LIBRARY OF THE UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN rvo. *5^>- "OG OOHf.«« ENGINEERING The person charging this material is re- sponsible for its return on or before the Latest Date stamped below. Theft, mutilation and underlining of books are reasons for disciplinary action and may result in dismissal from the University. UNIVERSITY OF. .]LUNOJS_ _LIBi*A£Y._AT_UI£B4NA-CJiAMPAIGN CONFERENCE L161— O-1096 Digitized by the Internet Archive in 2013 http://archive.org/details/effectsofbenthic55hovi C- 2 ^ CIVIL ENGINEERING STUDIES C* mm SANITARY ENGINEERING SERIES NO. 55 EFFECTS OF BENTHIC DEPOSITS ON DISSOLVED OXYGEN AND ORGANIC CONCENTRATIONS IN A SMALL STREAM X £ (X < Qg o Z £9 13 <2 3 -J — z CD Z it 3 LU UJ 0* co Z S 3 «■* v-'J o : z T Ul D UF ILLiHG* MAR 24 \m LIBRARY By JOSEPH C. HOVIOUS Supported By FEDERAL WATER POLLUTION CONTROL ADMINISTRATION RESEARCH GRANT WP 01020 and PUBLIC HEALTH SERVICE TRAINEESHIP GRANT EH 68-616 DEPARTMENT OF CIVIL ENGINEERING UNIVERSITY OF ILLINOIS URBANA, ILLINOIS JANUARY, 1970 EFFECTS OF BENTHIC DEPOSITS ON DISSOLVED OXYGEN AND ORGANIC CONCENTRATIONS IN A SMALL STREAM by Joseph C. Hovious Special Problem submitted in Partial Fulfillment for the Requirements of the Master of Science Degree in Sanitary Engineering Department of Civil Engineering University of Illinois Urbana, Illinois 61801 December 1969 ABSTRACT Four recirculating laboratory chambers were constructed to measure the changes in dissolved oxygen (DO) and organic concentrations caused by stream benthos. The incident lighting and the velocity and temperature of the chambers were controlled in the laboratory environment. Two of the chambers were constructed of opaque material to prevent photosynthesis and thus to evaluate the effects of floating and attached algae. Experiments were conducted with benthic samples obtained from a small stream in two of the chambers with the remaining two used as controls. All chambers contained streamwater. Results indicated that the bottom samples studied removed oxygen from the water at a rate described by y = 6.17 C . 2 in which y = oxygen uptake in mg/ft -hr C = oxygen concentration in mg/1 The chemical oxygen demand (COD) levels were approximately equal in all chambers and increased organic concentration was insufficient to explain the large differences in oxygen uptake between benthic and nonbenthic systems. A model based on the data of this study is proposed to predict stream oxygen concentration and compared with actual stream DO profiles. li ACKNOWLEDGMENTS The equipment described below was developed as part of a study "Oxygen Relationships in Small Streams" sponsored by the Federal Water Pollution Control Administration, Department of the Interior, under Research Grant WP 01020. Additional support was provided to the author by the United States Public Health Service in the form of a Traineeship and by the Chemical Industries Council, Midwest in the form of a Graduate Training Fellowship. Special thanks are given to Professors J. H. Austin and B. B. Ewing and to Dr. F. W. Sollo, Jr. who provided guidance during the course of equipment development and experimentation. 111 TABLE OF CONTENTS Page ABSTRACT ii ACKNOWLEDGMENTS iii LIST OF TABLES v LIST OF FIGURES vi INTRODUCTION 1 EXPERIMENTAL APPARATUS 2 SYSTEM HYDRAULICS 6 SAMPLING TECHNIQUES 9 EXPERIMENTAL PROCEDURE 10 RESULTS AND COMPUTATIONS Initial Tests 11 Tests with Benthic Samples 15 DISCUSSION 26 APPLICATIONS OF RESULTS 46 CONCLUSIONS 49 REFERENCES 53 APPENDIX I 55 APPENDIX II o . . . . 60 IV LIST OF TABLES Table Page I PHYSICAL PROPERTIES OF BENTHIC SAMPLE, EXPERIMENT VI . 15 II VOLUME AND CROSS -SECTIONAL AREA 17 III ADJUSTED VELOCITIES IN BENTHIC CHAMBERS 17 IV FACTORS AFFECTING DO AND BOD . . . 26 V SLOPE AND INTERCEPT VALUE FOR y = aC b 39 VI CHANGES IN OXYGEN UPTAKE IN LIGHT AND DARK PLANKTONIC CHAMBERS 42 VII GAIN OF COD IN BENTHIC CHAMBERS 45 LIST OF FIGURES Figure Page 1 SYSTEM SCHEMATIC ................... 3 2 EXPERIMENTAL APPARATUS IN OPERATION . . „ . . » . . . 4 3 DO VS TIME FOR TRACER TEST . . . . 7 4 THEORETICAL VS OBSERVED DETENTION TIMES . . . . . . . 8 5 OXYGEN UPTAKE FOR EXPERIMENT I--GLUCOSE-GLUTAMIC ACID 13 6 OXYGEN UPTAKE FOR EXPERIMENT II- -DOMESTIC SEWAGE ... 14 7 LB CHAMBER WITH BENTHIC SAMPLE ............ 16 8 OXYGEN UPTAKE FOR EXPERIMENT III 18 9 OXYGEN UPTAKE FOR EXPERIMENT IV . 19 10 OXYGEN UPTAKE FOR EXPERIMENT V 20 11 OXYGEN UPTAKE FOR EXPERIMENT VI . 21 12 COD AND BOD DATA- -EXPERIMENT III .......... , 22 13 COD AND BOD DATA- -EXPERIMENT IV .„ ... ..... . 23 14 COD AND BOD DATA- -EXPERIMENT V. ........... 24 15 COD AND BOD DATA- -EXPERIMENT VI ........... 25 16 OXYGEN UPTAKE VS CONCENTRATION- -LB, EXPERIMENT III . . 30 17 OXYGEN UPTAKE VS CONCENTRATION- -DB, EXPERIMENT III . . 31 18 OXYGEN UPTAKE VS CONCENTRATION- -LB , EXPERIMENT IV . . 32 19 OXYGEN UPTAKE VS CONCENTRATION- -DB, EXPERIMENT IV . „ 33 20 OXYGEN UPTAKE VS CONCENTRATION- -LB, EXPERIMENT V „ . . 34 21 OXYGEN UPTAKE VS CONCENTRATION- -DB, EXPERIMENT V . . . 35 22 OXYGEN UPTAKE VS CONCENTRATION- -LB, EXPERIMENT VI . . 36 23 OXYGEN UPTAKE VS CONCENTRATION- -DB, EXPERIMENT VI . . 37 24 SAMPLE WEIGHT VS BENTHIC OXYGEN UPTAKE RATE ..... 40 25 BENTHIC UPTAKE RATE VS SAMPLE COLLECTION DATE .... 41 VI LIST OF FIGURES (continued) Figure Page 26 EFFECT OF WATER DEPTH ON PROPORTION OF TOTAL OXYGEN UPTAKE BY RIVER MUD . . „ „ „ 44 27 STREAM DO PROFILES . . „ . . . . 50 AI-1 ORFICE METER „ . . . . 56 AI-2 PROBE HOLDER ...... . 57 AI-3 CHAMBER . . 58 AI-4 FRAME „ o . . o 59 AII-1 CUMULATIVE OXYGEN UPTAKE BY WATER IN DB, EXPERIMENT IV 61 vix INTRODUCTION Many advances have occurred since the classical work of Streeter and Phelps (1925) in the prediction of effects of waste disposal on a receiving stream. One factor which has recently received a great deal of attention is the effect of benthal deposits. Baity (1938) and Fair, Moore, and Thomas (1941) were among the earliest to examine benthal decomposition of organic wastes. Both investigations used either sewage sludges or highly organic muds from river bottoms in laboratory evaluations. Their proce- dures have been used by several other authors with similar types of sedi- ments or apparatus (Oldaker, Burgum, and Pahren, 1966; Hanes and Irving, 1966; and Hanes and Davison, 1969). The in situ measurements are ordi- narily conducted under naturally varying conditions of stream temperatures and light. Recently, studies of natural stream cores under controlled laboratory conditions have been conducted by Knowles, Edwards, and Briggs (1962), Edwards and Rolley (1965) and McDonnell and Hall (1967). Another factor which is important in evaluation of a small stream is algal photosynthesis and respiration. Leifer (1969) has recently pinpointed shortcomings in the light and dark bottle technique and has suggested revised techniques. This report covers testing of equipment designed to measure photosyn- thesis and respiration of both