Application To Subsurface Treatment

The application of adsorption to contaminated groundwater remediation is not only an important subject, but one we could expand upon into several volumes unto itself. At best, all we can do is try to provide a concise overview in this volume. When we discuss this subject, we cannot separate groundwater treatment from subsurface soil treatment, as the two often go hand in hand. Furthermore, carbon adsorption is not the only technology applicable to subsurface (soil and water) remediation, but it...

Applications

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...

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,...

Cone Of Flowing Solids

Illustrates angle of internal friction. Figure 4. Illustrates angle of internal friction. The angle of repose is sensitive to the conditions of the supporting surface the smoother the surface, the smaller the angle. The angle may also be reduced by vibrating the supporting surface. When handling slow moving materials having large angles of repose, well-designed, bunkers and hoppers are provided with highly polished internal surfaces and low amplitude vibrators. The angle is also...

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...

Filter Media Selection Criteria

Due to the wide variety of filter media, filter designs, suspension properties, conditions for separation and cost, selection of the optimum filter medium is complex. Filter media selection should be guided by the following rule a filter medium must incorporate a maximum size of pores while at the same time providing a sufficiently pure filtrate. Fulfilment of this rule invokes difficulties because the increase or decrease in pore size acts in opposite ways on the filtration rate and solids...

Fouling Considerations

A critical consideration with UF technology is the problem of fouling._Foulants interfere with UF by reducing product rates- sometimes drastically-and altering membrane selectivity. The story of a successful UF application is in many respects the story of how fouling was successfully controlled. Fouling must be considered at every step of UF process development in order to achieve success. When we talk about this subject, the term foulant or foulant layer comes to the forefront. Foulant, or...

General Properties Of Loose And Granular Media

The physical properties of loose and granular media are important, both from the standpoint of the operation of the filtration device, but also from the standpoints of feeding and storing these materials in bins and silos. These considerations are equally important and quite pertinent to dry chemicals that are used as filtration aids (Chapter 3). In a general sense, loose solid matter is comprised of large numbers The ratio of pmaJpmin can be as high as 1.52 depending on the material....

Granular Media Filtration

Granular media filtration is used for treating aqueous waste streams. The filter media consists of a bed of granular particles (typically sand or sand with anthracite or coal). The anthracite has adsorptive characteristics and hence can be beneficial in removing some biological and chemical contaminants in the wastewater. This material may also be substituted for activated charcoal. The bed is contained within a basin and is supported by an underdrain system which allows the filtered liquid to...

Info

There are no major technical obstacles to desalination as a means of providing an unlimited supply of fresh water, but the high energy requirements of this process pose a major challenge. Theoretically, about 0.86 kWh of energy is needed to desalinate 1 m3 of salt water (34,500 ppm). This is equivalent to 3 kJ kg1. The present day desalination plants use 5 to 26 times as much as this theoretical minimum depending on the type of process used. Clearly, it is necessary to make desalination...

Introducing The Physical Treatment Methods

The following technologies are among the most commonly used physical methods of purifying water Heat Treatment - Boiling is one way to purify water of all pathogens. Most experts feel that if the water reaches a rolling boil it is safe. A few still hold out for maintaining the boiling for some length of time, commonly 5 or 10 minutes, plus an extra minute for every 1000 feet of elevation. One reason for the long period of boiling is to inactivate bacterial spores (which can survive boiling),...

Ion Exchange And Carbon Adsorption

Ion exchange and carbon adsorption are unrelated technologies, and often have different objectives. They are however oftentimes used in compliment to achieve Ion exchange is a reversible chemical reaction wherein an ion (an atom or molecule that has lost or gained an electron and thus acquired an electrical charge) from solution is exchanged for a similarly charged ion attached to an immobile solid particle. These solid ion exchange particles are either naturally occurring inorganic zeolites or...

Lets Look At How A Single Particle Behaves In A

During the motion of viscous flow over a stationary body or particle, certain resistances arise. To overcome these resistances or drag and to provide more uniform fluid motion, a certain amount of energy must be expended. The developed drag force and, consequently, the energy required to overcome it, depend largely on the flow regime and the geometry of the solid body. Laminar flow conditions prevail when the fluid medium flows at low velocities over small bodies or when the fluid has a...

