Showing papers on "Effluent published in 2002"

Measurement of triclosan in wastewater treatment systems

Abstract: The objective of this study was to investigate the fate and removal of triclosan (TCS; 5-chloro-2-[2,4-dichloro-phenoxy]-phenol), an antimicrobial agent used in a variety of household and personal-care products, in wastewater treatment systems. This objective was accomplished by monitoring the environmental concentrations of TCS, higher chlorinated derivatives of TCS (4,5-dichloro-2-[2,4-dichloro-phenoxy]-phenol [tetra II]; 5,6-dichloro-2-[2,4-dichloro-phenoxy]-phenol [tetra III]; and 4,5,6-trichloro-2-(2,4-dichloro-phenoxy)-phenol [penta]), and a potential biotransformation by-product of TCS (5-chloro-2-[2,4-dicholoro-phenoxy]-anisole [TCS-OMe]) during wastewater treatment. These analytes were isolated from wastewater by using a C18 solid-phase extraction column and from sludge with supercritical fluid CO2. Once the analytes were isolated, they were derivatized to form trimethylsilylethers before quantitation by gas chromatography-mass spectrometry. Recovery of TCS from laboratory-spiked wastewater samples ranged from 79 to 88% for influent, 36 to 87% for final effluent, and 70 to 109% for primary sludge. Field concentrations of TCS in influent wastewater ranged from 3.8 to 16.6 microg/L and concentrations for final effluent ranged from 0.2 to 2.7 microg/L. Removal of TCS by activated-sludge treatment was approximately 96%, whereas removal by trickling-filter treatment ranged from 58 to 86%. The higher chlorinated tetra-II, tetra-III, and penta closans were below quantitation in all of the final effluent samples, except for one sampling event. Digested sludge concentrations of TCS ranged from 0.5 to 15.6 microg/g (dry wt), where the lowest value was from an aerobic digestion process and the highest value was from an anaerobic digestion process. Analysis of these results suggests that TCS is readily biodegradable under aerobic conditions, but not under anaerobic conditions. The higher chlorinated closans were near or below the limit of quantitation in all of the digested sludge samples. Based on results from this study, the chlorinated analogues and biotransformation by-product of TCS are expected to be very low in receiving waters and sludge-amended soils.

An LCA of alternative wastewater sludge treatment scenarios

Abstract: Life Cycle Assessment (LCA) was carried out in order to compare the environmental impacts of five alternative treatment scenarios of sewage sludge in the French context. The scenarios were composed of one main process (incineration, agricultural land application, or landfill), one stabilization process (lime stabilization, composting, or anaerobic digestion) and transports of sludge. Average data on literature, real site data and simulation result were used for accomplishing the assessment. The indicator results of environmental impact were normalized by reference contributions of one person in the West-Europe over 1 year in order to better understand their relative magnitude. The normalization results were finally weighted to give one aggregated result of the comparative LCA with sensitivity analysis on the weighing factors. The study result showed: the combination of anaerobic digestion and agricultural land application was most environmentally friendly tanks to less emissions and less consumption of energy; the most important substances contributing to human toxicity and ecotoxicity were heavy metals released from the atmospheric effluent of incineration and from the sludge applied to agricultural fields; finally appropriate tools were required to control the non-point-source pollutants like the methane of the dispersed landfill gas and the effluent gases of transport vehicles.

Removal of fragrance materials during U.S. and European wastewater treatment.

Abstract: The concentrations and removals of 16 fragrance materials (FMs) were measured in 17 U.S. and European wastewater treatment plants between 1997 and 2000 and were compared to predicted values. The average FM profile and concentrations in U.S. and European influent were similar. The average FM profile in primary effluent was similar to the average influent profile; however, the concentration of FMs was reduced by 14.6−50.6% in primary effluent. The average FM profile in final effluent was significantly different from the primary effluent profile and was a function of the design of the wastewater treatment plant. In general, the removal of sorptive, nonbiodegradable FMs was correlated with the removal of total suspended solids in the plant, while the removal of nonsorptive, biodegradable FMs was correlated with 5-day Biological Oxidation Demand removal in the plant. The overall plant removal (primary + secondary treatment) of FMs ranged from 87.8 to 99.9% for activated sludge plants, 58.6−99.8% for carousel p...

