When ph of sample water was maintained at 7, after coagulation with alum the resultant ph was seen closer to 6 whereas with other coagulants it was witnessed from 9 to 11.5 (Fig. 7). Even at lower pH of sample water, the resultant ph of treated water still remains higher because of strong alkaline nature of coagulants (Figs. 8, 9). Fig. The optimum pH was 7 and was similar to the obtained results by Divakaran (Divakaran and Pillai 2002). The best performance of alum was observed at pH 7 over the selected range of turbidity but its performance decreased to some extent at pH values of 6 and 8. Coagulation efficiency of alum at pH 6 was almost close to that of at pH 7 The optimum pH for the coagulation and flocculation process must be determined experimentally. It is spe-cific to each application and is dependent upon the sample, the coagulation and flocculation agents used, the desired clarity of the water, and the water's end use. pH MONITORING AND CONTROL pH control of the sample prior to clarification. Aluminum sulfate (alum), ferrous sulfate, ferric chloride and ferric chloro-sulfate pH, coagulant and flocculants concentrations . Coagulation or flocculation process was conducted for the treatment of industrial wastewater to achieve maximum removal of COD, TP and TSS. Therefore, The optimum pH, dosag
Through RSM optimization, the optimum dose for alum was 7 mg/l and for polymer was 0.004 mg/l. Optimum pH for the coagulation operation obtained through traditional methods and RSM was 7.6. The final turbidity, pH after coagulation and residual aluminium recorded were all within acceptable limits For alum the pH zone for optimum coagulation is quite narrow, ranging from about 6.5-7.5. The comparable range for ferric sulphate is considerably broader, a pH range of about 5.5-9.0 (Fig. 14.1). When the results of a jar test are plotted, this type of curve is typical. The most common method of dosing the alum or ferric sulphate is in the form o Optimum pH for Alum and PAC were found by adding a fixed dose of coagulants to samples having various pH ranging from 3 to 11. pH was adjusted using sulfuric acid. It can be seen from ( Fig. 3 ) that PAC gives the same color removal over a wide pH range of 3-11 and also shows very good color removal at pH 3
pH 3-4 is pretty strongly acidic. If the wastewater already has that pH, then such a coagulant would be excellent for that wastewater. Following the coagulation and clarification steps, the.. Determination of optimum coagulant dose Fill jars Adjust pH of all jars at optimum (6.3 found from first test) while mixing using H 2 SO 4 or NaOH/lime Add different doses of the selected coagulant (alum or iron) to each jar (Coagulant dose: 5; 7; 10; 12; 15; 20 mg/L) Rapid mix each jar at 100 to 150 rpm for 1 minute. The rapi The optimal pH ranges for coagulation with aluminum and ferric salts are 5 to 7 and 5 to 8, respectively. At pH values above 7, the removal performance of aluminum-based coagulants drops markedly. Feed water pH should be adjusted to the appropriate range prior to coagulant addition
in determining effective coagulation. Each coagulant has a narrow optimum operating pH range. For example, alum tends to work best at a dosed-water pH of 5.8-6.5. If the pH is lower or higher than this optimum, then problems of high residual colour and aluminium or disinfection by-products may occur in the finished water •Two important factors in coagulant addition are pH and dose. The optimum dose and pH must be determined from laboratory tests. The optimum pH range for alum is approximately 5.5 to 7.7 with adequate coagulation possible between pH 5 and 9 under some conditions. •Ferric salts generally have a wider pH range for effective coagulation than. Effect of raw water quality on coagulant dosage and optimum pH. 2006. Yannie Benson. 2003; Pernitsky, 2001; Dennett et. al., 1996) 2.5 The alum coagulation diagram and its relationship to zeta 13 potential (Source: AWWA and ASCE, 1990) 2.6 Diagram of One-Factor-At-A-Time shows of the 19 turbidity versus alum dose (Source: Adopted from. The optimum pH range for alum coagulation is 5 to 8. Alkalini ty must be present for the alum reaction to work effectively. If there is insufficient alkalinity in the raw water, the pH will be lowered to a point where soluble aluminum ion is formed instead of aluminum hydroxide For optimal coagulation and flocculation it is important that aggregates of certain size, strength and density are formed. These properties are largely determined by coagulant type, dose, pH and mixing intensity [4, 51. In order to determine the optimum pH, first the initial dosage of coagulant was determined using 200 m1 of sample
