The Effect of Algae on BOD Measurements Author(s): George P. Fitzgerald Source: Journal (Water Pollution Control Federation), Vol. 36, No. 12 (Dec., 1964), pp. 1524-1542 Published by: Water Environment Federation Stable URL: http://www.jstor.org/stable/25035197 Accessed: 21-01-2016 19:17 UTC Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at http://www.jstor.org/page/ info/about/policies/terms.jsp JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. Water Environment Federation is collaborating with JSTOR to digitize, preserve and extend access to Journal (Water Pollution Control Federation). http://www.jstor.org This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions THE EFFECTOF ALGAEON BOD MEASUREMENTS George P. Fitzgerald to measure A study has been made of various the BOD species of algae with bacteria alone and in association of 5-days' conditions under incubation time in the dark and at a temperature if algae have an of 20 ?C to determine under the effect on BOD measurements conditions. standard Initial studies have been carried out the green alga, Chlorella pyre using This alga is es noidosa (Wis. 2005). to various culture pecially adaptable and can be used as a basis conditions for comparison with other algae having more restricted conditions. culture used to sup The culture procedures tests are the BOD for Chlorella ply and the growth rates of this described alga in four different media were meas there is little informa Because ured. on the measure tion in the literature ment of dissolved oxygen (DO) in the presence of algae, tests were carried this out to observe if algae affected measurement. Another series of tests was made if the algae to determine used in BOD tests under the standard the 5 days conditions would survive in the presence of bacteria. of darkness The effect of adding sewage bacteria to cultures of algae was also determined, of the algae and both on the activity in the effect of the culture supernatant the BOD test. Materials The 2005) As soon as some of the preliminary studies on the effect of algae on the various measurements involved and the effects of mixing algae and bacteria were known, studies were made of the factors the activity of the affecting algae during the BOD tests. The vari ous factors have studied been the amount of algae, the source of algae in which the algae (i.e., the medium were and the age of the cultured), at the time of use in algal cultures the BOD test (i.e., the factors causing in algal cultures two senility using and secondary sewage media, Gorham's effluent). As an extension of the data collected as a test organism, fur using Chlorella ther studies were carried out compar of the blue-green, ing the activity bloom-forming alga, that to ginosa (Wis. 1036) rella. Also, the activity and blue-green aeru Microcystis of other green was algae of Chlo measured: mus Nostoc dimorpha, echinulata. corum, and Gloeotrichia Studies on the influence of the dilu Scenedesmus tion medium in the BOD test have been made. of the BOD Comparison in dilution of Chlorella water, algal culture media, and in lake waters, as well as seasonal in the influ changes ence of lake are waters reported. and Methods Chlorella (Wis. pyrenoidosa as a pure used was maintained the with is associated P. Fitzgerald George and Sanitary College Lahoratones, Hydraulic of University of Wisconsin, Engineering, Wis. Madison, culture and a volume of about 15 ml was to inoculate used each experi mental A culture. 2-1 Erlenmeyer flask with 1,500 ml of medium was used as a culture ported vessel. a 6-mm diam A cotton glass plug sup tube with 1524 This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions a 12 Vol. 36, No. BOD MEASUREMENTS 1525 end that was used for bub constricted a C02-air mixture bling 1.25-percent the Each bubbler culture. through was attached rubber tub by surgical ing to a 25- X 200-mm glass tube con A 50-mm cotton as a filter. taining was in teflon-covered magnet placed each flask. The culture vessel, media, and filter were sterilized magnet, by were Inoculations autoclaving. The composition of the four media are listed used for culturing Chlorella in Table water me I. The dilution dium is BOD dilution water (1) plus 30 mg/1 of nitrogen from NaN03. The is near 7.4 at har pH of this medium vest time. Allen's medium (2) is also a neutral medium, the final pH being near 7.0. Myers' medium (3) is more the pH being near 6.5. Gor acidic, ham's medium (4) is alkaline, with a final pH of near 9.0. The algae to be used in an experi ment were centrifuged from their cul ture solution after their concentration made with sterile syringes. Motors (1/100 Elec. hp shaded pole motor, Dayton with magnets Mfg. Co., Chicago, 111.) attached to their shafts were mounted on wooden frames below the vertically and the speed of 15 culture vessels stirred cultures was con magnetically trolled with one variable transformer. The algae were cultured under continu ous light [180 ft-c (1,940 lumen/sq in a constant m)] (23 ? temperature culture 1?C) wTas room. TABLE I.?Media A. Salt Used for Culture Concentration Dilution Water NH4CI of Chlorella of salts used for BOD in media Gorham's Experiments Myers' 50 496 1,000 KN03 1,210 8.5 KH2PO4 K2HP04 1,230 21.75 39 250 75 27 58 6 1 513 50 33.4 Na2HP04-7H20 Fe Citrate 0.15 FeCls Fe2(S04)3 52 22.5 MgS04-7H20 CaCl2 27.5 Na2Si03-9H20 Citric Acid EDTA Na 2,460 195 Citrate 20 Na2COs Total was supernatant (mg/1) Allen's 1.7 182.0 NaN03 the measured, the cells were washed with discarded, and recentrifuged. pH 7 P04-buffer, in a The cells then were suspended volume of PO^buffer and convenient measured added to di seeded samples lution water for mixing and filling of 297.5 Salts B. Ion N P Fe Mg Ca S K Concentration Dilution Water 30 10 0.05 2 10 728 of essential 1,866 ions Gorham's 82 7 1 7 10 3 10 12 17 in media 5,147 (mg/1) Allen's Myers' 178 45 1 50 18 67 112 168 295 15 243 This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions 323 353 1526 JOURNAL WPCF BOD bottles. bottles were Duplicate the initial DO con used to determine and triplicate centrations bottles were used for after analysis containing black room. wrere algae incuba 5-days' tion at 20 ?C in a dark Bottles covered as a further precaution light from entering during incubation to the were Measurements period. made as suggested ods (1). in Standard