Sample pointSample point

Configuration of column scale-up tests. It is also preferred where suspended solids create a high pressure drop, or dissolved gases create bubbles in the carbon bed. For a downflow or percolation system, an influent line should be installed at the top of the column, with an effluent at the bottom. To prevent the column from draining during operation, the effluent line from the last column should extend from the bottom of the column to above the top of the column. This will keep the...

H

Halophilic or Halotolerant Bacteria which thrive in a highly salt environment, up to 25 NaCl. Headworks The facilities where wastewater enters a wastewater treatment plant. The headworks may consist of bar screens, comminutors, a wet well and pumps. Heterotroph A microorganism which uses organic matter for energy and growth. HRT Hours of Retention Time. House Sewer The pipeline connecting the house and drain and the septic tank. Humus The dark organic material in soils, produced by the...

Biosolids Regulations

EPA has developed comprehensive federal biosolids use and disposal regulations , which are organized in five parts. These parts are general provisions, land application, surface disposal, pathogens and vector attraction reduction, and incineration. Parts of the regulations which address standards for land application, surface disposal, and incineration practices consist of general requirements, pollutant limits, operational requirements, management practices, frequency of monitoring,...

Chemical Mixing And Solids Contact Processes

Chemical mixing and flocculation or solids contact are important mechanical steps in the overall coagulation process. Application of the processes to wastewater generally follows standard practices and employs basic equipment. Chemical mixing thoroughly disperses coagulants or their hydrolysis products so the maximum possible portion of influent colloidal and fine supracolloidal solids are absorbed and destabilized. Flocculation or solids contact processes increase the natural rate of contacts...

Applications

Air Floatation And Precipitation

Applications of carbon adsorption go far beyond conventional water treatment applications which we will discuss in a general sense shortly. Table 8 provides a summary of the key applications of carbon adsorption systems for liquid phase applications. Table 8. Liquid Phase Applications of Carbon Adsorption. Table 8. Liquid Phase Applications of Carbon Adsorption. Granular activated carbons (GAC) installed in rapid gravity filters Removal of dissolved organic contaminants, control of taste and...

Chlorine

Chlorine is familiar to most people as it is used to treat virtually all municipal water systems in the United States. Chlorine has a number of problems when used for field treatment of water. When chlorine reacts with organic material, it attaches itself to nitrogen containing compounds (ammonium ions and amino acids), leaving less free chlorine to continue disinfection. Carcinogenic trihalomethanes are also produced, though this is only a problem with long-term exposure. Trihalomethanes can...

C

Cake The solids discharged from a dewatering apparatus. Calendering A process by which fabric or wire is passed through a pair of heavy rolls to reduce thickness, to flatten the intersections of the threads wires and to control air permeability. Rolls are heated when calendering synthetic materials. Carbonized threads Nylon or polyester therads that have been treated to include varrying degrees of carbon. Cation exchange capacity The ability of a soil or other solid to exchange cations...

Water Treatment In General

Water must have eye appeal and taste appeal before we will drink it with much relish. Instinctively we draw back from the idea of drinking dirty, smelly water. Actually far more important to our well-being is whether or not a water is safe to drink. If it holds disease bacteria, regardless of its clarity and sparkle, we should avoid it. Let's consider these two highly important aspects of water potability and palatability. Regardless of any other factors, water piped into the home must be...

Algae Protozoa And Multicellular Animals

Algae are microscopic photosynthetic plants. They are among the simplest plant forms, having neither roots, stems, nor leaves. Algae typically range from single-cell entities (which impart a green color to surface waters) to branched forms that can be seen by the naked eye. The latter often appear as attached green slime on surface bodies of water. Diatoms refers to singlecelled algae which are housed in silica shells. The blue-green algae generally associated with water pollution are...

Germicidal Destruction

Chlorine's ability to destroy bacteria and various microorganisms results from chemical interference in the functioning of the organism. Specifically, it is the chemical reaction between HOC1 and the bacterial or viral cell structure which inactivates the required life processes. The high germicidal efficiency of HOC1 is attributed to the ease by which it is able to penetrate cell walls. This penetration is comparable to that of water and is due both to its low molecular weight (that is, it's a...

Industrial Water And Wastewater Treatment

The markets for ozone in industrial water and wastewater treatment are quite small. Industrial applications for ozone could grow. The use of ozone for treating photoprocessing solutions is a novel application that has been limited, but might grow. In this process, silver is recovered electrolytically then the spent bleach baths of iron ferrocyanide complexes are ozonated. Iron cyanide complexes are stable to ozonation so that the ferrous iron is merely oxidized to ferric, which is its original...

The Benefittocost Ratio

The benefit to cost (B C) ratio is a benchmark that is determined by taking the total present value of all of the financial benefits of a water treatment project and dividing it by the total present value of all the costs of the project. If the ratio is greater than unity, then the benefits outweigh the costs, and we may conclude that the project is economically worthwhile. The present values of the benefits and costs are kept separate, and expressed in one of two ways. First, as already...

What Viruses

Viruses are ultramicroscopic organisms. They are parasites they need to infest a host in order to duplicate themselves. Viruses excreted with human and animal feces are called enteric viruses, and more than 100 such organisms have been identified. As many as one million viruses can be found in one gram of excrement. The concentration in raw sewage varies over a wide range as many as 463,500 infectious particles per liter of raw sewage have been detected. Viruses found in surface waters are...

