Andrew J. Englande

Comparison of E. coli, Enterococci, and fecal coliform as indicators for brackish water quality assessment.

Escherichia coli (E. coli), enterococci, and fecal coliform data were collected and compared as potential indicators for swimmablility assessment of a brackish waterbody (Lake Pontchartrain, Louisiana). These indicators were measured during lake background conditions, in stormwater runoff (before dilution with lake water), and in the outfall plume within the lake following storm events. Microbial indicator titers associated with suspended particles and lake-bottom sediments were also investigated. Overall reduction rate constants for fecal coliform, E. coli, and enterococci in lake water and sediment were measured and reported. Attachment of microbial indicators to suspended matter and subsequent sedimentation appeared to be a significant fate mechanism. A slower reduction rate of indicator organisms in sediment further suggested that bottom sediment may act as a reservoir for prolonging indicator organism survival and added concern of recontamination of overlaying waters due to potential solids resuspension. Results indicated that enterococci might be a more stable indicator than E. coli and fecal coliform and, consequently, a more conservative indicator under brackish water conditions.

Comparative analysis of nutrient data in the lower Mississippi River

Abstract As the second phase of a large-scale Tulane University Mississippi River water-quality database project, nutrient data on the lower Mississippi River have been examined for potential differences among sampling agencies, geographic locations and chemically similar nitrogen parameters. These data represent the most comprehensive source of information on nutrients in the Mississippi River available as a single database. Monthly means, grouped by parameter, sampling location and agency, were calculated and compared as paired sets, excluding months where data were not available for both sets. Evaluations using ANOVA indicated few differences among agencies providing nitrogen-compound data, although differences were observed in phosphorus-compound data from different sources. Unfiltered and filtered fractions of nitrate–nitrite were found to be comparable throughout the study area. Spatial examination of the nutrient data indicated few differences in inorganic nitrogen concentrations throughout the study area, but significant variability in total Kjeldahl nitrogen (TKN). Orthophosphate and total phosphorus concentrations increased through the study area from Arkansas [river miles (RM) 500–810] downstream to St. Francisville (RM 231–315), but with little or no change from Baton Rouge (RM 111–230) to the Gulf of Mexico. Results provide a combined data set from which preliminary calculations of daily nutrient loads in the Mississippi River between 1960 and 1997 were conducted.

Application of multiple toxicity tests in monitoring of landfill leachate treatment efficiency

Leachate from a closed landfill used for co-disposal of municipal and tannery waste was submitted to coagulation treatment, air stripping, adsorption on granular activated carbon, and Fenton oxidation with the aim to reduce toxicity of the leachate. Optimal operational conditions for each process were identified. The performance of the treatment was monitored by determination of organic matter (COD, DOC, BOD5), inorganic components (N-NH4+, Cl−, alkalinity, metals), organic compounds (BTEX, PAHs, PCBs, OCPs) while changes in toxicity were followed by multiple toxicity tests. Among the applied treatment techniques, adsorption on granular activated carbon was the most efficient method for removal of organic matter and metals while air stripping was the most efficient for removal of N-NH4+ and reduction of toxicity. Lower reduction of organic matter content and toxicity was obtained during coagulation treatment. Fenton oxidation was effective for removal of COD; however, it negatively affected toxicity reduction. The combination of adsorption on granular activated carbon and air stripping led to an appreciable reduction of organic and inorganic pollutants and to leachate detoxification. Application of bioassays was helpful for assessing suitability of treatment methods and demonstrated that they are, together with physicochemical parameters, an indispensable part for monitoring of treatment efficiency.

Influence of size and density on filtration rate modeling and nutrient uptake by green mussel (Perna viridis)

This study investigates green mussel filtration rates based on variation of the mussel size and density, and attempts to correlate these with the amount of Chaetoceros calcitrans consumed by kinetic modeling. The filtration rates were found to be more effective in small mussels and with greater volumes of seawater/mussel which represent low mussel densities in the mussel farms. Under field condition, the first order kinetic model is useful for evaluation of mussel filtration rate. However, the composite exponential kinetic model was determined to better describe filtration rates in a close system. Higher ratios of seawater volume L/g DW mussel tissue, resulted in an increasing filtration rate until a maximum plateau was reached at 10.37 L/h/g DW tissue as determined by first order kinetics. Based on the filtration rate, carbon, nitrogen, and phosphorus uptake by green mussels were found to be 2128.72, 265.41, and 66.67 mg/year/indv, respectively.

Katrina and the Thai Tsunami - water quality and public health aspects mitigation and research needs.

The South East Asian Tsunami in Thailand and Hurricane Katrina in the United States were natural disasters of different origin but of similar destruction and response. Both disasters exhibited synonymous health outcomes and similar structural damage from large surges of water, waves, and flooding. A systematic discussion and comparison of the disasters in Thailand and the Gulf Coast considers both calamities to be similar types of disaster in different coastal locations. Thus valuable comparisons can be made for improvements in response, preparedness and mitigation. Research needs are discussed and recommendations made regarding potential methologies. Recommendations are made to: (1) improve disaster response time in terms of needs assessments for public health and environmental data collection; (2) develop an access-oriented data sharing policy; and (3) prioritize natural geomorphic structures such as barrier islands, mangroves, and wetlands to help reduce the scale of future natural disasters. Based on the experiences gained opportunities to enhance disaster preparedness through research are presented.

Equalization design techniques for conservative substances in wastewater treatment systems

Abstract A frequency response solution and spectral analysis of input-output data is employed as a basis of equalization basin design for wastewater treatment system. Design equations for conservative substances are developed based on various possible system inputs including pulse, unit step function, harmonic and random signals. Practical applications and a design example are also discussed.

Survival of Enterococci facalis in estuarine sediments

A laboratory‐based microcosm study was conducted to assess the survival of Enterococci faecalis in the estuarine sediments of Lake Pontchartrain, Louisiana, USA. The survival curves of E. faecalis were characterized by a growth phase followed by a stationary phase, a logarithmic decay period, and/or finally by a tailing region. The usual exponential decay model could not be applied to E. faecalis survival in the estuarine sediments. The estuarine sediments appeared to stimulate E. faecalis reproduction within 10 days of incubation. Furthermore, the estuarine sediments prolonged the survival of E. faecalis for a period of at least a month under the study conditions. Based on research results, the amount of organic matter and nutrients did not significantly affect the survival of E. faecalis in the estuarine sediments. This outcome may have occurred due to the small sample size. Throughout the duration of the 45 day experiment, relatively the same proportion of E. faecalis remained culturable. Therefore, the estuarine sediments appear to provide a favorable environment for E. faecalis.

Effluent variability estimation for complete-mix activated sludge treatment systems

Abstract A frequency transform technique has been employed for development of the mathematical models describing the wastewater influent variability removal for completely-mixed biological treatment plants. The influent variability was simulated by pulse input step function harmonic variations, and random variations. Experimental and theoretical results were compared for random, pulse and step function inputs. Observed influent-effluent variation characteristics correlated well with the theoretical relationship.