which enter into this bulletjn are as follows: Field No. I-Corn -- Field No. 2-Corn and hay -- Field No.3-Hay. -- Field No.6-Hay -- Field No.7-Wheat, oats, and rye. -- Field No.8-Corn

The Mars observer camera

A camera designed to operate under the extreme constraints of the Mars Observer Mission was selected by NASA in April, 1986. Contingent upon final confirmation in mid-November, the Mars Observer Camera (MOC) will begin acquiring images of the surface and atmosphere of Mars in September-October 1991. The MOC incorporates both a wide angle system for low resolution global monitoring and intermediate resolution regional targeting, and a narrow angle system for high resolution selective surveys. Camera electronics provide control of image clocking and on-board, internal editing and buffering to match whatever spacecraft data system capabilities are allocated to the experiment. The objectives of the MOC experiment follow

Jupiter’s interior and deep atmosphere: The initial pole-to-pole passes with the Juno spacecraft

On 27 August 2016, the Juno spacecraft acquired science observations of Jupiter, passing less than 5000 kilometers above the equatorial cloud tops. Images of Jupiter’s poles show a chaotic scene, unlike Saturn’s poles. Microwave sounding reveals weather features at pressures deeper than 100 bars, dominated by an ammonia-rich, narrow low-latitude plume resembling a deeper, wider version of Earth’s Hadley cell. Near-infrared mapping reveals the relative humidity within prominent downwelling regions. Juno’s measured gravity field differs substantially from the last available estimate and is one order of magnitude more precise. This has implications for the distribution of heavy elements in the interior, including the existence and mass of Jupiter’s core. The observed magnetic field exhibits smaller spatial variations than expected, indicative of a rich harmonic content