Water quality management

Calcium carbonate precipitation and formation of clog particles inside the leachate
collection pipe can cause catastrophic failures in landfill operation. This study focuses on
quantifying the effectiveness of electronic scale control to reduce the clog formation within
the pipe network. A field scale model (40ft × 20ft) was constructed, featuring side-by-side
flow of electronically treated and untreated composite leachate. Data obtained in the first
phase of this study indicate that electronic scale control system does not have any
statistically significant effect on water quality parameters. The second phase of this study
identified calcite (CaCO3) to be the predominant phase present in the precipitates using
XRD/XRF diffraction pattern analyzed through a search match calculation program
(MATCH! Version 3.2.0) which concur with the previous studies. Furthermore, Rietveld
refinement using FullProf Suite confirms that there were no differences between the treated
and untreated precipitate based on the phases identified in the respective samples.

A study conducted by the World Health Organization and United Nations Children's Fund, concluded that approximately 768 million people worldwide are not receiving sanitary drinking water suitable for consumption. While there are many water treatment methods, lime softening proves to be one of the more effective approaches as it removes a wide variety of harmful compounds including arsenic, lead, mercury, and cadmium under the correct conditions. The greatest issues with lime softening on a smaller scale include the complexity of the chemistry and need for monitoring. By designing the system for groundwater sources and with a smaller capacity, this thesis hoped to reduce the level of monitoring, chemical expertise, and cost needed for operation. While promising results occurred in the removal of arsenic and total hardness, this project was unable to obtain consistent results and final water samples with pH values between the recommended standard of 6.5 to 8.

The viability of the eastern oyster, Crassostrea virginica, is designated as an ecological performance measure for the management of freshwater inflows to the St. Lucie Estuary, Florida. Thus, oysters derived from the St. Lucie Estuary were tested for their physiological response to stress, measured as altered condition index and RNA/DNA ratios, resulting from changes in salinity and infection by the protozoan parasite Perkinsus marinus, the agent of Dermo, a common oyster disease. Pilot studies consisted of the development of a real-time PCR-based assay for P. marinus infection, procedures to infect oysters with the pathogen by injection method and procedures for the measurement of RNA/DNA ratios. The general experimental design was to assess the response of non-injected and injected C. virginica to low salinity challenges. Two scenarios for salinity stress were tested: one in which oysters were subjected to a single reduction in salinity and one in which an initial reduction in salinity was followed by a recovery phase and then subjected to a second challenge of reduced salinity. Condition index was more responsive to changes in salinity regimes than to P. marinus infection. Changes in the RNA/DNA ratio were responsive to the infection status, but not changes in salinity; the pattern of change in the RNA/DNA ratio generally followed changes in the measured levels of infection. The lack of mortalities showed that these oysters were able to tolerate short periods of reduced salinity.

The tunicate Styela plicata (Ascidiacea) was investigated for its potential use in bioremediation of bacteria and microalgae blooms from estuarine waters. Salinity tolerances, filtration rate, substrate selection, and effects on digested bacteria and ichthyofaunal communities were examined. If acclimated slowly, Styela can be placed in salinities as low as 24 parts per thousand (ppt) before increased fatalities result. An immediate decrease in salinity from 32 ppt to 20 ppt was not detrimental at short term exposure (four days). One average-sized (~40g) Styela, exposed to 105 and 106 bacteria or microalgae mL-1, can filter as much as 4.7 L hr-1 and 3.3 L hr-1, respectively. Individual tunicate filtration rates varied from hour to hour, independent of organism size, indicating that filtration rates for this species would be better reported on a population basis rather than on an individual weight or size basis. Bacterial viability in tunicate feces was assessed by ATP analysis. Bacteria were found to be non-viable after passage through the tunicate digestive tract. Filtration of eggs or larvae of recreationally or commercially important fish is of concern. The smallest eggs (~0.6mm) reported in the Indian River Lagoon belong to Cynoscion nebulosus (spotted seatrout) and Bairdiella chrysoura (silver perch). Over the course of two hours, 72.5% of 0.5 mm glass beads (simulated fish eggs) were initially retained, but many were later expelled by the tunicates. For 1.0 mm beads, 49.4% were initially retained and for 2.0 mm beads, 43.5% were initially retained. Neither the size of the oral siphon nor the size of the overall animal was correlated to bead retention. Substrate selection was investigated using the tunicate Phallusia nigra.