Glossary

Anion membrane An electrodialysis membrane that allows passage of anions. Apolar membrane An RO membrane in which the nonpolar regions exceed the polar regions. Activation The process of enhancing a particular characteristic. Active zone A small length of column where adsorption is taking place. Activated carbon Carbon with enhanced adsorption characteristic. Adsorbate The solute adsorbed onto the surface of a solid. Adsorbent The solid that adsorbs the adsorbate. Adsorption The process of...

Info

Bubble aerators were discussed in a previous Chapter 6 (Mixing and Flocculation). In that chapter, the rise velocities of bubbles vb as derived by Peebles and Garber were presented. The formulas are _ 2(r)2(p -pg) 2(rfpl 2p y < 2 vb 0.33 076 (r)128 2 < Re < 4.02G-2'214 Vb 1.35 ( J 4.02Gf214 < Re < 3.10G7 Vb 1.53 (n)025 3.10G-(X25 < Re < G2 Re is a Reynolds number g is the acceleration due to gravity is the absolute viscosity of fluid pl is the mass density of fluid a is the...

P

N, -- Po called the power number (6.2) To solve for n2, write D21 L2(FT L2) FT. To eliminate FT, write D2 (1 pND4a) FT 1 (FT2 L4)(1 T)L4 1. Thus, n2 1 - n2 pND-')'1 Re called the Reynolds number (6.3) pND2 1 To solve for n3, write Da g (L) (L T2) T2. To eliminate T2, write (Da g) N2 T2 1 IT2 1. Thus, n3 Fr called the Froude number (6.4) Including the shape factors and assuming there are n geometric measurements in the vessel, the functional relationship Equation (6.1) becomes P N pDa , , Sj,...

Symbols

Aadd Alkalinity to be added to water Aadd geq Gram equivalents per liter of alkalinity to be added to water Acadd Acidity to be added to water Acadd geq Gram equivalents per liter of acidity to be added to water Acur Current alkalinity of water Acur geq Gram equivalents per liter of current alkalinity of water A Fe mg mg L of ferrous to be removed FeOH+ Monohydroxo Fe(II) complex ion FeOH2+ Monohydroxo Fe(III) complex ion Fe (OH)+ Dihydroxo Fe(III) complex ion Fe (OH)- Trihydroxo Fe(II) complex...

V

Where T is equal to dA dy, a derivative of A with respect to y. T is the top width of the flow. A T is called the hydraulic depth D. The expression V JgD is called the Froude number. The flow over the weir is rectangular, so D is simply equal to yc, thus Equation (3.4) becomes where V has been changed to Vc, because V is now really the critical velocity Vc. Equation (3.4) shows that the Froude number at critical flow is equal to 1. Equation (3.5) may be combined with Equation (3.2) to eliminate...

O Constituents of Water and Wastewater

Given a wastewater, what process should be applied to treat it biological, chemical, or physical Should it be treated with a combination of processes These questions cannot be answered unless the constituents of the wastewater are known. Thus, before any wastewater is to be treated, it is important that its constituents are determined. On the other hand, what are the constituents of a given raw water that make it unfit to drink Are these constituents simply in the form of turbidity making it...

Jyj

X the concentration of X V control volume A the bounding surface area of the control volume n outward-pointing normal vector v velocity vector. Because aeration is done only in the reactor, this is the place where growth of organisms occurs. Thus, although it is said that V is the volume of the control volume, in reality, this volume is simply the volume of the reactor. d X dt was previously given in Equation (15.71) combining this with Equation (15.73) after integrating over the volume of the...

O

Organic acids Organic compounds with the general formula RC-OH, where R is a hydrocarbon group. Organic nitrogen The nitrogen content in protein of an organic matter. Organic phosphorus The phosphorus content of organic matter. Orthophosphates The ions and salts of the three phosphoric acid dissociation products dihydrogen phosphates containing the H2PO4 ion, hydrogen phosphate containing the HPO4 ion, and the phosphates containing the Oxidation state A measure of the degree of affinity of the...

Xoc

,, S _ Q Xu + (Q0-Q ) Xe -Q0 X0 + mKTis - XTi kd (15'77) The same mathematical operations may be applied to the substrate. These will not be repeated but the result will be written at once, which is -V IF TTTb X V - 0 + (-GoE 5o + (Qo - Qw) 5 + Qw 5 ) Note that the total derivative and Eulerian derivative are prefixed by a negative sign. This is because they represent a rate of decrease of the mass of the substrate as opposed to the rate of increase of the mass of the microorganisms. Equation...

A h f n V

(a) hL fp n3d 2g dpave 1 (0.01) + 0.7 (0.05) + 0.54(0.15) + 0.46 (0.18) + 0.38(0.18) + 0.32(0.20) + 0.27 (0.15) + 0.23 (0.07) + 0.18(0.01) 0.40 mm 9.33m3 m2 d 1.08(10-4) m s f - i 75 , 1550(1-77) Re dVsp d 1.24 0 333dp 3 0.77 d 1.24 (0.770333)(0.40)(10-3) 0.45( 10-3) m fi 15( 10-4) kg m s at 20 C Re 0.45(10-3)(1.08)(10-4)(1000- 00324 15 (10-4) . hL n3 2gEfpid) Rg _ dj(0.00135)(1000) _ 15(10-4) _ 1.24(0.77)Q3 (0.00135)(1000) _ 102298d 15(10-4) . p f _ 1 75+ 150 11 0 42) _ i)> .85 + 175 jp...

[Sno 1 f rs1

dnmiK.NO- + NO, JiK + SjJ where 6cdn MCRT for the denitrifiers, kddn kd for denitrifiers, and SNO lim limiting value of SNO . Values for kddn range from 0.04-0.08 per day, typical 0.04 d. As mentioned, three types of kinetics are involved in the removal of nitrogen nitrification kinetics, denitrification kinetics, and carbon kinetics. Carbon kinetics refer to the kinetics of the heterotrophic aerobic reactions. By analogy with the nitrification or denitrification kinetics, where c specific...