The effective coagulant, the suspended solids, previously pH range for its use is small, 6.5 to 8.3, and may in calculated, were subtracted from the sludge many cases; require the addition of external alkali salts, thereby rendering it costlier. Alum is the most production. By doing this, it was possible to widely used primary coagulant Alum (aluminum sulfate) is a commonly used coagulant in water treatment. Adding alum to water creates insoluble precipitates such as aluminum hydroxide AI(OH)3 to form. The optimum pH range for alum coagulation is 5 to 8. Alkalinity must be present for the alum reaction to work effectively. If there is insufficient alkalinity in the raw water. The results of the present study on different doses of the coagulants indicated the optimum conditions for Alum and ferrous sulphate were 1000 mg/L and pH 5. In these conditions, COD removal efficiency from wastewater of dairy products industry was 68 and 62% for alum and ferrous sulphate respectively
Using a sedimentation beaker, experiments were conducted, leading to optimum coagulant dosage in some parameters. Coagulation experiments of the turbid water at the coagulant dosage of 10g per 3 litres, gave the following coagulation efficiencies with alum as the coagulant: pH (44.92%),. More about alum from other sources: There are a variety of primary coagulants which can be used in a water treatment plant. One of the earliest, and still the most extensively used, is aluminum sulfate, also known as alum. Alum can be bought in liquid form with a concentration of 8.3%, or in dry form with a concentration of 17%
Hannah5 suggested that the optimum coagulation of three types of clays occurred during a pH range of 7.5 to 8.5. Black and Chen6 found that the pH range for optimum co agulation varied with alum dosage and types of suspended river sediment. Effective flocculation took place within a pH range of 6.5 to 7.5 when the alum dosage was 10 mg/1 or. The measure of alkalinity is the amount of acid that would have to be added to water to lower the pH to 4.5 and there is where the confusion arises. Coagulation is most effective in the pH range of 5-7 because of the waters ability to react with alkalinity its performance decreased to some extent at pH values of 4, 5, and 8. Coagulation efficiency of alum at pH 6 was almost close to that of at pH 7. The highest turbidity re-moval was attained at pH 7 when 10 mg/L alum was used except for initial turbidity of 1000 NTU. The optimum alum dosage was higher (20 mg/L) for initial turbidity o
pH. optimum . est égal à Aluminium (Alum) determination at low level is of particular interest in potable water units because experiment was to investigate the influence of water initial pH on coagulation efficiency at the pre-determined coagulant dosage and agitation speed of 40 mg.L-1 Alum have variable amount of water of crystallization (Al 2 (SO 4) 3.nH 2 O ( n is14 to 18) To produce the hydroxide floc, enough alkalinity should present in the water If alkalinity is not enough, then it should be added. Usually hydrated lime is used for that purpose Optimum pH is 5.5-6.5 and operating pH is 5 - 8 Al 2 (SO 4) 3.14H 7. Plot pH versus alum dose in a graph paper and observe the effect of alum dose on pH. 8. Plot turbidity (NTU) versus the coagulant (alum) dose (mg/L) in a graph paper. Determine optimum coagulant dose of alum from this plot. 9. Repeat steps 3-8 with higher dose of alum, if necessary. Observation and calculation: Concentration (ppm) pH.