phytoplankton and benthal samples from shallow streams under controlled conditions. EXPERIMENTAL APPARATUS The equipment used for the evaluation of benthic oxygen demand was based on four chambers constructed of 0.5 in plexiglass. The inside dimen- 3 sions of the chamber were 3 in by 6 in by 48 in for a 0.5 ft or 13.9 1 volume. Two chambers were constructed of clear Plexiglass G while the others were made of black plexiglass. All chambers were fitted with a clear or black plexiglass top and a rubber gasket and steel clamping device to prevent liquid leaks. At the downstream end of each chamber lid a 0.75 in plexiglass tube was used to vent gases, to provide a positive pressure on the liquid within the chambers, and to allow sampling of the liquid within the system. The vent was also used to insert a thermistor into each chamber. Each chamber formed part of a separate system. The systems consisted of the sealed chamber, a stainless steel pump to provide liquid recircula- tion, a stainless steel coil immersed in a constant temperature bath, an orifice meter for flow measurement, and temperature and dissolved oxygen (DO) probes. The volume of water contained in the accessory equipment was 13 9 1.1 1. The chamber contained ' = 92.8 per cent of the total volume within any system. The various system components were connected with clear 0.5 in I.D. Tygon tubing. A schematic drawing and a photograph of the four systems in operation are shown in Figures 1 and 2 while detailed equipment drawings and a list of components are given in Appendix I. All components were selected to avoid any contaminants which would hinder biological activity. Leifer (1969) has shown that Plexiglass G is nontoxic by bioassy procedures. All other components of the systems were stainless steel, polyvinyl chloride piping, or the aforementioned Tygon tubing. Suspended approximately 1.5 ft over the clear chambers was a light source consisting of three General Electric Daylight Fluorescent tubes 2 Water Manometer DO Probe and Holder Orifice Meter Stainless Steel Screens To Minimize Jet Flow Sealed Chamber Containing Water- With Or Without Benthic Sample Recirculation Pump Stainless Steel Coil In Constant Temperature Bath FIGURE I SYSTEM SCHEMATIC FIGURE 2. EXPERIMENTAL APPARATUS IN OPERATION (see Figure 2). The light transmission capacity of Plexiglass G in the ranges necessary for algal growth has been shown by Leifer (1969) to be at least 90 per cent of the incident radiation. The light available provided sufficient illumination for algal photosynthesis. An interesting feature of the equipment was the automatic DO monitoring system based on the YSI BOD bottle probe*. The entire flow of the system was circulated past the probe in order to provide sufficient velocity for accurate readings and to represent DO concentrations within each chamber. Dissolved oxygen probes were calibrated at various temperatures against a standard probe. The standard probe was calibrated before each use by the alkaline-iodide azide modification of the Winkler DO test ( Standard Methods , 1965). The outputs from the four oxygen probes and thermistors were intro- duced into a stepping switch. The switch sequentially transmitted each temperature and DO value for a period of three minutes along with an internal check of zero and midscale readings, giving a recycle time of 0.5 hr. Read- out was on a Sargent Model SRG recorder with special slow speed drive. Another important part of the experimental equipment consists of the benthic sampling trays. The trays were constructed from 12 Ga stainless steel and covered with an open mesh rubber laboratory mat to allow for growth of benthic organisms and collection of sediments. Dimensions of the 2 trays were 5 in by 43 in for a 1.49 ft sample area. The chambers and associated equipment were completely cleaned before and after every test. In order to eliminate any carryover of contaminants or seed organisms from one test to another, the entire system including all tubing was scrubbed in soap (Alconox) and water. After two tap water rinses, * Product of the Yellow Springs Instrument Company, Yellow Springs, Ohio 5 a chlorine rinse (approximately 30 mg/1 NaOCl) , and another tap water rinse, the system was flushed three times with deionized water and allowed to air dry. An orthotolodine test showed no chlorine residual on filling the assembled system with deionized water after cleaning and drying. SYSTEM HYDRAULICS In order to determine the flow characteristics within the systems and to insure that no portion of the water was unmixed, tracer studies were con- ducted at various flows. A chamber and associated apparatus were filled with air-saturated water and the flow was established and measured. The DO recording apparatus was set on constant readout and the depletion of oxygen due to a catalyzed slug dose of sodium sulfite was used as a tracer. The catalyzed sulfite was introduced into the effluent line through the sampling vent by use of a pipet with a curved tip. The drop in DO was then read directly on the recorder. Figure 3 shows a typical trace of DO versus time. The dips in the DO reading indicate the passage of the zone of sulfite depleted water while the rise between minimums is due to passage of water as yet unaffected by the sulfite in the recycling system. The elapsed time between the dips is the time of flow through the chamber. At all flow rates, after two passages of the depleted water, the oxygen concentration attained an equilibrium value which indicates that the depleted water was completely mixed. Figure 4 shows a plot of theoretical versus observed detention time in the chamber. The data indicate that some short-circuiting existed at medium flow rates. At very low flow rates the data are less accurate due to broad, flat secondary peaks. 3 E i o> c •o o or c o ■D 0) _> o 70 60 50 40 30 20- 10 i i i i i i — i i i i i i i i i ' ■ ' ' — r -* >- 3.3 Measured Flow =0.77 gpm = 2.92 i/min. Theoretical Detention Time = 151/2.92 i/min. =5.l9min. Measured Detention Time = 3.3 min. ■ ' ' J I l_l I I I L J I I L J— J I I L-L 10 15 20 Arbitrary Time Scale-min. 25 FIGURE 3 DO VS TIME FOR TRACER TEST 2 3 4 5 6 Actual Detention Time-min. 8 FIGURE 4 THEORETICAL VS OBSERVED DETENTION TIMES SAMPLING TECHNIQUES Benthic samples were collected 5.1 mi below the Urbana and Champaign Sanitary District outfall in the Saline Branch of the Salt Fork of the Vermilion River. The stream, waste flows, and physical conditions existing have been described previously (Austin and Sollo, 1969). In brief, the stream at the sampling point is shallow (0.5 - 2.0 ft) with a velocity of 0.5-2 ft/sec. The primary constituents of the stream bottom are sand and small stones. Eight sampling trays were secured to the stream bottom by wiring them to 0.5 in diameter steel rods driven 3 ft into the bottom. The securing stakes were positioned so that they were between the trays and did not inter- fere with stream