Bibliography

Cornwell (1991). Introduction to Environmental Engineering. MacGraw-Hill, New York. Doran, G. F., et al. (1998). Evaluation of technologies to treat oil field produced water to drinking water or reuse quality. Proc. SPE Annu. Western Regional Meeting, May 11-15, Bakersfield, CA, Soc. Pet. Eng. (SPE). Richardson, TX. Kedem, O. and G. Zalmon (1997). Compact accelerated precipitation softening (CAPS) as a pretreatment for membrane desalination I. softening by NaOH,...

A Removal of Phosphorus by Chemical Precipitation

Phosphorus is a very important element that has attracted much attention because of its ability to cause eutrophication in bodies of water. For example, tributaries from as far away as the farmlands of New York feed the Chesapeake Bay in Maryland and Virginia. Because of the use of phosphorus in fertilizers for these farms, the bay receives an extraordinarily large amount of phosphorus input that has triggered excessive growths of algae in the water body. Presently, large portions of the bay...

Cake Filtration

Sludges may be reduced in volume by using the unit operation of dewatering to remove excess water. In dewatering using a vacuum (such as using a vacuum filter) or the plate-and-frame press, a cake is formed on the surface of the filter cloth. Thus, these processes of dewatering may be called cake filtration. In cake filtration, the flow of the filtrate in its most elementary form, may be considered as through a tightly packed bank of small crooked tubes across the cake. The rightmost drawing of...

Ch3chchchchchchchchchchchchchchchchCOH

Organic compounds with the general formula R-OH are called alcohols. An example of an alcohol is glycerol. It has three OH groups and is called a triol and has the formula OHcH2cH(OH)cH2OH. When glycerol reacts with a saturated fatty acid, fats are typically formed. Fats are solid substances. When the product of the reaction is not a solid, it is called oil. When glycerol reacts with unsaturated fatty acids, oils are typically formed. The reaction is similar to that with the saturated fatty...

Chemical Reaction Of The Phosphate Ion With Alum

To precipitate the phosphate ion as aluminum phosphate, alum is normally used. The chemical reaction is shown next AlPO4(s) I Al3 + PO4- Ksp,aipo4 10-21 As shown in these reactions, the phosphorus must be in the phosphate form. The reaction occurs in water, so the phosphate ion originates a series of equilibrium orthophosphate reactions with the hydrogen ion. This series is shown as follows (Snoeyink and Jenkins)

Design Of Ion Exchangers

Generally, designs of ion exchangers should include the following quantity of exchange materials and regenerants dimension of the bed (volume of bed) interval of bed regeneration, backwash, and rinse water requirements. The amount of exchange materials determines the dimension of the bed. The interval of regeneration may be arbitrarily set from which the quantity of exchange bed material may be calculated. Regeneration, backwash, and rinse waters may pose pollution problems. 16.6.1 Quantity of...

Chemical Reactions Of The Ferrous And The Ferric Ions

The chemical reactions of the ferrous and the ferric ions were already discussed in a previous chapter. From the topic in the preceding section, iron is more efficiently removed as ferric hydroxide. The natural iron is in the form of Fe(II), so this ferrous must therefore oxidize to the ferric form in order to precipitate as the ferric hydroxide, if, in fact, the iron is to be removed in the ferric form. In Chapter 12, this was done using the dissolved oxygen that is relatively abundant in...

Colloid Behavior

Much of the suspended matter in natural waters is composed of silica, or similar materials, with specific gravity of 2.65. In sizes of 0.1 to 2 mm, they settle rapidly however, in the range of the order of 10-5 mm, it takes them a year, in the overall, to settle a distance of only 1 mm. And, yet, it is the particle of this size range that causes the turbidity and color of water, making the water objectionable. The removal of particles by settling is practical only if they settle rapidly in the...

Background Prerequisites

Physical-Chemical Treatment of Water and Wastewater Unit Operations and Unit Processes Coverage Clean Water Act Regulatory Requirements Federal Financial Assistance Permits and Enforcement Federal and State Relationships Safe Drinking Water Act Highlights of the Safe Drinking Water Act Development of MCLs and MCLGs Drinking Water Regulations under the Act Federal Financial Assistance Federal and State Relationships Relationship of This Book to the Acts Glossary Background Chemistry and Fluid...

Coagulation

Colloids are agglomerates of atoms or molecules whose sizes are so small that gravity has no effect on settling them but, instead, they stay in suspension. Because they stay in suspension, they are said to be stable. The reason for this stability is the mutual repulsion between colloid particles. They may, however, be destabilized by application of chemicals. Coagulation is the unit process of applying these chemicals for the purpose of destabilizing the mutual repulsion of the particles, thus...

Chemical Reactions Using Activated Carbon

Carbon is a reducing agent thus, it follows that when in contact with chlorine it will reduce it to the chloride state. Carbon, itself, will be oxidized to carbon dioxide. The chemical reactions follow C + 2H2O CO2 + 4H+ + 4e- (17.57) 2HOCl + 2H+ + 4e- 2Cl- + 2H2O (17.58) C + 2HOCl CO2 + 2Cl- + 2H+ (17.59) The unit operation of carbon adsorption is discussed in Part II of this book. The use of activated carbon in dechlorination will use the same unit operation, except that in the present case,...

Flow Measurements and Flow and Quality Equalizations

This chapter discusses the unit operations of flow measurements and flow and quality equalizations. Flow meters discussed include rectangular weirs, triangular weirs, trapezoidal weirs, venturi meters, and one of the critical-flow flumes, the Parshall flume. Miscellaneous flow meters including the magnetic flow meter, turbine flow meter, nutating disk meter, and the rotameter are also discussed. These meters are classified as miscellaneous, because they will not be treated analytically but...

Dimensions Of The Overall Mass Transfer Coefficients

Kx ( xi - x ) is the mass of solute passing across the interfacial area per unit time per unit cross-sectional area of the interface. The interfacial area of mass transfer is largely indeterminate. To make sense of the expression, first define the term destination medium. Destination medium is the overall entity inside the control volume from or into which the gas and liquid phases flow. For example, in an aeration basin, the destination media are the bulk contents of the tank in a packed...