Optimum coagulant dose Repeat all the previous steps This time adjust pH of all jars at optimum (6.3 found from first test) while mixing using H2SO4 or NaOH/lime Add different doses of the selected coagulant (alum or iron) to each jar (Coagulant dose: 5; 7; 10; 12; 15; 20 mg/L) Rapid mix each jar at 100 to 150 rpm for 1 minute This time adjust pH of all jars at optimum (@ 7) while mixing using H 2 SO 4 or NaOH/lime Add different doses of the selected coagulant (alum or iron) to each jar (Coagulant dose: 0 to 50 mg/Lit- interval of 10 mg/Lit) Rapid mix each jar at 100 to 150 rpm for 1 minute. The rapid mix helps to disperse the coagulan Two important factors in coagulant addition are pH and dose. The optimum dose and pH must be determined from laboratory tests. The optimal pH range for alum is approximately 5.5 to 6.5 with adequate coagulation possible between pH 5 to pH 8 under some conditions
S. Haghiri et al.: Optimum coagulant forecasting by modeling jar test experiments 3 Table 1. Ranges of available data. NTU represents nephelometric turbidity units. The characteristics of the input water The characteristics of the output water pH Temperature Alkalinity Turbidity pH Temperature Alkalinity The Fina • Coagulation is a physical and Chemical reaction occurring between the alkalinity of the water and the coagulant added to the water which results in the formation of insoluble floc • For a specific coagulant the pH of the water determines which hydrolysis species predominate • The best pH for coagulation usually falls in the range of 5 to In order to obtain the optimum pH for coagulation-flocculation process, the pH is varied and fixed the coagulant dosage at 5000 mg/L initially. The pH values selected for the run are pH 1.0, 2.0, 3.0, 5.0, 7.0 and 9.0. On the other hand, the various ranges of dosage are within 1000 mg/L to 10000 mg/L for both coagulants disinfection. An enhanced coagulation with alum was then conducted by standard jar test to optimize coagulation pH and alum dose. Optimum removal of turbidity (98%) and dissolved organic carbon (DOC) (70%) was achieved for 100 mg alum L-1 at pH 5. Alum dose and pH control of coagulation were found to be important factors governing DOM removal The influence of PH, temperature, coagulant and coagulant aid dosages on the coagulation process was studied and conditions were optimized corresponding to the best removal of organic matters, viruses, colloids, bacteria, color and decrease in turbidity. 85-98% reduction of turbidity from raw water can be achieved by using the optimum coagulant.
An enhanced coagulation with alum was then conducted by standard jar test to optimize coagulation pH and alum dose. Optimum removal of turbidity (98%) and dissolved organic carbon (DOC) (70%) was achieved for 100 mg alum L-1 at pH 5. Alum dose and pH control of coagulation were found to be important factors go 1. Aluminum sulfate (Al 2 (SO 4) 3 or alum): Aluminum sulfate (commonly called alum) is used as a coagulant, causing colloidal particles to clump together and settle out of the water. Alum was once the most common coagulant used in West Virginia, but today it is being replaced by the more prevalent use of polymers. In order for alum to be an. used for the coagulation of algal suspensions by alum. Coagulation of algae is caused mainly by the insoluble floes of aluminum hydroxide. Other aluminum species also have coagulative properties but are far less effective. The destabilization o pH range of 6.5-7.5. Ferric chloride is also a com-monly used coagulant and is effective over a wider pH range of 4-11. The ferric hydroxide ﬂoc is also heavier than the alum ﬂoc, improving its settling characteristics and reducing the size of the clari-ﬁer. Neither ferric sulfate nor ferrous sulfate i
Improving the effectiveness of coagulation and flocculation will greatly enhance the efficiency of small scale water treatment systems, which will drive down costs and make the technology more feasible and attractive to communities. One of the important contributors to the formation of flocs is the chemical coagulant aluminum sulfate (Alum) Alum coagulation was able to remove 80% of fluoride from natural waters with a 500 mg/L alum dose; however, 50% fluoride removal was observed to be possible with an alum dose of 150-170 mg/L. The optimum pH for fluoride removal in synthetic and natural waters was observed to be approximately 6.5 and was found to be an important factor in.
