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Stream reaeration using molecular oxygen
42
River Pollution
indicate the probability of single values exceeding the limits. Only 32 per cent of all the values analysed lie outside the limits of the mean standard deviation s and only 18 per cent lie out of the limits of the mean+ 1.35 s. In the example given in I~G. 1 the relationship between oxygen saturation deficit and saprobity is given. On the basis of such an investigation it is possible without difficulty to give a classification as follows: A mainly oligosaprobic water with an oxygen saturation deficit of more than 30 per cent in only 9 per cent of the observed values was of very good quality and therefore placed in class I. On the other hand a mainly polysaprobic water which in 9 per cent had an oxygen saturation deficit of more than 70 per cent, was of bad quality and belonged to class IV. The limit between classes II and III is drawn at the limit between the 1~- and ct-mesosaprobic range, because the correlation between saprobity and B e D here has a point of inflexion KLOTrEg and I-IANTGE(1966). This limit lies at an oxgyen saturation deficit of 50 per cent (Fro. 1). On the base of such investigations it is possible to give exact limiting values for the four classes of water quality and for six parameters of water quality in running water (TABLE1). The limiting values except for saprobity have all the same probability of 9 to 15 per cent for exceeding the limits and they are correlated with the saprobic state of the water. In the waters examined by us we have found the same probability of the figures exceeding the limits under average water-flow conditions in an average year, which is mostly used as the critical conditions for water pollution control. The correlations of the limit values considered together enables conclusions to be made concerning particular conditions where the classification of different parameters do not agree. The classification makes it possible in a survey of water quality to arrive at the probability and duration of limiting values being exceeded. It also gives an insight of special features about the state of water quality, which is of advantage in the application of limiting values for water quality based on statistical methods. REFERENCES DIETEPaCH B. (1958) Die Einordnung des Oberfl/lchenwassers in die Wasserglitewirtschaft. Stuttg. Ber. SiedlungsWasserw. 1, 1-217. HAMMA. et aL (1965) Ober die Grundlagen der Abwasserphysiologie. B. Die Bewertung der Wassergiite nach dem Sauerstoffhaushalt im fliessenden Gewasser. Wasserwirtschaft 55, 304--310. KLOTTER H.-E. and HAN'rOE E. (1966) CIber die Auswertung biologischer Gewitssertmtersuchungen und ihre Relationen zum biochemiscben Sauerstoffbedarf (BBSs). Wasserwirtschaft 56, 21-26. LnmmAh'N H. (1962) Handbuch der Frischwasser- und Abwasserbiologie. Vol. 1, 2nd ed. Fischer, MEYER H. J. (1962) Probleme der Klassifizierung von Oberfl,'ichen gewllssern nach BeschafferLheit und Giite. Wiss. Z. K.. Marx-Univ. Lpz. 11, math.-nat. R. H. I, 149-151. PAI,rrLE R. and BUCK H. (1955) Die biologische f2berwachung der Gew~isser und die Darstellung der Ergebnisse. Gas Wassrf 96, 604. SLAOE6EgV. (1965) The future of the saprobity system. Hydrobiologia 25, 518-537. TOMPLrNo W. YON (1965) Ober den Zusammenhang zwischen Saprobiezustand und Faktoren des Sauerstoffhaushaltes in Fliel3gewassern. Verh. int. Ver. LimnoL In press. TOMPLrNG, W. VON(1966) Ober die statistische Sicherheit soziologlscher Methoden in der biologischen Gewlisseranalyse. Limnologica 4, 235-244. TOMPLING W. VON (1967) Zusammenh~inge zwischen Sauerstoffhaushalt und Saprobiezustand der Gewitsser. Fortschr. Wasserchem. In press.
S t r e a m r e a e r a t i o n using m o l e c u l a r o x y g e n . H . R. AMBERG, C a m a s , W a s h i n g t o n , U . S . A . Low dissolved oxygen levels in streams are generally associated with drought flows and high water temperatures, i.e. conditions which occur during the summer and possibly early fall months. Furthermore, waste treatment facilities are designed to protect the stream or provide adequate dissolved oxygen for conditions which may exist for only short periods of the year and may affect only a small portion of the total stream length. Design is generally based upon more drastic conditions, i.e. stream drought flows which can be expected once in ten, twenty, or thirty years.