1

A Anlon-permeable membrane C - Cation-permeable membrane FIGURE 8.1 Cation filtering membrane (a) the electrodialysis process (b). ions in the membranes. As shown in the figure, two compartments become cleaned of ions and one compartment (the middle) becomes dirty of ions. The two compartments are diluting compartments the middle compartment is a concentrating compartment. The water in the diluting compartments is withdrawn as the product water, and is the filtered water. The concentrated...

Flow And Quality Equalizations

In order for a wastewater treatment unit to operate efficiently, the loading, both hydraulic and quality should be uniform. An example of this hydraulic loading is the flow rate into a basin, and an example of quality is the BOD in the inflow however, this kind of condition is impossible to attain under natural conditions. For example, refer to Figure 3.9. The flow varies from a low of 18 m3 h to a high of 62 m3 h, and the BOD varies from a low of 27 mg L to a high of 227 mg L. To ameliorate...

Chemical Requirements For pH Adjustments

The formulas for the kilograms of carbon dioxide, M CO H, needed to lower the pH and the kilograms of lime, M CaOpH, needed to raise the pH were derived in Chapter 12. For convenience, they are reproduced below mco2ph 22i ACadd geq A geq + 10--10-W (13.54) M CaOpH 28.05 A add geq V 28.05( Accur geq + 10-j-10-jV (13.55)

Hoh

The values of the AH298's are obtained from Table 11.2. Note that the values in the table indicate A H298 of formation having negative values. Thus, if the reaction is not a formation but a breakup such as HOHw H2 + 2o2 , the sign is positive. This reaction indicates that to break the water molecule into its constituent atoms +68.317 kcal gmmol of energy is required. The + sign indicates that the reaction is endothermic requiring energy for the reaction to occur. For the ionization of the water...

High pH Range

Under this category, iron is removed as Fe(OH)2 and manganese is removed as Mn(OH)2. The unit operations will then involve a unit (tank) for containing the addition of the hydroxide source (lime) to raise the pH and for mixing the chemicals and allowing completion of the precipitation of Fe(OH)2 and Mn(OH)2. The precip) itates formed will still be in suspension thus, it is necessary for them to flocculate by adding a flocculation tank. After the flocculation tank will be a settling tank. The...

Effect Of The Ksps On The Precipitation Of Phosphorus

The worst of the precipitants are the ferric salts. Compare Ksp,Fe( OH)3 . 1.1(10-3D) and Kjp,FepO 10-219. These two Ksp's produce comparable concentrations of the ferric ion to precipitate either Fe(OH)3 or FePO4. Thus, at high pH conditions, the phosphate ion would have a big competitor in the form of the hydroxide ion. An Fe3+ available in solution is grabbed by the OH- ion to form the ferric hydroxide, leaving less amount of Fe3+ to precipitate ferric phosphate. The ferric salts are,...

Gyi y2

As mentioned before, Phyd ump must have a value that corresponds to the value of G that is correct for effective mixing. 6.4.3 Volume and Detention Times of Hydraulic-Jump Mixers Referring to the bottom of Figure 6.9, let L be the length of the hydraulic jump. Then the volume Vjump of the hydraulic jump is simply the volume of the trapezoidal prism of volume. Thus,

XL In [ C m 1X In [ C

Neglect tests 6 and 7, because the additional values of 0.06's would not conform to the Langmuir equation. Test No. PAC Added M (g) C (mg L) In C X M In X M 1 0.25 6.0 1.79 0.076 -2.58 2 0.32 1.0 0 0.075 -2.59 a 0.076 (25 -6)(1) 0.25(1000) other values in the column are computed similarly. Z +1 n C -(m- )Z1 n C 3(0.09 + 0.06) - 2 (6.0 + 1.0 + 0.25) I(Xm+1 In - (m -1)X 1 In 0.45 -14.5 3(- 3.69 - 4.07) - 2(- 2.58 - 2.59 - 3.02)

Aor

As mentioned before, specification of aeration equipment requires the determination of SOR. From Equation (9.13), this involves finding the values of the aeration parameters AOR, 3, and a. The parameter a, in turn, requires the determination of the KLa values. Each wastewater is unique in its characteristics, so these parameters should be determined experimentally. The literature reports values of (KLa)w20 in the neighborhood of 2.5 per hour, a in the range of 0.7 to...

Bkk

Again, in this reaction, the H in the amine group of the amine, epiamine, reacts with the chloride of isophthaloyl chloride forming HCl. The N, in turn, of the amine group, from which the H that reacts with the C chloride were taken, bonds with the C of the carboxyl group of isophthaloyl chloride producing the PA-300 membrane. As shown in its structure, this membrane is also a cross-linked membrane. meta-Phenylene diamine reacting with trimesoyl chloride produces the FilmTec FT-30 membrane...

Comments On The Optimum pH Ranges

When the ferric salts are used to precipitate FePO4, the PO - ion must compete with the OH- ion. When the pH is high, there will be a large concentration of the OH-and the phosphate ion can lose the competition and fail to precipitate Fe(OH)3 may precipitate instead of FePO4. Thus, to precipitate the phosphate ion, the concentration of OH- must be suppressed. This is done by adding more H +, which reacts with the OH-. If the OH- is busy satisfying the hydrogen ion, the Fe3+ ion is now available...

Chemical Reactions Of The Ferric

The ferric salts used as coagulant in water and wastewater treatment are FeCl3 and Fe2(SO4)3. They have essentially the same chemical reactions in that both form the Fe(OH)3(s) solid. When these coagulants are dissolved in water, they dissociate according to the following equations Fe2(SO4)3 2Fe3+ + 3SO4- (12.32) As in any coagulation process, these ions must be rapidly dispersed throughout the tank in order to effect the complete coagulation process. The solid precipitate Fe(OH)3(s) and...

H

The value of Hopt may be solved by trial error. Example 12.2 A raw water containing 140 mg L of dissolved solids is subjected to coagulation treatment using copperas. Calculate the optimum pH that the operation should be conducted. Assume the temperature of operation is 25 C.