Coagulant Dosage And Optimum PH Were Determined To Be 50 Mg/l Of Alum Al2(SO4)3 And 6.05 Respectively From Jar Tests. The Bicarbonate Alkalinity In The Water Is Found To Be 30 Mg/l As CaCO3. The Plant Treats 40,000 M3/day Of Water And Has 30 Mg/l Of Suspended And Colloidal Solids. The Alum Salt Reaction In Water Is Given Below: A Coagulation and Flocculation Process Fundamentals 1 optimum size and strength, water is ready for sedimentation. Inorganic coagulants may alter the pH of the water since they consume alkalinity. When applied in a lime soda ash softening process, alum and iron salts generate demand for lime and soda ash . 3: The effect of slow mixing on the performance parameters during alum coagulation. 4: The effect of settling time on the removal of performance parameters during alum coagulation optimum pH range of 6-7 was similar to the findings of Georgantas and Grigoropoulou, (2006). Even though the removal of phosphate was higher for pH 6 at lo
.10: Fluoride removal in natural waters using alum coagulation in systems with pH adjustment to 6.5 (pH 6.5 systems) and without pH adjustment (pH Natural systems)...66.11: Experimental determination of optimum pH for organic removal using natural waters B DETERMINATION OF OPTIMUM pH Repeat the jar test of Part A using the observed optimum dosage of ferric sulfate but adjusting sample pH to 6, 7, 8, and 9 with NaOH or H2SO4 prior to adding coagulant. Measure final pH, turbidity or color of the supernatant of each sample. Measure the depth of sludge in the beaker. Plot turbidity or color versus pH Coagulation-flocculation as a relatively simple physical-chemical technique was applied in this study. This study examined aluminum sulfate (alum) and ferric chloride in treating a stabilized leachate, and compared the results in respect to the removal of suspended solid (SS), chemical oxygen demand (COD), color and ammoniacal nitrogen optimal (e.g., pH between 5.5 and 6.5) is more difficult and cannot be easily achieved through the addition of coagulant alone (Miltner et al., 1994; Anonymous, 1999). NOM removal is higher at low pH values for all coagulants. To achieve the NOM removals designated by the D/DBPs rule, coagulation may be accomplished by increased coagulant dosages
The maximum dye removal occurred when pH was 7 and 5 for PAC and alum, respectively. Both coagulants efficiently removed the dye (about 85%) with a relatively low dosage (40 mg/l) in their optimum pH range. By adding kaolinite as a coagulant aid, the removal efficiencies tended to increase, especially for lower dosages of PAC and alum effectiveness of alum, commonly used as a coagulant, is severely affected by low or high pH. In this pH range, the white flocs obtained were very coarse and settled almost in less than 10 min. The obtained results on optimum pH were in agreement with studies done on alum as coagulan Thus, pH must be controlled to establish optimum conditions for coagulation. Alum and Ferric Chloride reacts with natural alkalinity in water as follows: Al 2 (SO 4) 3.14H 2 O + 6 HCO 3- 2 Al (OH) 3 (s) + 6CO 2 +14 H 2 O + 3 SO 42- FeCl 3 + 3 HCO 3- Fe (OH) 3 (S) +3 CO 2 + 3 Cl Through RSM optimization, the optimum dose for alum was 7 mg/l and for polymer was 0.004 mg/l. Optimum pH for the coagulation operation obtained through traditional methods and RSM was 7.6. The ﬁnal turbidity, pH after coagulation and residual aluminium recorded were all within acceptable limits. The RSM method wa synthesized single diagram for alum sta-bility and coagulation. Using the diagram it is possible to predict specific alum dos-ages and pH where optimum coagulation would occur. A design and operation dia-gram for practical use in predicting and analyzing optimum conditions for alum coagulation is developed. The second part deals with a.
low pH values (below pH 11), with tannin as a pri-mary coagulant, the phenomenon of restabilization was clearly observed from Figure 1. It was found in the studies on the removal of turbidity using tannin, that the optimumtannin dose was 0.03mg tannin/L, in which the optimum pH was 11 for 10 and 20 FTU turbidities (Figure 2). It was also found. Usually hydrated lime is used for that purpose (optimum pH is 6.5 - 8.5) 28. •Under normal circumstances Dose of Alum varies from 10 to 30 mg/lit of water. Advantages 1.Alum reduces taste and odour 2.Cheap 3.Easily available 4.Soluble in water Disadvantages 1
The floe formed by alum coagulant will disappear if the pH value is lower than the optimum. Similarly if pH value is more, aluminium hydroxide ionizes into aluminate, which is also soluble in water. Table 12.1 gives the normal dose and pH value required for best floe formation with various coagulant The most commonly used aluminum coagulant is aluminum sulfate, 2 Al2(SO4)3 ! nH2O, which is commonly referred to as alum. Liquid alum is manufactured pH under conditions normally found in surface waterbodies. Over time, the freshly parameters such as the optimum coagulant dose required to achieve the desired water quality goals.