flow under normal conditions. Occasionally, clumps of floating algae would entangle on the stakes creating a higher velocity over the sampling trays. Periodic cleaning of the stakes eliminated the change in velocity. Shortly after the trays were set into the stream, the increased flow of a thundershower deposited 1 to 2 in of substrate onto them. By the end of a 4-week acclimatization period, the only distinguishing characteristics of the sampling location were the stakes used for securing the trays. The rooted aquatic Elodea grew on one of the trays while Cladophera was present on several others. After the first trays were removed for testing, another storm removed the rooted and attached growths and deposited another 4 to 5 in of bottom material onto the trays. As the accumulated depth was too great to fit into the laboratory chambers, the excess was removed to a 1 in depth. Large growths of rooted plants or attached algae did not occur in the stream during the remainder of the sampling period. The trays were transported into the laboratory in a waterproofed box which kept them moist and separate. Care was taken to avoid excessive disturbance of the sample as it was transferred from the stream bottom to the transport box. Along with the benthic sample, 80 1 of streamwater was transported to the laooratory in Nalge carboys. Samples for chemical oxygen demand (COD) analysis were obtained from the vent in the top of the chamber. Uniform depth of the samples was established by fitting a rubber stopper on a 20 ml volumetric pipet. After sampling, the vent was refilled with deionized water. The dilution provided by the practice • • i i i j • t j 1 x 20 m l n „ j 1 1 ^ - was minimal--ten samples would yield T~r~Z™ — 1 — = 1.3 per cent dilution. 15 ,000 ml EXPERIMENTAL PROCEDURE The experimental procedure for the batch systems proceeded as follows: Before the samples were collected from the stream, all equipment was assembled and the tops were clamped onto the light (hereafter designated as LP) and dark (DP) chambers to be tested with streamwater only. The P refers to the testing of planktonic algae in the light and dark chambers. Immediately after collection, the samples were brought into the laboratory (15 to 20 min trip). The streamwater was aerated using filtered air and diffuser stones in a large plexiglass container with a submersible pump used to provide mixing. Benthic samples were placed in the light and dark benthic (LB and DB) chambers and the tops sealed. To provide uniform water in the chambers, each was half filled after- which the filling was completed. The submersible mixing pump was used to fill the chambers. After filling, the circulation pumps were started to fill the tubing and the chambers topped off. The downstream (vent) end of each chamber was elevated 4 in to allow gas escape. After setting flows and checking for leaks, DO and temperature recording equipment was put into place and data collection begun. 10 Initial pH measurements were made on the excess streamwater and samples from each chamber and initial streamwater were taken for COD tests. Initial 5-day biochemical oxygen demand (BOD) of the streamwater was also determined. During the course of an experiment, samples for COD determinations were collected at 3 hr intervals during the day and 6 hr or greater intervals at night. Due to the great oxygen demand of the benthic samples, the DO resource within these chambers had to be augmented by periodic addition of pure oxygen gas. A curved tube was inserted into the vent and bubbles of pure oxygen were released into the outlet of the chamber. The pump dispersed the large bubbles into fragments and greatly aided in the oxygen transfer process. Cumulative oxygen uptakes were corrected for addition of oxygen as described under DISCUSSION. At the end of the one-day experiment, final COD samples were obtained and the pumps stopped. Supernatant water samples ware taken for final BOD aid pH determinations. The water was drained from the benthic chambers and the wet weight of the sample was determined. In one experiment, dried and volatile solids ware also determined at this point. After disposal of the sample, the cleanup was begun. RESULTS AND COMPUTATIONS Initial Tests Prior to tests on benthic samples, an experiment was conducted in which all four chambers were filled with a standard glucose-glutamic acid solution to check performance under identical conditions. During this test, it was discovered that one of the constant temperature baths did not have sufficient cooling capacity to dissipate the heat generated by the recirculation and mixing pumps. Consequently, the sets of light and dark chambers ware 11 maintained at up to 8°C temperature differences. Also, during this test, it was shown that the standard COD technique did not have sufficient accuracy to measure changes occurring. Consequently, the modified COD technique was used for the remainder of the tests. Oxygen uptake versus time curves for the glucose-glutamic acid test are shown in Figure 5. The two curves with the greater uptake rates were those at the higher temperatures (DP and DB) . The initial BOD of the water in the boxes was 8.4 mg/1. If a first order BOD utilization model is assumed over the first 24 hrs of the test, the model yields a K (base e) of 0.65 day for the cooler and 0.77 day for the warmer chambers. Using the mean temperature difference over the first 24 hrs of 4°C and the relationship of the deoxygena- tion coefficient, K(T) (T - T') K(T') - found by Streeter (1935) yields a 9 of 1.044. The computed 9 compares well with the 1.047 value found by Streeter. A BOD determination made on the glucose-glutamic acid yielded a value of 237 mg/1 which is within the 224 to 242 mg/1 range presented by Standard Methods (1965) for samples seeded with river water. In spite of the first order assumption made for the above computations, it is obvious that the uptake curves shown in Figure 5 are not classic first order oxygen uptake. It was thought that the initial lag period might be due to inadequate seed. In order to test the seed concentration and to use a more varied substrate, the oxygen uptake of a solution of raw domestic sewage was determined. Uptake curves are shown in Figure 6. In this and all subsequent tests, the temperature was adjusted by maintaining a flow of cool tap water into the bath. The temperature for the remainder of the tests was maintained between 18° C and 21° C. The COD and BOD data for test II were all 12 1000 1400 1800 2200 0200 Time of Day 0600 1000 1400 20 18 I6h Dark Chambers -DP • -DB 1000 1400 1800 2200 0200 0600 1000 1400 Time of Day FIGURE 5 OXYGEN UPTAKE FOR EXPERIMENT I-GLUCOSE- GLUTAMIC ACID 13 1000 1400 1800 2200 0200 Time of Day 0600 1000 1400 1000 1400 1800 2200 0200 0600 1000 1400 Time of Day FIGURE 6 OXYGEN UPTAKE FOR EXPERIMENT II- DOMESTIC SEWAGE erroneous, apparently due to material gained from passage through rubber tubing used to