used to measure the procedure absorbed of oxygen by algae the 5-day BOD determinations during was to measure used by the oxygen The amount seeded Meth water dilution with hoods prevent December 1964 and seeded (24-hr settled dilution wa sewage seed) ter plus algae. in the The difference was referred to as oxygen depletion being caused by the algae and reported as A DO per mg algae. Results Growth of Chlorella Media in Different Because there is no one growth meas common to all algae labora urement growth tories, were measurements made on cultures as suspended solids, volatile COD [dichromate solids, method with Ag2S04 catalyst (1)], cell counts, and packed volume. The between these general relationships measurements of Chlorella cultures of are 10 of age approximately days in Table II. presented on Dissolved of Algae Measurement Oxygen Effect The effect of the presence of algae in measuring dissolved oxygen (DO) by the Alsterberg (azide) modification of the Winkler method (1) was de termined. It was found that concentrations of as high as 5 X 106 cells/ml Chlorella did not appreciably affect the meas was urement of DO. The end-point with but slightly obscured, experience the overcame measurement Once advantage. fate and alkaline TABLE Culture Medium Dilution Gorham's Allen's Myers' water the this manganous iodide reagents IL?Relative Growth dis sul were of Chlorella vs it was found that up to two added, hour intervals between the addition of acid or titration the sulfuric did not in the pres affect the DO measured ence of Chlorella. Effect of Seed Activity Volume of Algae on were carried out in Experiments which the oxygen absorbed by different volumes of 20- to 24-hr (3.0 to 30 ml/1) settled sewage seed in dilution water was measured as well as the total a amount of oxygen absorbed when amount definite of Chlorella from a dilution water culture was added to each seed volume in dilution water. The results of these tests indicated that a variation of 10 fold in seed vol ume or 7 fold in oxygen absorption due to the seed had little or no effect on the amount of oxygen absorbed by the added amount of algae. of Contaminating Effect Chlorella on Cultures with Subse Sewage quent BOD Measurements Settled sewage was added to cultures of Chlorella (one to five ml sewage after 10 Days in Different Media ss (mg/1) (mg/l) COD (mg/1) Cell Count (cell/ml XI06) 125 175 375 375 100 200 350 350 175 250 550 550 12.5 5.0 50.0 50.0 This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions Vol. 36, No. BOD MEASUREMENTS 1527 12 that previously per liter of culture) for BOD measure had been sampled about five additional ments. After in the culture room days of incubation the normal conditions under growth cultures were again sampled for BOD The effects of both measurements. washed algal cells and of the culture were measured in seeded supernatants dilution water tests. A total of 45 tests was carried out on algae from dilution water, Allen's that had been in and Myers' media, cubated with It was found sewage. that the average activity of the algae cultures was within from contaminated the experimental limits for that me as compared from dium with algae was data it these cultures. From pure that algae from either pure concluded have or contaminated cultures would the same effect on the BOD essentially measurement. a very different effect of cultures with Chlorella contaminating sewage on the results in BOD measure There was ments by the supernatants produced in It was found from the cultures. from 12 tests with cultures of Chlorella ' me and Myers dilution water, Allen's of contamination effect that the dia, in the sewage caused a decrease with to the of the supernatant the BOD extent that the BOD was 1/5 or less for 5 with after incubation sewage as the with supernatant days compared of the cultures prior to contamination. of course, be This is to be expected, cause the organic matter accumulated had been in algal culture supernatants of sew found to increase the activity was further seed age proof and, thus, could be that some of this material broken down by sewage organisms. Comparison of Live and Dead Algae The literature states (5) (6) (7) (8) had considerably algae than live algae. demands higher oxygen In order to check this a series of BOD live algae from tests was made with cells which similar Allen's medium, that dead and cells which autoclaved, freeze-dried. were first carried out Experiments of Chlorella cells to test the viability which had (a) no treatment, (b) had been frozen only, and (c) which had final freeze-dried been (3.6-percent as compared content to 83 moisture in fresh cells). Tests percent moisture in either indicated that cells suspended 8-wk old distilled water or autoclaved culture and then frozen supernatant, of time required for the same period in the freeze-drying process (1 to 3 of about 20 per days), had a viability had had been been as cent compared to unfrozen controls. were of up in freeze-dried viable to 10,000 cells but, in samples one experiment, 4 algae cells out of 500,000 cells survived the freeze-drying treatment. it may be con Therefore, cluded that freeze-dried Chlorella cells for these tests are, by and large, non to viable, but may still be considered be chemically intact much the same as live cells, as compared to cells which have been killed by autoclaving. The results of 8 BOD tests each with and autoclaved fresh, freeze-dried, Chlorella cells indicated that the aver factors age activity (A DO/mg SS) were 0.13, 0.44, and 0.48, respectively. Thus, it has been confirmed that dead than algal cells exert higher BOD's live cells, and the BOD of cells killed are nearly as great by freeze-drying as the BOD of cells killed by auto No cells claving. of Viability and Comparison Capacity Photosynthetic of al tests of the mixture Viability dilution water gae and seeded BOD before and after incubation were made of the mixture samples by diluting buffer using sterile, pH 7.2 phosphate in dishes and with petri plating (1) extract The agar. glucose tryptone colonies un viable algal cells forming der these conditions were counted after in the constant-light culture incubation room for at least 10 days. The algal This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions 1528 JOURNAL WPCF cell counts in some plates were less than in duplicate plates