SOLIDS (2540)/Introduction
2-55
2540 25 40 SO SOLI LIDS DS** 2540 25 40 A. Int Intro rodu duct ction ion Solids refer to mat Solids matter ter suspended suspended or dis dissol solved ved in wat water er or wastewater. Solids may affect water or ef fluent quality adversely in a number of ways. Waters with high dissolved solids generally are of inferior palatability and may induce an unfavorable physiological reaction in the transient consumer. For these reasons, a limit lim it of 500 mg dis dissol solved ved sol solids ids/L /L is desi desirab rable le for drinking drinking waters. water s. Highl Highly y miner mineralized alized waters also are unsui unsuitable table for many industrial indust rial applications. applications. Waters Waters high in suspend suspended ed solid solidss may be esthetically unsatisfactory for such purposes as bathing. Solids analyses are important in the control of biological and physical wastewater waste water treatment treatment proce processes sses and for assessi assessing ng compl compliance iance with regulatory regulatory agency wastewater wastewater ef fluent limitations. 1.
Definitions
“Total solids” is the term applied to the material residue left in the vessel after evaporati evaporation on of a sam sample ple and its subsequen subsequentt drying in an oven at a de fined temperature. Total solids includes “total suspended solids,” the portion of total solids retained by a filter, and “total dissolved solids,” the portion that passes through the filter. The type of filter holder, the pore size, porosity, area, and thickness of the filter and the physical nature, particle size, and amount of material deposited on the filter are the principal factors affecting separatio separ ation n of suspe suspended nded fro from m diss dissolve olved d soli solids. ds. “Diss Dissolve olved d soli solids ds” is the portion portion of sol solids ids that pas passes ses thr throug ough h a filter of 2.0 m (or smaller) nominal pore size under specified conditions. “Suspended solids” is the portion retained on the filter. solidss” is the term applied applied to the res residu iduee of total, total, “Fixed solid suspend sus pended, ed, or dis dissol solved ved sol solids ids aft after er heat heating ing to dry drynes nesss for a specified time at a speci fied temperature. temperature. The weight loss on ignition is called “volatile solids.” Determinations of fixed and volatile volat ile solid solidss do not disti distinguis nguish h preci precisely sely betwe between en inor inorganic ganic and organic matter because the loss on ignition is not confined to organic matter. It includes losses due to decomposition or volatilization of some mineral salts. Better characterization of organic matter can be made by such tests as total organic carbon (Section (Sect ion 5310), BOD (Sect (Section ion 5210), and COD (Section (Section 5220). “Settleable solids” is the term applied to the material settling out of suspension within a defined period. It may include floating material, mater ial, depending on the techni technique que (2540 (2540F.3 F.3b). 2.
Sources of Error and Variability
Sampling, subsampling, and pipeting two-phase or three-phase samples may introduce serious errors. Make and keep such samples homoge hom ogeneo neous us dur during ing tr trans ansfer fer.. Use spe specia ciall han handli dling ng to ins insur uree sam sample ple integrity when subsampling. Mix small samples with a magnetic stirrer. If suspended solids are present, pipet with wide-bore pipets.
* Approved by Standard Methods Committee, 1997. Joint Task Group: 20th Edition —Brannon H. Wilder (chair), Harold S. Costa, Christine M. Kosmowski, William E. Purcell.
If part of a sample adheres to the sample container, consider this in evaluating and reporting results. Some samples dry with the formation of a crust that prevents water evaporation; special handling is required requ ired to deal with this this.. Avoi Avoid d usin using g a magn magneti eticc stir stirrer rer with samples containing magnetic particles. The temperature at which the residue is dried has an important bearing on results, because weight losses due to volatilization of organic matter, mechanically occluded water, water of crystallization, and gases from heat-induced chemical decomposition, as well as weight gains due to oxidation, depend on temperature and tim timee of hea heatin ting. g. Eac Each h sam sample ple req requir uires es clo close se att attent ention ion to desiccation after drying. Minimize opening desiccator because moist air enters. Some samples may be stronger desiccants than those used in the desiccator and may take on water. Residues dried at 103 to 105°C may retain not only water of crystallization but also some mechanically occluded water. Loss of CO2 will result in conversion of bicarbonate to carbonate. Losss of org Los organi anicc mat matter ter by vol volati atiliz lizati ation on usu usuall ally y wil willl be ver very y slight. Because removal of occluded water is marginal at this temperature, attainment of constant weight may be very slow. Residues dried at 180 2°C will lose almost all mechanically occluded water. Some water of crystallization may remain, especially if sulfates are present. Organic matter may be lost by volatilization, but not completely destroyed. Loss of CO 2 results from conversion of bicarbonates to carbonates and carbonates may be dec decomp ompose osed d par partia tially lly to oxi oxides des or bas basic ic sal salts. ts. Some chloride and nitrate salts may be lost. In general, evaporating and drying water samples at 180°C yields values for dissolved solids closer clo ser to tho those se obt obtain ained ed thr throug ough h sum summat mation ion of ind indivi ividual dually ly determ det ermine ined d min minera erall spe specie ciess tha than n the dis dissol solved ved sol solids ids val values ues secured through drying at the lower temperature. To rinse filters and filtered solids and to clean labware use Type III water water.. Speci Special al samples may requi require re a highe higherr quali quality ty water; see Section 1080. Results for residues high in oil or grease may be questionable becau be cause se of th thee di dif f ficu cult lty y of dr dryi ying ng to co const nstan antt we weig ight ht in a reasonable time. To aid in quality assurance, analyze samples in duplicate. Dry sample sam pless to con consta stant nt wei weight ght if poss possibl ible. e. Thi Thiss ent entail ailss mul multip tiple le drying-cooling-weighing cycles for each determination. Analyses Anal yses perf performe ormed d for some speci special al purp purposes oses may demand deviation from the stated procedures to include an unusual constituent with the measured solids. Whenever such variations of technique are introduced, record and present them with the results. 3.