The pH of Canyon Lake (pH= 9.1 for recently collected east bay samples) is typically above the optimum range for alum treatment (i.e., 5.5-8) , but it still may be effective in removing turbidity while not adding to the overal Efficiency and mechanism of coagulation-flocculation process depend on several factors, the most relevant being initial turbidity, pH, reagents (coagulant, adjuvant) dosage and type, system hydrodynamics in coagulation and flocculation stages, temperature, alkalinity [8-10]. The optimum conditions of coagulation-flocculation process have bee 68.9, 83, 94, 84 and 47.2 respectively, and this amount of removal by aluminum sulfate was 62, 80, 94, 73.5 and 48 respectively at neutral pH and concentration of coagulant was obtained equal to 150 mg/ L. Conclusion: According to the results, the use of coagulation and flocculation process combined with chemica The results have indicated optimum pH of two coagulants for leachate treatment was 6.5 and 10 and also effective coagulant dosages were 1400 and 1000 mg L-1 for alum and ferric chloride, respectively. In view of economical, ferric chloride is cost benefit Therefore, each coagulant has an optimal pH range in which it works best. For example, Alum works best at a pH of 5.8-6.5, Aluminium chlorohydrate (ACH) works at a pH range of 6.5-7.5. How to choose a coagulant? The choice of the coagulant will depend on various factors, including: Required rate; Price and availability; Raw water pH
Optimum pH range for ferric chloride and alum: Turbidity values after coagulation with ferric chloride at varying pH is shown in Figure 3. From the results, the optimum pH was obtained at 8. Beyond pH of 8, the turbidity values obtained showed little differences Aluminum sulfate ( alum) solution Hach turbidimet er Pipettes /syringes Burettes Erlenmeyer Flasks 0.02 N H2SO 4 Water samp le (Des Moines R iver water) Volumetric flasks Methyl orange (MO) indicat or PROCEDURE 1. Determine the turbidity and pH of the raw water sa mple. Also determine the alkalinity of raw water sample using the procedure below. 2 level at which TOC removal is optimal (e.g., pH between 5.5 and 6.5) is more difficult and cannot be easily achieved through the addition of coagulant alone . NOM removal is higher at low pH values for all coagulants. To achieve the NOM removals, coagulation may be accomplished by increased coagulant dosages, lower coagulation pH values, o An enhanced coagulation with alum was then conducted by standard jar test to optimize coagulation pH and alum dose. Optimum removal of turbidity (98%) and dissolved organic carbon (DOC) (70%) was achieved for 100 mg alum L-1 at pH 5. Alum dose and pH control of coagulation were found to be important factors governing DOM removal chloride, alum chloride, and ferrous sulfate. The optimum pH values and coagulant dose were determined for each coagulant. All coagulants were aided with lime. Lime has many positive effects. It adjusts the pH to the optimum value, acts as a coagulant aid, and improves sludge settle ability and stability. However, it ma
the charge of neutralization of natural particles. Within the coagulation pH range of 6.0 to 7.5 that is typical in water treatment processes, these aluminium hydroxide sols are usually present in significant excess relative to natural particles. [Ronald Hart, 2003] Water treatments in Malaysia basically use alum as a coagulant. Alum i PAC over alum are, PAC works well with pH range of 6-9 where as alum works better between pH 6.5-7.6, since, PAC works even at temperature below 10DC, so, it can be used during winter season. Also, quality of treated water is good, and possesses greater reaction speed due to its liquid state The process usually uses pH adjustment, addition of a chemical precipitant, and flocculation. Typically, metals precipitate from the solution as hydroxides, sulfides, or carbonates. The solubilities of the specific metal contaminants and the required cleanup standards will dictate the process used OES's performance was compared with Alum's, a conventional coagulant, and the results obtained reveal Alum as having a global minimum of zero turbidity, global optimum values for pH (7.4103) and dosage (301.6501mg/l) but a local optimum of 80min for settling time, while the optimum operating parameters for OES are 7.3740 (global), 500mg/l.
Finally, the experiment was repeated at the optimum values to combine speed, temperature, and pH using the optimum concentration of alum and M. oleifera with the ratios of 1:2, 1:1, and 2:1, respectively. Results In this study, the efficiency of coagulant materials M. oleifera, alum, and the simultaneous use of alum and M coagulation efficiency of a coagulant. The Phipps-Bird jar testing apparatus is recommended for use. It consists of six 1-Liter beakers or 2-Liter square jars and a gang mixer. A jar test is performed by first adding the same alum dose and varying the pH in each jar. The test can be repeated by holding the pH and varying the coagulant dose If alum is the coagulant, alum is dosed in 10mg/L increments, and TOC measurements made on raw and settled waters. For ferric coagulants, the dosage increments are 9.1 mg/L for FeCl3·6H2O and 9.5mg/L for Fe2(SO4) 3·6H2O. The pH conditions depending on raw water alkalinity are as indicated per Table 10.3. A second step, Step 2, is needed when. Raise pH back to Target pH (e.g. 6.3 for Alum) if it drops more than 0.3 units below. Do not raise pH too high as this will result in needing to feed a higher dosage of coagulant. Continue with chemical additions until charge equals 0 and pH is at target based on determination of the optimum dose of coagulant for calcium oxide, magnesium chloride, aluminum sulfate, etc., and difficultly soluble aluminosilicates including bentonite, Kaolin, diatomite, slag, etc. When used in acid condition, the compound coagulant is added into waste water before the pH value of the wastewater is regulated.
