Showing papers on "Wastewater published in 2000"

Ozonation of water and waste water

Abstract: Ozonation of water and waste water , Ozonation of water and waste water , کتابخانه دیجیتال جندی شاپور اهواز

Natural Wastewater Treatment Systems

Abstract: NATURAL WASTE TREATMENT SYSTEMS: AN OVERVIEW Natural Treatment Processes Project Development References PLANNING, FEASIBILITY ASSESSMENT, AND SITE SELECTION Concept Evaluation Site Identification Site Evaluation Site and Process Selection References BASIC PROCESS RESPONSES AND INTERACTIONS Water Management Biodegradable Organics Organic Priority Pollutants Pathogens Metals Nutrients References DESIGN OF WASTEWATER POND SYSTEMS Introduction Facultative Ponds Partial-Mix Aerated Ponds Complete Mix Aerated Pond Systems Anaerobic Ponds Controlled Discharge Pond System Complete Retention Pond System Hydrograph Controlled Release High-Performance Aerated Pond Systems (Rich Design) Proprietary Systems Nitrogen Removal in Lagoons Modified High-Performance Aerated Pond Systems for Nitrification and Denitrification Nitrogen Removal in Ponds Coupled with Wetlands and Gravel Bed Nitrification Filters Control of Algae and Design of Settling Basins Hydraulic Control of Ponds Removal of Phosphorus References POND MODIFICATIONS FOR POLISHING EFFLUENTS Solids Removal Methods Modifications and Additions to Typical Designs Performance Comparisons with Other Removal Methods References FREE WATER SURFACE CONSTRUCTED WETLANDS Process Description Wetland Components Performance Expectations Potential Applications Planning and Design Hydraulic Design Procedures Thermal Aspects Design Models and Effluent Quality Prediction Physical Design and Construction Operation and Maintenance Costs Troubleshooting References SUBSURFACE AND VERTICAL FLOW CONSTRUCTED WETLANDS Hydraulics of Subsurface Flow Wetlands Thermal Aspects Performance Expectations Design of SSF Wetlands Design Elements of Subsurface Flow Wetlands Alternative Application Strategies Potential Applications Case Study: Minoa, New York Nitrification Filter Bed Design of On-Site Systems Vertical-Flow Wetland Beds Construction Considerations Operation and Maintenance Costs Troubleshooting References LAND TREATMENT SYSTEMS Types of Land Treatment Systems Slow Rate Land Treatment Overland Flow Systems Soil Aquifer Treatment Systems Phytoremediation Industrial Wastewater Management References SLUDGE MANAGEMENT AND TREATMENT Sludge Quantity and Characteristics Stabilization and Dewatering Sludge Freezing Reed Beds Vermistabilization Comparison of Bed-Type Operations Composting Land Application and Surface Disposal of Biosolids References ON-SITE WASTEWATER SYSTEMS Types of On-Site Systems Effluent Disposal and Reuse Options Site Evaluation and Assessment Cumulative Areal Nitrogen Loadings Alternative Nutrient Removal Processes Disposal of Variously Treated Effluents in Soils Design Criteria for On -Site Disposal Alternatives Design Criteria for On-Site Reuse Alternatives Correction of Failed Systems References APPENDICES Appendix 1: Metric Conversion Factors (SI to U.S. Customary Units) Appendix 2: Conversion Factors for Commonly Used Design Parameters Appendix 3: Physical Properties of Water Appendix 4: Dissolved Oxygen Solubility in Freshwater INDEX

The fate of stormwater-associated bacteria in constructed wetland and water pollution control pond systems.

Abstract: The performances of a constructed wetland and a water pollution control pond were compared in terms of their abilities to reduce stormwater bacterial loads to recreational waters. Concentrations of thermotolerant coliforms, enterococci and heterotrophic bacteria were determined in inflow and outflow samples collected from each system over a 6-month period. Bacterial removal was significantly less effective in the water pollution control pond than in the constructed wetland. This was attributed to the inability of the pond system to retain the fine clay particles (< 2 µm) to which the bacteria were predominantly adsorbed. Sediment microcosm survival studies showed that the persistence of thermotolerant coliforms was greater in the pond sediments than in the wetland sediments, and that predation was a major factor influencing bacterial survival. The key to greater bacterial longevity in the pond sediments appeared to be the adsorption of bacteria to fine particles, which protected them from predators. These observations may significantly affect the choice of treatment system for effective stormwater management.

Phylogenetic Analysis of Bacterial Communities in Mesophilic and Thermophilic Bioreactors Treating Pharmaceutical Wastewater