Questions For Thinking And Discussing

Go to the proper U.S. environmental legislation and obtain the MCLs for the chemicals listed in Table 9. 2. Complete the following reactions that take place with hydrogen cation-exchange resins Na2(HC03)2 + H2 Z CaS04 + H2Z MgZ + H2S04 3. Complete the following reactions that take place for anion exchange reactions (weakly basis and strongly basis) R3N + H2S04 R3N + 2HC1 R3N-H2S04 + Na2C03 R4NOH + H2Si03 (R,N)2S04 + 2NaOH The symbol R3N represents the complex weakly basic anion-exchanger...

Disinfection By Chlorination

Disinfection has received increased attention over the past several years from regulatory agencies through the establishment and enforcement of rigid bacteriological effluent standards. In upgrading existing wastewater treatment facilities, the need for improved disinfection as well as the elimination of odor problems are frequently encountered. Adequate and reliable disinfection is essential in ensuring that wastewater treatment plants are both environmentally safe and aesthetically acceptable...

P Fl in32

Where P is present worth or present value, F is future value, i is the interest or discount rate, and n is the number of periods. As a simple example, if we have or hold 1,000, in one year at 6 percent interest compounded annually, the 1,000 would have a computed present value of Because our money can work at 6 interest, there is no difference between 943.40 now and 1,000 in one year because they both have the same value now. Economically, there is an additional factor at work in present value,...

Some More Important Comments On Thickening

Gravity Thickening - This process involves the concentration of thin sludges to more dense sludge in special circular tanks designed for this purpose. Its use is largely restricted to the watery excess sludge from the activated sludge process, and in large plants of this type where the sludge is sent direct to digesters instead of to the primary tanks. It may also be used to concentrate sludge to primary tanks or a mixture of primary and excess activated sludge prior to high rate digestion. The...

Wool Cloths

Wool cloths can be used to handle acid solutions with concentrations up to 5-6 . Wool cloth has a life comparable to that of cotton in neutral liquors. Wool is woven in the duck-like square cloth weave, or with a raised nap or it may be formed as a felt. Originally the smooth cloth weave was used for filtering electrolytic slimes and similar slurries. The hairlike fibers, as in cotton cloth, ensure good filtrate clarity. Long-nap wool cloth has found wide application in sewage sludge dewatering...

Tortuosity

Tortuosity is defined as the relative average length of a flow path (i.e., the average length of the flow paths to the length of the medium). It is a macroscopic measure of both the sinuosity of the flow path and the variation in pore size along the flow path. Both porosity and tortuosity correlate with permeability, but neither can be used alone to predict permeability. Tortuosity and connectivity are difficult to relate to the nonuniformity and anisotropy of a medium. Attempts to predict...

Introduction

Filtration generally requires the use of various chemicals known as filter aids. These chemicals include those used in the process of coagulation, and to accelerate and enhance the particle sedimentation process (called flocculants), as well as to provide a precoat filter to enhance the suspended particle removal efficiency. Both an understanding of the physical and chemical forces involved in the filtration process are important to proper selection and operation of filters in waster treatment...

Pore Structure

A microscopic description characterizes the structure of the pores. The objective of a pore-structure analysis is to provide a description that relates to the macroscopic or bulk flow properties. The major bulk properties that need to be correlated with pore description or characterization are the four basic parameters porosity, permeability, tortuosity and connectivity. In studying different samples of the same medium, it becomes apparent that the number of pore sizes, shapes, orientations and...

Soda

Soda ash, Na2C03, is available in two forms. Light soda ash has a bulk density range of 35 to 50 lb cu ft and a working density of 41 lb cu ft. Dense soda ash has a density range of 60 to 76 lb cu ft and a working density of 63 lb cu ft. The pH of a 1 percent solution of soda ash as 11.2. It is used for pH control and in lime treatment. The molecular weight of soda ash is 106. Commercial purity ranges from 98 percent to greater than 99 percent Na2C03. Soda ash by itself is not particularly...

Sand And Gravel

Sand and gravel are the most widely used of the rigid media simple contact. Most of the sand used this way is for the clarification of water for drinking or industrial uses. Washed, screened silica sand is sold in standard grades for this work and is used in depths ranging from a few inches to several feet, depending on the type of filter and clarification requirements. Heavy, irregular grains, such as magnetite, give high rates of flow and low penetration by the solid particles, and are easily...

Disinfection With Bromine Chlorine

In chlorination, chlorine's reaction with ammonia forms chloramines, greatly reducing its bactericidal and virucidal effectiveness. The biocidal activity of monochloramine is only 0.02 - 0.01 times as great as that of free chlorine. Typical ammonia concentrations found in secondary sewage range from 5-20 ppm, which is about an order of magnitude greater than the amount needed to form monochloramine from normal chlorination dosages (which requires about 5-10 ppm). Therefore, monochloramine is...

Equipment Selection Methodology

Equipment selection is seldom based on rigorous equations or elaborate mathematical models. Where equations are used, they function as a directional guide in evaluating data or process arrangements. Projected results are derived most reliably from actual plant operational data and experience where duplication is desired from standards set up where there are few variations from plant to plant, so that results can be anticipated with an acceptable degree of confidence (as in municipal water...