Sample Handling and Preservation
Use resistant-glass or plastic bottles, provided that the material in suspension does not adhere to container walls. Begin analysis as soon as possible because of the impracticality of preserving the sample. Refrigerate sample at 4 °C up to the time of analysis to minimize microbiological decomposition of solids. Preferably do not hold samples more than 24 h. In no case hold sample more than 7 d. Bring samples to room temperature before analysis.
2-56 4.
PHYSICAL & AGGREGATE PROPERTIES (2000)
Selection of Method
5. Bibliography
Method Met hodss B thr throug ough h F are sui suitab table le for the det determ ermina inati tion on of solids in potable, surface, solids surface, and salin salinee water waters, s, as well as domest domestic ic and industrial wastewaters in the range up to 20 000 mg/L. Method G is suitable for the determination of solids in sediments,, as well as solid and semis ments semisolid olid materials materials produced during water and wastewater treatment.
THERIAULT , E.J. & H.H. WAGENHALS. 1923. Studies of representative representative sewage plants. Pub. Health Bull. No. 132. U.S. ENVIRONMENTAL PROTECTION AGENCY. 1979. Methods for Chemical Analysis of Water and Wastes. Publ. 600/4-79-020, rev. Mar. 1983. Environmental Monitoring and Support Lab., U.S. Environmental Protection Protec tion Agency Agency,, Cincinn Cincinnati, ati, Ohio.
2540 25 40 B. To Tota tall Solid Solids s Drie Dried d at at 103 103–105°C 1.
General Discussion
a. Princ Principle: iple: A well-mixed sample is evaporated in a weighed dish and dried to constant weight in an oven at 103 to 105 °C. The increase in weight over that of the empty dish represents the total solids. The results may not represent the weight of actual dissolved and suspended solids in wastewater samples (see above). Highly ly mine minerali ralized zed wate waterr with a sign signiificant b. Interferenc Interferences: es: High concentration of calcium, magnesium, chloride, and/or sulfate may be hygroscopic and require prolonged drying, proper desiccation, and rapid weighing. Exclude large, floating particles or submerged agglomerates of nonhomogeneous materials from the sample if it is determi dete rmined ned that thei theirr incl inclusio usion n is not desired in the final result. Disperse visible floating oil and grease with a blender before withdrawing a sample portion for analysis. Because excessive residue in the dish may form a water-trapping crust, limit sample to no more than 200 mg residue (see 2540A.2). 2.
Apparatus
a. Evapor Evaporating ating dishes: dishes: Dishes of 100-mL capacity made of one of the following materials: 1) Porce Porcelain, lain, 90-mm 90-mm diam. 2) Plati Platinum num—Generally satisfactory for all purposes. 3) HighHigh-silic silicaa glass.* b. Mu Muf f fl e furnace for operation at 550°C. c. Steam bath. d. Desic Desiccator, cator, provided with a desiccant containing a color indicator of moisture concentration or an instrumental indicator. e. Dryin Drying g oven, for operation at 103 to 105°C. f. Analytical balance, capable of weighing to 0.1 mg. g. Magne Magnetic tic stirrer stirrer with TFE stirring bar. h. WideWide-bore bore pipets pipets.† i. Gradua Graduated ted cylinder. cylinder. j. Low-form beaker.‡ 3.