N

NPDES Permit National Pollutant Discharge Elimination System permit is the regulatory agency document issued by either a federal or state agency which is designated to control all discharges of pollutants from point sources into U.S. waterways. NPDES permits regulate discharges into navigable waters from all point sources of pollution, including industries, municipal wastewater treatment plants, sanitary landfills, large agricultural feed lots and return irrigation flows. Nitrification An...

Preface

This volume covers the technologies that are applied to the treatment and purification of water. Those who are generally familiar with this field will immediately embrace the subject as a treatise on solid-liquid separations. However, the subject is much broader, in that the technologies discussed are not just restricted to pollution control hardware that rely only upon physical methods of treating and purifying wastewaters. The book attempts to provide as wide a coverage as possible those...

Principles Of Ozone Effluent Treatment

Ozone was first discovered by the Dutch philosopher Van Marun in 1785. In 1840, Schonbein reported and named ozone from the Greek word ozein, meaning to smell. The earliest use of ozone as a germicide occurred in France in 1886, when de Meritens demonstrated that diluted ozonized air could sterilize polluted water. In 1893, the first drinking water treatment plant to use ozone was constructed in Oudshorrn, Holland. Other plants quickly followed at Wiesbaden (1901) and Paderborn (1902) in...

Properties Of Ozone

Ozone is an unstable gas, having a boiling point of -112 C at atmospheric conditions. Its molecular weight is 48. Ozone is partially soluble in water (approximately 20 times more soluble than oxygen), and has a characteristic penetrating odor which is readily detectable at concentrations as low as 0.01 - 0.05 ppm. Ozone is the most powerful oxidant currently available for use for wastewater treatment. Commercial generation equipment generates ozone at concentrations of 1 percent to 3 percent in...

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...

Rapid Sand Filtration

Rapid filtration is performed either in open gravitational flow filters or in closed pressure filters. Rapid pressure filters have the advantage of being able to be inserted in the pumping system, thus allowing use of a higher effective loading. Note that pressure filters are not subject to development of negative pressure in a lower layer of the filter. These filters generally support higher speeds, as the available pressure allows a more rapid flow through the porous medium made up by the...

Reactions for Hydrogen Cation Exchanger Resins Regeneration Reactions

Calcium, Magnesium and or Sodium-Cation Exchanger (Insoluble) + Sulfuric Acid (Soluble) Hydrogen Cation Exchanger (Insoluble) + Calcium, Magnesium and or Sodium Sulfates (Soluble). Reactions for Hydrogen Cation-Exchanger Resins -Reactions with Sulfates or Chlorides Ca, Mg, Na2 S04, Cl2 + H2Z Ca, Mg, Na2 Z + H2S04 or HCl Calcium, Magnesium and or Sodium as Sulfates and or Chlorides (Soluble) + Hydrogen Cation Exchanger (Insoluble) Calcium, Magnesium and or Sodium-Cation Exchanger (Insoluble) +...

Recommended Resources For The Reader

The following references offer some good general reading and design-specific 1. Cheremisinoff, P.N., Wastewater Treatment Pocket Handbook, Pudvan Publishing, Northbrook, IL, 1987. 2. Cheremisinoff, P.N., Pocket Handbook for Solid-Liquid Separations, Gulf Publishing Co., Houston, TX, 1984. 3. Noyes, R., Unit Operations in Environmental Engineering, Noyes Publishers, NJ, 1994. 4. Kirkpatrick, J., Mathematics for Water and Wastewater Treatment Plant Operators, Ann Arbor Science Pub., Ann Arbor,...

Region Of Light Phase Liquid

Separation is achieved by use of stack discs. The position of the separating zone is controlled by adjusting the back pressure of the discharged liquids or by means of exchangeable ring dams. Figure 16 illustrates the main features of a disk-bowl centrifuge, which includes a seal ring (1), a bowl (2) with a bottom (13) a central tube (18), the lower part of which has a fixture (16) for disks a stack of truncated cone disks (17), frequently flanged at the inside and outer diameters to...

