Showing papers on "Water treatment published in 1985"

Water supply and pollution control

Abstract: Water management - institutions and technology water management - environmental considerations water use and wastewater generation the availability of water water quanitity water quality hydrology and water management surface-water supplies reservoirs groundwater conveying and distributing water types of aqueducts hydraulic considerations design considerations distribution systems pumping wastewater and stormwater systems design of sanitary sewers design of storm drainage systems water quality microbiological quality chemical quality of drinking water quality criteria for surface waters selected pollution parameters systems for treating wastewater and water wastewater treatment systems water treatment systems physical treatment processes flow-measuring devices screening devices hydraulic characteristics of reactors mixing and flocculation sedimentation filtration chemical treatment processes chemical considerations water softening iron and manganese removal chemical disinfection and by-product formations disinfection of potable water disinfection of wastewater taste and odour fluoridation corrosion and corrosion control reduction and dissolved salts nitrate removal volatile organic chemical removal synthetic organic chemical removal biological treatment processes biological considerations characteristics of wastewater trickling (biological) filters rotating biological contractors activated sludge stabilization ponds odour control individual on-site wastewater disposal marine wastewater disposal processing of sludges sources, characteristics, and quantities of waste sludges arrangement of unit processes in sludge disposal gravity thickening flotation thickening biological sludge digestion vacuum filtration pressure filtration centrifugation recovery of chemicals ultimate disposal advanced wastewater treatment processes limitations of secondary treatment selection of advanced wastewater treatment processes suspended-solids removal carbon adsorption phosphorous removal nitrogen removal wastewater reclamation water-quality models.

Surrogate parameters for monitoring organic matter and thm precursors

Abstract: L'absorbance UV a 254 nm est un excellent parametre pour evaluer les concentrations de carbone organique non purgeable et de precurseurs de trihalomethanes

Water Treatment Principles and Design

Abstract: Physical and Chemical Quality. Microbiological Quality. Water Quality Criteria and Standards. Principles of Process Engineering. Precipitation, Coagulation, Flocculation. Gravity Separation. Filtration. Adsorption. Ion Exchange and Demineralization. Gas Transfer. Disinfection. Residuals Management. Water Reuse. Inorganics. Organics. Taste and Odor. Corrosion. Predesign. Plant Siting. Facilities Design. Special Plant Hydraulic Topics. Process Control. Operation and Maintenance. Construction and Operating Cost Estimating. Index.

Water quality : characteristics, modeling, modification

Abstract: 1. Sources and Uses of Water. 2. Physical, Chemical, and Biological Characteristics of Water. 3. Significance of the Characteristics of Water. 4. Water Quality: Standards and Global Perspectives. 5. Stoichiometry, Reaction Kinetics, and Materials Balances. 6. Mathematical Models of Physical Systems. 7. Movement of Contaminants in the Environment. 8. Water Quality in Rivers and Estuaries and Near Ocean Outfalls. 9. Water Quality in Lakes and Reservoirs. 10. Water Quality in Groundwater Systems. 11. Introduction to Water and Wastewater Treatment. 12. Physical Treatment Methods. 13. Chemical Treatment Methods. 14. Biological Treatment Methods. 15. Synthesizing Water and Wastewater Treatment Systems.

Slow sand filtration: influences of selected process variables

Abstract: Biological activity within the sand bed had the strongest influence on removal efficiency of total coliform bacteria by slow sand filtration, as determined by six pilot filters (shown above). Temperature, sand bed depth, and sand size also had strong influence. Research was conducted to determine the influences of selected process variables on the treatment efficiency of slow sand filtration.1-2 Phase 1 of the research,

Elimination of viruses and indicator bacteria at each step of treatment during preparation of drinking water at seven water treatment plants.