Procedure
a. Prepar Preparation ation of evaporating evaporating dish: If volatile solids are to be measured ignite clean evaporating dish at 550°C for 1 h in a muf fle furnace. If only total solids are to be measured, heat clean
* Vycor, product of Corning Glass Works, Corning, NY, or equivalent. † Kimble Nos. 37005 or 37034B, or equivalent. ‡ Class B or better.
dish to 103 to 105°C for 1 h. Store and cool dish in desiccator until needed. Weigh immed immediatel iately y befor beforee use. b. Sampl Samplee analysis: analysis: Choose a sample volume that will yield a residue between 2.5 and 200 mg. Pipet a measured volume of well-mixed sample, during mixing, to a preweighed dish. For homogeneous samples, pipet from the approximate midpoint of the container but not in the vortex. Choose a point both middepth and midway between wall and vortex. Evaporate to dryness on a steam bath or in a drying oven. Stir sample with a magnetic stirrer stirr er duri during ng trans transfer. fer. If necessa necessary, ry, add success successive ive sample portions to the same dish after evaporation. When evaporating in a drying dryin g oven, lower temperature temperature to appro approximat ximately ely 2 °C below boiling to prevent splattering. Dry evaporated sample for at least 1 h in an oven at 103 to 105°C, cool dish in desiccator to balance temperatur tempe rature, e, and weigh weigh.. Repeat cycle of dryin drying, g, cooli cooling, ng, desiccating, and weighing until a constant weight is obtained, or until weight change is less than 4% of previous weight or 0.5 mg, whichev whi chever er is les less. s. Whe When n wei weighi ghing ng dri dried ed sam sample ple,, be ale alert rt to change in weight due to air exposure and/or sample degradation. Analyz Ana lyzee at lea least st 10% of all samples samples in dup duplic licate ate.. Dup Duplic licate ate determinat deter minations ions should agree within 5% of their average weight.
4.
Calculation
mg total solids/L
( A
B ) 1000
sample volume, mL
where: A weight of dried residue dish, mg, and B weight of dish, mg.
5.
Precision
Single-laboratory duplicate analyses of 41 samples of water and wastewater were made with a standard deviation of differences of 6.0 mg/L.
6. Bibliography SYMONS, G.E. & B. MOREY. 1941. The effect of drying time on the determi dete rminat nation ion of soli solids ds in sewa sewage ge and sew sewage age slud sludges. ges. Sewage Works J. 13:936.
SOLIDS (2540)/Total Dissolved Solids Dried at 180°C
2-57
2540 C. Tot Total al Disso Dissolve lved d Solids Solids Dri Dried ed at at 180°C 1.
General Discussion
well-mix -mixed ed sampl samplee is filtered through a stana. Princ Principle: iple: A well dard glass fiber filter, and the filtrate is evaporated to dryness in a wei weighe ghed d dis dish h and dried to con consta stant nt weight weight at 180°C. The increase in dish weight represents the total dissolved solids. This procedure may be used for drying at other temperatures. The results may not agree with the theoretical value for solids calculated from chemical analysis of sample (see above). Approximate methods for correlating chemical analysis with dissolved solids are available.1 The filtrate from the total suspended solidss deter solid determinat mination ion (Section 2540D) may be used for deter determimination of total dissolved solids. b. Interfe Interferences: rences: See 2540A.2 and 2540B.1. Highly mineralize eral ized d wat waters ers wit with h a cons conside iderabl rablee calc calcium ium,, magn magnesiu esium, m, chloride, and/or sulfate content may be hygroscopic and require prolonged drying, proper desiccation, and rapid weighing. Samples high in bicarbo bicarbonate nate require careful and possibly prolonged drying at 180°C to insure complete conversion of bicarbon bica rbonate ate to carb carbonat onate. e. Beca Because use exce excessiv ssivee resi residue due in the dish may form a water-trapping crust, limit sample to no more than 200 mg residue. 2.
4.
Calculation
Apparatus
Apparatus listed in 2540B. Apparatus 2540B.2 2a-h is required, and in addition: without ut organi organicc binde binder. r. a. Glass Glass-- fi fiber ber filter disks* witho b. Filt Filtratio ration n apparatus: apparatus: One of the following, suitable for the filter disk selec selected: ted: 1) Membrane filter funnel. 2) Gooch crucib capacity, with Gooch crucible, le, 25-mL to 40-mL capacity, crucible adapter. 3) Filt with h res reserv ervoir oir and coa coarse rse (40 (40-- to Filtratio ration n appara apparatus tus wit 60-m) fritted disk as filter support.† c. Sucti Suction on fl ask, ask, of suf ficient capacity for sample size selected. d. Dryin Drying g oven, for operation at 180 2°C. 3.