Abstract: Most municipal and industrial wastewaters generated in industrialized nations are treated to prevent the deterioration of surface water quality. Aerobic biological strategies are commonly used to treat wastewater containing soluble and particulate organic material. These bioreactors support mixed consortia of microorganisms that can simultaneously convert a broad spectrum of compounds into new cells, innocuous byproducts, carbon dioxide, and water. In spite of the importance of these processes, there is only a limited understanding of the relationship between microbial community structure and function. This is largely due to an inability to cultivate a large fraction of the organisms identified by direct counts, typically less than 15% for wastewater treatment processes (3). Recent developments in cultivation-independent techniques, such as the rRNA approach (25), now permit considerably more detailed and accurate analysis of mixed microbial communities. These studies have confirmed the presence of complex microbial communities that are likely the underlying reason for the functionally robust nature of biological wastewater treatment systems (for examples, see references 2, 5, 22, and 33). These studies have generally demonstrated that the dominant members of aerobic reactors treating municipal wastewater are from the β subdivision of the division Proteobacteria (5, 22, 33). Manz et al. (22), however, found that the dominant members of an industrial treatment facility were from the Cytophaga-Flavobacterium-Bacteriodes division. Nonetheless, there have been very few studies investigating how different operating variables (temperature, pH, etc.) impact bacterial community structure and diversity. Our recent efforts have focused on the investigation of thermophilic aerobic biological treatment processes. These systems are often reported to be advantageous compared to conventional treatment processes because of more-rapid biodegradation rates and reduced cell yield without loss of physiological function (29, 34). However, the results from our laboratory studies suggest that thermophilic reactors are less adept at simultaneously utilizing multiple substrates (19) and in achieving efficient removal of carbonaceous substances (T. M. LaPara, C. H. Nakatsu, L. M. Pantea, and J. E. Alleman, submitted for publication) compared to analogous mesophilic systems. Our hypothesis was that these reductions in reactor function were associated with a reduction in reactor microbial diversity. Preliminary results provided by denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA genes suggested that fewer distinct phylotypes were present in bench-scale thermophilic bioreactors as determined by band counting (16, 19). Herein, we analyze the bacterial community structures from a full-scale industrial wastewater treatment facility consisting of seven reactors operated in series. This treatment facility is quite unique (10); its first four reactors are typically operated at thermophilic temperatures (45 to 65°C), while the final three reactors are operated at much lower temperatures (25 to 35°C). The objective of this study was to determine if the thermophilic reactors supported reduced biodiversity compared to the mesophilic reactors. The phylogenetic diversity of the thermophilic and mesophilic bioreactors was studied by two complementary methods: (i) PCR-DGGE of the variable V3 region of the 16S rRNA gene and (ii) cloning and determination of the nucleotide sequence of nearly complete 16S rRNA genes amplified by PCR.

Treatment of high strength organic wastewater by a mixed culture of photosynthetic microorganisms

Abstract: The growth characteristics and nutrient removal fromsynthetic wastewater by Rhodobacter sphaeroides,Chlorella sorokiniana and Spirulinaplatensis were investigated under aerobic dark(heterotrophic) and aerobic light (photoheterotrophic)conditions. Both in terms of economy and efficiency,aerobic dark conditions were the best for wastewatertreatment using R. sphaeroides and C.sorokiniana, but light was necessary with S.platensis. Neither growth nor nutrient removalcharacteristics of the cells were affected insynthetic wastewater with as high as 10 000 ppmacetate, 1000 ppm propionate, 700 ppm nitrate and 100 ppmphosphate. Although R. sphaeroides and C. sorokiniana showed good growth in syntheticwastewater containing 400 ppm of ammonia, S.platensis was completely inhibited.When grown as a monoculture, none of thestrains could simultaneously remove acetate,propionate, ammonia, nitrate and phosphate from thewastewater. R. sphaeroides could remove allthe above nutrients except nitrate, but the rate of removal was relatively low. The rate of nutrientsremoval by C. sorokiniana was higher, but theorganism could not remove propionate; S.platensis could efficiently remove nitrate, ammoniaand phosphate, but none of the organic acids. A mixedculture of R. sphaeroides and C.sorokiniana was therefore used for simultaneousremoval of organic acids, nitrate, ammonia andphosphate. The optimum ratio of the cells depended onthe composition of the wastewater.

Evaluation of parameters for monitoring an anaerobic co-digestion process

Abstract: The system investigated in this study is an anaerobic digester at a municipal wastewater treatment plant operating on sludge from the wastewater treatment, co-digested with carbohydrate-rich food-processing waste. The digester is run below maximum capacity to prevent overload. Process monitoring at present is not extensive, even for the measurement of on-line gas production rate and off-line pH. Much could be gained if a better program for monitoring and control was developed, so that the full capacity of the system could be utilised without the risk of overload. The only limit presently set for correct process operation is that the pH should be above 6.8. In the present investigation, the pH was compared with alkalinity, gas production rate, gas composition and the concentration of volatile fatty acids (VFA). Changes in organic load were monitored in the full-scale anaerobic digester and in laboratory-scale models of the plant. Gas-phase parameters showed a slow response to changes in load. The VFA concentrations were superior for indicating overload of the microbial system, but alkalinity and pH also proved to be good monitoring parameters. The possibility of using pH as a process indicator is, however, strongly dependent on the buffering capacity. In this study, a minor change in the amount of carbohydrates in the substrate had drastic effects on the buffering effect of the system.

Trace Analysis of Fragrance Materials in Wastewater and Treated Wastewater

Abstract: An analytical method was developed and used to measure trace levels of fragrance materials (FMs) in municipal wastewater and treated wastewater. Sixteen FMs were selected as analytes because of their wide range of physical chemical properties. The analytical method included the use of nine perdeuterated FMs as internal standards, a high-flow C18 speed disk for the extraction of FMs from aqueous matrices, and an accelerated solvent extraction system for the extraction of FMs from solid matrices. For aqueous matrices, average FM recoveries (relative to the perdeuterated FM internal standard) were 97−115%, with limits of quantitation ranging from 0.5 to 35 ng/L. For activated sludge solids and primary influent solids, the average FM recovery from the extraction procedure was 81%. Concentrations and removal of FMs at an activated sludge and a trickling filter wastewater treatment plant were determined in the U.S. FM influent concentrations ranged from 0.3 to 154 μg/L, while FM effluent concentrations ranged f...