Qhf

Ai13(OH)34c - 10 7ai13(oh)34c - 10 - 0.20 a1i3(OH)34ck1P3,AI(OH)3YHI 65 (10-974)(10-33 )13 (0.94)5 - 65 (0.94 )5 2.30( 104) H+p( +3 + 4.45 (109) H+p 4 + 9.63( 1015) H+pi 5 + 9.50 (1021) H+pi 6 - 2.26 (10) Solving by trial and error, let Y - 2.30(104) H+p( 3 + 4.45(109) H+p( 4 + 9.63( 1015) H+. 5 + 9.50(1021) H+p( 6

Introduction

This book is titled Physical-Chemical Treatment of Water and Wastewater. This chapter begins by defining wastewater and physical-chemical treatment of water and wastewater and treats briefly the coverage. It also addresses the unit operations and unit processes. In addition, in the environmental engineering field, construction of water and wastewater treatment plants and the requirements of their levels of performance are mostly driven by government laws and regulations. For example, the Clean...

Kc nTLTy213

DR 0 dL(kLc-ky-y' L2(KLC - kcy - y')(y) (2.14) In the previous equations, kcLc and kc are the parameters of the partial differentiation. Thus, in Equation (2.14), where the differentiation is with respect to kc, the partial derivative of kcLc with respect to kc is zero, since the whole expression kcLc is taken as a parameter. From Eqs. (2.13) and (2.15), Lc, the ultimate oxygen demand, may finally be solved producing

Qwr

CaCO3 -3 ' 3 - 7.97( 10-6) gmol L Yh 0.94 YCaHCO3c YCaOHc K 10-1033 CaHCO+ WW ) (10-67) 1.74(10-14) gmol L 0.94( 10 26 ) YCa 0.77 KCaOHc 10-149 Yso4 0.77 so4- 312( 10-6) gmol L 2+ 7.0( 10-4) - 7.97( 10-6) - 1.74(10-14) Ca - -- 1 + c .'- 'T IO-,14- , + (0.77)(0.77) 3.12(10-6) -6-926(10-4)-- 6.92 (10-4) gmol L 11.2.3 Total Alkalinity as Calcium Carbonate The unit of concentration that we have used for alkalinity is equivalents per unit volume. This unit follows directly from the chemical...

K2

Subscript symbol for aqueous Total molar concentration of species containing the calcium atom Molar concentration of the calcium ion Calcium ion concentration after occurrence of precipitation potential Calcium ion concentration before occurrence of precipitation potential Precipitation potential of the calcium ion Precipitation potential of CaCO3 Carbonate complex of calcium ion Bicarbonate complex of calcium ion Hydroxide complex of calcium ion Moles of carbon dioxide per unit volume of flow...

Linear Momentum Equation Applied To Filters

The motion of water through a filter bed is just like the motion of water through parallel pipes. While the motion through the pipes is straightforward, however, the motion in the filter bed is tortuous. Figure 7.10 shows a cylinder or pipe of fluid and bed material. Inside this pipe is an element composed of fluid and bed material being isolated with length dl and interstitial area A and subjected to forces as shown. (We use the term interstitial area here because the bed is actually composed...

K

Kl is the proportionality constant of the inverse relationship. Substituting the expression for Po and Re, At high Reynolds numbers, friction losses become practically constant. If the Moody diagram for flow in pipes is inspected, this statement will be found to be true. Agitators are not an exception. If vortices and swirls are prevented, at high Reynolds numbers greater than or equal to 10,000, power dissipation is independent of Re and the relationship simply becomes Kt is the constant....

L

FIGURE 12.2 Primary charges of a hydrophilic colloid as a function of pH. sufficiently large, the attracted counterions can form a compact layer around the primary charges. This layer is called the Stern layer. The counterions, in turn, can attract their own counterions, the coions of the primary charges, forming another layer. Since these coions form a continuous distribution of ions into the bulk of the solution, they tend to be diffused and form a diffused layer. The second layer is called...

M

(Miw 12.15)(25,000) 182.25 kg d 0( 1 - f MgHC03) -------2---5---,--0---0---0--------- 3 182.25(1 - 0)' Na+ meq Na+ meqn + 18.9 (M ) 2 + 18.9( ) 2.758 meq L Ans I ____ __ MTCaHC03( 1- f CaHC0,)_ HC03 0Hmeq 0.32 meq L HTO3 m, meq 0 (1 - Ksp,HC03 + -s ,, ,, + 4Kp,HC03 Assuming temperature 25 C, K ,HCO 10

Natural Occurrences Of Iron And Manganese

Iron and manganese have the electronic configurations of Ar 3d 64s2 and Ar 3d 54s2, and are located in Groups VIIIB and VIIB of the Periodic Table, respectively. They are both located in the fourth period. Ar means that these elements have the electronic configuration of the noble gas argon. The letters d and s refer to the d and s orbitals the superscripts indicate the number of electrons that the orbitals contain. Thus, the d orbital of iron contains 6 electrons and that of manganese contains...

Mea

Al(OH)3(s)(fresh precipitate) Al3+ + 3OH- Ksp AKOHh 10-33 (12.8) Al(OH)3(S) + OH- Al( OH)- Kakoh)4c 10+ (12.9) 2Al3+ + 2H2O Al2 (OH )4+ + 2H+ Kai2(oh)2c 10- (12.10) The equilibrium constants apply at 25 C Note From the number of aluminum atoms they contain Al7(OH)4+, Al13(OH) +, and Al2(OH)4+ are polynuclear complexes. Also, the H+ and the OH- are participants in these reactions. This means that the concentrations of each of these complex ions are determined by the pH of the solution. In the...

Oxidationreduction Reactions Of Nitrogen Foods

Life processes involve electron transport. Specifically, the mitochondrion and the chloroplast are the sites of this electron movement in the eucaryotes. In the procary-otes, this function is embedded in the sites of the cytoplasmic membrane. As far as electron movement is concerned, life processes have similarity to a battery cell. In this cell, electrons move because of electrical pressure, the voltage difference. By the same token, electrons move in an organism because of the same electrical...

P A

This p may be substituted into s 4pYdn such that s 20p'Ydn. Substituting these newfound values of p and s into 2p - 3s 20p, we have 2p-3s 1-6Ydn (1548) -----2---0----p------ --------1---0------d--- n (15.48) (1 - 6Ydn) 10 (2p - 3s) 20p is the number of mmol L of ammonia nitrogen produced per mmol L of nitrate nitrogen destroyed. The p' mmol L of nitrate nitrogen constitutes a fraction of the total concentration of nitrate nitrogen produced during the nitrification process. Let this...