River Pollution
43
Extremely costly and sophisticated treatment facilities will be required in the near future to protect many of the world's major streams from the effects of increasing population pressure and industrialization. In many situations, it is questionable whether existing known waste treatment methods can accomplish the desired water quality criteria at costs commensurate with the socio-economic gains. A point is reached where conventional effluent treatment processes, per se, will be inadequate to maintain the desired dissolved oxygen levels. F r o m a n engineering standpoint, it appears that a thorough review of alternatives for the attainment of water quality criteria is needed at this time. One alternative or supplement to conventional waste treatment involves stream treatment and a typical example is artificial stream reaeration. Artificial stream reaeration affords a promising method for alleviating critical dissolved oxygen conditions in many streams. Because of relatively low capital investment it lends itself to short-term use during critical stream conditions. Artificial stream reaeration using air is not new and it has been studied by a number of investigators in the United States and Europe. Although stream reaeration has been widely studied and used, the only gas that has been used is air. The use of air is limited to situations where the dissolved oxygen deficit is fairly large, i.e. aeration efficiency with air is very poor as the saturation level is aapproached. This problem can be overcome by using molecular oxygen which has a solubility 500 per cent greater than oxygen in equilibrium with air. To our knowledge, no experimental work has been reported on the use of tonnage oxygen for stream aeration. The experiments described in this report were designed to determine the feasibility of adding substantial quantities of dissolved oxygen to the water by aerating with molecular oxygen at locations having relatively high dissolved oxygen levels. The first series of experiments was conducted on a stream in the Pacific Northwest by venting molecular oxygen into a power turbine. A second series of tests will be conducted on a stream in the southern part of the United States where oxygen will be introduced by means of a conventional gas diffuser system placed on the stream bottom. It was found that venting of the power turbine with oxygen at a rate of 95 cm2/ft per rain resulted in the addition of 2 ppm of dissolved oxygen to the 410 fta/sec of raw water passing through the turbine when the dissolved oxygen concentration into the turbine was 7.8 ppm (81 per cent saturated). On a volume basis, the oxygen feed rate was 0.39 per cent of the water flow through the turbine and at this oxygen addition rate about 4400 lb of dissolved oxygen were added per turbine. Oxygen absorption efficiences at oxygen feed rates up to I00 cm2/ft per min per power turbine averaged about 40 per cent, and oxygen absorption per kWh power loss under these conditions was 9.5 lb. Turbine aeration with air at the same location was found to be impractical because of the high dissolved oxygen concentration in the water entering the turbines. For example, the maximum dissolved oxygen input at a n air feed rate of 280 cm2/ft per min was 0.2 ppm. Facilities are presently being constructed which will permit reaeration of a stream by means of introducing molecular oxygen through conventional diffusers placed on the stream bottom. Again aeration will be conducted at relatively high dissolved oxygen saturation values of about 80 per cent. Since the depth of water over the aeration system has an effect upon oxygen absorption efficiency, the aeration depth will be varied from 5 to 20 ft. These tests will be completed during the summer of 1967 and included in the report to be presented to the Conference. In summation, stream reaeration with tonnage oxygen appears to be feasible under certain conditions. Relatively large amounts of dissolved oxygen can be added to a water course even though the dissolved oxygen saturation level at the point of aeration is relatively high. Reaeration with oxygen permits intoduction of dissolved oxygen at almost any location along the stream, i.e. it is not limited to locations having a high dissolved oxygen deficit. With tonnage oxygen available at costs ranging from $10 to $30/ton, the cost of oxygenating a stream will range from about 1.5 cents to 4"0 cents/ pound of oxygen put into the solution.