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...

Sludge Conditioning Using Chemicals

Sludge conditioning is a process whereby sludge solids are treated with chemicals or various other means to prepare the sludge for dewatering processes. Chemical conditioning (sludge conditioning) prepares the sludge for better and more economical treatment with vacuum filters or centrifuges. Many chemicals have been used such as sulfuric acid, alum, chlorinated copperas, ferrous sulfate, and ferric chloride with or without lime, and others (refer back to discussions in Chapter 8). The local...

Sludge Lagoons

This is a technique that relies both on the settling characteristics of sludge and solar evaporation. The considerable labor involved in sludge drying bed operation may be avoided by the use of sludge lagoons. These lagoons are nothing but excavated areas in which digested sludge is allowed to drain and dry over a period of months or even a year or more (refer to Figure 22 for an example). They are usually dug out by bulldozers, or other dirt-moving equipment, with the excavated material used...

Stabilization Via Anaerobic Digestion

The purpose of digestion is to attain both of the objectives of sludge treatment a reduction in volume and the decomposition of highly putrescible organic matter to relatively stable or inert organic and inorganic compounds. Additionally, anaerobic sludge digestion produces a valuable by-product in the form of methane gas (the primary constituent of natural gas, which we can burn for heat or convert to electricity). Sludge digestion is carried out in the absence of free oxygen by anaerobic...

Sterilization Using Ozone

Ozone (03) is a powerful oxidant, and application to effluent treatment has developed slowly because of relatively high capital and energy costs compared to chlorine. Energy requirements for ozone are in the range of 10 to 13 kWh lb generated from air, 4 kWh lb from oxygen, and 5.5 kWh lb from oxygen-recycling systems. Operating costs for air systems are essentially the electric power costs for oxygen systems the cost of oxygen (2 to 30 lb) must be added to the electrical cost. Capital costs of...

Strongly Acidic Cation Resins

Strongly acidic cation resins derive their exchange activity from sulfonic functional groups (HSO). The major cations in water are calcium, magnesium, sodium, and potassium and they are exchanged for hydrogen in the strong acid cation exchanger when operated in the hydrogen cycle. The following stoichiometric equation represents the exhaustion phase, and is written in the molecular form (as if the salts present were undissociated). It shows the cations in combination with the major anions, the...

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...

The Clean Water

Drinking water standards are not the only regulations we need to comply with in the U.S. Today's Clean Water Act has its origins from the late 1940s. The original 1948 statute (Chapter 758 PL 845), the Water Pollution Control Act, authorized the Surgeon General of the Public Health Service, in cooperation with other federal, state, and local entities, to prepare comprehensive programs for eliminating or reducing the pollution of interstate waters and tributaries and improving the sanitary...

The Drinking Water Standards

When the objective of water treatment is to provide drinking water, then we need to select technologies that are not only the best available, but those that will meet local and national quality standards. The primary goals of a water treatment plant for over a century have remained practically the same namely to produce water that is biologically and chemically safe, is appealing to the consumer, and is noncorrosive and nonscaling. Today, plant design has become very complex from discovery of...

The Final Touches To Water

< > Disinfection - water completely free of suspended sediment, is treated with a powerful oxidizing agent usually chlorine, chlorine and ammonia (chloramine), or ozone. A residual disinfectant is left in the water to prevent reinfection. Chlorine can form harmful byproducts and has suspected links to stomach cancer and miscarriages. < > pH adjustment - so that treated water leaves the plant in the desired range of 6.5 to 8.5pH units. conditioner, as well as a some fertilizer value....

The Horizontal Belt Filter

This devise consists of a continuous traveling horizontal belt that looks like a conveyor belt. Slurry is loaded at one end and vacuum is pulled on the underside of the belt. The filtrate passes through the belt and the solid cake remains on top. As the belt moves the cake is washed and dried and is then discharged off the end of the belt as is wraps around under the machine. This equipment is usually used for slurries that have solids that are not easily suspendible in solution. Although there...