siphon water from blanks. Tests indicated that water passed through the hose gained a COD of 15.7 mg/1. Once again, the uptake curves are obviously not first order. The chambers did perform similarly under the conditions of the test. Tests with Benthic Samples The pH existing in the initial streamwater after transport to the labo- ratory was neutral or slightly above. The pH change in the plankton chambers during the course of a test was less than that in the benthic chambers by 0.3 to 0.4 units. The benthic chambers had a pH decrease of 0.4 to 0.6 units during each 24-hour test period. In one case where the benthic unit was allowed to go without oxygen for a period of 6 hrs, the final pH had dropped 1 unit—from 7.2 to 6.2. In one test, samples of the benthos were taken for determination of specific weight, per cent moisture, and volatile content. The material collected on sampling trays was quite heterogeneous as may be seen in Figure 7 and exhibited a considerable spread between samples. The results and ranges of data are presented in Table I. TABLE I PHYSICAL PROPERTIES OF BENTHIC SAMPLE, EXPERIMENT VI Average Maximum Minimum Specific weight 105.9 lb/ft 3 119.1 lb/ft 3 84.9 lb/ft 3 Per cent water in wet sample 27.4 44.1 13.8 Per cent volatile solids 3.48 4.94 1.93 The sample wet weights for the benthic tests were determined by weighing the chamber and tray after each test. Using the average specific weight and the tray length of 3.583 ft, a volume and average cross-sectional area can be determined for each sample as in Table II. 15 FIGURE 7 LB CHAMBER WITH BEMTHIC 5ANAPLE 16 TABLE II VOLUME AND AVERAGE CROSS- SECTIONAL AREA Li fiht Sample Dark Sample Test Wt, Volume Area Wt. Volume Area III 9.141 lbs .0863 ft 3 0.024 ft 2 15.06 lbs 0.1421 ft 3 0.040 ft IV 18.59 .1755 .049 16.41 .1551 .043 V 18.06 .1706 .048 19.70 .1861 .052 VI 17.27 .1631 .046 19.68 .1860 .052 The experiments involving the benthic samples were conducted at three flow rates, 0.5, 0.75, and 1.0 gpm. The data on sample area from Table II have been combined with flow data to yield the average velocities shown in Table III. TABLE III ADJUSTED VELOCITIES IN BENTHIC CHAMBERS Adjusted Velocity Test Flow 1.0 gpm Nominal 1.07 Veloci Et/min ty Light Chamber Dark Chamber III 1.32 ft/min 1.57 ft/min IV 1.0 1.07 1.76 1.63 V .5 .535 .89 .91 VI .75 .802 1.27 1.37 Dissolved oxygen readings from the various ejcperiments were corrected for temperature and plotted versus time in Figures 8-11. Chemical oxygen demand and BOD data from the experiments are shown in Figures 12-15. The dotted line through the COD data in Figure 14 indicates the time after which samples were filtered through a mat of spun glass to remove the larger particulates, particularly those in the benthic chambers. 17 5r E E O Q Light Chambers -LP • -LB 1800 2200 0200 0600 1000 Time of Day 1400 1800 2200 20 18 16 1 ' 1 r Dark Chambers -DP • -DB 1800 FIGURE 8 2200 0200 0600 1000 1400 1800 2200 Time of Day OXYGEN UPTAKE FOR EXPERIMENT HI 18 1200 1600 2000 2400 0400 Time of Day 0800 1200 1600 20 18 161- Dark Chambers -DP • -DB 1200 1600 2000 2400 0400 0800 Time of Day FIGURE 9 OXYGEN UPTAKE FOR EXPERIMENT IE 1200 1600 19 1200 1600 2000 2400 0400 Time of Day 0800 1200 1600 Dark Chambers -DP • -DB 1200 1600 2000 2400 0400 0800 1200 1600 Time of Day FIGURE 10 OXYGEN UPTAKE FOR EXPERIMENT IZ 20 000 1400 1800 2200 0200 0600 1000 1400 Time of Day 20 18 16 1 ' 1 r Dark Chambers -DP • -DB 1000 1400 1800 2200 0200 0600 1000 1400 Time of Day FIGURE II OXYGEN UPTAKE FOR EXPERIMENT ZEE 21 100 90 80 70 ~~i 1 1 1 O COD, Water Only • COD, Benthos A BOD, Water Only A BOD, Benthos === ^ ------ -^ 20 10 Light Chambers 20 18 16 14 12 10 E Q O 8 QQ 6 4 2 6 8 10 12 14 16 18 20 22 24 26 Elapsed Time ,hr Initial Streamwater COD = 45,4 mg/j? 28 100 90 80 O COD, Water Only • COD, Benthos A BOD, Water Only A BOD, Benthos — — — - A ' 30 20 10 Dark Chambers 20 8 -116 14 12 o -8 ao -6 -4 2 E 2 4 8 10 12 14 16 18 20 22 24 26 28 Elapsed Time,hr FIGURE 12 COD AND BOD DATA , EXPERIMENT HI 22 lOOr- 90- 80- O COD, Water Only • COD, Benthos A BOD, Water Only A BOD, Benthos 20 10 Light Chambers 1 20 18 16 14 12 5 o> F 10 a o 8 00 5 8 10 12 14 16 18 20 22 24 26 Elapsed Time ,hr Initial Streamwater COD = 37.6 mg/X 6 4 2 28 00 90h 80 O COD, Water Only •' COD, Benthos A BOD, Water Only A BOD, Benthos> 20 10 Dark Chambers I I J I 20 18 16 14 12 10 E Q O 8 E 10 a O 8 oq -4 2 8 10 12 14 16 18 20 22 24 26 28 Elapsed Time,hr FIGURE 14 COD AND BOD DATA , EXPERIMENT 3L 2k 100 90 80 70 O COD, Water Only • COD, Benthos A BOD, Water Only A BOD, Benthos 30 20 10 Light Chambers 20 -118 16 14 12 10 8 6 4 2 1 4 6 8 10 12 14 16 18 20 22 24 26 28 Elapsed Time ,hr Initial Streamwater COD = 46.7 mg/je 100 90 80 70 60| O COD, • COD, Water Only Benthos A BOD, Water Only A BOD, Benthos ^^~-^~~~~ ___& 30h 20 10 Dark Chambers J L 20 18 16 14 12 10 H6 4 2 2 4 6 8 10 12 14 16 18 20 22 24 26 28 Elapsed Time,hr FIGURE 15 COD AND BOD DATA , EXPERIMENT 321 25 DISCUSSION Analysis of the experimental data must take into account all of the processes occurring within the chambers. Table IV indicates oxygen and BOD producing and consuming reactions and the chambers in which they will occur. TABLE IV FACTORS AFFECTING DO AND BOD Process and Fun cti on Where Occurring I. Oxygen producing processes a. Phytoplankton photosynthesis LP, LB b. Benthic algal photosynthesis LB c. Rooted aquatic photosynthesis LB II. Oxygen consuming processes a. Microbial uptake in water LP, LB, DP, DB b. Microbial uptake in benthos LB, DB c. Macroinvertebrate respiration LB, DB d. Phytoplankton respiration LP, LB, DP, DB e. Benthic algal respiration LB, DB f. Nitrification LP, LB, DP, DB g. Rooted aquatic respiration LB, DB III. BOD producing processes a. Diffusion from benthos of anaerobic products LB, DB b. Bacterial death and lysing LP, LB, DP, DB c. Macroinvertebrate death and lysing LB, DB 26 TABLE IV (continued) IV. BOD consuming processes a. Microbial uptake LP, LB, DP, DB b. Macroinvertebrate uptake LB, DB c. Anaerobic decomposition LB, DB d. Adsorption onto bottom sediments LB, DB e. Settling out of particulates LP, LB, DP, DB If certain assumptions are made, then the oxygen and BOD records can be separated into the fractions contributed by the benthos and overlying water, and those due to photosynthesis and respiration. For example, if it is assumed that the same amount of bacterial oxygen uptake occurs in the LP and DP chambers and that an equal number of plankton are contained in each, then the difference in uptake in LP and DP can be attributed to photosynthesis. Similarly, by assuming equal amounts of photosynthesis and bacterial respi- ration in the water phase of LP and LB, the effects of the benthos on the oxygen profile will be determined. In order to subtract the uptake of the overlying water from the benthal demand, it was necessary to convert from concentration to milligrams of oxygen utilized via use of the chamber