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Reaction kinetics and validity of BOD test for domestic wastewater released in marine ecosystems Submitted to: Prof. A. B. Gupta Deptt. Of Civil Engg. MNIT, Jaipur Submitted by: T. Sunder rami reedy 2012 PCE 5010 Deptt. Of CE MNIT, Jaipur Downloaded from CivilDigital.com

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CONTENTS : Introduction. Materials and methods. Results and discussion. Observations. Summary and conclusions. Downloaded from CivilDigital.com

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Introduction : cities have resulted in faster growth rate. 17 coastal megacities covering about 25% of the world's population. The availability of oxygen in the ocean is limited due to high chlorides. The biochemical degradation rates are slower in salinity water. BOD is a wet oxidation process, which follows first-order kinetics. The values of kinetic rate constants are expected to differ with varying salinities and temperatures. Research is carried out using glucoseglutamic acid and domestic wastewater to evaluate the impact of salinity on biodegradation of carbonaceous waste at 20C and 27C. Inverse relationship between rate of biodegradation and salinity. BOD exertion at 20C (5 days) and 27C (3 days) for the marine environment is comparable at selected salinities. Downloaded from CivilDigital.com

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Exertion of BOD is: 1. P H,osmotic conditions,salinity,o 2. 2. temp.,time of incubation, seed acclimatization. k ranging from 0.1 to 0.6 per day at 20C for the domestic wastewaters (Thomann1974). BOD for glucoseglutamic acid showed lower value in seawater than that observed in freshwater. Finding the of BOD exertion of GGA and domestic wastewater under specific salinities expressed in terms of chloride concentrations at 20C and 27C. Downloaded from CivilDigital.com

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Glucoseglutamic acid solution with ultimate BOD (L) as 480 mg/L Days Average BOD (mg/L) 0 mg/L chlorides 5,000 mg/ L chlorides 10,000 mg/ L chlorides 15,000 mg/ L chlorides 20,000 mg /L chlorides 1107131724441 21832251586471 3213241225164158 4307265245194181 5337285255200221 6373295268214244 7380281282240248 8390315295264261 9395344324279271 10397350338300284 BOD of glucoseglutamic acid solution exerted with varying chloride concentrations in dilution media at 20C. Downloaded from CivilDigital.com

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Glucoseglutamic acid solution with ultimate BOD (L) as 480 mg/L Days Average BOD (mg/L) 0 mg/L chlorides 5,000 mg/ L chlorides 10,000 mg/ L chlorides 15,000 mg/ L chlorides 20,000 mg /L chlorides 12332351624233 2277254262215216 3333281282249240 4370344319249260 5420358346302280 6443368356315286 7440371359315296 8443381372322293 9451380375326302 10455396387329306 BOD of glucoseglutamic acid solution exerted with varying chloride concentrations in dilution media at 27C. Downloaded from CivilDigital.com

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Glucoseglutamic acid solution with ultimate BOD (L) as 480 mg/L Chlorides (mg/L) BOD exerted at 20C on the 5th day, mg/L/percentage BOD exerted at 27C on the 3rd day, mg/L/percentage 0336 (70%)334 (69.6%) 5,000285 (59.3%)281 (58.5%) 10,000255 (53.1%)282 (58.5%) 15,000200 (41.7%)249 (51.8%) 20,000221 (45.8%)240 (50%) Comparison of BOD of glucoseglutamic acid solution exerted with varying chloride concentrations at 20C on the fifth day and 27C on the third day. Days Chlorides (mg/L) Day 1Day 2Day 3Day 4Day 5 Average k k value for the reaction constant at 20C 00.250.240.200.250.24 5,0000.32 0.230.200.180.25 10,0000.160.200.210.180.150.18 15,0000.100.070.140.130.11 20,0000.090.080.130.12 0.11 Days Chlorides (mg/L) Day 1Day 2Day 3 Average k Average values of k at 20C and 27C for glucoseglutamic acid. k value for the reaction constant at 27C 00.670.430.400.50 5,0000.670.380.290.45 10,0000.410.400.300.37 15,0000.090.300.240.21 20,0000.070.300.230.20 Downloaded from CivilDigital.com