or algal colo nies were in some duplicate smaller inhibition because of plates, resulting the presence of certain bac of types teria. The results of viability tests com the number of cells viable at paring the time BOD tests were started (zero the number of viable cells time) with found in BOD after bottles 5-days' incubation in the dark indicated that 88 percent of the cells from Allen's medium of (17 tests) and 76 percent cells from dilution water medium (34 tests) were alive after the incubation in comparing data period. However, of individual was it found experiments that the amount of oxygen used per mg of suspended solids (A DO/mg SS) was not to related necessarily the re sults of viability the tests; essentially same A DO/mg SS was obtained from re which had 100-percent experiments in covery of cells as from experiments re which there was only 52-percent covery (dilution water algae). The photosynthetic of the capacity algae-seed was mixtures measured 5 days' incubation DO analyses by comparing duplicate of samples in the dark with held samples exposed to 350 ft-c (3,770 lu men/sq m) of light for 2 hr just before The amount of oxygen that analysis. in the light in ex the algae produced cess of that used in the dark was con trolled by the physical of conditions the medium at the time of analysis, such as C02 content of the water in the BOD bottles, as well as the physio logical state of the algae. However, since this test was used to compare sources but from different in algae same medium after the same in cubation it was to considered times, be a reliable test for the comparative of the different activity algae at that time. particular The amount or rate of oxygen pro as the change in duced was expressed oxygen per mg suspended solids the two-hr period. The average rate of 35 tests of algae from Allen's me at the start of the dium measured BOD tests was 0.093A DO/mg SS, while it was 0.083A DO/mg SS when tested after 5-days' a de incubation, crease of 11 percent. The average of these two rates of oxygen production, 0.088A DO/mg SS, for a 2-hr period of light exposure is equivalent to 5.3 for a 5-day mg of oxygen production/1 or a considerably rate period, higher than the average rate for respiratory algae from this source (0.10A DO/mg SS). (See also reference 6.) The photosynthetic capacity of algae from dilution water medium (32 tests) had an average rate of 0.056A DO/mg SS at zero time and 0.024A DO/mg SS a decrease, after 5-days' in incubation, ca in photosynthetic 5-days' time, of 57 percent. it pacity Therefore, seem that the higher would activity in the BOD test of algae from dilution water medium be due to the may death of some cells from dilution water medium and the resulting stimulation of bacterial respiration. at zero time and after the 1964 December for of Algal Comparison Under Bacterial-Free Rates Activity Conditions The procedure used to measure the amount of oxygen that algae would use in five days, in the absence of bacteria, was to add algae from pure cultures to sterile BOD dilution water and siphon the mixture to sterile BOD bottles. At the same time as these tests were tests were also run in run, duplicate seeded dilution water identical using samples of algae. The results of the bacterial-free and seeded BOD tests indicated that 12 percent more oxygen was consumed in seeded solids per mg suspended BOD tests than in bacterial-free BOD tests with algae from Allen's medium and 34 percent more with (8 tests), algae from the dilution water medium The average BOD of algae (12 tests). from Allen's medium (bacterial-free) was 0.12 as compared to 0.10A DO/mg This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions Vol. 36, No. 12 BOD MEASUREMENTS 1529 SS for the average for all seeded BOD tests with algae from Allen's medium. the average BOD of dilution However, water algae in the bacterial-free tests was 0.13 as compared to 0.19A DO/mg SS for all seeded tests. The similarity of the activity of these algae under bacterial-free conditions (Allen's, 0.12; and dilution water, 0.13 A DO/mg SS) should be noted. of measurements of the Comparisons of the algae photosynthetic capacity from the two media under seeded and bacterial-free conditions that indicated there was little difference in the photo synthetic activity of algae from Allen 's medium at zero time (0.093 seeded vs. 0.095 sterile A DO/mg SS). However, in the case of algae from the dilution water the medium, average zero Seed only _ Seed and Algae (13 mg/1) 6h Seed and Algae (27 mg/1) Time (Days) FIGURE 1.?Oxygen 27 mg/1 time increased from photosynthetic capacity 0.056A DO/mg SS for the seeded tests to 0.071A DO/mg SS for bacterial-free tests. ca The average photosynthetic pacity of all seeded tests after 5-days? water incubation for dilution algae utilization by seed and Chlorella in seeded dilution 13 mg/1 Chlorella and water. This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions 1530 JOURNAL WPCF December 1964 Algae (Dark plus 2-hr light before analysis) Algae (Initial 2-hr light) Algae( Dark Only) Time (Days) utilization by Chlorella (13 mg/1) from Allen's FIGURE 2.?Oxygen medium in seeded dilution water [Light: 2 hr, 350 ft-c (3,770 lumen/ sqm)]. In SS. (32 tests) was 0.024A DO/mg the contrast, capacity photosynthetic under con of algae from this medium for 5 days ditions of sterile incubation was 0.054A DO/mg SS, or twice the rate of tests run in seeded BOD bottles. Daily and Long-Term BOD Studies A series of BOD tests has been run to establish used the rate of oxygen by algae on a daily basis and for long The of time, up to 16 days. periods tests were set up as for normal BOD measurements samples were except analyzed that duplicate at the times re ported. 