Synthetic Fiber Cloths

Cloths from synthetic fibers are superior to many of the natural cloths thus far considered. They do not swell as do natural fibers, are inert in many acid, alkaline and solvent solutions and are resistant to various fungus and bacterial growths (the degree depending on the particular fiber and use). Several synthetic fibers resist relatively high temperatures, and have a smooth surface for easy cleaning and good solids discharge. Some of the most widely used synthetic filter media are nylon,...

Establishing Baseline Costs

To properly determine the cost of any engineering project, we first need to establish a baseline for comparative purposes. If nothing else, a baseline defines for management the option of maintaining the status quo. If we are faced with meeting a legal discharge limit, then obviously we need to do something other than status quo to remain in business. But here is where we can develop some interesting and very detailed justifications for one water treatment technology or piece of equipment over...

Toxicity Of Aquatic Life

Bromamines are considerably less stable than chloramines in receiving waters. Bromamines tend to break down into relatively harmless constituents typically in under 60 minutes. Consequently, BrCl is less damaging to marine life than chlorine. Chloramines at concentrations below 0.1 ppm have resulted in fish kills. There are also indirect effects from chloramine contamination. For example, fish populations tend to avoid toxic regions, even at very low levels of concentrations. Consequently,...

Nomenclature

A diraensionless coefficient or Archimedes force, N Ar Archimedes number, dimensionless a coefficient accounting for liquid entrapped between sludge layers Cr constant or centrifugal force, N C0 upward gas stream velocity, m sec. d particle diameter or distance, in., xm Ga Galileo number, dimensionless SEDIMENTATION, CLARIFICATION, FLOTATION AND COALESCENCE mass feed rate, kg s or volumetric flowrate in m3 hr physical properties correction factor for slurries product of Archimedes number and...

Chlorine Contact Tanks

The configuration of contact tanks can result in appreciable differences between actual and theoretical contact times. Contact times and germicidal efficiency depend on a number of parameters, the most important being the mixing characteristics of the basin. Proper designs must account for possible flow pattern elimination via short circuiting, acceptable dosage rates, optimum pH range, and upstream removal Rapid dispersement of chlorine at the addition point increases chlorine contact and...

Poisons

The presence of various inorganic and organic substances in a digester can cause inhibition or toxicity. Heavy metals, light metal cations, oxygen, sulfides and ammonia are potential toxic materials. The best method of controlling digester toxicity is to prevent the toxic materials from entering the system. A strong industrial waste ordinance which is enforced is the ideal solution. The cause of toxicity should be identified. Temporary relief from toxicity may be achieved by (I) increasing the...

Uv Light

Ultraviolet light has been known to kill pathogens for a long time. A low pressure mercury bulb emits between 30 to 90 of its energy at a wave length of 253.7 nm, right in the middle of the UV band. If water is exposed to enough light, pathogens will be killed. The problem is that some pathogens are hundreds of times less sensitive to UV light than others. The least sensitive pathogens to UV are protozoan cysts. Several studies show that Giardia will not be destroyed by many commercial UV...

Pressure Filtration

Pressure filtration is a process similar to vacuum filtration where sludge solids are separated from the liquid. Leaf filters probably are the most common type of unit. Refer back to Chapter 5 for a detailed discussion. Like vacuum filtration, a porous media is used in leaf filters to separate solids from the liquid. The solids are captured in the media pores they build up on the media surface and they reinforce the media in its solid-liquid separation action. Sludge pumps provide the energy to...

Blending

Stabilization can be aided by the technique of blending sludge. Blending is a process where two or more types of sludge are blended together to facilitate a higher sludge solids concentration and a more homogenous mixture of sludge prior to dewatering. Blending operations tends to decrease the chemical demand for conditioning and dewatering sludge. The blending operation usually takes place in sludge holding tanks normally where primary sludge is mixed with waste activated sludge. The amounts...

S

Saprophytic Bacteria that breakdown bodies of dead plants and animals (nonliving organic material), returning organic materials to the food chain. Saprophytic bacteria are usually non-pathogenic, too. Most Aiken Clear-Flo products are saprophytic. SAR Sodium Adsorption Ratio - this ratio expresses the relative activity of sodium ions in the exchange reactions with the soil. SCFM Cubic feet of air per minute at standard conditions of temperature, pressure and humidity (0 , 14.7 psi and 50...

Silver

Silver has been suggested by some for water treatment and may still be available outside the U.S. Its use is currently out of favor due to the EPA's establishment of a 50 ppb MCL (Maximum Contaminate Level) limit on silver in drinking water. This limit is set to avoid argyrosis, a cosmetic blue gray staining of the skin, eyes, and mucous membranes. As the disease requires a net accumulation of 1 g of silver in the body, one expert calculated that you could drink water treated at 50 ppb for 27...

Ceramic Media

Ceramic filter media are manufactured from crushed and screened quartz or chamotte, which is then thoroughly mixed with a binder (for example, with silicate glass) and sintered. Quartz media are resistant to concentrated mineral acids but not resistant to low-concentration alkalies or neutral water solutions of salts. Chamotte media are resistant to dilute and concentrated mineral acids and water solutions of their salts, but have poor resistance to alkali liquids. The rough surface of ceramic...