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Materials and methods : BOD, which measures oxygen requirement for aerobic stabilization of the organic matter, is a bioassay test. The natural seawater with 3536 parts per thousand (ppt) of salinity has about 20,000 mg/L of chlorides. The experiments were conducted for a 10-day period to achieve maximum exertion of carbonaceous BOD. A cotton-filtered domestic wastewater was used as "seed to provide a heterogeneous population of microorganisms. In view of the fact that BOD exerted at 20C for 5 days is equivalent to the BOD at 27C for 3 days. The incubated samples various time slots were analyzed for the existence and adequacy of heterotrophic microorganisms under various chloride concentrations using Zobel/nutrient agar media. Downloaded from CivilDigital.com

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Results and discussions : the decomposition rate of organic contaminants phenomenon occurs due to restriction of osmoregulatory processes responsible for the breakdown of organic compounds within the cells of microorganisms. According to the first-order equation of chemical kinetics (Sawyer et al.2010), the rate of decomposition is directly proportional to the amount of undecayed material and may be mathematically expressed as = - sign indicates the loss of material with time. = C is the concentration of oxidizable organic matter. at the start of the time interval t. = K is the rate constant. The BOD curve can be described by a first-order kinetics equation (Metcalf and Eddy, Inc.2003) dL 0/dt = -k L 0 Downloaded from CivilDigital.com

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y = Amount of oxygen consumed (or BOD) at time t t = Time elapsed since the start of the assay L0 = Total amount of oxygen consumed in the reaction (or ultimate BOD) k = Reaction constant Domestic wastewater solution with ultimate BOD (L) as 300 mg/L Chlorides (mg/L) BOD exerted at 20C on the 5th day, mg/L/percentage BOD exerted at 27C on the 3rd day, mg/L/percentage 0167 (55.7%)168 (56.0%) 5,000103 (34.3%)127 (42.3%) 10,000115 (38.3%)126 (42.0%) 15,000103 (34.0%)104 (34.7%) 20,00094 (31.3%)110 (36.7%) Comparison of BOD of domestic wastewater exerted with varying chloride concentrations in dilution media at 20C on the fifth day and 27C on the third day. Downloaded from CivilDigital.com

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Days Chlorid es (mg/L) Day 1Day 2Day 3Day 4Day 5 Averag e k k value for the reactio n constan t at 20C 00.250.200.230.180.160.20 5,0000.15 0.120.100.080.12 10,0000.190.140.120.110.100.13 15,0000.220.150.120.100.080.13 20,0000.210.150.110.08 0.13 Days Chlorid es (mg/L) Day 1Day 2Day 3 Averag e k k value for the reactio n constan t at 27C 00.390.250.270.30 5,0000.270.190.180.21 10,0000.270.190.180.21 15,0000.250.200.140.20 20,0000.300.210.150.22 Average values of k at 20C and 27C for domestic wastewater. The importance of the reaction rate constant k for BOD was realized, and it was felt that k values must be known for a particular environmental condition for proper evaluation of ultimate BOD status. Downloaded from CivilDigital.com

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Coefficient of determination (r 2 ), a measure of the proportion of variability in a data set that is accounted for by a statistical model; often called R 2 ; equal in a single-variable linear regression to the square of Pearson's product-moment correlation coefficient. (The strength of the linear relationship between the values).Coefficient of determination The better the linear regression (on the right) fits the data in comparison to the simple average (on the left graph), the closer the value of is to one. The areas of the blue squares represent the squared residuals with respect to the linear regression. The areas of the red squares represent the squared residuals with respect to the average value. Correlation coefficient (r), a broad class of statistical relationships between two or more random variables or observed data values. Correlation Downloaded from CivilDigital.com

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Chlorides (mg/L) Glucoseglutamic acid 20C27C Correlation coefficient (r) Coefficient of determinatio n (r 2 ) Correlation coefficient (r) Coefficient of determinatio n (r 2 ) 00.9820.9650.9760.953 5,0000.9750.9510.9710.942 10,0000.9890.9790.9710.943 15,0000.9790.9580.9190.844 20,0000.9860.9720.8840.781 Domestic wastewater 00.9700.9410.9830.967 5,0000.9920.9840.9880.977 10,0000.9980.9950.9800.961 15,0000.9970.9940.9820.964 20,0000.9820.9650.9950.990 Values of r 2 and r for BOD of glucoseglutamic acid and domestic wastewater under varying concentration of chlorides. the two variables is the correlation coefficient (r). A positive correlation states that increasing values in one variable correspond to increasing values in the other variable, while a negative correlation states that increasing values in one variable correspond to decreasing values in other variables. Values close to 1 indicate excellent linear reliability. Linear regression gives the relationship between two variables, by fitting the observed data into a linear equation. The square of the correlation coefficient (r) is a useful value in evaluating linear regression. Downloaded from CivilDigital.com