Problems

3.1 The system in Figure 3.1 is indicating a flow of 0.3 m3 s. The head over the weir and its length are 0.2 m and 2 m, respectively. Calculate the height of the weir. 3.2 The system in Figure 3.1 is indicating a flow of 0.3 m3 s. The head over the weir and its height are 0.2 m and 1 m, respectively. Calculate the length of the weir. 3.3 The head over a fully contracted weir of length equal to 2 m is 0.2 m. If the height of the weir is 1 m, what is the discharge 3.4 A suppressed weir measures a...

Modes Of Phosphorus Removal

Again, as in previous chapters, the best place to investigate for determining the modes of removal is the table of solubility products constants as shown in Table 14.1. A precipitation product that has the lowest Ksp means that the substance is the most insoluble. As shown in the table, the phosphate ion can be precipitated using a calcium precipitant producing either Ca5(PO4)3(OH)(s) or Ca3(PO4)2. Of these two precipitates, Ca5(PO4)3(OH)(s) has the smaller Ksp of 10 thus, it will be used as...

Modes Of Nitrogen Removal

The physical removal of nitrogen using the unit operation of stripping was discussed in a previous chapter. The present chapter concerns only the removal of nitrogen by biochemical means, as mediated by microorganisms. The technique of the unit process is to release the nitrogen in the form of the gas N2 to the atmosphere. This will first entail nitrifying the nitrogens using the species of bacteria Nitrosomonas and Nitrobacter. Nitrosomonas oxidizes the ammonium ion into nitrites, deriving...

Pressure Membranes

Pressure membranes are membranes that are used to separate materials from a fluid by the application of high pressure on the membrane. Thus, pressure membrane filtration is a high pressure filtration. This contrasts with electrodialysis membranes in which the separation is effected by the impression of electricity across electrodes. Filtration is carried out by impressing electricity, therefore, electrodialysis membrane filtration may be called electrical filtration. According to Jacangelo...

Modes Of Removal Of Iron And Manganese

The best place to investigate for determining the mode by which the elements can be removed is the table of solubility products constants as shown in Table 13.1. In general, a precipitation product that has the lowest Ksp means that the substance is the most insoluble. As shown in the table, for iron, the lowest Ksp is that of Fe(OH)3, an Fe(III) iron, and has the value of 1.1(10 38). For manganese, the lowest K is that of MnS, an Mn(II) manganese, and has the value of 1.1(10 ). These Ksp's...

Nature of the Suspending Fluid

In addition to the time of contact and age of the microorganism, the nature of the suspending fluid also affects the effectiveness of a given disinfectant. For example, extraneous materials such ferrous, manganous, hydrogen sulfide, and nitrates react with applied chlorine before the chlorine can do its job of disinfecting. Also, the turbidities of the water reduces disinfectant effectiveness by shielding the microorganism. Hence, for most effective kills, the fluid should be free of...

Re 0075702997 597 105 88 104

From c of Figure 3.5, at d D 75 150 0.5, K 1.02 therefore, 2(9.81)(26000) nmo 3. nmi 3, 0.032 m s 0.031 m s Therefore, design values approach diameter 150 mm, throat diameter 75 mm, Figure 3.6 shows the plan and elevation of a Parshall flume. As indicated, the flow enters the flume through a converging zone, then passes through the throat, and out into the diverging zone. For the flume to be a measuring flume, the depth somewhere at the throat must be critical. The converging and the subsequent...

Table 114

Equilibrium Constants for Various Complexes of Calcium at 25 C These complexes are weak enough that, in the complexometric titration determination using EDTA, they break and are included in the total calcium hardness reported. Thus, the total calcium hardness is composed of the legitimate cation, Ca2+, plus the complex ions as shown in the previous equations. This total calcium hardness must be corrected by the concentrations of the complexes in order to determine the correct activities of the...

T

FIGURE 8.6 (a) schematic representation of preferential sorption-capillary flow theory (b) critical pore diameter for separation (c) flux decline with time (d) correction factor for surface area of cellulose acetate and (e) solute rejection as a function of operating time. FIGURE 8.6 (a) schematic representation of preferential sorption-capillary flow theory (b) critical pore diameter for separation (c) flux decline with time (d) correction factor for surface area of cellulose acetate and (e)...

Table 139

Summary of Equivalent Masses, Manganous Reactions Mn2+ OH- CaO NaOH Cl2 NaClO Ca(ClO)2 KMnO4 O3 O2 High pH 27.45 17.0 28.05 40.0 range Low pH 27.45 35.5 37.25 35.78 52.67 8.0 8.0 range These tables show that, except for Fe2+ and Mn2+, the equivalent masses are the same in both the ferrous and manganese reactions. Now, let kilograms of lime used for the ferrous reaction kilograms of caustic used for the ferrous reaction kilograms of chlorine used for the ferrous reaction kilograms of sodium...

Sludge Production

For convenience, the chemical reactions responsible for the production of sludge solids are summarized next. These equations have been derived at various points. Fe2+ + 2OH- Fe( OH )2(s)i (13.69) Fe2+ + 2-Cl2 + 3H2O Fe(OH)3(s)i + Cl- + 3H+ (13.70) Fe2+ + 1-KMnO4 + -H2O Fe(OH)3(s)i + 1-MnO2i + 1-K+ + (13.71) Fe2+ + -O3 + O Fe(OH 3(s)i + 2H+ (13.72) Fe2+ + 2 O + O2 Fe ( OH + 2H+ (13.73) Mn2+ + 2OH- Mn( OH ) 2(s)i (13.74) Mn2+ + Cl2 + 2H2O MnO2(s)i + 2Cl- + 4H+ (13.75) Mn2+ + i KMnO4 + 2H2O...