Physical-chemical treatment of water and wastewater

Abstract: BACKGROUND PREREQUISITES Introduction Wastewater Physical-Chemical Treatment of Water and Wastewater Unit Operations and Unit Processes Coverage Clean Water Act Safe Drinking Water Act Relationship of This Book to the Acts Glossary Background Chemistry and Fluid Mechanics Units Used in Calculation General Chemistry Fluid Mechanics Glossary Problems Bibliography PART I: CHARACTERISTICS OF WATER AND WASTEWATER QUANTITY OF WATER AND WASTEWATER Probability Distribution Analysis Quantity of Water Types of Wastewater Sources and Quantities of Wastewater Population Projection Derivation of Design Flows of Wastewaters Deriving Design Flows of Wastewaters from Field Survey CONSTITUENTS OF WATER AND WASTEWATER Physical and Chemical Characteristics Normal Constituents of Domestic Wastewater Microbiological Characteristics PART II: UNIT OPERATIONS OF WATER AND WASTEWATER TREATMENT FLOW MEASUREMENTS AND FLOW AND QUALITY EQUALIZATIONS Flow Meters Miscellaneous Flow Meters Liquid Level Indicators Flow and Quality Equalizations PUMPING Pumping Stations and Types of Pumps Pumping Station Heads Pump Characteristics and Best Operating Efficiency Pump Scaling Laws Pump Specific Speed Net Positive Suction Head and Deep-Well Pumps Pumping Station Head Analysis SCREENING, SETTLING, AND FLOTATION Screening Settling Flotation MIXING AND FLOCCULATION Rotational Mixers Criteria for Effective Mixing Pneumatic Mixers Hydraulic Mixers Flocculators CONVENTIONAL FILTRATION Types of Filters Medium Specification for Granular Filters Linear Momentum Equation Applied to Filters Head Losses in Grain Filters Backwashing Head Loss in Granular Filters Cake Filtration ADVANCED FILTRATION AND CARBON ADSORPTION Electrodialysis Membranes Pressure Membranes Carbon Adsorption AERATION, ABSORPTION, AND STRIPPING Mass Transfer Units Interface for Mass Transfer, and Gas and Liquid Boundary Layers Mathematics of Mass Transfer Dimensions of the Overall Mass Transfer Coefficients Mechanics of Aeration Absorption and Stripping PART III: UNIT PROCESSES OF WATER AND WASTEWATER TREATMENT WATER SOFTENING Hard Waters Types of Hardness Plant Types for Hardness Removal The Equivalent CaCO(3) Concentration Softening of Calcium Hardness Softening of Magnesium Hardness Lime-Soda Process Order of Removal Role of CO(2) in Removal Excess Lime Treatment and Optimum Operational pH Summary of Chemical Requirements and Solids Produced Sludge Volume Production Chemical Species in the Treated Water Relationships of the Fractional Removals Notes on Equivalent Masses Typical Design Parameters and Criteria Split Treatment Use of Alkalinity in Water Softening Calculations WATER STABILIZATION Carbonate Equilibria Criteria for Water Stability at Normal Conditions Recarbonation of Softened Water COAGULATION Colloid Behavior Zeta Potential Colloid Destabilization Coagulation Process Chemical Reactions of Alum Chemical Reactions of the Ferrous Ion Chemical Reactions of the Ferric Ion Jar Tests for Optimum pH Determination Chemical Requirements Chemical Requirements for pH Adjustments Alkalinity and Acidity Expressed as CaCO(3) Sludge Production REMOVAL OF IRON AND MANGANESE BY CHEMICAL PRECIPITATION Natural Occurrences of Iron and Manganese Modes of Removal of Iron and Manganese Chemical Reactions of the Ferrous and the Ferric Ions Chemical Reactions of the Manganous Ion [Mn(II)] Oxidation of Iron and Manganese Unit Operations for Iron and Manganese Removal Chemical Requirements Alkalinity Expressed in OH(-) and Acidity Expressed in H(+) Chemical Requirements for pH Adjustments Sludge Production REMOVAL OF PHOSPHORUS BY CHEMICAL PRECIPITATION Natural Occurrence of Phosphorus Modes of Phosphorus Removal Chemical Reaction of the Phosphate Ion with Alum Chemical Reaction of the Phosphate Ion with Lime Chemical Reaction of the Phosphate Ion with the Ferric Salts Comments on the Optimum pH Ranges Effect of the K(sp)'s on the Precipitation of Phosphorus Unit Operations for Phosphorus Removal Chemical Requirements Sludge Production REMOVAL OF NITROGEN BY NITRIFICATION-DENITRIFICATION Natural Occurrence of Nitrogen To Remove or Not to Remove Nitrogen Microbial Thermodynamics Oxidation-Reduction Reactions of Nitrogen Foods Modes of Nitrogen Removal Chemical Reactions in Nitrogen Removal Total Effluent Nitrogen Carbon Requirements for Denitrification Alkalinity Production and Associated Carbon Requirement Reaction Kinetics ION EXCHANGE Ion Exchange Reactions Unit Operations of Ion Exchange Sodium, Hydrogen Cycle, and Regeneration Production of "Pure Water" Active or Exchange Zone Design of Ion Exchangers Head Losses in Ion Exchangers DISINFECTION Methods of Disinfection and Disinfectant Agents Used Factors Affecting Disinfection Other Disinfection Formulas Chlorine Disinfectants Dechlorination Disinfection Using Ozone Disinfection Using Ultraviolet Light APPENDICES INDEX Each chapter contains: Glossary, Symbols, Problems and Bibliography

