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FIG.75. Biological aeration tank.FIG.76. Mobil tracer lab and tracer bottle for injection.FIG.77. Location of probes: D 2 immerged and D 3 inside detection chamber.69
FIG.78. Experimental RTD curves in two tests.The tracer movement for a normal assumed flow regime should go from the inlet to the probeD 1 , after to the probe D 2 and at the end to the probe D 3 . Fig. 78 shows that the response signalrecorded by detector D 3 comes before the signal recorded by detector D 1 . This indicates that asignificant part of the wastewater flow is bypassing directly from the inlet to the outlet. The flowregime in this aeration tank was found abnormal and modification of the inlet position and installationof baffles were recommended to improve the efficiency of this WWTP’s unit.4.12. 99M TC AS A TRACER FOR THE LIQUID RESIDENCE TIME DISTRIBUTIONMESUREMENT IN ANAEROBIC DIGESTER: APPLICATION IN A SUGARWASTEWATER TREATMENT PLANT4.12.1. BackgroundDifferent chemical and radioactive tracers have been employed for diagnosing thehydrodynamic of anaerobic processes: K 82 Br, HTO, K 131 I, rhodamine-WT and lithium chloride totrace wastewater, and 113m In (InCl 3 ), 140 La and 198 Au for the sludge. However, for the countries whichdo not have nuclear reactor facilities for the production of such radioisotopes, the only possibility toextend the application of radiotracer techniques in sanitary engineering is the employment ofradioisotope generators.Among the commercial radioisotope generators the 99 Mo/ 99m Tc generator, due its generalizationin nuclear medicine for the production of labeled compounds, seems to be an attractive approach.However, the use of this tracer in anaerobic process must be preceded by the study of the physicochemicalbehavior of the eluate: the pertechnectate ion ( 99m TcO 4 - ).The validation of 99m Tc-pertechnetate as radiotracer to measure the RTD of the liquid phase inanaerobic digester has to be done. For this purpose, a new digester developed by the Cuban ResearchInstitute of Sugar for the treatment of the effluent of the sugar factory has been selected. The anaerobicdigestion processes need physico-chemical conditions easy to work: temperature around 30°C, pHbetween 6.8 and 7.8, absolute anaerobic medium, volatile fatty acids concentration around 1 g·L -1 .Previous investigations have shown that the lithium tracer was adsorbed slightly onto thepacking medium and held up within the biomass. Similar observation has been made for rhodaminedye diffused into the biofilm during the influx of tracer, and out-diffused slowly. The consequenceswere as much as 100% error in retention time. Therefore, when attempting to model reactorhydraulics, extreme care must be exercised in the choice of tracer compound and in the ultimateinterpretation of RTD functions obtained.70
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Radiotracer Applications inWastewat
Page 3 and 4:
The following States are Members of
Page 5 and 6:
TRAINING COURSE SERIES No. 49RADIOT
Page 7 and 8:
EDITORIAL NOTEThe use of particular
Page 9 and 10:
PRACTICAL RECOMMENDATIONS .........
Page 11 and 12:
The success of radiotracer applicat
Page 13 and 14:
skimmed out. Flotation, as currentl
Page 16 and 17:
1.3.3. Primary clarifiersA clarifie
Page 18 and 19:
esidence times of phases, mixing ch
Page 20 and 21:
FIG.8. Secondary clarifier: periphe
Page 22 and 23:
processes that occur in natural env
Page 24 and 25:
The RTD and MRT are parameters that
Page 26 and 27:
(b) Perfect mixers in series modelA
Page 28 and 29: and practically it has better sense
Page 30 and 31: The experimental RTD curve gives ma
Page 32 and 33: FIG.18. Experimental and CFD calcul
Page 34 and 35: Optical tracers can be divided in t
Page 36 and 37: Table 1b. Liquid tracers.- Field of
Page 38 and 39: TABLE 2. SOME WATER RADIOTRACERSIso
Page 40 and 41: The detection efficiency (ϕ) is de
Page 42 and 43: Since on-line radiotracer technique
Page 44 and 45: source. The dose received is direct
Page 46 and 47: 4. CASE STUDIESWastewater from indu
Page 48 and 49: FIG.26. Scheme of equalizer-clarifi
Page 50 and 51: FIG.29. Exp. RTD of S2 and S3 jet m
Page 52 and 53: FIG.33. Experimental RTD curves mea
Page 54 and 55: 1. Radiotracer testsRadiotracer Br-
Page 56 and 57: 4.00E-033.50E-03ExperimentalModel3.
Page 58 and 59: 3. Conclusions• The aeration tank
Page 60 and 61: FIG.50. Experimental response curve
Page 62 and 63: 4.8. DIAGNOSIS OF A CYLINDRICAL TWO
Page 64 and 65: FIG.56. RTD simulation for experime
Page 66 and 67: The radiotracer was chosen to trace
Page 68 and 69: (a) D1 - D3 (b) D1 - D4(c) D1 - D6
Page 70 and 71: (d) ConclusionsThe diagnosis of dig
Page 72 and 73: • average gamma energy of 400 keV
Page 74 and 75: To estimate the MRT of the mud insi
Page 76 and 77: FIG.71. Experimental RTD curve and
Page 80 and 81: 4.12.2. Radiotracer experiment(a) L
Page 82 and 83: FIG.80. The experimental RTD curve
Page 84 and 85: FIG.84. Experimental RTD curve of l
Page 86 and 87: FIG.88. Characteristic curves of se
Page 88 and 89: tracer background level detection.
Page 90 and 91: As seen from Fig. 94, the tanks-in-
Page 92 and 93: FIG.99. Experimental RTD curves wit
Page 94: The experimental RTD curves obtaine
Page 98: BIBLIOGRAPHYBORROTO J.I., DOMINGUEZ
Page 102: CONTRIBUTORS TO DRAFTING AND REVIEW
Page 106: I S S N 1 0 1 8 - 5 5 1 8
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