min are requi required red to compl complete ete filtration, increase filter size or decrease sample volume. d. Sample analysis: Stir sample with a magnetic stirrer and pipet a measured volume onto a glass-fiber filter with applied vacuum. Wash with three successive 10-mL volumes of reagent-grade water, allowing complete drainage between washings, and continue suction for about 3 min after filtratio ltration n is complete. Transfer total filtrate (with washings) to a weighed evaporating dish and evaporate to dryness on a steam bath or in a drying oven. If necessary, add successive portions to the same dish after evaporation. Dry evaporated sample for at least 1 h in an oven at 180 2°C, cool in a desiccator to balance temperature, and weigh. Repeat drying cycle of dry dryin ing, g, coo cooli ling, ng, des desic iccat cating ing,, and wei weighi ghing ng unt until il a con const stant ant wei weight ght is obt obtain ained ed or unt until il wei weight ght change change is le less ss tha than n 4% of pr previ evious ous weight or 0.5 mg, whichever is less. Analyze at least 10% of all samples in duplicate. Duplicate determinations should agree within 5% of their average weight. If volatile solids are to be determined, follow procedure in 2540E.
Procedure
a. Prepar Preparation ation of glassglass- fi fiber ber filter disk: If pre-prepared glass fiber filter disks are used, eliminate this step. Insert disk with wrinkled side up into filtrat ltration ion appar apparatus. atus. Apply vacuum and wash was h dis disk k wit with h thr three ee succ success essive ive 2020-mL mL vol volume umess of rea reagen genttgrade gra de wat water. er. Continue Continue suc suctio tion n to rem remove ove all tr traces aces of wat water. er. Discard washings. b. Prepar Preparation ation of evaporating evaporating dish: If volatile solids are to be measured, measur ed, ignite cleaned evaporating evaporating dish at 550°C for 1 h in a muf fle furnace. If only total dissolved solids are to be measured, heatt cle hea clean an dish to 180 2°C for 1 h in an oven. Store in desiccator desicc ator until needed needed.. Weig Weigh h imme immediate diately ly befor beforee use. c. Select Selection ion of of fi filter and sample sizes: Choose sample volume to yield between 2.5 and 200 mg dried residue. If more than 10
* Whatman grade 934AH; Gelman type A/E; Millipore type AP40; E-D Scienti fic Specialties grade 161; Environmental Express Pro Weigh; or other products that give demonstrably equivalent results. Practical filter diameters are 2.2 to 12.5 cm. † Gelman No. 4201 or equivalent.
mg total dissolve dissolved d solids/L
( A
B ) 1000
sample volume, mL
where: A weight of dried residue dish, mg, and B weight of dish, mg.
5.
Precision
Single-laboratory analyses of 77 samples of a known of 293 mg/L wer mg/L weree mad madee wit with h a sta standa ndard rd dev deviat iation ion of dif differ ferenc ences es of 21.20 mg/L.
6. Reference 1. SOKOLOFF, V.P. 1933. Water of crystallization in total solids of water analysis. Ind. Eng. Chem., Anal. Ed. 5:336.
7. Bibliography HOWARD, C.S. 1933. Determination of total dissolved solids in water analysis. Ind. Eng. Chem., Anal. Ed. 5:4. U.S. GEOLOGICAL SURVEY. 1974. Methods for Collect Collection ion and Analysis of Water Samples for Dissolved Minerals and Gases. Techniques of Water-Resources Investigations, Book 5, Chap. A1. U.S. Geological Surv., Washington, D.C.
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PHYSICAL & AGGREGATE PROPERTIES (2000)
2540 D. Tot Total al Susp Suspend ended ed Solid Solids s Dried Dried at at 103–105°C 1.
General Discussion
well-m l-mixe ixed d sam sample ple is filte ltered red thr throug ough h a a. Princ Principle: iple: A wel weighed standard glass-fiber filter and the residue retained on the filter is dried to a constant weight at 103 to 105 °C. The incre increase ase in weight of the filter represents the total suspended solids. If the suspended material clogs the filter and prolongs filtration, it may be necessary to increase the diameter of the filter or decrease the sample volume. To obtain an estimate of total suspended solids, calculate the difference between total dissolved solids and total solids. 2540B.1. 1. Exclude large b. Inter Interferenc ferences: es: See 2540A.2 and 2540B. floatin oating g parti particles cles or submer submerged ged agglom agglomerate eratess of nonhom nonhomogeogeneous materials from the sample if it is determined that their inclusion is not representative. Because excessive residue on the filter may form a water-entrapping crust, limit the sample size to that yielding no more than 200 mg residue. For samples high in dissolved solids thoroughly wash the filter to ensure removal of dissolved material. Prolonged filtration times resulting from filter clogging cloggi ng may produce high result resultss owing to incr increased eased colloidal colloidal materials captured on the clogged filter. 2.