Three dimensional surface plots and their respective contour plots were obtained for alum driven coag-flocculation based on the effects of the three factors (pH, coagulant dosage and settling time) at two levels. Furthermore, the optimum region was identified based on the interpretation of the final form of equation 2 by MATLAB 7.0 .3... 50 Figure 14. Variation of residual color with powdered ac-tivated carbon dose added along with 300 mg/L alum at pH 5.5 or 300 mg/L ferric chloride at pH 4.0 to treat the Main Mill wastewater. . 52 Figure 15. Determination of optimum pH for color remova
Coagulation and flocculation is simple and rapid technique. This is most often used pretreatment technique to treat the effluent. Aluminum sulfate (alum), ferrous sulfate, ferric chloride and ferric chloro-sulfate were commonly used as coagulants. determine the optimum pH condition of the treatment system Without the WAS addition, the concentrations of 800 mg/L aluminum sulfate at the optimum pH value of 8 and 2208 mg/L ferric chloride at the optimum pH value of 12 were the optimum chemical dosages. It appears that aluminum sulfate was more effective than ferric chloride based on the chemical dosage and removal efficiency . A conventional jar test apparatus was employed for the tests. The optimum pH was observed between 7 to 7.5 for all turbidities. The optimum doses of alum and chitosan when used in conjunction, were 10mg/L and 1mg/L, 5mg/L and 0.5mg/L
The coagulation of organic halide precursors was investigated with and without ozone pretreatment. Alum was found to remove all organic halide precursors within the same alum dose-pH region (optimum pH = 5.0-5.5). Preozonation shifted this removal region up into the high alum dose range . In this demonstration, the pH of the sample starts at 7.66 but quickly drops with the addition of aluminum sulfate. For this test, the target pH for the treatment process has been defined as 6.3 A set of jar test experiments was conducted to find the optimal pH and coagulant dosage. Results: Results demonstrated that coagulation process can assure turbidity removal from low to medium turbidity waters effectively, using relatively low levels of aluminum sulfate and ferric chloride (10-20 mg L−1) coagulant alum series of jar test was conducted in this study using low alkalinity wastewater to evaluate the optimum pH, dosage and performance parameters. From the experiment, it was found that the dosage of coagulant and removal of phosphorus depend upon the pH .The final optimum pH for efficient P removal was found to be within the range of. seen at 22 g/L. Figure 8 shows that optimum pH for using alum as coagulant was 11. When Alum was used, 61% and 31% reductions in colour and COD were achieved. Based on colour and COD removal performance, ferrous sulphate and alum were selected for double coagulation study in combination with lime. Figure 7
at an optimum pH of 3 and 140 mg/L dosage concentration. JC seeds, on the other hands, showed the potential to remove about 93% turbidity at the optimum of pH of 3 and with 120 mg/L dosage. Furthermore, the performance of JC as a bio-coagulant was compared to aluminum sulphate (alum) coagulant determine a standard optimal dosage based on phosphorus and suspended solids removal. Using combination with alum as coagulant/ﬂocculant aids for microscreen backwash efﬂuent. Materials and Methods pH 7.45 (0.13) Temperature (C) 19.4 (1.4) Alkalinity (mg/L) 279 (13 The process of chemical coagulation and flocculation was found quite effective in removing bacteriophages T4 and MS2 from water. The opti- mum coagulant dosages and pH values were 40 to 50 mg/l of aluminum sul- fate at pH 5.24 for bacteriophage ~4 and at pH 6.0 for bacteriophage MS2. The highest removals attained were 98.0 and 99.9 percent, respec