Y

-11 J01 n-5) y-10-11 7.14( 10-7) - 4.81( 10-5) -11 J01 n-5) y-10-11 7.14( 10-7) - 4.81( 10-5) 10-11 - 10-12 4.81 (10-5) - 2.74( 10-7) y 7.14(10-7) y 1.08 (10-12) gmol L H+pi 10-12 2.74 (10-7) Therefore, pH -log101.08( 10-12) 11.97 Ans Example 13.3 From the optimum pH's of 11.97, calculate the concentrations spMn in mg L. Assume the water contains 140 mg L of dissolved solids. Ksp, Mn(OH)2Yh H Ksp, Mn(OH)2Yh H Ksp, Mn(OH)2 spMn rj + j +' YMnKW YMn( OH) cK MnOHcKw KMn( OH)2c Ksp, Mn(OH)2 4.5( 10...

W

FIGURE 3.7 Discharge coefficient for the Parshall flume. Example 3.7 (a) Design a Parshall flume to measure a rate of flow for a maximum of 30 cfs. (b) If the invert of the incoming sewer is set at elevation 100 ft, at what elevation should the invert of the outgoing sewer be set Solution As mentioned previously, in design problems, the designer is at liberty to make any assumption provided she or he can justify it. This means, that two people designing the same unit may not have the same...

Table

Average Rates of Water Use for Institutional Facilities Boarding school Student 0.28 Day school with cafeteria, gym, Student 0.09 and showers Day school with cafeteria Student 0.06 Day school with cafeteria and gym Student 0.04 As mentioned earlier, basically two quantities are addressed in this chapter those of water and those of wastewater. Quantity of water has already been addressed in the previous treatments, so it is now time to address quantity of wastewaters. Before discussing quantity...

Water Softening

Softening is the term given to the process of removing ions that interfere with the use of soap. These ions are called hardness ions due to the presence of multivalent cations, mostly calcium and magnesium. In natural waters, other ions that may be present to cause hardness but not in significant amounts are iron (Fe2+), manganese (Mn), strontium (Sr ), and aluminum (Al ). In the process of cleansing using soap, lather is formed causing the surface tension of water to decrease. This decrease in...

Table 163

Some Additional Properties of Cation Exchangers Sulfonated polystyrene Homogeneous resin 1 cross-linked 2 cross-linked 4 cross-linked 5-6 cross-linked 8-10 cross-linked 12 cross-linked 14 cross-linked 16 cross-linked 20 cross-linked Macroporous Sulfonated phenolic resins Resins from phenol methylene Acrylic or meta acrylic Homogeneous resin 5 cross-linked 10 cross-linked Macroporous Phenolic and related condensation products Polystyrene phosphonic acid Polystyrene iminodiacetate Inorganic...

Mc

Gram equivalents per liter of calcium bicarbonate alkalinity Gram equivalents per liter of alkalinity being computed on the basis of CaCO3 having an equivalent mass of 50 Fractional removal of original suspended of raw water Equilibrium constant of the hydrogen phosphate ion Equilibrium constant of the dihydrogen phosphate ion Equilibrium constant of phosphoric acid Solubility product constant of aluminum hydroxide Solubility product constant of aluminum phosphate Solubility product constant of...

Table 113

Solubility Product Constants of Solid Carbonates at 25 C 8.1(10-9) 2.5(10-14) 4.8(10-9) 1.0(10-12) 1.37(10-10) 2.11(10-11) 1.5(10-13) 1.0(10-5) 8.8(10-11) 9(10-17) 1.36(10-7) 8.2(10-12) 9.42(10-10) 6(10-11) they are of no use as dead ends if they do not exist. The other cation that exists in abundance in natural waters is magnesium. In fact, this is the other constituent hardness ion in water. Comparing the Ksp's of the carbonate of these cations, however, CaCO3 is the smaller. Thus, as far as...

Unit Operations For Iron And Manganese Removal

The unit operations involved can be divided into two general categories removal at the pH range of 11.5 to 12.5 and removal at the pH range of 5.5 to 12.5. The former range is called the high pH range and the latter is called the low pH range. The latter is arbitrarily categorized as low, because it is possible to adjust the operation at a low pH value. In these ranges, both iron and manganese can be removed at the same time and at the same unit. The differences and similarities of these...

Ypo4

Kilograms of ferric chloride that reacts with the phosphate phosphorus of the raw water Kilograms of ferric hydroxide solids produced in the removal of phosphorus Kilograms of ferric phosphate solids produced in the removal of phosphorus Total solids produced in removing phosphorus using the ferric salts as precipitants (including suspended solids in raw water) Kilograms of solids produced from the original suspended solids in the removal of phosphorus Total kilograms of ferric sulfate used for...

XiTqilC DQtmt r1000

Also, assume that all of the cations are removed. q. C+. i 8meq L 0.004 geq L 1 1412.8 gea 1412.8 000 1.96 M ) uit m3 720( 1000) g g (Ti n1qi C+sq' )(Q)(tint)(1 + swell) 10001 CatTBedVol (1 + 0.8) 0.13 m3 Ans 16.6.2 Quantity of Regenerant Let CatRegenerant in kilogram equivalents be the quantity of regenerant required and R be the regenerant requirement in equivalents per equivalent of solute removed. The concentration of removable cations in gram equivalents per liter is CatT eq X Ilqi Cs.'...

Nm KMH4 [SnhJGko [So2CpH

Qw Xnu + (Qo - Qw ) XBe - Qo where subscripts n are appended to signify nitrification. However, Qw& null + iQo-QwnXnel-QolXno J_ XJV Qcn where fin is the specific growth rate and 6cn is the mean cell retention time (MCRT) for the nitrifiers. Thus, the equation becomes Typical range of values for kdn is 0.03-0.06 per day typical value of p,n 0.05 d. Our interest is in being able to determine the length of time that the nitrifiers are to be grown so that the size of the reactor can be...

Quantity of Water and Wastewater

Related to and integral with the discussion on quantity are the important knowledge and background on the types of wastewater, sources of water and wastewater, and methods of population projection. The various categories of quantities in the form of design flow rates are also very important. These topics are discussed in this chapter. Because of various factors that have influenced the rate of wastewater generation in recent times, including water conservation and the expanded use of onsite...