1 presents data from an ex Figure the daily change in periment showing dissolved in BOD bottles of oxygen seeded dilution seed 13 water, plus and seed plus 27 mg/1 algae, mg/1 from Allen's medium. These algae data indicate that oxygen utilization over the by the algae is fairly uniform in the dark. 5-day period 2 presents data obtained Figure This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions BOD MEASUREMENTS 1531 12 Vol. 36, No. was medium when algae from Allen's added to seeded dilution water (13 mg and some bottles were either algae/1) (in analyzed kept in the dark until exposed to 2 hr of 350 ft-c duplicate), (3,770 lumens/sq m) of light and then to 2 hr kept in the dark, or exposed of of 350 ft-c m) (3,770 lumens/sq light just before analysis after incuba The initial DO con tion in the dark. of centrations samples can be increased of the samples with algae by exposure to light with little significant change in from utilization rate of oxygen samples not exposed to an initial light of treatment (there was an average six of in increase activity five-percent to light as compared samples exposed to samples without light treatment). The data showing the level to which are raised in the DO concentrations to light just before samples exposed on a daily basis 2) (Figure analysis indicate that for the 5-day period with there is medium algae from Allen's ca little change in the photosynthetic the 6X Seed Only Algae (Allen's Medium) Algae (Dilution Water Medium) Time FIGURE Allen's seeded medium, dilution 3.?Oxygen and (Days) utilization by 6X seed, Chlorella (14 mg/1) Chlorella (16 mg/1) from dilution water from medium water. This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions in 1532 JOURNAL WPCF December 1964 Algae (Dark plus 2hr light before analysis ) Algae (Dark Only) Time (Days) utilization by Chlorella (28 mg/1) from Allen's FIGURE 4.?Oxygen medium in seeded dilution water [Light: 2 hr, 350 ft-c (3,770 lumen/ sqm)]. (average oxygen pacity of these algae of 35 samples at zero time production was SS and 0.083A 0.093A DO/mg SS for 5-day samples). DO/mg BOD tests were also run for as long as 16 days to determine the rate at which oxygen was consumed by algae over periods of time in excess of the usual 5-days' time used in BOD tests. 3 shows the rate at which oxy Figure gen was consumed by sewage seed (at 6 times the amount used to seed the water the algae dilution used with tests) and the rate of oxygen utiliza tion by algae from Allen's medium (14 as compared with that of algae mg/1) water medium from dilution (16 mg/1). 4 presents the rate at which Figure of algae oxygen was used by 28 mg/1 over a 16-day medium from Allen's period, as well as the amount of oxy of samples gen produced by exposure to 350 ft-c (3,770 lumen/sq m) of light It can be for 2 hr prior to analysis. seen that bottles became the BOD This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions Vol. 36, No. 12 BOD MEASUREMENTS 1533 in about 9 anaerobic (DO exhausted) the algae pres days' time. However, ent continued to produce oxygen when to exposed light, but at a decreasing rate. Viability tests of samples from these bottles at zero, 5, 12, 14, and 16 no loss in viability indicated days (average percent viable cells were 100, 94, 120, 123, and 115, respectively). Thus, these data confirm the results of et al. (9) who found Chlorella Golueke re and Scenedesmus to be relatively to anaerobic sistant and of digestion et al. (10) who found Chlorella Finkle to be viable after 70 days in the dark. The Effect of the Culture Medium indicated Preliminary experiments that the activity in the of Chlorella test could range BOD from 0.06 to 0.31 mg 02 used per mg suspended solids per 1 (A DO/mg SS), depend in which the ing on the medium The distress algae had been cultured. from these data was ing observation that the apparent of the algae activity from the different media to appeared be inversely to the potential correlated in the media; growth rate of Chlorella that is, algae from the two more con centrated media, Myers' and Allen's, showed less activity in the BOD test than algae from the very dilute dilu tion water medium. Other data, such as the results of bacterial-free BOD indicated that perhaps tests, however, the measured BOD of algae from the water medium a dilution was really combination of algal respiration and stimulated bacterial respiration. Because cell counts and viability tests by the dilution gave technique little correlation to other data, meas urements of the photosynthetic capac and dilution ity of algae from Allen's water media at the start and end of tests were made. BOD These data ca indicated that the photosynthetic of algae from Allen's medium pacity 11 percent decreased whereas there was a decrease of 57 percent with algae over from the dilution water medium ' a period of 5-days time. A re-evaluation of the effect of the different culture media on the activity in the BOD of Chlorella test was car ried out by comparing the apparent of the algae over the 5-day respiration the photosynthetic capac period with after 5 ity of the algae as measured in the dark. incubation The days' results are presented in Table III. These data indicate that algae grown in the three media, Myers ',Allen's, and have about the same photo Gorham's, after 5-days' incu synthetic capacity bation in the dark, but there is about a 50-percent increase in the activity of the algae in the BOD test. The algae from the dilution water medium have the highest in the BOD test, activity but demonstrate in the lowest activity the photosynthetic test. capacity The Effect of the Age of on Algal Activity Culture the In order to measure the effect the of age of a culture had on the activity algae in the BOD test, algae were used from cultures considered young or old, on the growth rate of depending the algae in the particular medium. A was made of these two comparison of cultures for dilution water, "ages" and Gorham's Allen's, Myers', (air for The results of these aeration) media. tests are summarized in Figure 5 as the amount of oxygen used by the solids algae per mg of suspended (A ages of SS) for the different DO/mg the cultures. The circles indicate the factor for each age average activity of the culture media tested and the lines running the cir heavy through cles indicate the range of ages used. lines are used to make the lines Light for each medium continuous. The number of samples used to determine the average value is indicated by the at each dot. The figure in parentheses are also ranges of pH of the media The pH values presented presented. are for the cultures at the time of har This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions 1534 JOURNAL WPCF TABLE III.?The Effect of the Culture 1964 December on Medium the Activity of Chlorella in the BOD Test BOD* Culture Medium pH 6.5 Myers' Allen's Capacity! Range Avg. Range 23 0.069-0.12 0.090 0.065-0.22 0.044-0.23 0.12 -0.31 0.11 0.14 0.087-0.18 