ume onto the seated glass-fiber filter. For homogeneous samples, pipet from the approximate midpoint of container but not in vortex. Choose Cho ose a poi point nt bot both h mid middep depth th and mi midwa dway y bet betwee ween n wal walll and vortex. vort ex. Wash filter with three successive successive 10-m 10-mL L volu volumes mes of reagent-grade water, allowing complete drainage between washings, and continue suction for about 3 min after filtration is complete. Samples with high dissolved solids may require additional washings. Carefully remove filter from filtratio ltration n apparatus and transfer to an aluminum weighing dish as a support. Alternatively, remove the crucible and filter combination from the crucible adapter if a Gooch cruc cr ucib ible le is us used ed.. Dr Dry y fo forr at le leas astt 1 h at 10 103 3 to 10 105 5°C in an ov oven en,, co cool ol in a desiccator to balance temperature, and weigh. Repeat the cycle of dry dryin ing, g, coo cooli ling, ng, des desic iccat cating ing,, and wei weighi ghing ng unt until il a con const stant ant wei weight ght is ob obta tain ined ed or un unti till th thee we weig ight ht ch chan ange ge is le less ss th than an 4% of th thee pr prev evio ious us weight or 0.5 mg, whichever is less. Analyze at least 10% of all samples in duplicate. Duplicate determinations should agree within 5% of their average weight. If volatile solids are to be determined, treat the residue according to 2540E. 4.
mg total suspend suspended ed solids/L
Apparatus
Apparatus listed in Sections 2540B.2 and 2540C.2 is required, except for evap except evapora oratin ting g dis dishes, hes, ste steam am bat bath, h, and 180°C drying oven. In addit addition: ion: Aluminum weighing dishes.
( A
B ) 1000
sample volume, mL
where: A weight of filter dried residue, mg, and B weight of filter, mg. 5.
3.
Calculation
Precision
Procedure a. Prepar Preparation ation of glassglass- fi fiber ber filter disk: If pre-prepared glass
fiber filter disks are used, eliminate this step. Insert disk with wrinkled side up in filtration apparatus. Apply vacuum and wash
disk wit disk with h thr three ee succ success essive ive 2020-mL mL por portio tions ns of rea reagen gentt-gra grade de water. wat er. Con Contin tinue ue suc suctio tion n to rem remove ove all traces of wat water, er, turn vacuum off, and discard washings. Remove filter from filtration apparatus and transfer to an inert aluminum weighing dish. If a Gooch crucible is used, remove crucible and filter combination. Dry in an oven at 103 to 105°C for 1 h. If volatile solids are to be measured, ignite at 550°C for 15 min in a muf fle furnace. Cool in desic desiccator cator to balan balance ce tempe temperatur raturee and weigh. Repeat cycle of drying or igniting, cooling, desiccating, and weighing until a constant weight is obtai obtained ned or until weight weight change is less than 4% of the previous weighing or 0.5 mg, whichever is less. Store in desiccator until needed. b. Select Selection ion of of fi filter and sample sizes: Choose sample volume to yield between 2.5 and 200 mg dried residue. If volume filtered fails to meet minimum yield, increase sample volume up to 1 L. If compl complete ete filtr ltrati ation on tak takes es mor moree tha than n 10 min min,, inc increa rease se filter diameter diame ter or decre decrease ase sampl samplee volum volume. e. c. Samp Sample le analysis: analysis: Assemble filtering apparatus and filter and begin begi n suct suction. ion. Wet filte lterr wit with h a sma small ll vol volume ume of rea reagen gentt-gra grade de wat water er to seat it. Stir sample with a magnetic stirrer at a speed to shear larger particles, if practical, to obtain a more uniform (preferably homogeneous) particle size. Centrifugal force may separate particles by size and density, resulting in poor precision when point of sample withdrawal is varied. While stirring, pipet a measured vol-
The standard deviation was 5.2 mg/L (coef ficient of variation 33%) at 15 mg/L, 24 mg/L (10%) at 242 mg/L, and 13 mg/L (0.76%) at 1707 mg/L in studies by two analysts of four sets of 10 determinations each. Single-laboratory duplicate analyses of 50 samples of water and wastewater were made with a standard deviation of differences of 2.8 mg/L. 6. Bibliography DEGEN, J. & F.E. N USSBERGER . 1956 1956.. Note Notess on the determinat determination ion of suspended suspende d solids. Sewage Ind. Wastes 28:237. CHANIN, G., E.H. C HOW, R.B. ALEXANDER & J. POWERS. 1958. Use of glass fiber filter medium in the suspended solids determ determination. ination. Sewage Ind. Wastes 30:1062. NUSBAUM, I. 1958. New method for determination of suspended solids. Sewage Ind. Wastes 30:1066. SMITH, A.L. & A.E. GREENBERG. 1963. Evaluation of methods for determining suspended solids in wastewater. J. Water Pollut. Control Fed. 35:940. WYCKOFF, B.M B.M.. 1964 1964.. Rap Rapid id soli solids ds det determ ermina ination tion using glas glasss fiber filters. Water Sewage Works 111:277. NATIONAL COUNCIL OF THE PAPER INDUSTRY FOR AIR AND STREAM IMPROVEMENT. 1975. A Preliminary Review of Analytical Methods for the Determination of Suspended Solids in Paper Industry Ef fluents for Compliance with EPA-NPDES Permit Terms. Spec. Rep. No. 7501. National National Council Council of the Pap Paper er Industry Industry for Air & Str Stream eam Improvement, New York, N.Y. NATIONAL COUNCIL OF THE PAPER INDUSTRY FOR AIR AND STREAM IMPROVE1977.. A Stu Study dy of the Effect Effect of Alte Alterna rnate te Pro Proced cedure uress on MENT. 1977
SOLIDS (2540)/Settleable Solids
2-59
Ef fluen uentt Susp Suspende ended d Sol Solids ids Mea Measure suremen ment. t. Str Stream eam Imp Improve rovemen mentt Tech. Bull. No. 291, National Council of the Paper Industry for Air & Stream Improvement, New York, N.Y.