Abstract: Seven drinking water treatment plants were sampled twice a month for 12 months to evaluate the removal of indicator bacteria and cytopathogenic enteric viruses. Samples were obtained at each level of treatment: raw water, postchlorination, postsedimentation, postfiltration, postozonation, and finished (tap) water. Raw water quality was usually poor, with total coliform counts exceeding 105 to 106 CFU/liter and the average virus count in raw water of 3.3 most probable number of cytopathogenic units (MPNCU)/liter; several samples contained more than 100 MPNCU/liter. All plants distributed finished water that was essentially free of indicator bacteria as judged by analysis of 1 liter for total coliforms, fecal coliforms, fecal streptococci, coagulase-positive staphylococci, and Pseudomonas aeruginosa. The total plate counts at 20 and 35 degrees C were also evaluated as a measure of the total microbial population and were usually very low. Viruses were detected in 7% (11 of 155) of the finished water samples (1,000 liters) at an average density of 0.0006 MPNCU/liter the highest virus density measured being 0.2 MPNCU/liter. The average cumulative virus reduction was 95.15% after sedimentation and 99.97% after filtration and did not significantly decrease after ozonation or final chlorination. The viruses isolated from treated waters were all enteroviruses: poliovirus types 1, 2, and 3, coxsackievirus types B3, B4, and B5, echovirus type 7, and untyped picornaviruses.

Improvement in the Effectiveness of Ozonation of Drinking Water through the Use of Hydrogen Peroxide

Abstract: Addition of hydrogen peroxide to water during ozonation increases the rate of oxidation of organic compounds and ozone transfer. Coupling ozone with hydrogen peroxide can increase the efficiency of a drinking water treatment line, for example in removing THM precursors. To optimize this oxidation process, the quantity of hydrogen peroxide added and the point of injection must be carefully selected.

Bacterial Adhesion and Fouling of Reverse Osmosis Membranes

Abstract: Adhesion of selected bacteria to cellulose actetate (CA) reverse osmosis (RO) membranes used in wastewater reclamation processes was investigated to determine its role in membrane fouling and reduced process efficiency. Adhesion of a hfycohcterium sp. previously isolated from an early stage of RO membrane biofouling was relatively unaffected by large variations in the ionic strength or pH of the buffer system. However, trace quantities of a polyoxyethylene ether nonionic detergent almost completely inhibited attachment. The mycobacteria were found to adhere to the CA membrane surface (or to a CA-affinity column) approximately 2.5fold more effectively than a wild-type strain of Escherichia coli The ability of Mycobucterium and E. coli to adhere to the membrane was correlated with their relative surface hydrophobicities as determined by their affinities for n-hexadecane. A similar correlation was established between a hydrophilic wild-type strain of Acinetobactev phos&devorus containing a single 17.8 mega-Dalton plasmid (PYGl) and a more hydrophobic isogenic derivative strain (P7P-) lacking the PYGl plasmid. Unlike the P7WT parent strain, the P7P-derivative produced more fimbrialike appendages, which may account for its enhanced hydrophobic and adhesive properties. The results suggest that hydrophobic interactions between bacterial cell surface components and the CA membrane surface play an important role in the initial stages of bacterial adhesion and RO membrane biofilm formation. The reuse of municipal and industrial wastewaters is considered an essential component of modern water management practices. This is especially true in arid Middle Eastern countries and in the southwestern region of the United States where potable and irrigation waters must be imported at great expense. The reclamation and purification of wastewater may be further justified in view of growing concern over the contamination of domesticgroundwater sources by a broad spectrum of anthropogenic organic compounds. Many of these compounds, particularly when chlorinated, exhibit mutagenic or carcinogenic activity in mammalian systems, and therefore pose a finite hazard to public health. Advanced chemical and biological treatment processes used in wastewater reclamation can significantly reduce the concentrations of potentially harmful organic compounds. The Orange County Water District (OCWD) operates an advanced wastewater treatment plant known as Water Factory 21, which is located near Fountain Valley along the Southern California

Particles, Pretreatment, and Performance in Water Filtration

Abstract: Relationships among raw water quality, pretreatment facilities, and the design of packed bed filters are presented and applied. The particle size, particle concentration, particle surface characteristics, and solution chemistry in the raw water supply have important and predictable effects on filter design. An integrative approach to water treatment plant design, from raw water quality to filter bed performance, will facilitate process evaluation and has the potential for providing a basis for optimal plant design.

Particles, Pretreatment, and Performance in Water Filtration

Abstract: Relationships among raw water quality, pretreatment facilities, and the design of packed bed filters are presented and applied. The particle size, particle concentration, particle surface characteristics, and solution chemistry in the raw water supply have important and predictable effects on filter design. An integrative approach to water treatment plant design, from raw water quality to filter bed performance, will facilitate process evaluation and has the potential for providing a basis for optimal plant design.