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Observations : BOD exertion was 10% to 15% higher at 27C as compared to 20C for all media. With incremental increase in chloride concentration, BOD exerted for conventional time and temperature (20C, 5 day) dropped progressively from 70% to 46% for glucoseglutamic acid solution and from 56% to 31% for domestic wastewater.With incremental increase in chloride concentration, BOD exerted for conventional time and temperature (20C, 5 day) dropped progressively from 70% to 46% for glucoseglutamic acid solution and from 56% to 31% for domestic wastewater. The values of BOD exerted at 20C, 5 days, and 27C, 3 days.The values of BOD exerted at 20C, 5 days, and 27C, 3 days Sudden rise in BOD exertion was not observed after the sixth or seventh day when oxidation of nitrogenous waste is expected to start.Sudden rise in BOD exertion was not observed after the sixth or seventh day when oxidation of nitrogenous waste is expected to start Adequate microorganisms were present at higher chloride concentrations for the whole test period at both the temperatures. Existence, survival, and multiplication of microbes were not the limiting factors for reducing the trend in BOD exertion at various chloride concentrations.Adequate microorganisms were present at higher chloride concentrations for the whole test period at both the temperatures. Existence, survival, and multiplication of microbes were not the limiting factors for reducing the trend in BOD exertion at various chloride concentrations. The k values had lowered with increase in chloride concentrations. Significantly higher values for k were observed at 27C as compared to 20C indicating faster rate of oxidation at elevated temperature.Significantly higher values for k were observed at 27C as compared to 20C indicating faster rate of oxidation at elevated temperature The values of the square of the correlation coefficient (r 2 ) were negative and greater than 0.9 indicating good strength of the negative association between two variables, i.e., degradation rate and chloride concentration. This trend analysis indicates that as the chloride concentration increases, the rate of degradation of organic matter decreases.The values of the square of the correlation coefficient (r 2 ) were negative and greater than 0.9 indicating good strength of the negative association between two variables, i.e., degradation rate and chloride concentration. This trend analysis indicates that as the chloride concentration increases, the rate of degradation of organic matter decreases. Downloaded from CivilDigital.com

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Summary and conclusions : Ten percent to 15% higher BOD was observed at 27C when compared to 20C for all media. Negative impact of chlorides on the oxidation of organic matter was observed showing decrease in BOD exertion at higher chloride concentrations. This observation permits adoption of BOD test at 27C with shorter duration for saline waters. Nitrogenous oxidation was not observed at selected test conditions till 10 days. How ever additional oxygen will be required for nitrogenous BOD and needs consideration while designing waste discharges. Availability of microbes was not the limiting factor for reduction trend in oxidation of organic matter at increased chloride concentrations. The values of k reduced significantly at elevated salinities. the correlation coefficient values. The values indicate decreasing trend in degradation with increasing salinities. Downloaded from CivilDigital.com

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Those are indicated the necessity for critical consideration of slow degradation rates while planning the disposal options for organic wastes in the marine environment. Downloaded from CivilDigital.com

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References : http://link.springer.com/article/10.1007/s10661-011-2341- y/fulltext.html.http://link.springer.com/article/10.1007/s10661-011-2341- y/fulltext.html Thom Ann, R. (1974). Systems analysis and water quality management. New York: McGraw Hill. http://en.wikipedia.org/wiki/Pearson_product- moment_correlation_coefficient.http://en.wikipedia.org/wiki/Pearson_product- moment_correlation_coefficient http://en.wikipedia.org/wiki/Coefficient_of_determination.http://en.wikipedia.org/wiki/Coefficient_of_determination OSPAR (2001) OSPAR convention for the protection of marine environment of the North-East Atlantic. Meeting of working group on priority substances (SPS [2] 01/4),ARONA (SECRETARIAT/EC): October 1519, 2001 Downloaded from CivilDigital.com