0.030-0.26 0.031-0.22 0.14 32 0.20 0.014-0.039 0.027 34 14 Gorham's Dil. water Photosynthetic No. of Tests Avg. 0.13 0.13 *A DO/mg SS/5 days. f A DO/mg SS/2 hr, 350 ft-c (3,770 lumens/sq m) light, in There was little change vesting. the pH of the cultures the throughout growth period. It is evident that the average algal factor for young and old cul activity tures of dilution water (0.18 and 0.18A and Allen's medium (0.11 SS) DO/mg com and 0.12A DO/mg indicate SS) little change in activity per paratively as the age of the mg of cell material culture increases within the limits in the case of algae tested. However, in the other two media cultured there was a definite in older loss in activity cultures as compared with young cul tures. The average value for young and old cultures was 0.094 and 0.063A SS for algae from Myers' me DO/mg 0.20 Dilution Water (pH 7.4) 0.15 h Allen's (pH 7.2-7A) Gorham's 0.10 (pH 8.7-9.1) 0.05 h" Myer's (pH 6.0-6.7) 12 16 20 24 Age (Days) FIGURE 5.?Effect of age of culture on activity of Chlorella (four media). This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions SS dium and 0.16 and 0.12A DO/mg medium. for algae from Gorham's (dilu as the two media Inasmuch that had the and Allen's) tion water age of in activity with least decrease neu approximately the culture were be possible tral in pH value, it might removed from that pH values further the neutral value may be the principal cause of the senility of the cultures. Effect of Medium 1535 BOD MEASUREMENTS Vol. 36, No. 12 the pH of Gorham's on Algal Activity sec Because the data of the previous tion had pointed out that there might the pH of the be a relation between and the activity of the culture medium algae, further studies were carried out using Gorham's medium. It had been found that the range in in Gorham 's for cultures pH values these cul medium was 8.7 to 9.1 when tures were aerated with air, and pH the 1.25 7.0 to 7.8 when aerated with percent C02-air mixture. Therefore, aside from changes in the soluble min because of changes in eral composition to could be used pH, this medium and the effect of near neutral study of alkaline pH values on the activity Chlorella. A series of 34 tests was made with me algae from the alkaline Gorham's dium (aerated with air), 15 tests using 3 to 8 days old and 19 tests cultures A 19 to 23 days old. cultures with second series of 34 tests was made the neutral Gorham 's medium with a 1.25-pereent C02-air (aerated with 3 to mixture), 18 tests using cultures 7 days old and 16 tests using cultures 16 to 23 days old. The average values and range in obtained for each medium 6 as in Figure ages are summarized the amount of oxygen used per mg of suspended solids (A DO/mg SS). in There was a loss of 24 percent the activity of algae from older cul to tures at pH 8.7 to 9.1 as compared cultures (0.12 vs. 0.16A DO/ younger mg SS), whereas algae from cultures of at pH 7.0 to 7.8 had a difference only 11 percent between old and young cultures (0.15 vs. 0.17AV DO/mg SS). as a comparison of When expressed cultures of similar ages, at different pH values, there was only a 4-percent cultures at difference between young pH 7.0 to 7.8 and pH 8.7 to 9.1; of from old cultures whereas, algae pH 7.0 to 7.8 were 18 percent more active than algae from similar cultures of pH 8.7 to 9.1. Thus, it is indicated that the pH of the culture medium will affect the ac the effect being tivity of the algae, more pronounced as the age of the culture increases. However, this effect may not be the result of the difference in pH but may have been caused by these pH other factors accompanying such as a lack of dissolved changes, in the CO2 at pH 9, or a change nitrogen utilization at the different pH values. Studies with Chlorella Grown in Secondary Sewage Effluent Because the data obtained from stud ies with the previously discussed syn indicated thetic media that differences in the activity of the algae could be in the medium, caused by variations studies were made on Chlorella grown in different variations of autoclaved secondary sewage effluent. The gen eral composition of this effluent was approximately 20 mg NH3-N/l, 7 mg 950 mg total solids/l, P04-P/l, 380 mg methyl orange alkalinity (as CaCO3) /1, 10 to 30 mg BOD/l, and a pH of 7.8. Autoclaved Madison, Wisconsin, sec ondary sewage effluent, referred to as sewage effluent or S.E., was used as the culture medium for Chlorella in the same manner as the synthetic dia. The cultures were aerated a 1.25-pereent C02-air mixture at until growth was well established, me with least usu ally 2 days. The cultures continuously aerated with the 1.25-pereent CO2-air mixture maintained a pH of 7.3 to 7.8 pH of sewage effluent was (original 7.8, while the pH of autoclaved effluent was about 9). Cultures which were This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions December 1964 JOURNAL WPCF 153(; 0.20 0.15 - Gorham's 7.0-7.8) ~~~~~~~(pH \ Gorham's (pH 8.7 - 9,1) 0.10 _ CL) cn E 0.05 0 4 8 24 20 16 12 Age (Days) FIGURE 6.-Effect of pH of Gorham's medium aerated with only air after the initial period of growth had a range of pH these high pH from 8.8 to 9.4. At values considerable salts could be pre of suspended cipitated (40 to 90 mg/l solids and about 75 percent of soluble (12) ; also, there was P04-P) (11) little or no dissolved CO2 present. The amount of suspended solids formed when and sewage effluent was then aerated for six autoclaved days with the 1.25-percent C02-air mixture was about 40 mg/l, whereas about 65 mg/l were formed when only air was used. of in for these amounts Corrections organic suspended solids were made in calculating the supended solids of the algal cultures. the algae grown The tests run with to in in sewage effluent were designed the activity of algae dicate whether in the BOD test was different when on activity of Chorella. cultured under conditions of C02-lim ited growth (pH 9) as compared to The average sufficient CO2 (pH 7.5). activity factor, A DO/mg SS, for all added with sewage effluent cultures whereas CO2 was 0.29 (41 samples), it was 0.27 (41 samples) for algae grown under C 02 deficiency and a higher pH (ratio of 1.1). The aver age factor A DO/109 cells, was 1.5 for pH 7.5 cultures and 1.6 for pH 9 cul tures (ratio of 0.93). These results with algae cultured in modifications of sewage effluent