Modified filter m e d i a f r o m r e m o v a l o f w a t e r pollutaats. C. D. AGARWAL a n d A. V. S. PRABHAKARA RAO, K a n p u r , I n d i a Many of the harmful effects of polluted water are generally due to the particulate pollutants, both the larger visible suspended matter and the colloidal particles that are responsible for turbidity and
River Pollution
indicate the probability of single values exceeding the limits. Only 32 per cent of all the values analysed lie outside the limits of the mean standard deviation s and only 18 per cent lie out of the limits of the mean+ 1.35 s. In the example given in I~G. 1 the relationship between oxygen saturation deficit and saprobity is given. On the basis of such an investigation it is possible without difficulty to give a classification as follows: A mainly oligosaprobic water with an oxygen saturation deficit of more than 30 per cent in only 9 per cent of the observed values was of very good quality and therefore placed in class I. On the other hand a mainly polysaprobic water which in 9 per cent had an oxygen saturation deficit of more than 70 per cent, was of bad quality and belonged to class IV. The limit between classes II and III is drawn at the limit between the 1~- and ct-mesosaprobic range, because the correlation between saprobity and B e D here has a point of inflexion KLOTrEg and I-IANTGE(1966). This limit lies at an oxgyen saturation deficit of 50 per cent (Fro. 1). On the base of such investigations it is possible to give exact limiting values for the four classes of water quality and for six parameters of water quality in running water (TABLE1). The limiting values except for saprobity have all the same probability of 9 to 15 per cent for exceeding the limits and they are correlated with the saprobic state of the water. In the waters examined by us we have found the same probability of the figures exceeding the limits under average water-flow conditions in an average year, which is mostly used as the critical conditions for water pollution control. The correlations of the limit values considered together enables conclusions to be made concerning particular conditions where the classification of different parameters do not agree. The classification makes it possible in a survey of water quality to arrive at the probability and duration of limiting values being exceeded. It also gives an insight of special features about the state of water quality, which is of advantage in the application of limiting values for water quality based on statistical methods. REFERENCES DIETEPaCH B. (1958) Die Einordnung des Oberfl/lchenwassers in die Wasserglitewirtschaft. Stuttg. Ber. SiedlungsWasserw. 1, 1-217. HAMMA. et aL (1965) Ober die Grundlagen der Abwasserphysiologie. B. Die Bewertung der Wassergiite nach dem Sauerstoffhaushalt im fliessenden Gewasser. Wasserwirtschaft 55, 304--310. KLOTTER H.-E. and HAN'rOE E. (1966) CIber die Auswertung biologischer Gewitssertmtersuchungen und ihre Relationen zum biochemiscben Sauerstoffbedarf (BBSs). Wasserwirtschaft 56, 21-26. LnmmAh'N H. (1962) Handbuch der Frischwasser- und Abwasserbiologie. Vol. 1, 2nd ed. Fischer, MEYER H. J. (1962) Probleme der Klassifizierung von Oberfl,'ichen gewllssern nach BeschafferLheit und Giite. Wiss. Z. K.. Marx-Univ. Lpz. 11, math.-nat. R. H. I, 149-151. PAI,rrLE R. and BUCK H. (1955) Die biologische f2berwachung der Gew~isser und die Darstellung der Ergebnisse. Gas Wassrf 96, 604. SLAOE6EgV. (1965) The future of the saprobity system. Hydrobiologia 25, 518-537. TOMPLrNo W. YON (1965) Ober den Zusammenhang zwischen Saprobiezustand und Faktoren des Sauerstoffhaushaltes in Fliel3gewassern. Verh. int. Ver. LimnoL In press. TOMPLrNG, W. VON(1966) Ober die statistische Sicherheit soziologlscher Methoden in der biologischen Gewlisseranalyse. Limnologica 4, 235-244. TOMPLING W. VON (1967) Zusammenh~inge zwischen Sauerstoffhaushalt und Saprobiezustand der Gewitsser. Fortschr. Wasserchem. In press.
S t r e a m r e a e r a t i o n using m o l e c u l a r o x y g e n . H . R. AMBERG, C a m a s , W a s h i n g t o n , U . S . A . Low dissolved oxygen levels in streams are generally associated with drought flows and high water temperatures, i.e. conditions which occur during the summer and possibly early fall months. Furthermore, waste treatment facilities are designed to protect the stream or provide adequate dissolved oxygen for conditions which may exist for only short periods of the year and may affect only a small portion of the total stream length. Design is generally based upon more drastic conditions, i.e. stream drought flows which can be expected once in ten, twenty, or thirty years.