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Domestic wastewater solution with ultimate BOD (L) as 300 mg/L Chlorides (mg/L) BOD exerted at 20C on the 5th day, mg/L/percentage BOD exerted at 27C on the 3rd day, mg/L/percentage 0167 (55.7%)168 (56.0%) 5,000103 (34.3%)127 (42.3%) 10,000115 (38.3%)126 (42.0%) 15,000103 (34.0%)104 (34.7%) 20,00094 (31.3%)110 (36.7%) Comparison of BOD of domestic wastewater exerted with varying chloride concentrations in dilution media at 20C on the fifth day and 27C on the third day. Downloaded from CivilDigital.com

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Glucoseglutamic acid solution with ultimate BOD (L) as 480 mg/L Chlorides (mg/L) BOD exerted at 20C on the 5th day, mg/L/percentage BOD exerted at 27C on the 3rd day, mg/L/percentage 0336 (70%)334 (69.6%) 5,000285 (59.3%)281 (58.5%) 10,000255 (53.1%)282 (58.5%) 15,000200 (41.7%)249 (51.8%) 20,000221 (45.8%)240 (50%) Comparison of BOD of glucoseglutamic acid solution exerted with varying chloride concentrations at 20C on the fifth day and 27C on the third day. Domestic wastewater solution with ultimate BOD (L) as 300 mg/L Chlorides (mg/L) BOD exerted at 20C on the 5th day, mg/L/percentage BOD exerted at 27C on the 3rd day, mg/L/percentage 0167 (55.7%)168 (56.0%) 5,000103 (34.3%)127 (42.3%) 10,000115 (38.3%)126 (42.0%) 15,000103 (34.0%)104 (34.7%) 20,00094 (31.3%)110 (36.7%) Comparison of BOD of domestic wastewater exerted with varying chloride concentrations in dilution media at 20C on the fifth day and 27C on the third day. Downloaded from CivilDigital.com

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Percent exertion of BOD for domestic wastewater at various chloride concentrations at 20C. Percent exertion of BOD for domestic wastewater at various chloride concentrations at 27C Downloaded from CivilDigital.com

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Counts/100 mL a Chlorides (mg/L) 20C27C 5 days10 days3 days10 days 047322718 5,00056449068 10,00017012511791 15,0002001477053 20,0001139810187 Total colony-forming units of heterotrophic bacteria during different incubation periods at variable chloride concentrations. All values to be multiplied by a factor of 10 8All values to be multiplied by a factor of 10 8 Downloaded from CivilDigital.com

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Days Chlorides (mg/L) Day 1Day 2Day 3Day 4Day 5 Average k k value for the reaction constant at 20C 00.250.200.230.180.160.20 5,0000.15 0.120.100.080.12 10,0000.190.140.120.110.100.13 15,0000.220.150.120.100.080.13 20,0000.210.150.110.08 0.13 Days Chlorides (mg/L) Day 1Day 2Day 3 Average k k value for the reaction constant at 27C 00.390.250.270.30 5,0000.270.190.180.21 10,0000.270.190.180.21 15,0000.250.200.140.20 20,0000.300.210.150.22 Average values of k at 20C and 27C for domestic wastewater Downloaded from CivilDigital.com

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Chlorides (mg/L) Glucoseglutamic acid 20C27C Correlation coefficient (r) Coefficient of determination (r 2 ) Correlation coefficient (r) Coefficient of determination (r 2 ) 00.9820.9650.9760.953 5,0000.9750.9510.9710.942 10,0000.9890.9790.9710.943 15,0000.9790.9580.9190.844 20,0000.9860.9720.8840.781 Domestic wastewater 00.9700.9410.9830.967 5,0000.9920.9840.9880.977 10,0000.9980.9950.9800.961 15,0000.9970.9940.9820.964 20,0000.9820.9650.9950.990 Values of r 2 and r for BOD of glucoseglutamic acid and domestic wastewater under varying concentration of chlorides. Downloaded from CivilDigital.com

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BOD exertion and values of coefficient of determination of glucoseglutamic acid at 20C. BOD exertion and values of coefficient of determination of glucoseglutamic acid at 27C. Downloaded from CivilDigital.com

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Percent exertion of BOD for domestic wastewater at various chloride concentrations at 27C. BOD exertion and values of coefficient of determination of domestic wastewater at 20C Downloaded from CivilDigital.com