TREES, C.C. 1978. Analytical analysis of the effect of dissolved solids on suspended suspende d solids determ determination. ination. J. Water Pollut. Control Fed. 50: 2370.
2540 254 0 E. Fix Fixed ed and and Volat Volatile ile Soli Solids ds Ignit Ignited ed at at 550°C 1.
General Discussion
a. Princ Principle: iple: The residue from Method B, C, or D is ignited to constant weight at 550°C. The remaining solids represent the fixed total, dissolved, or suspended solids while the weight lost on ignition is the volatile solids. The determination is useful in control of wastewater treatment plant operation because it offers a rough approximation of the amount of organic matter present in the solid fraction of wastewater, activated sludge, and industrial wastes. b. Inter Interferenc ferences: es: Negative errors in the volatile solids may be produced by loss of volatile matter during drying. Determination of low concentrations of volatile solids in the presence of high fixed solids concentrations may be subject to considerable error. In such cases, measure for suspect volatile components by another oth er tes test, t, for exa exampl mple, e, tot total al org organi anicc car carbon bon (Se (Secti ction on 531 5310). 0). Highly Hig hly alk alkali aline ne res residu idues es may rea react ct wit with h sil silica ica in sam sample ple or silica-containing crucibles. Apparatus
2.
one sample and/or heavier residues may overtax the furnace and necessitate necessi tate longer ignition ignition times times.. Let dish or filte lterr dis disk k coo cooll partially in air until most of the heat has been dissipated. Transfer to a desiccator for final cooling in a dry atmosphere. Do not overload desiccator. Weigh dish or disk as soon as it has cooled to balance temperature. Repeat cycle of igniting, cooling, desiccating, and weighing until a constant weight is obtained or until weight change is less than 4% or 0.5 mg, whichever is less. Analyz Ana lyzee at lea least st 10% of all samples samples in dup duplic licate ate.. Dup Duplic licate ate determinat deter minations ions should agree within 5% of their average weight. Weightt loss of the blank filter is an indication of unsuitability of Weigh a particular brand or type of filter for this analysis. 4.
mg volatile solids/L
mg fixed solids/L
( A
B ) 1000
sample volume, mL ( B
C ) 1000
sample volume, mL
where: A weight of residue dish before ignition, mg, B weight of residue dish or filter after ignition, mg, and C weight of dish or filter, mg.
See Sections 2540B.2, 2540C.2, and 2540D.2. 3.
Calculation
Procedure
Ignite residue produced by Method 2540B, C, or D to constant weight in a muf fle furnace at a temperature of 550°C. Ignite a blank glass fiber filter along with samples. Have furnace up to temper tem peratu ature re bef before ore ins insert erting ing sam sample ple.. Usu Usuall ally, y, 15 to 20 min ignition are required for 200 mg residue. However, more than
5.
Precision
The standard deviation was 11 mg/L at 170 mg/L volatile total solids in studies by three laboratories on four samples and 10 replicates. Bias data on actual samples cannot be obtained.
2540 254 0 F. Se Sett ttle leab able le So Solid lids s 1.
General Discussion
Settleable solids in surface and saline waters as well as domestic and industrial wastes may be determined and reported on either a volume (mL/L) or a weight (mg/L) basis. 2.
Apparatus
The volumetric test requires only an Imhoff cone. The gravimetric test requires all the apparatus listed in Section 2540D.2 and a glass vessel with a minimum diameter of 9 cm. 3.