Conditions That Impact On Performance

Adsorption usually increases as pH and temperature decrease. Chemical reactions and forms of chemicals are closely related to pH and temperature. When pH and temperature are lowered many organic chemicals are in a more adsorbable form. The adsorption process is also influenced by the length of time that the AC is in contact with the contaminant in the water. Increasing contact time allows greater amounts of contaminant to be removed from the water. Contact is improved by increasing the amount...

Connectivity

Connectivity is a term that describes the arrangement and number of pore connections. For monosize pores, connectivity is the average number of pores per junction. The term represents a macroscopic measure of the number of pores at a junction. Connectivity correlates with permeability, but cannot be used alone to predict permeability except in certain limiting cases. Difficulties in conceptual simplifications result from replacing the real porous medium with macroscopic parameters that are...

Some General Comments

So there we have it - a broad overview of a complex subject that spans both technical and legal arenas. Much of the discussions have focused on drinking water, but from this point forward we will depart from the subject and only address this in passing. Recognize that there are a large number of technologies that are applied to treating water. The combination of technologies needed for a water treatment application depend on what we are ultimately trying to achieve in terms of final water...

Biological Growth Factors

Major factors affecting biological growth are temperature, nutrient availability, oxygen supply, pH, degree of sunlight, and the presence of toxins. Bacteria are classified by their optimum temperature range for growth. For example, mesophilic bacteria grow best in an optimum temperature range for growth. For example, mesophilic bacteria grow best in a temperature range of 10 - 40 C (optimum at 37 C In general, the rate of biological activity almost doubles for every 10-15 C rise in temperature...

Fungi And Molds

Fungi are microscopic nonphotosynthetic plants which include in their classification yeast and molds. Yeasts have a commercial value as they are used for fermentation operations in distilling and brewing. When anaerobic conditions exist, yeasts metabolize sugar, manufacturing alcohol from the synthesis of new cells. Alcohol is not manufactured under aerobic conditions and the yield of new yeast cells is greater. Filamentous forms of fungi are molds. These best resemble higher orders of plant...

Fill

Application as fertilizer or soil conditioner Burial is used principally for raw sludge, where, unless covered by earth, serious odor nuisances are created. The sludge is run into trenches two to three feet wide and about two feet deep. The raw sludge in the trenches should be covered by at least 12 inches of earth. Where large areas of land are available, burial of raw sludge is probably the most economical method of sludge disposal as it eliminates the costs of all sludge treatment...

Ozonation

Ozone has been used continuously for nearly 90 years in municipal water treatment and the disinfection of water supplies. This practice began in France, then extended to Germany, Holland, Switzerland, and other European countries, and in recent years to Canada. Ozone is a strong oxidizing substance with bactericidal properties similar to those of chlorine. In test conditions it was shown that the destruction of bacteria was between 600 and 3,000 times more rapid by ozone than by chlorine....

Variablerate And Pressure Filtration

The dynamics of variable-rate and -pressure filiations can be illustrated by pressure profiles that exist across the filter medium. Figure 7 shows the graphical representation of those profiles. According to this plot, the compressed force in the cake section is where p, pressure exerted on the sludge over the entire cake thickness ps static pressure over the same section of cake p corresponds to the local specific cake resistance (rw)x. At the sludge-cake interface ps( pj and p 0 and for the...

What Microfiltration And Nanofiltration

In the case of microfiltration, a more porous membrane is used than in the other membrane separation technologies, thus yielding a relatively higher flux. It is mainly useful in removing turbid causing materials and can replace conventional granular filtration processes. The most significant design parameters are Size and geometry of modules The clean water flux across a membrane without any material being deposited follows Darcy's Law The net pressure differential across a membrane, taking...

Washing And Dewatering

When contaminated, polluted, or valuable suspension liquors are present, it becomes necessary to wash the filter cake to effect clean separation of solids from the mother liquor or to recover the mother liquor from the solids. The operation known as dewatering involves forcing a clean fluid through the cake to recover residual liquid retained in the pores, directly after filtering or washing. Dewatering is a complex process on a microscale, because it involves the hydrodynamics of two-phase...

Loose Rigid Media

Filter media may also be composed of particles that are rigid in structure, but are applied in bulk loose form. That is, individual particles merely contact each other. This form has the advantage of being cheap and easy to keep clean by rearrangement of the particles. When the proper size and shape of particles are selected, the section of passage may be regulated over extremely wide limits. The disadvantages of a rigid medium in simple contact are that it can be used conveniently only in a...

Industrial Chemical Synthesis

There has been only one major use for ozone today in the field of chemical synthesis the ozonation of oleic acid to produce azelaic acid. Oleic acid is obtained from either tallow, a by-product of meat-packing plants, or from tall oil, a byproduct of making paper from wood. Oleic acid is dissolved in about half its weight of pelargonic acid and is ozonized continuously in a reactor with approximately 2 percent ozone in oxygen it is oxidized for several hours. The pelargonic and azelaic acids...

Coagulants And Flocculantstheory and Practice

1st Printing 1995 ISBN 0-927188-04-X By Dr. Yong H. Kim. Softcover, 96 pages. Price 23. The purpose of this book is to provide engineers and plant operators who are involved in solid-liquid separation with a fundamental understanding of coagulation and flocculation. Applications include water and wastewater treatment, pulp and paper industries, mineral processing, and enhanced oil recovery. The readers of the book will obtain an appropriate knowledge of coagulants and polymeric flocculants,...