have indicated, therefore, that, as in the case of the synthetic media tested, al conditions gae grown under of suffi cient CO2 (pH 7 to 7.5) were more active per mg of suspended solids in the BOD test than algae from C02 deficient cultures (pH 9) . Other tests indicated that this difference This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions is ap Vol. 36, No. BOD MEASUREMENTS 1537 12 enhanced age by increased parently but does not appear of the cultures to be related to the supply of nitrogen as NH3-N, or to the presence or ab sence of salts which might be removed from solution at the higher pH value. Effect on of Glucose and Fructose of Chlorella BOD thus far have The data reported dealt with the BOD of Chlorella when in an inorganic medium with measured amounts of dis the addition of minor in solved or suspended organic matter the form of settled sewage (the BOD of seeded dilution water being about 0.5 In order to demonstrate the mg/1). between of the relationship complexity the BOD of algae in such an environ ment to the BOD of algae in an en vironment containing organic mate a series rials in appreciable quantities, of five tests was carried out using glu cose and fructose. These two organic represent compounds readily available to bacteria while being se compounds to Chlorella. available Glu lectively cose is known to be an available source of energy fructose (13) (14), whereas un has been shown to be relatively available to certain of species algae, in these those used tests including (14). These tests were carried out in the normal manner of testing seeded dilu tion water with or without algae and seeded dilution water 4.3 containing mg of glucose or fructose per liter with or without The results of the algae. __ K = / Log cell number as an added five tests with fructose that the pres substrate have indicated ence of Chlorella had no effect on the bacterial BOD of fructose (less than variation with 10-percent controls). of bacterial stimulation respira Also, tion by the presence of fructose had no effect on the BOD of Chlorella (less In effect, than 5-percent variation). in the presence the BOD of Chlorella to the of fructose was merely additive In contrast, in the BOD of fructose. studies in which glucose was used as an the algae had a de added substrate, cided effect on the bacterial BOD. The presence of Chlorella decreased the bacterial BOD of glucose by about 50 percent. This effect could be in to indicate that the algae terpreted absorbed some of the glucose from solu tion, but the effect of this absorbed on the apparent BOD of the glucose amount not as as great of glucose an absorbed equivalent by sewage bacteria. Comparative Growth Studies with and Microcystis Rate Chlorella Studies Studies have been carried out com the rate of growth of Chlorella paring pyrenoidosa (Wis. 2005) and the blue bloom green producing alga, Micro cystis aeruginosa (Wis. 1036) when these two algae are cultured in Gor ham's medium. The rate of growth of the algae was followed of by counts of the number as follows: calculated and cells/ml at ?_2\ { Log cell number at <_J/ of time were Two different periods used to compare the rate of growth: 3 to 5 days after inoculation (increase in cell counts 3 mil approximately to 10 mil and 5 cells/ml cells/ml) to 12 days after inoculation (increase in cell counts 10 mil approximately to 28 mil It was cells/ml cells/ml). found in preliminary that experiments these two periods generally had differ was algae / . ~ (U ^ w. i (m days)" ent rates of growth and could be used to compare the algae under different conditions. physiological In two experiments with aerated Gorham's medium (pH 9) the growth rates for Chlorella were 0.22 and 0.25 for the younger cultures and 0.10 and 0.09 for the older cultures. In the same experiments, the growth rates for were 0.22 and 0.19 for the Microcystis This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions 1538 JOURNAL WPCF of Age of the Effect IV.-Summary and Microcystis of Chlorella Capacity TABLE (Averages of at Least December pH on the BOD in Gorham's Grown and 16 Tests and Photosynthetic Medium per Condition) Chlorella Ages (days) Medium Gorham's pH 7 Gorham's pH pH 7 9 pH 9 Gorham's Gorham's 3-8 19-24 0.17 0.15 3-8 19-24 0.16 0.12 Microcystis Photosynthetic Capacityf BOD* 1964 Photosynthetic Capacity! BOD* 0.15 0.16 0.085 0.11 0.073 0.093 0.075 0.13 0.16 0.042 0.083 0.11 *A DO/mg SS/5 days. f A DO/mg SS/2 hr, 350 ft-c (3,770 lumens/sq m) light. cultures and 0.09 for the older younger cultures. When medium Gorham's was gassed with C02 in 1.25-percent of air (pH 7), the rates of growth in young and Microcystis Chlorella cultures were tively, while old the rates 0.20, 0.33 and 0.24, respec 5- to 7-days in cultures of growth were 0.15, and respectively. the of Measurements suspended solids in the cultures during the period of 3- to 5-days' growth from the time of inoculation that the sus showed solids increased from approxi pended 40 to 110 mg/1. the mately During in the pH 7 of 5 to 7 days period medium the suspended solids increased in 110 to 240 mg/1, from whereas the pH 9 medium the suspended solids increase for the 5- to 12-days' period was only 110 to 300 mg/1. Effects of pH and Age A series of tests was carried out in and Micro which cultures of Chlorella ages from Gorham's cystis of different medium were used in the BOD test (at least 16 samples per condition). The cultures were either aerated and were or alkaline 8.9 to 10.6) (pH range were gassed with in C02 1.25-percent air and were neutral (pH range 6.5 to 7.8). A summary of the data from BOD tests and tests of the photosynthetic in incubation after five-days' capacity in Table IV. the dark is presented The activity of Chlorella decreases the age of the cultures and this with in activity with age is more decrease with pronounced algae from the pH as compared 9 medium to algae from the pH 7 medium. In contrast, it was found with Microcystis whereas that, the activity of the algae in the BOD test and the photosynthetic capacity of the algae decreased with the age ca of the cultures, the photosynthetic more from of the pacity Microcystis was much 9, medium alkaline, pH than that from the neutral greater medium. Effect of Mixing cystis Since to show Chlorella some workers and Micro have between antagonism been able various species