volume. The volume of the benthic sample was used to determine the amount of water in the benthic chambers and the uptake of water was corrected for the change in volume between the plank- tonic and benthic chambers. Subtraction of milligrams of oxygen utilized in the complementary planktonic chamber from that used in the benthic chamber then yielded the benthic oxygen uptake. An example of computations is included in Appendix II. The apparent gain in oxygen in the LB chamber immediately after aeration is thought to be due to slow transfer from bubbles of pure oxygen into the 27 system. Bubbles were observed clinging to the top of the chamber immediately after addition of oxygen. These bubbles disappeared after a period of 2 to 3 hours. It was not possible to observe the presence or absence of bubbles in the dark chamber. Why gas exchange would take place more efficiently in one of the seemingly identical chambers has not been satisfactorily ex- plained to date. In order to compute cumulative oxygen used, a straight line was extended upward from the point of inflection of the uptake curve. For the straight line approximation to be a valid representation of what actually happened within the system, it would be necessary to have a certain amount of oxygen gas available in the form of bubbles which would pass into the liquid over a period of time. For example, at 1600 hrs the LB in experiment VI 1'4.3 mg./l (estimated) - 10.4 mg/1 (actual) = 3.9 mg./l 15 1 (1 - .35) = 9.75 1 in system 3.9 mg/1 (9.75 1) = 38 mg of oxygen 32 mg of oxygen gas form 1 m mole at STP (||)(22.4 ml/m mole) = 26.4 ml volume at STP 293 26.4 (jjz) = 28.3 ml at 20°C would be required to make up the oxygen difference observed During the 2 to 3 hour period after oxygen addition, the water level in the sampling vent on LB was observed to decrease while that on DB remained sta- tionary. A decrease in volume would be expected if gas were going in solution in the chamber. The total volume enclosed in the sampling tube was of the order (25 ml) of volume of oxygen needed to account for the hypothesized increase from bubbles in the system. It was observed that when the chamber was reaerated to a lower concentration, the problem disappeared—witness the LB in experiments III and VI. 28 The cumulative oxygen uptake curves derived from the above procedure cannot be compared due to the approximations made at the high concentrations immediately after aeration in the LB chamber. However, comparison of uptake rates obtained are valid if the rates based on the approximated oxygen con- centration curves are not included. To compare uptake rates and to test the dependency upon the oxygen concentration in the overlying water, the change in oxygen concentration and mean concentration for each hourly period were computed. Logarithmatic plots which indicate the uptake rates versus DO concentration are shown in Figures 16-23. The uptake versus average concentration curves reveal that, in all cases, uptake rate is dependent upon oxygen concentration. Past studies of the effects of oxygen concentration on uptake rates have yielded results dependent upon the population in the deposit under study. Baity (1938) , Fair et al_. (1941) , and Hanes and Davison (1968) have all indicated the rate of oxygen uptake to be independent of the oxygen concentration in the supernatant water. The samples studied by the above investigators contained no macroinvertebrate populations. Studies on deposits with significant macroinvertebrate populations by Knowles ejt al. (1962); Edwards and Rolley (1965); and McDonnell and Hall (1957) show the uptake rate to be dependent upon oxygen concentration. Results of this study in which a significant population of macroinvertebrates (primarily tubificids with some chironomids and psychodid larvae) existed agree with che latter authors. Knowles e_t a_l. indicated dependency only below 3 mg/1. In this study, dependency continues to a much greater concentration than 3 mg/1. 29 o> E i o D o £ C CD 40 20- 10- 6 4 2r- .0 0,1 T 1 I | I T 1 1 | I I aoA ° .XT I 1 I I ,2 .4 .6 1,0 2 4 6 10 Average Oxygen Concentration , mg /I 20 FIGURE 16 OXYGEN UPTAKE VS CONCENTRATION -LB , EXPERIMENT HI 30 E a o jz c 0) CD 40 20 1 I 1 i 1 i i 1 | | i | 1 | 1 TT'l 99(5 - 10 — — 6 4 — 2 1.0 J_ ,1.1 1 1 1 1 . 1 1 1 1 1 1 1 1 1 0,1 2 .4 .6 1.0 2 4 6 10 Average Oxygen Concentration , mg /I 20 FIGURE 17 OXYGEN UPTAKE VS CONCENTRATION - DB , EXPERIMENT HH 31 E o a D y c a> GQ 40- 20- 10- 6 4 2h .0 0,1 1 1 1 1 1 1 ll| | 1 | 1 ! i i i| — — -o^> ^^^° Cfe^-(5o — — — 1 1 1 1 I 1 .1 l , 1 , 1 , . , 1 2 .4 .6 1.0 2 4 6 10 Average Oxygen Concentration , mg /I 20 FIGURE 18 OXYGEN UPTAKE VS CONCENTRATION - LB , EXPERIMENT 131 32 E i o => u c 00 2 .4 .6 1,0 2 4 6 10 20 Average Oxygen Concentration , mg /£ FIGURE 19 OXYGEN UPTAKE VS CONCENTRATION - DB , EXPERIMENT m 33 E o Z> o c 0) 00 2 .4 .6 1.0 2 4 6 10 Average Oxygen Concentration , mg /£ 20 FIGURE 20 OXYGEN UPTAKE VS CONCENTRATION - LB , EXPERIMENT IE lh E o 3 o Jc c GD 40 ! J I 1 1 ll| | 1 J T 1 T T 7 J 20 10 6 4 X o 0y y O y o oy / - 2 — — 1.0 1 1 1 i ! i 1,1 1 , 1 l 1 , . ,1 0,1 2 .4 .6 1,0 2 4 6 10 Average Oxygen Concentration , mg /£ 20 FIGURE 21 OXYGEN UPTAKE VS CONCENTRATION - DB , EXPERIMENT 3C 35 en E i o Q. D o il c 0> CD 40- 20- 10- 6 4 2h .0 0, — 1 1 1 ' III 1 1 1 1 1 1 1 1 1 — — — — 1 ill I i i i I i i I i 1 i i 1 1 — 2 .4 .6 1,0 2 4 6 Average Oxygen Concentration , mg /£ 10 20 FIGURE 22 OXYGEN UPTAKE VS CONCENTRATION - L B , EXPERIMENT 3ZT 36 E CD J* O Q. Z> u c CD CD 40 1 1 | l | 1 1 1 1 | 1 | i | ! ! ! ! °-6 o 20 O^ ~ ^ ^-^ o 10 S* ^ o 0^ JV^ 6 <> 4 i — 2 1.0 1 1 1 1 1 1 i > 1 1 , 1 . 1 , , , 1 0.1 2 .4 .6 1.0 2 4 6 10 Average Oxygen Concentration , mg /£ 20 FIGURE 23 OXYGEN UPTAKE VS CONCENTRATION - DB , EXPERIMENT ZZE 37 Edwards and Rolley suggested the relationship b y = aC where y = oxygen uptake rate C = oxygen concentration in the overlying water a, b = constants for a system in which both diffusion and reaction take place. The relation- ship was said to apply to 10 mg/1 (approximately 150 mg in this system). If the above relationship does apply to the data of this study, the data should plot as a straight line on log-log paper. The data of this study seem to follow a similar relationship except at low DO concentrations. Deviation from the straight line at low DO values would be expected as microbial as well as macroinvertebrate respiration is limited by low concentrations (Zobell and Stadler, 1940). Slope and intercept values for the four experi- ments are compared in Table V. The difference between the means of the light and dark benthic chambers is not significant when compared with the standard deviation from the mean of all values. Any effects of photosynthesis in the benthos are masked by the 2 much larger oxygen uptake. Converting from mg/hr to mg/ft -hr yields a mean value of a equal to 6.17 for all uptakes and 6.0.5 and 5.30 for LB and DB. The mean value of b equal to 0.422 agrees relatively well with the 0.45 figure found in most cases by Edwards and Rolley. The mean oxygen uptake equation then becomes y = 6.17 C * 422 in mg/hr-ft 2 In the past, benthal oxygen uptake rates for compacted or continuously deposited samples have been considered as a function only of deposit surface area. If DO uptake rate were independent of sample depth then it should be 38 TABLE V SLOPE AND INTERCEPT VALUES FOR y - aC b Experiment I02 a b III LB 1.00 0.480 III DB 1.182 .471 IV LB . 