Ultraviolet Radiation

Ultraviolet radiation around 254 mm renders bacteria incapable of reproduction by photochemically altering the DNA of the cells A fairly low dose of ultraviolet light can kill 99 percent of the fecal coliform and fecal streptococcus. Bacterial kill is independent of the intensity of the light but depends on the total dose. Simultaneous treatment of water with UV and ozone results in higher microorganism kill than independent treatment with both UV and ozone. When ultrasonic treatment was...

U

Unicellular Single celled organism, such as bacteria. Upset An upset digester does not decompose organic matter properly. The digester is characterized by low gas production, high volatile acid alkalinity relationship, and poor liquid-solids separation. A digester in an upset condition is sometimes called a sour or stuck digester. Ultrasonic (processes) Process which utilizes specially designed tooling usually vibrating at 15-80 KHz. Processes are designed to cause localized heating of...

Constantrate Filtration

When sludge is fed to a filter by a positive-displacement pump, the rate of filtration is nearly constant (i.e., dV dx constant). During constant-rate filtration, the pressure increases with an increase in cake thickness. Therefore, the principal variables are pressure and filtrate volume, or pressure and filtration time. Equation 9 is the principal design relation, which may be integrated for a constant-rate process. The derivative, dV dt, may be replaced simply by V x The ratios in...

V

Vadose zone Unsaturated zone of soil above the groundwater, extending from the bottom of the capillary fringe all the way to the soil surface. Vector (i) Plasmid or virus used in genetic engineering to insert genes into a cell, (ii) Agent, usually an insect or other animal, able to carry pathogens from one host to another. Vegetative cell Growing or feeding form of a microbial cell, as opposed to a resting form such as a spore. Vesicles Spherical structures, formed intracellularly, by some...

Odor Control

In the United States, the largest existing market for ozone systems is odor control. Much of this market is in sewage treatment plants. Industrial markets for ozone in odor control are smaller than for sewage treatment plants. Established applications include cooking odors at restaurants pharmaceutical fermentations fish, meat, and food processing plastics and rubber processing paint and varnish manufacture and rendering plants. Nearly all of these industrial odor control applications use less...

Flexible Metallic Media

Flexible metallic media are especially suitable for handling corrosive liquors and for high-temperature filtration. They have good durability and are inert to physical changes. Metallic media are fabricated in the form of screens, wire windings, or woven fabrics of steel, copper, bronze, nickel and different alloys. Perforated sheets and screens are used for coarse separation, as supports for filter cloths or as filter aids. Metallic cloths are characterized by the method of wire weaves as well...

Y

Yeast Fungus whose thallus consists of single cells that multiply by budding or fission. Zoogleal film A complex population of organisms that form a slime growth on a trickling-filter media and break down the organic matter in wastewater. Zoogleal mass Jelly-like masses of bacteria found in both the trickling filter and Zoospore An asexual spore formed by some fungi that usually can move in an aqueous environment via one or more flagella. Zygospore Thick-walled resting spore resulting from...

Properties Of Bromine And Bromides

Bromine (from the Greek word bromos, meaning stench) has an atomic weight 79.909, atomic number 35, melting point - 7.2 C, and boiling point 58.78 C. As a gas it has a density of 7.59 g 1 and as a liquid 3.12 g 1 (20 C). The element was discovered by Balard in 1826 but not prepared in quantity until 1860. It is a member of the halogen group of elements. Bromine is found mainly in the bromide form, widely distributed and in relatively small proportions. Extractable bromides occur in the ocean...

The Internal Rate Of Return

You are likely more familiar with the term return on investment, or ROI, than internal rate of return. The ROI is defined as the interest rate that would result in a return on the invested capital equivalent to the project's return. For illustration, if we had a water treatment project with a ROI of 30 percent, that's financially equivalent to investing resources in the right stock and having its price go up 30 percent. As before, this method is based in the net present value of benefits and...

Make Note Of Physical And Chemical Properties

Forces of physical attraction or adsorption of contaminants to the pore walls is the most important AC filtration process. The amount and distribution of pores play key roles in determining how well contaminants are filtered. The best filtration occurs when pores are barely large enough to admit the contaminant molecule. Because contaminants come in all different sizes, they are attracted differently depending on pore size of the filter. In general AC filters are most effective in removing...

Key Words

The following are key words you will run across in reading over the next several chapters. air flotation - This treatment usually follows oil-water separation. Wastewater is pressurized to 3-5 times normal atmospheric pressure in the presence of air to produce a saturated air-water solution. When this solution is released to normal pressure in the flotation unit, tiny air bubbles form throughout the liquid the same effect is observed when a bottle of pop is opened. As the air bubbles form they...

Equipment And Operation

Ion exchange processing can be accomplished by either a batch method or a column method. In the first method, the resin and solution are mixed in a batch tank, the exchange is allowed to come to equilibrium, then the resin is separated from solution. The degree to which the exchange takes place is limited by the preference the resin exhibits for the ion in solution. Consequently, the use of the resins exchange capacity will be limited unless the selectivity for the ion in solution is far...