of algae (15) (16), a series of 16 tests was carried out in which dif ferent relative concentrations of Chlo rella from Allen's medium and Micro cystis from Gorham's (pH 9) medium were used separately and in combina tions in the BOD and photosynthetic tests. capacity From the activity of the algae when in these tests, cal measured separately were made ac culations of expected rates of the various tivity mixtures, depending on the relative concen tration of each alga. The results of 16 BOD tests of mixtures of these an average A DO/mg algae indicated SS of 0.10, the range being 0.069 to the range of ac 0.13, or well within measured for the algae sepa tivity The results of the photosyn rately. thetic capacity in tests, after 5-days' This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions BOD MEASUREMENTS 1539 12 Vol. 36, No. in the dark, separately cubation and that the meas indicated in mixtures were 99 ured rates for the mixtures rates for of theoretical to 108 percent such calculated mixtures, when measured algae wrere from rates tested sepa one can say that the Thus, rately. and Microcystis, of Chorella activities in these tests, were addi when mixed tive and not antagonistic. BOD Long-Term Studies of oxygen used The (BOD) of either and photosynthetic capacity or Microcystis in seeded BOD Chlorella at have been followed water dilution for as long as 1- to 3-day intervals run with tests were 28 days. Four and media different from 3 Chlorella from Gorham's 3 tests with Microcystis In all tests with (pH 9) medium. de either alga, there was a gradual crease in DO in the BOD bottles until zero DO was reached (7- to 12-days' ca The photosynthetic incubation). was measured of the up algae pacity to and after the time the bottles be amount came anaerobic. It was found that, in the samples ca the photosynthetic wTith Chlorella, decreased pacity of the algae gradually after the bottles became anaerobic, but as wTas still measureable for periods as anaerobic under long eight days conditions. capacity of Photosynthetic from 0.18 to 0.078A Chlorella decreased SS during 8 days under anae DO/mg in a typical robic conditions experi ment. In the tests with Microcystis, the photosynthetic capacity of the alga was maintained at a higher rate for a longer period of time. Photosynthetic from decreased capacity of Microcystis 19 0.12 to 0.079A DO/mg SS during in one days under anaerobic conditions experiment. BOD of Other Algae The effects of three other algal spe cies on the BOD test have been studied. was The first, Scenedesmus dimorpha, isolated from a sewage oxidation pond at Lancaster, and was California, for study as a representative of the types of green algae species found in such installations. It was found that Scenedesmus could in Allen's medium be cultured readily The average effect for the BOD tests. on the BOD test in seeded dilution wa ter of 37 tests indicated it had an ac SS and tivity factor of 0.13A DO/mg an average capacity photosynthetic in the dark of 0.13A after 5 days SS. DO/mg A few tests (a total of eight) were run with the blue-green alga, Nostoc muscorum This alga is (Wis. 1013). well known studies of for the many to fix atmospheric its ability nitrogen factor (17) (18). The average activity in the BOD test of this alga was 0.093A SS and the average photosyn DO/mg in the after 5 days thetic capacity dark was 0.081A DO/mg SS. chosen The echinulata Gloeotrichia alga, (Wis. 1052), was chosen as a repre sentative of the blue-green algae that cause obnoxious in lakes and blooms are also nitrogen fixers. This alga was in three different media, Gor cultured minus the nitrogen ham's, Gorham's source, and Allen's. The average ac in the BOD test were: tivity factors from Gorham's medium (16 tests), 0.091A DO/mg from Gorham's SS; minus nitrogen (6 tests), 0.13A DO/mg (6 tests), 0.048A SS; and from Allen's ca SS. The photosynthetic DO/mg of these algae after 5 days in pacity to be the dark was generally found small for the majority of the samples tested. As a result of this observation of the low photosynthetic of capacity a series of BOD Gloeotrichia, daily and photosynthetic tests was capacity In the first two tests ?.n carried out. water seeded dilution of Gloeotrichia in Gorham's cultured it was medium, noted that the algae ceased to evolve on the second or third day oxygen when exposed to light. Within 48 hr of the time when the algae ceased to a sudden there was photosynthesize, in the rate at which increase oxygen This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions 1540 JOURNAL WPCF was as compared to the consumed rate of the first 3 to 4 days and to the rate of oxygen in Chlorella consumed tests run at the same time. A third series of tests with Gloeo trichia from Gorham's (pH 9) medium was carried out with seeded dilution seeded Gorham's and water, medium, raw lake water as the BOD test me dium. The in results of the tests seeded dilution water and seeded Gor are plotted ham's medium in Figure 7. The results of the tests in raw lake were water similar to these results the rate of oxygen used was except factors for di greater; BOD activity lution water, Gorham's and medium, o December 1964 lake water were 0.14, 0.15, and 0.59A days, respectively. DO/mg SS/5 From the data of Figure 7, Gloeo trichia seems to die after three to four of the BOD days under the conditions test (the point at which the algae cease a situation to photosynthesize), that had been found to be the previously case in studies of marine diatoms (8). the organic matter of Subsequently, the algae becomes avail apparently able to the bacteria and an present increased BOD activity results (a cal culation of the projected BOD of the water in dilution the algae during period, 5 to 10 days, would give a BOD rate of about 0.38A DO/mg SS). 6 3 Time 4 (Days) FIGURE utilization by Gloeotrichia (10 mg/1) in seeded 7.?Oxygen dilution water or seeded Gorham's medium [Light: 2 hr, 350 ft-c (3,770 lumen/sq m)]. Solid line, dark only; dotted line, dark plus 2-hr light. This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions Vol. 36, No. 12 BOD MEASUREMENTS 1541 Summary and Conclusions 1. The rate of growth of Chlorella in different media has been followed in the culture of by measurements volatile solids, suspended solids, COD, cell counts, and packed volume. 