River Pollution
43
Extremely costly and sophisticated treatment facilities will be required in the near future to protect many of the world's major streams from the effects of increasing population pressure and industrialization. In many situations, it is questionable whether existing known waste treatment methods can accomplish the desired water quality criteria at costs commensurate with the socio-economic gains. A point is reached where conventional effluent treatment processes, per se, will be inadequate to maintain the desired dissolved oxygen levels. F r o m a n engineering standpoint, it appears that a thorough review of alternatives for the attainment of water quality criteria is needed at this time. One alternative or supplement to conventional waste treatment involves stream treatment and a typical example is artificial stream reaeration. Artificial stream reaeration affords a promising method for alleviating critical dissolved oxygen conditions in many streams. Because of relatively low capital investment it lends itself to short-term use during critical stream conditions. Artificial stream reaeration using air is not new and it has been studied by a number of investigators in the United States and Europe. Although stream reaeration has been widely studied and used, the only gas that has been used is air. The use of air is limited to situations where the dissolved oxygen deficit is fairly large, i.e. aeration efficiency with air is very poor as the saturation level is aapproached. This problem can be overcome by using molecular oxygen which has a solubility 500 per cent greater than oxygen in equilibrium with air. To our knowledge, no experimental work has been reported on the use of tonnage oxygen for stream aeration. The experiments described in this report were designed to determine the feasibility of adding substantial quantities of dissolved oxygen to the water by aerating with molecular oxygen at locations having relatively high dissolved oxygen levels. The first series of experiments was conducted on a stream in the Pacific Northwest by venting molecular oxygen into a power turbine. A second series of tests will be conducted on a stream in the southern part of the United States where oxygen will be introduced by means of a conventional gas diffuser system placed on the stream bottom. It was found that venting of the power turbine with oxygen at a rate of 95 cm2/ft per rain resulted in the addition of 2 ppm of dissolved oxygen to the 410 fta/sec of raw water passing through the turbine when the dissolved oxygen concentration into the turbine was 7.8 ppm (81 per cent saturated). On a volume basis, the oxygen feed rate was 0.39 per cent of the water flow through the turbine and at this oxygen addition rate about 4400 lb of dissolved oxygen were added per turbine. Oxygen absorption efficiences at oxygen feed rates up to I00 cm2/ft per min per power turbine averaged about 40 per cent, and oxygen absorption per kWh power loss under these conditions was 9.5 lb. Turbine aeration with air at the same location was found to be impractical because of the high dissolved oxygen concentration in the water entering the turbines. For example, the maximum dissolved oxygen input at a n air feed rate of 280 cm2/ft per min was 0.2 ppm. Facilities are presently being constructed which will permit reaeration of a stream by means of introducing molecular oxygen through conventional diffusers placed on the stream bottom. Again aeration will be conducted at relatively high dissolved oxygen saturation values of about 80 per cent. Since the depth of water over the aeration system has an effect upon oxygen absorption efficiency, the aeration depth will be varied from 5 to 20 ft. These tests will be completed during the summer of 1967 and included in the report to be presented to the Conference. In summation, stream reaeration with tonnage oxygen appears to be feasible under certain conditions. Relatively large amounts of dissolved oxygen can be added to a water course even though the dissolved oxygen saturation level at the point of aeration is relatively high. Reaeration with oxygen permits intoduction of dissolved oxygen at almost any location along the stream, i.e. it is not limited to locations having a high dissolved oxygen deficit. With tonnage oxygen available at costs ranging from $10 to $30/ton, the cost of oxygenating a stream will range from about 1.5 cents to 4"0 cents/ pound of oxygen put into the solution.
Modified filter m e d i a f r o m r e m o v a l o f w a t e r pollutaats. C. D. AGARWAL a n d A. V. S. PRABHAKARA RAO, K a n p u r , I n d i a Many of the harmful effects of polluted water are generally due to the particulate pollutants, both the larger visible suspended matter and the colloidal particles that are responsible for turbidity and