What Filtration Is

Filtration is a fundamental unit operation that, within the context of this volume, separates suspended particle matter from water. Although industrial applications of this operation vary significantly, all filtration equipment operate by passing the solution or suspension through a porous membrane or medium, upon which the solid particles are retained on the medium's surface or within the pores of the medium, while the fluid, referred to as the filtrate, passes through. In a very general...

Treating The Sludge 583 Project Cost Estimating Principles

Approaches to project cost estimating have changed in recent years, to the point where smart companies and engineers apply principles of Total Cost Accounting. The term total-cost accounting (TCA) has come to be more commonly known as life-cycle costing (LCC). LCC is a method aimed at analyzing the costs and benefits associated with a piece of equipment, plant or a practice over the entire time of intended use. The idea actually originated in the federal government and was first applied in...

Wastewater Treatment Plant Operations

Before getting into the subject of sand filtration, we should first attempt to put the technologies of municipal wastewater treatment into some perspective. Wastewater treatment plants can be divided into two major types biological and physical chemical. Biological plants are more commonly used to treat domestic or combined domestic and industrial wastewater from a municipality. They use basically the same processes that would occur naturally in the receiving water, but give them a place to...

Toxic Effects Of Chlorine

The toxicity of chlorine residuals to aquatic life has been well documented. Studies indicate that at chlorine concentrations in excess of 0.01 mg 1, serious hazard to marine and estuarine life exists. This has led to the dechlorination of wastewaters before they are discharged into surface water bodies. In addition to being toxic to aquatic life, residuals of chlorine can produce halogenated organic compounds that are potentially toxic to man. Trihalomethanes (chloroform and bromoform), which...

Filtration Conditions

Two significant operating parameters influence the process of filtration the pressure differential across the filtering plate, and the temperature of the suspension. Most cakes may be considered compressible and, in general, their rate of compressibility increases with decreasing particle size. The temperature of the suspension influences the liquid-phase viscosity, which subsequently affects the ability of the filtrate to flow through the pores of the cake and the filter medium. In addition,...

The Role Of Mixing

Mixing plays an important role in digester operation Without well-mixed systems, the processes cannot acceptable levels of efficiency. There are a number of methods or combination of methods whereby proper mixing is attained. These include Stirring by rotating paddles and scum breaker arms. Forced circulation of sludge and or supernatant by pumps or by draft tubes with impeller. Discharge of compressed sludge gas from diffusers at the bottom of the digestion tank Mixing may be either...

Wastewater Treatment Applications

Subsequent chapters address the application of filtration techniques to wastewater treatment in some detail. For now, only some general comments and terminology are introduced as part of this introductory chapter. In a very general sense, there are two types of wastewater flows - municipal and industrial. Although municipal wastewaters vary in composition, there are ranges of properties that enable filtration equipment to be readily selected and specified. This is not always the situation when...

M

MacConkey Streak Laboratory test for the presence of gram negative bacteria We use this test to detect contamination of Bacillus products such as CF 1000, 1002, 4002 and som of the Enz-Odor products. Macronutrient An element required in large proportion by plants and other life forms for survival and growth. Macronutrients include Nitrogen (N), Potassium (K), and Phosphorous (P). Market grade (wirecloth) Screens that meet general industrial specifications and have a low percentage of open area....

Basic Principles Of Water Treatment

1st Printing 1996 ISBN 0-927188-05-8 By Cliff Morelli. Hardcover, 8272 pages. 60. Virtually all industries utilize water in their manufacturing process, either as a heat-transfer medium, as in the steam-electric generating industry or in the employment of cooling towers or as a product as in the case of beverages, foods and pharmaceutical preparations. Water is also employed as a working solvent, as in the case of manufacturing microelectronics, where the final product yield is highly dependent...

Metallic Media

Metallic filter media are widely used throughout the chemical and process industries in the form of perforated or slotted plates of steel, bronze or other materials. These designs provide for easy removal of coarse particles and for supporting loose rigid media. Powdered metal is a porous medium. The physical characteristics, chemical composition, structure, porosity, strength, ductility, shape and size can be varied to meet special requirements. The porosity ranges up to 50 void by volume,...

Gunnison Colo Case Study

This southern Colorado town uses about 32.5 ha (80 ac) of grass on a private ranch for application of biosolids slurry from its oxidation ditch. Application is approximately 56 dry Mg yr (62 dry tons yr) through a sprinkler gun. Other dry land parcels on ranches have also been used. Average annual precipitation in Gunnison is 28 cm (11 in.) the typical yearly application rate is 5 dry Mg ha (2.3 dry ton ac). Grazing on the biosolids-treated land has increased from once to twice per year....

Pre CoalescerInlet

Example of a pre-coalescer. Figure 31. Example of a pre-coalescer. Figure 30. Cut size curve for a deoiling hydroclone. One common construction is achieved by wrapping a secondary steel wall completely around the primary vessel. Each double wall vessel is constructed using the same basic fabrication techniques as used on single wall vessels, the area between the vessel walls, known as the interstice, can be monitored by a leak detection system installed in the monitor tube, located...

An Overview Of Membrane Processes

The following tables will give you a basic appreciation for the technologies. Table 1 provides a comparison of the factors that affect the performance of the five technologies. Table 1. Factors Impacting on the Performance of Membrane Processes Table 1. Factors Impacting on the Performance of Membrane Processes Table 2 provides a comparison of membrane structures. Between these two tables you should get an idea of the operating conditions viz., membrane structural types the driving forces...