870 .492 IV DB .954 .384 V LB 1.042 .421 V DB .832 .686 VI LB .909 .361 VI DB .919 .479 Mean .964 .422 Standard deviation from mean ±0.111 ±0.112 Mean LB .955 .444 Mean DB . 973 .400 independent of weight in this study as all samples are of approximately the 2 same surface area (1.49 ft ). Figure 24 illustrates this independence. Any relationship between uptake rate and time of sample exposure within the stream must be considered. If the uptake rate is dependent upon time of exposure, then the results will not represent actual stream conditions. All trays were placed in the stream on June 30, 1969. Figure 25 indicates that no definite relationship exists between uptake rate and date of collection. As stated previously, a thunderstorm on August 9 raised stream stages 4 feet as estimated from high water marks. The samples run on August 11 initially appeared to have fewer tubificids and less attached algae than other samples. By the end of the test, however, the tubifex had multiplied until they appeared to be present in concentrations similar to other tests. During the 39 f o o ! 1 o • - o • — _ o • _ o • _ - o • — - DO Level DO Level — - E g O _ — O • 1 lo t o <\J _ a> GO _ i^ _ o LU < a: LU CO * < V) \- 1 Q_ ID .«_ x: 2 U") o> LU - X 0) o Q. *- E CJ ^^ o X CO Z LU m ro > X C\J co LU o in o O ro O 0J CD < CO CVJ LU or ID CO jl|/6lu - ajoy 9>iD|dn 40 ro Ld I- < Q CD C\J O 1- 1^- o OJ Ld _l _l in CM o o ro 00 Ld _l Q_ CM 2 < CD if) CD if) t CD > „ Ld 4_ 1— m & — 3 < _ 3 ro < Ld X. < — H Q_ ID CD O h- X 1- z Ld IT) CD ro m CO Ld OC 3 O ji|/6w-9iDy a^Djdn ua6Axo ^imuag 4i earliest experiment shown in Figure 25, a large population of filamentous algae covered the stream bottom. The presence of this growth during the first experiment and absence during the later tests may explain the large variation between LB and DB uptakes which is not evident in the later tests. Analysis of the effects of floating (planktonic) algae is complicated by the shapes of the uptake curves. Apparently either a lag period or a period of inhibition exists at the beginning of each experiment. The rate of uptake increases from experiment beginning to end rather than the taoering off from a maximum initial rate which would be expected from a first order oxygen uptake model. Although it is difficult to compare results of the curving uptake graphs, the results of the first and last 12 hrs of operation have been converted to cumulative uptake and rates computed. Results are presented in Table VI. TABLE VI CHANGE IN OXYGEN UPTAKE IN LIGHT AND DARK PLANKTONIC CHAMBERS Experiment I Oxygen used in first 12 hr-mg Mg/l-hr Change Oxygen used in last 12 hr-mg |Mg/l-hr Change III IV V VI LP 16.7 0.093 DP 19.5 .108 LP 19.0 .106 DP 18.7 . 104 LP 16.1 .090 DP 36.0 .200 LP 24.5 .121 DP 56.2 .316 0.015 .110 195 20.1 0.112 23.3 .129 36.4 .202 45.9 .255 24.8 .138 54.0 .301 79.9 .444 116.5 .648 0.017 .053 .163 204 Although it may be objected that a lag period occurred during the first 12 hours of operation, the change in uptake rates between the light and dark chambers is relatively constant at the beginning and end of the tests. 42 Using the maximum change in uptake rates between LP and DP would indicate an oxygen resource of 0.204 mg/l/hr (24 hr/day) = 4.90 mg/l/day if light were available on a 24-hour basis or approximately 2.45 mg/l/day for a typical day. The oxygen resource of planktonic photosynthesis is not enough to insure aerobic conditions without supplemental oxygen sources when the system is subjected to benthic uptakes. The comparison and manipulation of oxygen uptake values within the four chambers to separate effects is based on the assumption of equal reactions in several of the chambers. The validity of some assumed equalities may be questionable, For example, in separating the benthal oxygen uptake from uptake of the overlying water, equal bacterial respiration and algal photo- synthesis is assumed in the two water phases. In actuality, the large microbial growth living in the aerobic zone of the benthos will seed the overlying water while the breakoff and suspension of attached algal forms will tend to increase the concentration in the benthal system. However, these factors are indeed an effect of the benthic layer upon the water and should be included when considering these effects. A more pertinent question would deal with the value of the uptake curves for streamwater alone. In a shallow stream where the benthal layer has a large influence on the overlying water, as shown in Figure 26, aa examination of the streamwater alone would be of little value without the added benthal effects. The COD and BOD data obtained for this series of experiments are par- ticularly important. As early as 1941, Fair et al. indicated that when natural river muds were studied, no consistent measurable increase in BOD of the overlying water was found after the first day or two. In recent years, however, several authors have indicated the principal mechanism of benthic 43 100 p o c O C o o c >x X O 12 3 4 Depth of Water — m Note: Depth in ft = 3.28 x Depth in m Grapth based on BOD utilization of 0.08 mg/l-hr and oxyge consumption of mud of 0.1 g/m -hr (9.32 mg/ft 2 -hr) FIGURE 26 EFFECT OF WATER DEPTH ON PROPORTION OF TOTAL OXYGEN UPTAKE BY RIVER MUD (Edwards and Owens,l965) kk oxygen uptake to be resuspension of BOD or solubilization of anaerobic end products (Camp, 1963; Oldaker e_t a_l . , 1966). Perhaps for a freshly deposited sample of predominantly organic material which consolidates with the outflow of a large quantity of interstitial liquids, or for a resuspension of solids by high velocities, addition of BOD is the controlling factor. However, the net change in COD between planktonic and benthic chambers is small, if exist- ent at all, for the low organic content deposits studied. Also, for the time covered in the experiments, there was little or no COD reduction with time. To illustrate, the mean COD values for each experiment and changes between benthic and planktonic chambers are listed in Table VII. TABLE VII GAIN OF COD IN BENTHIC CHAMBERS Gain in Benthic Chamber mg/1 0.6 12.3 2.2 6.4 3.4 3.2 -3.6 -3.6 * Some unfiltered samples included in mean The increase in COD in the benthic chambers over planktonic chambers ranges from 12.3 mg/1 to a loss of 3.6 mg/1. The increase in COD within the benthic chambers obviously cannot account for the increased oxygen uptake. In 45 Experiment Chamber LP Mean