The Plateandframe Filter Press

Filter Press Flowchart

This type of filter allows pressurized filtration of a slurry mixture to remove solids. A set of filter plates is sandwiched together in series with a configuration similar to the plates on a plate-and-frame heat exchanger. After the plates are compressed together hydraulically, a channel throughout all the plates allows the slurry to be pumped into one side of each of the plates. The filtrate goes through the filter media on the plate leaving the solid cake on the media. Filtrate on the other...

The Sedimentation Process In Greater Detail

To examine sedimentation in greater detail, let us examine the events occurring in a small-scale experiment conducted batchwise, as illustrated in Figure 9. Particles in a narrow size range will settle with about the same velocity. When this occurs, a demarcation line is observed between the supernatant clear liquid (zone A) and Figure 10. Plot of interface height and solids concentration versus time. Figure 10. Plot of interface height and solids concentration versus time. The plot shows the...

Theory And Practice Of Ion Exchange

Water can contain varying concentrations of dissolved salts which dissociate to form charged particles called ions. These ions are the positively charged cations and negatively charged anions that permit the water or solution to conduct electrical currents and are therefore called electrolytes. Electrical conductivity is thus a measure of water purity, with low conductivity corresponding to a state of high purity. The process of ion exchange is uniquely suited to the removal of ionic species...

Water And Wastewater Treatment Technologies Constant Rate Filtration

Filtration with gradual pore blocking is most frequently encountered in industrial practice. This process is typically studied under the operating mode of constant rate. We shall assume a unit area of medium which has Np pores, whose average radius and length are rp and 5p, respectively. The pore walls have a uniform layer of particles that build up with time and decrease the pore passage flow area. Filtration must be performed in this case with an increasing pressure difference to compensate...

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...

Waterborne Diseases

There are a number of infectious, enteric (that is, intestinal) diseases of man which are transmitted through fecal wastes. Pathogens (disease-producing agents) include bacteria, viruses, protozoa, and parasitic worms. Widespread diseases generally occur in regions where sanitary disposal of human feces is not practiced. The most common waterborne bacterial diseases are typhoid fever (Salmonella typhosa), Asiatic cholera (vibrio comma), and bacillary dysentery (Shigella dysenteriae). The first...

What Eletcrodialysis Is

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...

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...

What Reverse Osmosis Is

When pure water and a salt solution are introduced on opposite sides of a semipermeable membrane in a vented container, the pure water diffuses through the membrane and dilutes the salt solution, At equilibrium, the liquid level on the saline water side of the membrane will be above that on the freshwater side this process is known as osmosis and is depicted in Figure 9. The view on the left illustrates the commencement of osmosis and the center view presents conditions at equilibrium. The...

What Sludge Is

When we think of sludge, what automatically comes to mind is sewerage. Water carriage systems of sewerage provide a simple and economical means for removing offensive and potentially dangerous wastes from household and industry. The solution and suspension of solids in the transporting of water produces sewage. Thus, the role of solids and sludge removal at Sewage Treatment Plants is apparent. Sludge removal is complicated by the fact that some of the waste matters go into solution while others...

The Rotary Drum Filter

This continuous filter is used when the solids in the slurry can be easily suspended in solution and remain there. In this filter a cylindrical drum sets horizontally half submerged in a trough holding the filtration slurry. The drum is coated with a filter media and a vacuum is pulled on the inside of it. The filtrate passes through the filter media leaving the solids on the outside of the drum. The drum is rotated continuously allowing the solids to be washed and dried before they are removed...

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....

Disinfection With Halogen Mixtures

Two approaches that have been investigated recently for disinfection are mixtures of bromine and chlorine, and mixtures containing bromide or iodide salts. Some evidence exists that mixtures of bromine and chlorine have superior germicidal properties than either halogen alone. It is believed that the increased bacterial activity of these mixtures can be attributed to the attacks by bromine on sites other than those affected by chlorine. The oxidation of bromide or iodide salts can be used to...

Carbon Adsorption In Water Treatment How Adsorption Works

Activated carbon is a crude form of graphite, the substance used for pencil leads. It differs from graphite by having a random imperfect structure which is highly porous over a broad range of pore sizes from visible cracks and crevices to molecular dimensions. The graphite structure gives the carbon it's very large surface area which allows the carbon to adsorb a wide range of compounds. Activated carbon can have a surface of greater than 1000 m2 g. This means 5g of activated carbon can have...