Present Value Of Net Benefits

The present value of net benefits (PVNB) shows the worth of a project in terms of a present-value sum. The PVNB is determined by calculating the present value of all benefits doing the same for all costs and then subtracting the two totals. The result is an amount of money that would represent the tangible value of undertaking the project. This comparison evaluates all benefits and costs at their current or present values. If the net benefit (the benefits minus costs) is greater than zero, the...

National Secondary Drinking Water Regulations

National Secondary Drinking Water Regulations (NSDWRs or secondary standards) are non-enforceable guidelines regulating contaminants that may cause cosmetic effects (such as skin or tooth discoloration) or aesthetic effects (such as taste, odor, or color) in drinking water. EPA recommends secondary standards to water systems but does not require systems to comply. However, states may choose to adopt them as enforceable standards. The following table summarizes the secondary standards. Table 6....

What Bacteria Is

In addition to viruses, bacteria (microscopic organisms that can reproduce without a host in the proper conditions) are also found in water. In general, damage to the human body from bacterial infection is due to the action of the toxins they produce. Bacteria found in water are derived from contact with air, soil, living and decaying plants and animals, and animal excrements. Many of these bacteria are aerobic and anaerobic spore-forming organisms associated with varying densities of...

Chlorine Dosage Rates And Residuals

Table 3 gives recommended ranges of chlorine dosages for disinfection of various wastewaters. Recommended minimum bactericidal chlorine residuals are given in Table 4. Data in Table 4 are based on water temperatures between 20 C to 25 C after a 10-minute contact for free chlorine and a 60 minute contact for combined available chlorine. The minimum residuals required for cyst destruction and inactivation of viruses are much greater. Although chlorine residuals in Table 4 are generally adequate,...

T

Tangential crossflow filtration Process where the feed stream sweeps the membrane surface and the particulate debris is expelled, thus extending filter life. The filtrate flows through the membrane. Most commonly used in the separation of high-and-low-molecular weight matter such as in ultrapure reverse osmosis, ultrafiltration, and submicron microfiltration processes. Taxonomy The classification, nomenclature, and laboratory identification of organisms (Do not confuse with taxidermy - stuffing...

Contents

Preface, vii In Memory, ix About the Author, x Foreword, xi Chapter 1. An Overview of Water and Wastewater Treatment, 1 Introduction, 1 What We Mean by Water Purification, 4 Introducing the Physical Treatment Methods, 33 Energy Intensive Treatment Technologies, 40 List of Abbreviations Used in this Chapter, 57 Recommended Resources for the Reader, 58 Questions for Thinking and Discussing, 60 Chapter 2. What Filtration Is All About, 62 Introduction, 62 Terminology and Governing Equations, 63...

Effects Of Heterogeneity Nonuniforms And Anisotropy On Permeability

Heterogeneity, nonuniformity and anisotropy are terms which are defined in the volume-average sense. They may be defined at the level of Darcy's law in terms of permeability. Permeability, however, is more sensitive to conductance, mixing and capillary pressure than to porosity. Heterogeneity, nonuniformity and anisotropy are defined as follows. On a macroscopic basis, they imply averaging over elemental volumes of radius e about a point in the media, where e is sufficiently large that Darcy's...

Paper Pulp And Fiber Cloths

Paper pulp and fiber cloths are excellent materials for precoats and filter aids. Paper pulp gives a high rate of flow, is easily discharged and shows little tendency to clog. Paper pulp's disadvantage lies in its preparation. Soda or sulfate pulp, most commonly used, must be disintegrated and kept in suspension by agitation before precoating. This requires considerable auxiliary equipment. Diatomaceous earths, while they should be kept in suspension, are very easy to handle and do not undergo...

Iodine

Iodine's use as a water purification method emerged after World War 2, when the U.S. military was looking for a replacement for Halazone tablets. Iodine was found to be in many ways superior to chlorine for use in treating small batches of water. Iodine is less sensitive to the pH and organic content of water, and is effective in lower doses. Some individuals are allergic to iodine, and there is some question about long term use of iodine. The safety of long-term exposure to low levels of...

The Table Filter

These machines were first introduced to industry nearly 60 years ago and were of rather small and of a simple design. Early designs were greatly flawed. Their main limitation was at the discharge zone since the cake was contained in a fixed rim and special sealing arrangements must be provided in order to avoid the spillage of brine at the table's circumference. Another problem was that the thin heel left between the scroll and the surface of the table was dislodged by applying a back blow but...

Hydraulic Performance

The hydraulic performances required of the sand with slow filters are inferior to those for rapid filters. In the case of slow filters, one can use fine sand, since the average filtration velocity that is usually necessary lies in the range 2 to 5 m day. In slow filtration, much of the effect is obtained by the formation of a filtration layer, including the substances that are extracted from the water. At the early stages of the operation, these substances contain microorganisms able to effect,...

Fundamentals Of Fluid Filtration A Technical Primer

2nd edition 1998 ISBN 0-927188-01-5 By Peter R. Johnston Softcover, 136 pages . 29. This book is written as the book one wants to read when first starting the study of filtration. This book is intended for the person who has some technical background outside of filtration, and who now wants to get his feet wet in this subject This book is also for the old filtration hand who, while he has some experience in some special field of filtration, may now want to step back and see a larger view. And...