Effects of Urban Sewage on Dissolved Oxygen, Dissolved Inorganic and Organic Carbon, and Electrical Conductivity of Small Streams along a Gradient of Urbanization in the Piracicaba River Basin

Abstract: In Brazil most of the urban sewage is dumped without treatment into rivers. Because of this, it is extremely important to evaluate the consequences of organic matter rich sewage on the structure and functioning of river ecosystems. In this study we investigated the effects of urban sewage on the dissolved oxygen (O2), dissolved inorganic (DIC) and organic carbon (DOC), and electrical conductivity (EC) in 10 small streams of the Piracicaba River basin, southeast region of Brazil. In the Piracicaba River basin, which is one of the most developed regions of the country, only 16% of the total sewage load generated is treated. These streams were classified into two groups, one with heavy influence of urban sewage and another with less influence. Both concentrations and seasonal variability were distinct between the two groups. The streams that received sewage effluent had a combination of low O2 with high DIC, DOC, and EC. In the polluted streams, concentrations of dissolved carbon forms and EC were higher and O2 concentration lower during the low water period. In the less polluted streams seasonal variations in concentrations were small. We also investigated the efficiency of a sewage treatment plant installed two years ago in the catchment of one of these streams. It was observed an increase in the O2 concentration after the beginning of the treatment, and a decrease of DIC and DOC concentrations especially during the low water period. However, no significant change was observed in the EC, suggesting that the concentrations of major ions is still unaltered, and that a secondary treatment is necessary in order to reduce ion load into the stream.

Treatment of Mine Drainage Using Permeable Reactive Barriers: Column Experiments

Abstract: Permeable reactive barriers designed to enhance bacterial sulfate reduction and metal sulfide precipitation have the potential to prevent acid mine drainage and the associated release of dissolved metals. Two column experiments were conducted using simulated mine-drainage water to assess the performance of organic carbon-based reactive mixtures under controlled groundwater flow conditions. The simulated mine drainage is typical of mine-drainage waterthat has undergone acid neutralization within aquifers. This water is near neutral in pH and contains elevated concentrations of Fe(II) and SO4. Minimum rates of SO4 removal averaged between 500 and 800 mmol d(-1) m(-3) over a 14-month period. Iron concentrations decreased from between 300 and 1200 mg/L in the influent to between <0.01 and 220 mg/L in the columns. Concentrations of Zn decreased from 0.6-1.2 mg/L in the input to between 0.01 and 0.15 mg/L in the effluent, and Ni concentrations decreased from between 0.8 and 12.8 mg/L to <0.01 mg/L. The pH increased slightly from typical input values of 5.5-6.0 to effluent values of 6.5-7.0. Alkalinity, generally <50 mg/L (as CaCO3) in the influent, increased to between 300 and 1,300 mg/L (as CaCO3) in the effluent from the columns. As a result of decreased Fe(II) concentrations and increased alkalinity, the acid-generating potential of the simulated mine-drainage water was removed, and a net acid-consuming potential was observed in the effluent water.

Disinfection of Wastewater by Hydrogen Peroxide or Peracetic Acid: Development of Procedures for Measurement of Residual Disinfectant and Application to a Physicochemically Treated Municipal Effluent