The Advantages of Dissolved-air Flotation for Water Treatment

Abstract: Dissolved-air flotation as a primary clarification stage for the production of potable water is particularly effective for the treatment of algae-laden waters and low-turbidity, highly colored waters. Flotation has several process advantages over sedimentationit can produce better water quality; it can be operated at high surface loadings, resulting in relatively small and shallow plants; and it can be started up quickly, with a steady water quality being achieved within 45 min. Also, the solids concentration of the sludge produced is significantly higher (about 3 percent) than that of sludge produced by sedimentation. This article discusses the design parameters for dissolved-air flotation plants and gives detailed information on the design of flocculation and flotation tanks, the air saturation system, the production of microbubbles, and the different sludge removal systems that can be used. Performance data are given for flotation plants used for clarification of several raw waters, with special emphasis on the treatment of algae-laden waters and low-turbidity, highly colored waters. A cost comparison between flotation and sedimentation is also presented, taking into account both capital and operating costs. The overall costs of the two processes are similar. Therefore, the final process selection will depend on the additional advantages offered by both processes.

Sediments and water quality

Abstract: Sediments play a crucial role in water quality. On the one hand they remove pollutants from the water column whereas on the other hand pollutants accumulated in the sediments may provide the surface water (long after the source of pollution has ceased) with contaminants. An overview of the immobilization and remobilization processes affecting heavy metals and organic micro‐pollutants is given.

Bacterial Colonization of Point-of-Use Water Treatment Devices

Abstract: Point-of-use water treatment devices were investigated to identify organisms that may colonize these filters, to determine the magnitude of the postcolonization release of microorganisms into the product water during daily use or after periods of nonuse, and to demonstrate the effect of tap water of marginal bacteriological quality on the quality of the product water. The bacterial count was found to vary between units of different design, between units of the same design, and between water samples from the same filter unit collected at different times of the day; it was affected by the length of time the filter cartridge had been in use, the design of the cartridge, and the temperature of the water, as well as by the species of microorganism. Installation and use by the public of in-the-home, point-of-use water treatment devices have increased in the United States during the last several years. This trend has paralleled increased consumer awareness of the potential health risks posed by some community drinking water systems. Interest in these point-of-use devices is usually based on a desire to improve the aesthetic quality of drinking water, including a reduction of thecontaminants that cause taste and odor, turbidity, hardness. and other undesirable effects. Manufacturers of point-of-use water treatment devices have estimated that some 6 million families already use their products and that the market is increasing. A study of the designs of commercially available point-of-use devices indicates that granular activated carbon (GAC) is often the major component for treatment; other components include ion exchange resins, spirally wound acrylicfilament spools, controlled-pore-size membranes for reverse osmosis systems, and paper filters. The quantity of activated carbon ranges from 30 g in a faucetmounted device to 266-593 g in the larger cartridges. Some designs precoat the carbon on a fibrous fluted material or press the carbon into a dense core rather than packing the cartridge bed

Removal of Organic Matter in Water Treatment

Abstract: The performance of several types of water treatment plants in removing various molecular weight (MW) fractions of naturally occurring aquatic organic matter and humic substances is described. An assessment was made of the performance of direct filtration, conventional treatment, and softening in removing trihalomethane (THM) precursors from a diverse array of water sources. In addition, a comparison was made between conventional treatment and direct filtration in removing THM precursors from a common water source, the Colorado River. As a general rule, THM reactivity (μg THM/mg C) increased with MW although the <10,000MW range was found to be the most consistently reactive fraction of aquatic organic matter. All of the various treatments preferentially removed the most reactive fraction of precursor present in each molecular weight range. None of the various treatments proved to be very effective in removing precursor material below a MW of <500. The ability to remove THM precursors appears to be related ...

Removal by Coagulation of Trace Organics From Mississippi River Water

Abstract: In this study alum and ferric sulfate were evaluated for their effectiveness in removing four low-molecular-weight organic compounds- C14-labeled octanoic acid, salicylic acid, phenol, and benzoic acid- from Mississippi River water and from water samples free of natural organic matter. Removal of these model organic compounds ranged between 3 and 20 percent, which is similar to the removals observed for the < 1 K fraction of natural organic matter. Solution pH affected the removal of the aromatic compounds but not of octanoic acid. Except for benzoic acid, all the model compounds were removed better in the absence of natural organics.