A

The expression for (diV< pdV) d is straightforward. It is dJ< pdV dJv(< < p)avedV dJy X dV dmJydV d X V dJXX dt dt dt dt dt dt Substituting in Eqs. (92), (93), (94) into the Reynolds transport theorem, V m X - kd X j j V p + -Q Xo + Q X (95) This may be compared with Equation (75). As shown, the difference is in the confusion as to whether to use the total derivative or the partial derivative. This difference may be dismissed as trivial, but, of course, the use of the total derivative...

Carbon Requirements For Denitrification

As shown in the derivations, carbon is necessary during denitrification. Because the organisms responsible for this process are heterotrophs, sewage was provided as the source. The pertinent reactions for the heterotrophic side reaction, normal anoxic denitrification reaction, and the nitrite-reduction side reaction are given, respectively, in Eqs. (15.43), (15.44), and (15.45). From Equation (15.43), the number of moles of sewage needed per mole of oxygen is )))))r))))))) -...

Alkalinity Expressed In Oh And Acidity Expressed In H

Knowledge of the equivalent mass is needed in the succeeding discussions on the chemical requirements for pH adjustments, which entails adding acids or bases. As acids are added to water and wastewater to lower the pH, they need to react with existing alkalinities first before the pH changes. For the purpose of determining the equivalent masses of the acids as a result of the reaction due to this addition, the constituent species of the alkalinity need to be expressed in terms of a single...

Aa

Because the surface is an area, surface integral is an area integral. Note that in the surface intergral, we mentioned a function that applies on the surface of the solid. To have a visualization of this concept, consider a tank with water entering and leaving it. The function that would apply on the surface of this tank could be the velocity of the water that enters it and the velocity of the water that leaves it. (The places where the water enters and leaves the...

Qr

V (2-92) 2064.03 m3, for one tank 0r (2.49)(60)(60) (.207 m s Ans The third type of settling is zone settling. This is also called type 3 settling. Figure 5.11 shows a batch analysis of zone settling showing four zones A, B, C, and D. Zone A is cleared of solids thus, it is called a clarification zone. B is called uniform settling zone, since the concentration of the solids in this zone is constant. In zone C, the solids concentration increases or thickens from the value at the interface B-C to...

Sf

Equivalents or equivalents per liter of Nitrosomonas produced from one equivalent or one equivalent per liter of NH4-N based on Equation (18.15) The number offaradays or moles of electrons involved in a reaction equivalents or equivalents per liter of Nitrobacter cells produced based on Equation (18.22) per equivalent or equivalent per liter of NH4-N based on Equation (18.15) Equivalents or equivalents per liter of NO3-N, based on the NO-acceptor reaction, destroyed in the denitrification step...

Background Chemistry and Fluid Mechanics

As mentioned, this chapter discusses the background knowledge needed in order to understand the subsequent chapters of this book. The student must have already gained this knowledge, but it is presented here as a refresher. Again, the background knowledge to be reviewed includes chemistry and fluid mechanics. Before they are discussed, however, units used in calculations need to be addressed, first. This is important because confusion may arise if there is no technique used to decipher the...

Sjsy

In Equation (2.33), as n approaches N, ny in the numerator will cancel out with Ny in the denominator. Also, after the cancellation, all the factors in the numerator of the second factor will approach 1. Furthermore, as N approaches infinity, (1 - X N)-y approaches 1. Lastly, as n approaches infinity, we have from calculus limitn (1 - X N)n ex. Applying all these to Equation (2.33) produces Prob(y) y- e y 0, 1, 2, 3, (2.34) This distribution is called the Poisson distribution. This will be used...

A 60 A

Now, let us turn to a more elaborate problem of substituting into an equation. Of course, to use the equation, all the units of its parameters must be known. Accordingly, when the substitution is done, these units must be satisfied. For example, take the following equation 96,494 C0 (2n(m 2) 1 M (5- It is impossible to use the above equation if the units of the factors are not known. Thus, any equation, whether empirically or analytically derived, must always have its units known. In the above...

Chemical Reactions Of The Manganous Ion [MnII

Manganese can be removed as Mn(OH)2 using a suitable OH- source. Upon introduction of the hydroxide source, however, it is not only this solid that is produced. Manganese forms complex ions with the hydroxide. The complex equilibrium reactions are as follows (Snoeyink and Jenkins, 1980) Mn(OH)+ Mn2+ + OH- K MnOHc 10-34 (13.12) Mn(OH)2(S) Mn2 + + 2OH- K oh), 4.5(10-14) (13.13) Mn(OH)2 Mn2+ + 2OH- KMii(oh)2C 10-68 (13.14) Mn(OH)- Mn2++ 3OH- Km c 10-78 (13.15) The values of the equilibrium...

Alkalinity Production And Associated Carbon Requirement

If the nitrification reactions are inspected (see the overall reaction, in particular, reproduced next), it will be found that bicarbonate alkalinity is needed 1 + n,TT T+ m + nTT m + n 2-7 m -5 - _2_NH4 + _ HC 3 + -y- C 2 + 20 O2 C5H7N 2 + H++ N 3 + -) - -H2O (15.65) On the other hand, inspection of Table 15.2 for the half reaction of sewage as an electron donor reproduced as Equation (15.66) shows that bicarbonate alkalinity is produced from sewage. C oH19NO3 + 25H2O I-CO2 + 50NH+ + 50HCO3 +...

Aor B

Interfacial contact area per unit bulk volume of tower Concentration of dissolved oxygen in water at any given moment at a corresponding temperature and pressure Carbonaceous oxygen demand Concentration of dissolved oxygen in the effluent of the secondary sedimentation basin Concentration of dissolved oxygen in Qo Equilibrium concentration of oxygen in water at a particular temperature and pressure. This equilibrium concentration is also called the saturation concentration of the dissolved...

Chemical Requirements

The chemical reactions written so far are not usable for determining chemical requirements. They all apply at equilibrium conditions. When chemicals are added to water, it first has to react, after which equilibrium will set in. It is this first reaction that determines the amount of chemical, not when equilibrium has set in. Chemical requirements for the three methods of coagulation treatments discussed will now be addressed. The respective chemical reactions will first be derived. From the...

Cnh

Physical adsorption A type of adsorption brought about by weak van der Waals forces. Polarization A localized deficiency of ions in the vicinity of the membrane surfaces. Polar membrane An RO membrane in which the polar regions exceed the nonpolar regions. Pressure membrane A membrane that is used to separate materials from a fluid by the application of high pressure on the membrane. Product or permeate The portion of the influent that passes (permeates) through the membrane. Reverse osmosis A...