COD mg/1 III* 45.2 LB 45.8 DP 43.0 DB 55.3 IV* LP 37.4 LB 39.6 DP 39.1 DB 45.5 v* LP 37.2 LB 40.6 DP 41.8 DB 45.0 VI LP 50.5 LB 46.9 DP 51.6 DB 48.0 experiment VI, it appears that the benthic layer actually contributed to a decrease in the benthal system COD. The decrease might be due to adsorption of organics onto the benthal solids. An analysis of the BOD data within the system would seem to indicate a substantial increase in the benthal systems—almost double the initial BOD in one case. Two possible reasons are available to explain the increase in light of the small change in COD. The first is increased nitrification within water taken from the benthic samples. If the water overlying the ben- thos was seeded with an increased number of nitrifiers, the lag period before nitrification could be reduced. An increase in nitrification within the BOD bottles could account for the apparent increase of oxidizible material. Unfortunately, no nitrogen analyses are available to substantiate or deny the hypothesis. The method of sampling could provide another possible cause of increased BOD within the benthic chambers. At the end of each experiment the pumps were stopped and the Tygon tubing was removed from the upstream end of the chamber, allowing sufficient water to run out for the BOD tests. The increased velocity caused by sampling could have caused a resuspension of particulates as mentioned previously. In any event, the COD data indicate little addition of oxidizible materials from the benthos into the overlying water. APPLICATIONS OF RESULTS The chief limitation of the experiments was that all benthal samples were taken at the same distance downstream of the waste inflow. The next obvious step in experimentation would be a profile of uptakes along the length of stream. However, using the assumption of a uniform uptake between waste outfall and junction with the Salt Fork 10.15 miles downstream, some crude computations will show the effects of the measured benthal demand upon 46 stream DO. The following assumptions will be used: 1. Equal benthal oxygen uptake from treatment plant to junction 10.15 miles downstream. Described by , ._ J). 422 y = 6. 17 C 2 where y - uptake rate in mg/hr-ft C = oxygen concentration in mg/1 2. Oxygen uptake or production due to factors other than reaeration, BOD utilization, or benthic respiration are insignificant. 3. Reaeration coefficient may be described by the equation of Churchill, Elmore, and Buckingham (1962) -5/3 k 2 @ 20°C = 5.026 VH ' where V = mean velocity ft/sec H = mean depth ft based on reaeration rate measurements by Hovious (1968). 4. Oxygen uptake due to BOD utilization and respiration other than benthos is given by results of DP chambers--0.258 mg/l/hr selected as mean observed value over a 12-hr period. Constant uptake. 3 5. Mean low water flow of 20 ft /sec based on data of Austin and Sollo (1968). Constant flow. 6. All temperatures at 20° C. 7. Mean depth of 1.25 ft and width of 41.5 ft based on cross-sectional data. 47 Using the above data and assumptions 2 Cross-sectional area = 1.25 ft x 41.5 ft = 52 ft 20 ft /sec Mean stream velocity = —z — = 0.385 ft/sec 52 ft or 0.385 ft/sec (16.35 "?^ day ) = 6.30 mi/day ft/sec J or 10.15 mi/ (6.30 mi/day) = 1.61 days from treatment plant to junction Reaeration coefficient = k @ 20°C = 5.026 (.385) (1.25)" 5 ^ 3 =1.33 day" 1 (base 10) or K 2 (? 20° C = 0.128 hr" 1 (base e) Deriving an equation to predict oxygen concentration Ac* — = reaeration - oxygen uptake in water - oxygen uptake in benthos = K 2 (C s -C)(mg/l-hr) - 0. 258 (mg/l-hr) - , 17 -0.422, ,, _.2 W 1 N , 1 ft 3 N - 6.17 C (mg/hr-ft )( 1>25 f fc ) (jg^JT* = 0. 128(9. 2-C) - 0.258 - 0.174 C°* 422 4r = 0.922 - 0.128 C - 0.174 C°* 422 at The initial slope of the DO profile will depend upon the initial concen- tration at the waste inflow. With an initial concentration of 5 mg/1, ■— would be less than zero indicating decreasing concentration, while at a concentration of 4 mg/1 the concentration would be increasing. The stream DO would approach a value of 4.60 mg/1 at equilibrium. Although the above 48 model is not expected to give an exact tabulation of the actual DO profile, it does yield reasonable results compatible with those found in actual stream surveys. In the absence of algal blooms, the DO concentration within the stream has, in general, been found to vary between 2 and 7 mg/1 with no defined DO sag in the 10.15 mi reach below the waste inflow (Austin and Sollo, 1969). Samples of DO profiles and temperatures of measurement are given in Figure 27. Changing temperatures will affect all of the terms in the DO equation raising or lowering the equilibrium value. The above model gives a more rational result than the simple Streeter-Phelps (1925) model which would yield the following: Average BOD released from waste treatment plant = 30 mg/1 Assuming an uptake rate (K-) of 0.30 day (base e, a large estimate) or K = 0.0125 hr" 1 Maximum uptake rate = K-L = 0.0125 hr" (30 mg/1) = 0.375 mg/l/hr H = KjL - K 2 D = 0.375 mg/l/hr - 0.128 (D) where D = oxygen deficit = C - C or in cases where the initial deficit is at least 2.9 mg/1, the stream DO will begin to recover immediately toward saturation concentration. CONCLUSIONS The following conclusions are based on experimental observation. 1. Some short-circuiting existed within the chambers, however, a tracer was well mixed after one time of flow through the system. 2. The benthic sampling trays were undistinguishable from the stream bottom after a 4-week period. 49 •> o o a> o 00 CO CO K^ Cl »•— ^^ 6 O n" O) 1^- OJ h- *- a> c 3 c o o "3 2t LL o 1 a^ « of S O (/) *- *- o ° £ oj §. CD LZ :^ ^ °- 1- e O" ^ a) U Oh 6 3 0> 00 a> CD N- "= CO 1 o CO 3 o - m ro <\j o E o o c o (/> Q o 00 ■D c o < 00 LU O tr Q- o Q < LU CC h- 00 OJ LU a: z> CO U. ro oj — l/6tu-oa 50 3. During initial experiments run at different temperatures, the tem- perature coefficient was close to that which would be expected from work by previous investigators. 4. The samples collected were heterogeneous and composed primarily of gravel and sand with some fines. Average per cent water was 27.4 with 3.48 per cent of the sample volatile. 5. The primary macroinvertebrates collected were tubifix with some chironomid and psychodid larvae. 6. The oxygen uptake of the benthos was dependent upon the concentration in the overlying water. The data fit the relationship y = 6.17 C 2 where y = oxygen uptake mg/ft -hr C = oxygen concentration in mg/1 7. The difference between light and dark benthal uptake was within the limits of chance. 8. Oxygen uptake was independent of sample weight and exposure time. 9. The DO uptakes of chambers without benthic deposits was not first order. 10. The maximum oxygen resource attributable to photosynthesis was 2.45 mg/l/day and was not enough to maintain stream DO in the presence of benthic deposits. 