Procedure
a. Volum Volumetric etric:: Fill an Imhoff cone to the 1-L mark with a well-mixed sample. Settle for 45 min, gently agitate sample near
the sides of the cone with a rod or by spinning, settle 15 min longer, and record volume of settleable solids in the cone as milliliters per liter. If the settled matter contains pockets of liquid between betwee n larg largee settl settled ed parti particles, cles, estimate estimate volum volumee of these and subtract from volume of settled solids. The practical lower limit of measurement depends on sample composition and generally is in the range of 0.1 to 1.0 mL/L. Where a separation of settleable settleable and floatin oating g mater materials ials occurs, do not estimate the floating material as settleable matter. Replicates usually are not required. Where biological or chemical floc is present, the gravimetric method (3b) is preferred. b. Gravim Gravimetric etric:: 1) Deter Determine mine total suspended suspended solids as in Secti Section on 2540D. 2) Pou Pourr a wel well-m l-mixe ixed d sam sample ple into a gla glass ss vessel of not less than 9 cm diam using not less than 1 L and suf ficient sample to
2-60
PHYSICAL & AGGREGATE PROPERTIES (2000)
give a depth of 20 cm. Alternatively use a glass vessel of greater diameter and a larger volume of sample. Let stand quiescent for 1 h and and,, wit withou houtt dis distur turbin bing g the settled settled or floatin oating g mater material, ial, siphon sip hon 250 mL fro from m cen center ter of con contai tainer ner at a poi point nt hal halfwa fway y between the surface of the settled material and the liquid surface. Determine total suspended solids (milligrams per liter) of this supernatant liquor (Section 2540D). These are the nonsettleable solids. 4.
Calculation
5.
Precision and Bias
Precision and bias data are not now available.
6. Bibliography FISCHER, A.J. & G.E. S YMONS. 1944. The determination of settleable sewage solids by weight. Water Sewage Works 91:37.
mg settleable solids/L suspended d solids/L mg nonsettleable solids/L mg total suspende
2540 G. Tot Total, al, Fixed, Fixed, and Volat Volatile ile Solids Solids in Solid and and Semisol Semisolid id Samples Samples 1.
General Discussion
a. Appli Applicabil cability: ity: This method is applicable to the determination of total solids and its fixed and volatile fractions in such solid and semisolid samples as river and lake sediments, sludges separated from water and wastewater treatment processes, and sludge slu dge cak cakes es fr from om vac vacuum uum filtrat ltration, ion, centr centrifuga ifugation, tion, or other sludge dewatering processes. b. Interferences: The determination of both total and volatile solids in these materials is subject to negative error due to loss of ammonium carbonate and volatile organic matter during drying. Although this is true also for wastewater, the effect tends to be more pronounced with sediments, and especially with sludges and sludge cakes. The mass of organic matter recovered from sludge and sediment requires a longer ignition time than that specified for wastewaters, ef fluents, or polluted waters. Carefully observe specified ignition time and temperature to control losses of vol volati atile le ino inorga rganic nic salts if the these se are a pro proble blem. m. Mak Makee all weighings quickly because wet samples tend to lose weight by evaporation evapor ation.. After drying or ignit ignition, ion, residues often are very hygroscopic and rapidly absorb moisture from the air. Highly alkaline residues may react with silica in the samples or silicacontaining crucibles. 2.
Apparatus
All the appara apparatus tus listed in Secti Section on 2540B.2 is requi required red except that a magnetic stirrer and pipets are not used and a balance capable of weighing to 10 mg may be used. 3.
Procedure
a. Total solids: solids: 1) Preparation of evaporating dish—If volatile solids are to be measured, ignite a clean evaporating dish at 550°C for 1 h in a muf fle furnace. If only total solids are to be measured, heat dish at 103 to 105°C for 1 h in an oven. Cool in desiccator, weigh, and store in desiccator until ready for use. 2) Sampl Samplee analysis analysis a) Fluid samples—If the sample contains enough moisture to flow more or less readi readily, ly, stir to homogenize, homogenize, place 25 to 50 g in a prepared evaporating dish, and weigh. Evaporate to dryness on
a wa wate terr ba bath th,, dr dry y at 103 to 10 105 5°C for 1 h, cool to balance temperature in an individual desiccator containing fresh desiccant,, and wei cant weigh. gh. Rep Repeat eat hea heatin ting, g, coo coolin ling, g, desi desicca ccatin ting, g, and weighing procedure until the weight change is less than 4% or 50 mg, whichever is less. Analyze at least 10% of all samples in duplicate. Duplicate determinations should agree within 5% of their average weight. b) Solid samples—If the sample consists of discrete pieces of solid soli d mate materia riall (dew (dewater atered ed slud sludge, ge, for exam example) ple),, take cores from each piece with a No. 7 cork borer or pulverize the entire sample coarsely on a clean surface by hand, using rubber gloves. Place 25 to 50 g in a prepared evaporating dish and weigh. Place in an oven at 103 to 105°C overnight. Cool to balance temperature in a desiccator cat or and we weigh igh.. Rep Repeat eat dry drying ing (1 h) h),, coo cooli ling, ng, wei weighi ghing, ng, and desiccating steps until weight change is less than 4% or 50 mg, whichever is less. Analyze at least 10% of all samples in duplicate. Duplicate determinations should agree within 5% of their average weight. b. Fixed and volatile volatile solids: solids: Transfer the dried residue from 2)a) above to a cool muf fle furnace, heat furnace to 550°C, and ignite for 1 h. (If the residue contains large amounts of organic matter, first ignite it over a gas burner and under an exhaust hood in the presence of adequate air to lessen losses due to reducing conditions and to avoid odors in the laboratory.) Cool in desiccator cat or to bal balanc ancee tem temper peratu ature re and wei weigh. gh. Rep Repeat eat ign igniti iting ng (30 min), cooling, desiccating and weighing steps until the weight change is less than 4% or 50 mg, whichever is less. Analyze at least 10% of all samples in duplicate. Duplicate determinations should agree within 5% of their average weight. 4.