Contact Time pH And Temperature Effects

Hypochlorous acid and hypochlorite ion are known as free available chlorine. The chloramines are known as combined available chlorine and are slower than free chlorine in killing microorganisms. For identical conditions of contact time, temperature, and pH in the range of 6 to 8, it takes at least 25 times more combined available chlorine to produce the same germicidal efficiency. The difference in potency between chloramines and HOC1 can be explained by the difference in their oxidation...

The Tilting Pan Filter

The Tilting Pan Filter is predominantly employed in the phosphoric acid industry and, to some extent, in the washing of phosphate rock. There was a traditional rivalry over the years between the Pan and Belt Filter which now, owing to the substantial progress in rubber technology, swings in the favor of the later. The operation of Tilting Pan Filters is based on a series of horizontal independent trapezoidal pans mounted on a circular supporting structure that rotates under vacuum during the...

Recommended Resources For The Reader

The following references have been reviewed and are recommended for your further reading. Some of these references will greatly enhance your understanding of the subject matter covered in subsequent chapters. REVERSE OSMOSIS A PRACTICAL GUIDE FOR INDUSTRIAL USERS First Printing 1995, ISBN 0-927188-03-1 By Wes Byrne 461 pages, hard cover, 90 Reverse osmosis (RO) is a relatively new technology whose applications are rapidly growing. Several books have been written emphasizing the theory of...

Cartridge Filters

Cartridge filters are used extensively throughout the chemical process industries in applications from laboratory-scale to commercial operations ranging to more than 5,000 gpm. Figure 1 shows a photograph of a series of units that serve as a pretreatment stage to an RO unit for water treatment. Quite often cartridge filters are used as a pretreatment stage, but occasionally they may serve as polishing filters and even stand-alone systems. Table 1 lists typical filtering applications and...

What The Current Drinking Water Standards

The following matrices provide you with a summary of the NPDWRs or primary standards. You should visit the EPA Web site (www.epa.gov) and become familiar with the various documents that are publically available. You will not only find these regulations there, but detailed information that explains the reasoning behind each MCLG. You will also find the entire legislation on this site and can become familiar with all of the subtleties of this piece of complex environmental legislation. Tables 1...

Contaminant Properties

Organic contaminants in the subsurface can be present as a separate nonaqueous phase liquid, dissolved in the aqueous phase, in the vapor phase in the soil gas, partitioned into the soil organic matter, or adsorbed onto the solid mineral phase. The relative amount of the contaminant in each of these phases is determined largely by the properties of the contaminant. Generally, the most important property of the soil in determining the distribution of contaminants is the soil organic matter,...

Permeability And Darcys

The term reservoir description is applied to characterizing a homogeneous system as opposed to a heterogeneous one. A reservoir description defines the reservoir at a level where a property changes sufficiently so that more than a single average must be used to model the flow. In this sense, a reservoir composed of a section of coarse gravel and a section of fine sand, where these two materials are separated and have significantly different permeabilities, is heterogeneous in nature. Defining...

Electron Beam

The idea of using ionizing radiation to disinfect water is not new. Ionizing radiations can be produced by various radioactive sources (radioisotopes), by X-ray and particle emissions from accelerators, and by high-energy electrons. The advances in reliable, relatively low-cost devices for producing high-energy electrons are more significant. Unlike X-rays and gamma rays, electrons are rapidly attenuated. The maximum range of a 1-million-volt electron is about 4 m in air and about 5 cm in...

Separation Using Coalescers

A coalescer achieves separation of an oily phase from water on the basis of density differences between the two fluids. These systems obviously work best with non-emulsified oils. Applications historically have been in the oil and gas industry, and hence the most famous oil water separator is the API separator (API being the abbreviation for the American Petroleum Institute). Modern-day designs are more sophisticated than the early, simple separators of a few decades ago that were introduced by...

What Eletcrodialysis Is

Electrodialysis Cell

The principle behind electrodialysis is that electrical potential gradients will make charged molecules diffuse in a given medium at rates far greater than attainable by chemical potentials between two liquids as in conventional dialysis. When a DC electric current is transmitted through a saline solution, the cations migrate toward the negative terminal, or cathode, and the anions toward the positive terminal, the anode. By adjusting the potential between the terminals or plates, the electric...

Some Important Definitions

Maximum Contaminant Level (MCL) - The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to MCLGs as feasible using the best available treatment technology and taking cost into consideration. MCLs are enforceable standards. Maximum Contaminant Level Goal (MCLG) - The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety and are non-enforceable public health goals. Maximum...

Info

Electrodialysis process diagram. In addition to the membrane stacks in electrodialysis units, various supporting equipment is essential. This includes pumps for circulation of concentrating and diluting flows flushing streams for cathode and anode plates injection systems for pH control pressure concentration, pH alarms, and control systems and backflushing controls feed strainers and filters and grounding systems. Because of the high pH of the cathode stream, substances, such as...

Revenues Expenses Profits

The most important aspect of this is that profits can be increased by either an increase in revenues or a decrease in expenses. Water treatment operations are by and large end-of-pipe treatment technologies, and hence from the standpoint industry applications that must treat water, the investments required increase expenditures and decrease profit. Municipal facilities view their roles differently, because their end-product is clean water which is saleable, plus they may have addon revenues...