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...

Interhalogen Compounds And Their Properties

Interhalogen compounds are formed from two different halogens. These compounds resemble the halogens themselves in both their physical and chemical properties. Principal differences show up in their electronegativities. This is clearly shown by the polar compound IC1, which has a boiling point almost 40 C above that of bromine, although both have the same molecular weights. Interhalogens have bond energies that are lower than halogens and therefore in most cases they are more reactive. These...

The Sludge Pasteurization Process

Filter Press Sludge Treatment

This process is really sludge disinfection. Its aim is the destruction or inactivation of pathogenic organisms in the sludge. Destruction is defined as the physical disruption or disintegration of a pathogenic organism, while Inactivation is defined as the removal of a pathogen's ability to infect. In the United States procedures to reduce the number of pathogenic organisms are a requirement before sale of sludge or sludge-containing products to the public as a soil conditioner, or before...

The Pressure Leaf Filter

Diagram Agitated Nutsche Filter Dryer

This device is similar to a plate-and-frame filter press but the whole plate assembly is also housed in a tank or pressure vessel. This design allows higher pressures to be used, and also allows the filtration operation to be done more efficiently in many applications. There are two basic configurations, namely a horizontal plate and a vertical pressure leaf filter. Horizontal plate pressure filters were commonly applied to the fine chemical process industries such as antibiotics , pesticides...

Vacuum Filtration

We have already discussed this important technology in Chapter 5, but a review may be helpful in placing its importance to sludge processing into perspective. The vacuum filter for dewatering sludge is a drum over which is laid the filtering medium consisting of a cloth of cotton, wool, nylon, dynel, fiber glass or plastic, or a stainless steel mesh, or a double layer of stainless steel coil springs. The drum with horizontal axis is set in a tank with about one quarter of the drum submerged in...

An Alternative Analysis The Forgotten Method Of Dimensional Analysis

I often refer to dimensional analysis as lost art - because it is usually not heavily emphasized in engineering education today. However, for well over 100 years its has provided simply a wealth of practical design correlations that are still relied upon in virtually all aspects of chemical engineering, ranging from classes of problems dealing with heat and mass transfer, reaction kinetics, momentum exchanges in flow dynamics. Much of sedimentation theory, and indeed the basis for more...

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,...

Introduction Of Physical Methods Of Waste Treatment

We may organize water treatment technologies into three general areas Physical Methods, Chemical Methods, and Energy Intensive Methods. Physical methods of wastewater treatment represent a body of technologies that we refer largely to as solid-liquid separations techniques, of which filtration plays a dominant role. Filtration technology can be broken into two general categories - conventional and non-conventional. This technology is an integral component of drinking water and wastewater...

Air Flotation Systems

Air flotation is one of the oldest methods for the removal of solids, oil amp grease and fibrous materials from wastewater. Suspended solids and oil amp grease removals as high as 99 can be attained with these processes. Air flotation is simply the production of microscopic air bubbles, which enhance the natural tendency of some materials to float by carrying wastewater contaminants to the surface of the tank for removal by mechanical skimming. Many commercially available units are packaged...

It Makes Sense To Select A Filter Press

Of When a very low moisture content is required for thermal cake drying or incineration. rar When high f ltrate clarity is required for polishing applications. rar When good cake release assisted by squeezing is required. y When the cake is disposed as land fill for spreading with a bulldozer provided it is hard enough to carry its weight. When large filtration areas are required in a limited space. The shuttle shifter moves the plates one by one towards the follower and the cake discharges....

Stabilization Via Aerobic Digestion

Aerobic digestion is an extension of the activated sludge aeration process whereby waste primary and secondary sludge are continually aerated for long periods of time. In aerobic digestion the microorganisms extend into the endogenous respiration phase. This is a phase where materials previously stored by the cell are oxidized, with a reduction in the biologically degradable organic matter. This organic matter, from the sludge cells is oxidized to carbon dioxide, water and ammonia. The ammonia...