Dechlorination

Effluents from sewage treatment plants are not allowed to contain residual chlorine in excess of tolerable values as determined by water quality standards. For example, in discharges to trout streams, the residual chlorine should not exceed 0.02 mg L. Thus, chlorinated effluents should be dechlorinated. Sulfur dioxide, sodium sulfite, sodium metabisulfite, and activated carbon have been used for dechlorination. Because sulfur dioxide, sodium sulfite, and sodium metabisulfite contain sulfur, we...

Clean water act

To gain a broader perspective of the Clean Water Act, it is important to know about the United States Code (USC).* This code is a consolidation and codification of the general and permanent laws of the United States. It contains several titles in one of these titles, the Clean Water Act is codified. Because many of the general and permanent laws required to be incorporated into the code are inconsistent, redundant, and obsolete, the Office of the Law Revision Counsel of the House of...

Disinfection Using Ozone

Ozone is a very strong oxidizer and has been found to be superior to chlorine in inactivating resistant strains of bacteria and viruses. It is very unstable, however, having a half-life of only 20 to 30 min in distilled water at 20 C. It is therefore generated on site before use. Ozone may be produced by first refrigerating air to below the dew point to remove atmospheric humidity. The dehumidified air is then passed through desiccants such as silica gel and activated silica to dry to -40 to...

Fluid Mechanics

Of the fluid mechanics applications used in this book, the Reynolds transport theorem is a bit sophisticated. Hence, a review of this topic is warranted. This theorem will be used in the derivation of the amount of solids deposited onto a filter and in the derivation of the activated sludge process. These topics are discussed somewhere in the textbook. Except for these two topics, the theorem is used nowhere else. The general knowledge of fluid mechanics will be used under the unit operations...

Cv

FIGURE 3 Derivation of the Reynolds transport theorem. FIGURE 3 Derivation of the Reynolds transport theorem. The volume on the right with the hatching slanting upward to the left plus Volume bcde is the control mass, and the volume with the hatching is Volume II. Control mass is that part of the universe composed of masses identified for analysis as such, if a boundary is used to enclose the masses, no other masses are allowed to pass through this boundary. In other words, the system is...

Ith

FIGURE 7.11 (a) B chner funnel filtration assembly (b) leaf filter assembly and (c) mechanics of cake filtration. If pp is the density of solids, the mass dm in the differential thickness of cake dl is dm Sodl(1 - n)pp. Solving this for dl and substituting, Equation (7.56) becomes In this equation, 1 and Vs influence directly the flow characteristics of the filtering water. Since So determines the value of Vs, it also influences directly the flow characteristics of the fluid. All the other...

Lrq

Milligram moles per liter of alkalinity required in nitrification mg L of oxygen demand at end of five days mg L of BOD5 corresponding to SEW i mmol mg L of BOD5 corresponding to SEW Chemical oxygen demand, considered approximately equal to Fractional correction factor due to the effect of pH Mole of electron Electromotive force Electromotive force at H+ 10-7 moles per liter Ratio of BOD5 to BOD YBO mole cells mole sewage Fraction of p destroyed Number of coulombs per farady Free energy...

Dwu

Note When adding the equations, the respective equilibrium constants are multiplied. The activity of a solid is equal to unity. CaCO3 ---- -f-3 (11.33) The activity coefficient Yca 3c of CaCO3 is unity, since it is not dissociated. The determination of CaHCO+ will use, in addition to the equilibrium constant for CaCO3(s), the ionization constant for the bicarbonate ion, K3. The steps are as follows

Liquid Level Indicators

Liquid level is a particularly important process variable for the maintenance of a stable plant operation. The operation of the Parshall flume needs the water surface elevation to be determined for example, how are Ha and Hb determined As may be deduced from Figure 3.6, they are measured by the float chambers labeled Ha and Hb, respectively. Liquid levels are measured by gages such as floats (as in the case of the Parshall flume), pressure cells or diaphragms, pneumatic tubes and other FIGURE...

R

Fractional removal of particles also, recirculation ratio Time to thicken to underflow concentration Time to appearance of critical concentration Flow-through velocity in a rectangular clarifier Terminal settling velocity of particle removed 100 Terminal settling velocity of any size particle Settling velocity at thickening zone Underflow velocity computed at the thickening zone

Softening Of Magnesium Hardness

As in the case of calcium hardness, magnesium can also be present in the form of carbonate and noncarbonate hardness. The Ksp of Mg(OH)2 is a low value of 9(10 ). Thus, the hardness is removed in the form of Mg(OH)2. To remove the carbonate hardness of magnesium, a source of the OH ion is therefore added to precipitate the Mg(OH)2 as shown in the following softening chemical reaction Mg (HCO3 )2 + 4OH Mg (OH )2i + 2CO2 + 2HOH (10.10) The carbonate ions in the product side will pair with...

Table 1311

Equation (13.69) 27.9 44.9 Eqs. (13.70) through (13.73) 55.8 106.8 Eqs. (13.74) through (13.78) 27.45 44.45 43.45 Mn2+ + 1o3 + H2O MnO2(s)i + 2H+ (13.77) The solids produced from the previous reactions are Fe(OH)2(s), Fe(OH)3W, Mn(0H)2(s), and MnO2(s). From Equation (13.69), the equivalent mass of Fe(OH)2(s) is Fe(OH)2 2 44.9 and that of Fe2+ is Fe 2 27.9. From Eqs. (13.70) through (13.73), the equivalent mass of Fe(OH)3(s) is Fe(OH)3(s) 1 106.8 the corresponding equivalent mass of Fe2+ is Fe 1...

Low pH Range

Under this category, iron is removed as Fe(OH)3 and manganese is removed as MnO2, which involves oxidation of the metal ions to their higher oxidation states. The unit operations under the previous category are applicable under the present category, only that under the present scheme, oxidation of the metals is involved. The unit process involves one of Eqs. (13.23) through (13.25) for the case of manganese and similar equations for iron. The equation designed into the unit operations depends...