11. The differences in COD values between the planktonic and benthic chambers were small and were not sufficient to account for observed differ- ences in DO uptakes. 12. The COD concentrations within all chambers changed little with time. 13. The benthic layer may actually cause a decrease in the COD in some systems. 51 14. The increase in BOD in the benthic chambers is thought to be due to sampling technique or seeding and development of nitrifying organisms. 15. Use of the results from the experiments yield reasonable oxygen profiles while the conventional Streeter-Phelps equation does not. 52 REFERENCES APHA. 1965. Standard Methods for the Examination of Water and Wastewater . 12th Ed. Araer. Publ. Health Assoc, New York, N. Y. 769 p. Austin, J. H. and F. W. Sollo, Jr. 1969. Oxygen Relationships in Small Streams. Sanitary Engineering Series No. 52, Dept. of Civil Engineering, University of 111., Urbana, 111. 192 p. Baity, H. G. 1938. Some Factors Affecting the Aerobic Decomposition of Sewage Sludge Deposits. Sew. Works Jour . 10:539. Camp, T. R. 1963. Water and Its Impurities . Reinhold Publishing Corporation, New York, N. Y. Churchill, M. A., H. L. Elmore, and R. A. Buckingham. 1962. The Prediction of Stream Reaeration Rates. Jour. San. Eng. Div . Proc. ASCE. 88:SA4:1. Edwards, R. W. and M. Owens. 1965. The Oxygen Balance of Streams. In Ecology and the Industrial Society . Fifth Symposium of the British Ecological Society. Blackwell Scientific Pub. Oxford. Edwards, R. W. and H. L. J. Rolley. 1965. Oxygen Consumption of River Muds. Jour. Ecol . 53:1. Fair, G. M. , E. W. Moore, and H. A. Thomas, Jr. 1941. The Natural Purifica- tion of River Muds and Pollutional Sediments. Sew. Works Jour . 13:2, 270; 4, 756; 6, 1209. Hanes , N. B. and R. I. Davison. 1968. Effect of Depth on Oxygen Uptake of a Benthal System. Proc. 23rd Ind. Waste Conf . , Purdue Univ. Hanes, N. B. and R. I. Davison. 1969. Effect of Sludge Depth on the Oxygen Uptake of the Benthal System. Proc. 23rd Ind. Waste Conf . , Purdue Univ. Hanes, N. B. and R. L. Irving. 1966. Oxygen Uptake Rates of Benthal Systems by a New Technique. Proc. 21st Ind. Waste Conf . , Purdue Univ. Hovious , J. C. 1968. Atmospheric Reaeration in a Small, Heavily Polluted Stream. Undergraduate Special Problem, University of Illinois. Knowles, G. , R. W. Edwards, and R. Briggs. 1962. Polarographic Measurement of the Rate of Respiration of Natural Sediments. Limnol. Oceanog . 7:481. Leifer, M. E. 1969. Photosynthetic and Benthic Chambers for In Situ Dissolved Oxygen Measurements in Streams. M. S. Special Problem, University of Illinois, 56 p. McDonnell, A. J. and S. D. Hall. 1967. Effect of Environmental Factors on Benthal Oxygen Uptake. Proc. 22nd Ind. Waste Conf . , Purdue Univ. 53 O'Connell, R. L. and N. A. Thomas. 1965. Effect of Benthic Algae on Stream Dissolved Oxygen. Jour. San. Engineering Div . , ASCE, SA3 , 91:1. Oldaker, W. H. , A. A. Burgum, and H. R. Pahren. 1966. Report on Pollution of the Merrimack River and Certain Tributaries. Part IV--Pilot Plant Study of Benthic Oxygen Demand. FWPCA Merrimack River Project, Lawrence, Mass. 14 p. Streeter, H. W. 1935. Measures of Natural Oxidation in Polluted Streams. I. The Oxygen Demand Factor. Sew. Works Jour . 1: 251. Streeter, H. W. and E. B. Phelps. 1925. A Study of the Pollution and Natural Purification of the Ohio River. III. Factors Concerned in the Phenomena of Oxidation and Reaeration. USPHS Pub. Health Bull. 146, Washington, D. C. 75 p. Zobell, C. E. and J. Stadler. 1940. The Effect of Oxygen Tension on the Oxygen Uptake of Lake Bacteria. Jour. Bacteriology 39 :307. 54 APPENDIX I LIST OF SYSTEM COMPONENTS The components making up one system were as follows: 1. Plexiglass G chamber — either clear or black (Figure AI-3) 2. Clamping frame (Figure AI-4) 3. 1/20 HP Eastern D-6 pump with stainless steel head 4. 1/4 in by 3 in PVC nipples--6 5. Stainless steel cooling coil--l/2 in OD by 1/16 in wall, approximately 70 in long 6. 1/2 in PVC valve (Vanton Flex Plug) 7. 1/2 in ID by 1/8 in wall Tygon tubing—approximately 20 ft 8. DO probe holder (Figure AI-1) 9. Orfice meter (Figure AI-2) 10. YSI BOD bottle probe 11. Thermistor 12. 12 Ga stainless steel tray for benthic chambers 13. 5 3/4 in by 2 5/8 in stainless steel screens--3 55 -D to CO O x 0) o c/> 6 Q C\J \ ^— w i 0) ^^ ^— a> o 2 TJ Q> Q> U — O ^ 3 w w o to c o o 1 Q> M < Q) 5 LlI O 3 »^ O 56 Drill and Tap for 1/4" NPT (7/16" Tap Drill) Y 2-1/2 1/2' ,3/4' 1-1/2 Dia. 3/4 Dia. 23/32 Dia. Probe Holder Constructed of 1-1/2" Dia. Solid Plexiglass Tubing FIGURE AI-2 PROBE HOLDER 57 _ -Q o o o o to c Q> ^ o - E ■o C » if to ^ .6 5 c a> e ^ ^ c a> *- "D TtTHT CD o .c c ni'i'i'iii-iii'i : T 0) u o CD (/> o o < X a> 1} -H T a. £ o O ">< a> Z = id o a. o o 2 = P O < ^r C\J i_L ■D 3 V (iTTfiliT 3 C < or i LU or 59 APPENDIX II SAMPLE OXYGEN UPTAKE COMPUTATIONS FOR BENTHOS IN DB, EXPERIMENT IV Oxygen Uptake of Water From DP Weight of sample in DB = 16.411 lbs ( * lb/ft 3 ) (28.32 1/ft 3 ) = 4.40 1 volume of sample 4.40/15 = 0.293 = 29.3 per cent of volume as sample 70.7 per cent of volume as water 0« Used in a Volume of Water Time 2 mg/1 (from DP) (15 1 x 0.707) in DP Equal to That in DB 1209 84.8 1309 85.6 1409 84.5 1.1 1509 83.8 1.8 1609 82.9 2.7 1711 81.4 4.2 1811 81.1 4.5 1911 79.9 5.7 2011 79.5 6.1 2111 77.7 7.9 2211 76.2 9.4 2311 75.2 10.4 2411 74.2 11.4 0109 71.8 13.8 0209 69.4 16.2 0309 67.5 18.1 0409 64.8 20.8 0509 61.8 23.8 0609 57.5 28.1 0709 52.5 33.1 0809 44.7 40.9 60 I I 1 — i — i — i — i — i — r i — i — i — i — i — r t — r— i — r O O o I I I I I I I I I I I I I I I I I I IK Ocdojoo sro(0OJcosj-Oc0c\j£J iD^^rOrorocvioj — — — Q_ Q E & a> 3 Q. E o u V) < a LU Q. X LU qq" LU I >- CD LU < CL 3 LU >- X o < _J 3 O I a < 3 O 2n juawuadx3 1 qq jo asDijd jsjdm u| pasn ua6A*o JO &w 61 APPENDIX II (continued) CONSUMPTION OF OXYGEN DUE TO BENTHOS IN DB 0„ mg = concentration mg/1 (15.0 1) (0.707) 0« Used in Water Time P_2-2a 0„ Used (From Figure AI-1) 0„ Used in Benthos 1230 67.8 1330 53.9 13.9 0.6 13.3 1430 41.3 26.5 1.6 24.9 1530 28.8 39.0 2.3 36.7 1630 18.0 49.8 3.0 46.8 1630+ 110.7 -- — -- 1730 87.9 72.6 3.7 68.9 1830 68.8 91.7 4.5 87.2 1930 51.4 109.1 5.3 103.8 2030 36.0 124.5 6.4 118.1 2030+ 93.2 -- -- -- 2130 73.9 143.8 7.9 135.9 2230 55.1 162.6 9.3 153.3 2330 39.2 178.5 10.8 167.7 2430 22.4 195.3 12.4 182.9 2430+ 121.1 — — — 0130 94.7 221.7 14.3 207.4 0230 74.1 242.3 16.3 226.0 0330 52.9 263.5 18.7 244.8 0430 34.9 281.5 21.5 260.0 0530 18.0 298.4 25.0 273.4 0630 4.0 312.4 29.7 282.7 + estimated by extending DO vs time trace upward 62 APPENDIX II (continued) RATE OF OXYGEN UPTAKE BY BENTHOS IN DB Time DO Used in 1 hr Mean DO mg Mean DO m^/1 1230 13.3 60.8 5.75 1330 11.6 47.6 4.50 1430 11.8 35.0 3.31 1530 10.1 23.4 2.21 1630 22.1 99.3 9.38 1730 18.3 78.4 7.40 1830 16.6 60.1 5.68 1930 14.3 43.7 4.13 2030 17.8 83.6 7.90 2130 17.4 64.5 6.10 2230 14.4 47.2 4.46 2330 15.2 30.8 2.91 0030 24.5 107.9 10.19 0130 18.6 84.4 7.97 0230 18.8 63.5 6.00 0330 15.2 43.9 4.15 0430 13.4 26.4 2.50 0530 9.3 11.0 1.04 63