Abstract: The Montreal Urban Community Wastewater Treatment Plant (MUCWTP) located in Montreal. Quebec, Canada, uses physicochemical treatment processes prior to discharging wastewater into the St. Lawrence River via an outfall tunnel of 2 hours retention time. Although chlorination facilities exist, they are not being used, and the MUCWTP is seeking alternative methods for disinfection to achieve a 2- to 3-log fecal coliform reduction. Liquid chemical disinfectants were attractive options because of their low capital costs. This led to an investigation of the feasibility of using hydrogen peroxide or peracetic acid. A method for measuring peroxycompounds (hydrogen peroxide or peracetic acid plus hydrogen peroxide) was developed using the peroxidase-based oxidation of 2,2'-azino-bis(3-ethylbenz-thiazoline-6-sulfuric acid) diammonium salt (ABTS) with hydrogen peroxide. The validity of the method was confirmed using effluent from the MUCWTP. Recovery was higher than 90% for peracetic acid levels as low as 1.0 mg/L. Quenching of hydrogen peroxide was achieved with 50-mg/L catalase; quenching of peracetic acid was achieved with 100 mg/L of sodium thiosulfate, followed by 50 mg/L of catalase. Batch disinfection tests were conducted on MUCWTP effluent. Hydrogen peroxide and peracetic acid in wastewater over time could be modeled as a second-order decay, with the decay "constant" being a function of the initial concentration of peroxycompounds. This function was the same for both hydrogen peroxide and peracetic acid, possibly indicating similar decomposition pathways in wastewater matrices. Disinfection was modeled using a modified Hom equation. Required doses of hydrogen peroxide to reach the target fecal coliform levels ranged from 106 to 285 mg/L, with the higher doses occurring when ferric chloride instead of alum was used as the coagulant. Hence, hydrogen peroxide was infeasible as a disinfectant for this application. On the other hand, the peracetic acid dose needed to achieve the target fecal coliform level was only 0.6 to 1.6 mg/L. Therefore, peracetic acid seems to be a promising disinfectant for physicochemical or primary effluent, or combined sewer overflows.

Photo-Fenton treatment of a biorecalcitrant wastewater generated in textile activities: biodegradability of the photo-treated solution

Abstract: Photo-Fenton process was explored as photochemical pre-treatment to improve the biodegradability of a wastewater coming from a textile industry located in the south of France, which was characterized as very biorecalcitrant by means of Zahn–Wellens biodegradability test. The effect of H2O2, Fe(III) and temperature on the photo-mineralization processes have been studied and the optimal conditions were found. Experiments were made to obtain information concerning the evolution of the biodegradability of the treated effluent after 40 and 70% of photo-mineralization. The photo-treated effluent is not biocompatible and its complete mineralization cannot be performed by biological means. UV–VIS and high-performance liquid chromatography (HPLC) analyses show that aromatic intermediates remain in the effluent after the photo-treatment, which have been identified as the principal reason of the biorecalcitrance.

System and method for extracting energy from agricultural waste

Abstract: The present invention relates to a process and apparatus for processing agricultural waste to make alcohol and/or biodiesel. The agricultural wastes are subjected to anaerobic digestion which produces a biogas stream containing methane, which is subsequently reformed to a syngas containing carbon monoxide and hydrogen. The syngas is converted to an alcohol which may be stored, sold, used, or fed directly to a reactor for production of biodiesel. The solids effluent from the anaerobic digester can be further utilized as slow release, organic certified fertilizer. Additionally, the wastewater from the process is acceptable for immediate reuse in agricultural operations.

Fluorescence Excitation−Emission Matrix Characterization of River Waters Impacted by a Tissue Mill Effluent

Abstract: Fluorescence excitation-emission matrix (EEM) spectrophotometry was applied to five neighboring rivers, including one that is impacted by wastewater from a large tissue mill, to determine if fluorescence spectrophotometry could be used to differentiate between the river waters. River water samples from both the tissue mill effluent and the impacted river, the Park Burn, exhibited significantly higher fluorescence intensity than the other sites. This fluorescence was dominated by tryptophan fluorescence and a fluorescence center possibly due to the presence of fluorescent whitening agents. In contrast, the three other rivers exhibited lower fluorescence intensities typical of river systems with tryptophan (sewage), humic-like (peat derived color), and fulvic-like (natural organic matter) sources. It is suggested that fluorescence EEM spectrophotometry has the potential to provide a useful tool for pollution detection, monitoring, and control of paper industry impacts on river systems.

Ozonation of municipal wastewater effluents.

Abstract: The increasing use of ozone in the treatment of municipal wastewater effluents has been stimulated by the need to achieve higher effluent quality and greater compliance with physicochemical and microbiological quality standards before discharge. These standards are applied when the effluent may pose a risk to the public through direct contact and where the effluent is used for agricultural purposes or water reclamation. Although various alternative technologies exist for upgrading wastewater effluents, ozone treatment may be the most appropriate approach in particular cases. This review summarizes the current status of the use of ozone for treating municipal effluents with respect to disinfection efficiency, its effect on the treatability of the effluent and on aggregate effluent parameters, the potential for the formation of ozonation byproducts, and its effect on the toxicity and mutagenicity of the effluent. The importance of treatment conditions (e.g., contact time) is also reviewed.