Mutagenicity assessment of different drinking water supplies before and after treatments

Abstract: In this study, three qualitatively different raw water supplies together with their correspondent chlorinated drinking waters were investigated for their mutagenic properties using the Salmonella/microsome assay. A drinking water supply distributed through two different types of pipelines was chosen in order to study the effect of the distribution systems on water mutagenicity. A sequential liquid-liquid extraction at three different pHs and an in situ XAD-2 adsorption technique were used to prepare extracts and adsorbates from both untreated and treated water samples to compare mutagen recovery by these widely used methods and with a view to selecting a routine screening technique for evaluating the effect of treatments on drinking water mutagenicity.

Bactericidal properties of a new water disinfectant.

Abstract: The N-chloramine compound 3-chloro-4,4-dimethyl-2-oxazolidinone (agent I) has been compared with calcium hypochlorite as to its efficacy as a bactericide for the treatment of water. The study included concentration, contact time, pH, temperature, and water quality as controlled variables. The species of bacteria tested were Staphylococcus aureus, Pseudomonas aeruginosa, and Shigella boydii. In general, for highly pure, demand-free water, calcium hypochlorite was the more rapid disinfectant at a given total chlorine concentration, although for water containing a controlled amount of organic load, agent I was the better disinfectant. The differences in efficacy of each of the two disinfectants can be attributed primarily to their different stabilities in water at various controlled conditions.

Apparatus and method of recovering water from engine exhaust gases

Abstract: Water is recovered and purified from exhaust gases of internal combustion engines which produce water vapor when a hydrocarbon fuel is burned. The present invention passes the engine exhaust through a particulate filter then a catalytic reactor to remove the impurities and then through a precooler and a condenser so as to extract the water therein. The water is then passed through a polishing column and recovered for use in the vehicle.

Prevention of iron fouling of ion exchange resins

Abstract: A process for removing and preventing iron contamination of water treatment solids which tend to become iron fouled which comprises cyclically treating said water treatment solids with an aqueous solution containing an effective amount of: (a) a reducing agent; (b) a chelating agent; with a pH of said treating solution having been adjusted to within a range of about 4-6.

A water radiolysis model in a circulating flow system with a boiling region and its application to hydrogen alternate, water chemistry of boiling water reactors

Abstract: A gaseous mass transfer model has been proposed for quantitative evaluation of the chemical chain-back reaction system with volatile species in a boiling channel. Theoretical expression for concentration transients in liquid and vapor phases were obtained. The model was applied to water radiolysis in a boiling water reactor core channel with Bankoff's two-phase flow treatment. Hydrogen injection tests in the Oskarshamn-2 and Dresden-2 units were simulated. The calculated results showed that gas release and absorption rates in the boiling channel were not consistent with Henry's law. By using optimized parameters related to the gaseous mass transfer, calculated results agreed within a factor of 2 for lower hydrogen injection rates at the two plants. It was determined that more exact treatments are needed to determine the radiation level in the downcomer and catalytic decomposition rate of hydrogen peroxide in order to provide better evaluations of water radiolysis phenomena.

Analysis of drinking water for the detection of trihalomethanes

Abstract: Drinking water of the Dammam metropolitan area is a blend of raw well water and desalinated water obtained from the Al-Azizia seawater desalination plant. Chlorination is the only disinfection method applied to the blended water before the water is pumped into the distribution system. Chlorination of water containing organic compounds results in the formation of trihalomethanes. In general, the known carcinogenic and physiological effects of THMs other than chloroform are limited. However, based on their structural similarity to chloroform, these compounds can be considered health hazards. The present study was carried out in order to determine the extent of the occurrence of THMs in finished drinking water in some of the major cities of the Eastern Province of Saudi Arabia.

Treatment of Contaminated Groundwaters with Granular Activated Carbon and Air Stripping

Abstract: Over the past several years there have been Increasing reports of cases of contaminated groundwater. Many cases were caused by leaking from surface impoundments or landfills, or leakage from underground storage tanks. Treatment of groundwater use, discharge or recharge into the aquifer is becoming a major concern. Two widely used treatment techniques are adsorption with granular activated carbon and packed tower air stripping. Granular activated carbon is often applied when organic contaminants need to be removed to nondetectable levels, and should be a part of the process if nonvolatile contaminants are present. Air stripping is capable of 95-99 percent reduction of volatile contaminants and can be a cost effective treatment technology if nondetectable contaminant levels are not required and air pollution is not a factor. Should off-gas from an air stripper require treatment for removal of organic contaminants, granular activated carbon adsorption can be effectively applied as it was in the water phase. ...