Calculation
% total solids
% volatile solids
% fixed solids
( A
C
( A
( D
B ) 100
B
D ) 100
A
B
B ) 100
A
B
TEMPERATURE (2550)/Laboratory & Field Methods
2-61
6. Bibliography
where: A weight of dried residue dish, mg, B weight of dish, C weight of wet sample dish, mg, and D weight of residue dish after ignition, mg.
GOODMAN, B.L. 1964. Processing thickened sludge with chemical conditioners. Pages 78 et seq. in Sludge Concentration, Concentration, Filtrati Filtration on and Incineration. Univ. Michigan Continued Education Ser. No. 113, Ann Arbor. GRATTEAU, J.C. & R.I. DICK. 1968. Activated sludge suspended solids determinations. Water Sewage Works 115:468.
Precision and Bias
5.
Precision and bias data are not now available.
2550 TEMP TEMPERA ERATUR TURE* E*
2550 25 50 A. Int Intro rodu duct ction ion Temperature readings are used in the calculation of various forms of alkalinity, forms alkalinity, in studi studies es of saturation saturation and stability stability with respect to calcium carbonate, in the calculation of salinity, and in general gener al labor laboratory atory opera operations tions.. In limn limnologi ological cal studi studies, es, water * Approved by Standard Methods Committee, 2000.
2550 B.
temperatures as a function of depth often are required. Elevated temperatures resulting from discharges of heated water may have significant ecological impact. Identification of source of water supply, supp ly, such as deep wells, wells, oft often en is pos possib sible le by tem temper peratu ature re measurements alone. Industrial plants often require data on water temperature for process use or heat-transmission calculations.
Labora Lab orator tory y and and Fiel Field d Method Methods s
Laboratory and Other Non-Depth Temperature Measurements 1.
Normally Norm ally,, temp temperat erature ure meas measurem urements ents may be made with any good mercury-filled Celsius thermometer. As a minimum, the thermometer should have a scale marked for every 0.1°C, with markings etched on the capillary glass. The thermometer should have a minimal thermal capacity to permit rapid equilibration. Periodically check the thermometer against a precision thermometer certified by the National Institute of Standards and Technology (NIST, formerly formerly National Bureau of Standards)* that is used with its certi ficate and correction chart. For field operations use a thermometer having a metal case to prevent breakage. A total immersion thermometer is designed to indicate temperatures correctly when the bulb and the entire liquid column are exposed exposed to the temperat temperature ure bei being ng mea measur sured, ed, exc except ept for a minimal emergent length. A partial-immersion thermometer has a line around it at the immersion distance from the bottom. It indicates correctly when the bulb and the liquid column to that linee are exp lin expose osed d to the tem temper peratu ature re bei being ng mea measur sured ed and the emergent stem is at ambient temperature.
2.
Depth Temperature Measurements
Depth temperature required for limnological studies may be measured with a reversing thermometer, thermophone, or thermistor. The thermistor is most convenient and accurate; however, higher cost may preclude its use. Calibrate any temperature measurement devices with a NIST-certified thermometer before field use. Make readings with the thermometer or device immersed in water long enough to permit complete equilibration. Report results to the nearest 0.1 or 1.0 °C, depending on need. The thermometer commonly used for depth measurements is of the reversing type. It often is mounted on the sample collection apparatus so that a water sample may be obtained simultaneously. Correct readings of reversing thermometers for changes due to differences between temperature at reversal and temperature at time of reading. Calculate as follows:
T
(T 1 t ) ( T 1 V 0)
K
T 1 t ) ( T 1 V 0) 1
K
L
where: * Some commercial thermometers may be as much as 3 °C in error.
T correction to be added algebraically to uncorrected reading, uncorrected ected reading at revers reversal, al, T 1 uncorr