2. It was found that DO could be determined readily using the Winkler in solutions method Chlo containing at least as high rella in concentrations as 5 X 106 cells per ml. in seeded 3. The activity of Chorella dilution water in the BOD test appears to be independent of the volume of seed added (in the range of 3 to 30 ml seed/1). 4. There appeared to be no differ ence in the activity in the of Chlorella the original culture BOD test whether or was bacterial-free contaminated with sewage bacteria (one to five ml the addition of However, sewage/1). to cultures caused a five-fold sewage loss in the activity due to the super natant cultures when of the algal tested in BOD tests. or freeze 5. The BOD of autoclaved dried cells were Chlorella approxi four fold that of living cells. mately 6. No consistent could relationship be obtained between the amount of in the BOD oxygen used by Chlorella test and the number of viable cells measured and plating of by dilution incubation. samples after five-days' 7. The photosynthetic of capacity the algae before and after incubation in the BOD test indicated the physio logical state of the algae. Tests showed that this measurement could be used to indicate if algae were still active after different periods of dark incuba tion and the relative activity of algae from different cultures. 8. Tests of the BOD of Chlorella under seeded and bacterial-free condi the effect of algae from tions indicated were merely medium Allen's additive to the respiration of bacteria, whereas the more dilute dilution algae from water medium have caused a might to the respiration of slight stimulation bacteria present. 9. Daily and long-term of studies Chlorella in the BOD test showed that was quite the rate of oxygen utilization uniform until the BOD bottles became anaerobic. It was found that Chlorella to produce could continue oxygen by for at least seven days photosynthesis anae the BOD became bottles after robic. in the 10. The activity of Chlorella BOD test was found to vary consider ably, averages of activity ranging from 0.09- to 0.19-mg 02 used per mg sus on solids per liter, depending pended in which the algae had the medium been cultured. 11. The average and range of values in the BOD obtained test with Chlo rella from different culture media are in tabular form. presented 12. It was found that the activity of and Gorham's me algae from Myers' dia decreased with age of increasing the cultures. 13. Studies of the effect of pH of on Gorham's medium the activity in the BOD test indicated of Chlorella that algae from the more alkaline (pH a greater exhibited de 9) medium crease in activity with age increasing of the culture than algae from neutral (pH 7.0 to 7.8) medium. 14. Chlorella in autoclaved cultured a sewage effluent exhibited secondary in the BOD test higher activity (an of 0.27-mg O2 used per mg average than algae from the suspended solids) culture media. synthetic algae Also, from neutral pH cultures were more than algae from C02-deficient active cultures (pH 9). 15. The rate of oxygen utilization by in the BOD Chlorella test was found to be independent of any increase in bacterial due to the pres respiration ence of fructose. in the However, of glucose in the BOD presence test, the algae had a decided effect on the com bacterial BOD of this organic pound. 16. When comparative Chlorella and Microcystis tests with were made This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions 1542 JOURNAL WPCF were it was found that the rate of growth in the same medium of these algae (Gorham's pH 9) was remarkably similar. 17. Both exhibited Chlorella a decrease and Microcystis in activity with age of cultures. However, from Gorham's pH 9 me a higher photosynthetic ca increasing Microcystis dium had after pacity 5-days' the same alga from incubation than Gorham's 7 pH medium. 18. When were mixed found that Chlorella for and Microcystis test it was the BOD their activities separate 1964 December additive and not antago merely to each other. nistic was 19. Microcystis to be found able to photosynthesize after long pe riods of anaerobic (up to 19 days) or better as well conditions than Chlorella. 20. The effects of Scenedesmus di on the and Nostoc muscorum morpha to those of BOD test were similar and Microcystis. Chlorella 21. Tests with Gloeotrichia echinu lata indicated that this alga appears to die under the conditions of the BOD increased test, thereby causing bacterial respiration. Acknowledgment This research has been supported by a research grant (K-15) from the Na tional Institutes of Health, lic Health Service. U. S. Pub References 1. " Methods for the Examination '' and Wastewater. 11th Ed., Pub. York Health New Assn., Standard of Water Amer. (1960). 2. Allen, M. B., phyceae." many), 3. Burlew, "The Cultivation Arch. Mikrooiol. 17, of Myxo 34 S., Engineering San. Serv., Eng. 1958). Ohio (Mar. 7. Bartsch, A. F., "Algae on DO and BOD." R. Seminar, Center, A. Cincinnati, and Their rine Biol. Assn. United in Kingdom taas, C. H. G., B., W. Oswald, "Anaerobic J., and Cramer, M., and Reduction rella.f' Jour. and Digestion Go of 309 111, 1 Station, Myers, J., Assimilation Gen. 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Waksman, S. A., Stokes, L. J., and But of Bacteria to ler, M. R., "Relation in Sea Water." Diatoms Jour. Ma and D., of Chlorella (1957). 14. Griffiths, Health 47 11. Kaneshige, H. G. M., Fitzgerald, P., and G. "Stabilization Rohlich, A., Pond Studies.'' Univ. of Wisconsin 6. Wisniewski, Effects Taft 5, (1950). 13. Pub. Microoiol., 10. Finkle, B. J., Appleman, " Growth scher, E. K., in Dark." the garis ture of Microcystis Can. aeruginosa." Jour. Microoiol., 4, 225 (1958). 5. Oswald, W. H. B., "Pho J., and Gotaas, in Treatment." tosynthesis Sewage Proc. San. Eng. Amer. Soc. Civil Div., 686 Engr., 81, Sep. No. (1955). T. F., and Their "Algae on Dissolved and Bio Oxygen '' In " Oxy chemical Demand. Oxygen in Streams." U. S. gen Relationships Applied (1957). (Ger (1952). Culture: From "Algal to Pilot Plant." Laboratory Carnegie 600 No. Inst., Washington, (1953). 4. Hughes, E. O., Gorham, P. R., and Zehn Cul of a Unialgal der, A., "Toxicity J. " Algae. 433 (1937). Al of Blue-Green in Rice Fixation Soc. London Boyal Role 127, 121 (1939). This content downloaded from 170.140.26.180 on Thu, 21 Jan 2016 19:17:16 UTC All use subject to JSTOR Terms and Conditions