Batch No. 2 in SFBBR-1

Batch No. 2 was also operated for a total of 10 days with a HLR of 9,9 m/h and air flow rate of approximately 10,1 L/h. The initial volume of sludge water treated was approximately equal to 20,0 L and the pH was adjusted by using the 0,7 M K2CO3

solution. The daily change in volume of the treated sludge water was calculated in the

96

same way as already described for Batch No.1 in the SFBBR-1 system. The calculated loss rate value was equal to 119,5 mL/d and a total volume of 400,0 mL were sampled from the collection tank.

The operational condition values monitored during the treatment period are given in appendix C. The graphical representation of the collected data is given in figure 68.

Figure 68. Operational conditions measured during Batch No. 2 in SFBBR-1 system

As illustrated in figure 68, the temperature in the collection tank was in between 20,0 and 24,0°C with an average value of 22,6°C. The daily volume of the treated sludge water was calculated to a final volume of approximately 19,1 L which represented a decrease of approximately 900,0 mL from the initial volume of 20,0 L.

The pH values ranged in between 7,5 to 8,6 during the treatment period with a total consumed volume of the 0,7 M K2CO3 solution equal to 740,0 mL. The moles of hydrogen ions that reacted with the added carbonate ions, the acid capacity of the treated sludge water and the total acid capacity of the system were calculated as already described in the batch No. 1 section with values equal to 1,1 mol H⁺, 1,4 mol H⁺ and 2,5 mol H⁺ respectively.

For this batch the DO concentration was measured in the collection tank and at the top of the packed bed biofilm. The data analysis for the raw data recorded at the top of the packed bed biofilm was done in the same way as already described in batch No. 1. The calculated values and raw data are given in appendix C for batch No. 2.

The graphical representation of the calculated values are given in figure 69.

0,0

Vol_SW pH TK-T Vol. K2CO3 Cons.

97

Figure 69. DO conc. & T values measured during Batch No. 2 in SFBBR-1 system

The average DO concentration values at the top of the packed bed biofilm fluctuated during the treatment process in between 0,96 to 11,25 mg O2/L with an overall average value of 6,36 ± 1,09 mg O2/L. The overall average value is higher than the suggested value of 5 mg/L for nitrification in biofilm processes. The lower DO values were registered for days 3 and 4 with average values of 1,19 ± 0,30 mg O2/L and 0,96 ± 0,12 mg O2/L respectively. These values are below the theoretical value of 2,7 mg O2/L required for optimal growth of AOB. The oversaturated concentration of oxygen at the top of the column can be attributed to the already discussed intermittent foaming formation that occurred during the process which was more intense compare to batch No. 1 due to the higher HLR. Furthermore, the DO concentration in the collection tank varied in between 5,09 to 9,86 mg O2/L with an average value of 8,00 mg O2/L. The larger than 5 mg O2/L DO values registered in the collection tank and the top of the packed bed biofilm help to reduce the oxygen limitations for AOB and NOB growth and thus guaranteeing an efficient ammonium and nitrite oxidation during the treatment process.

Finally, the temperatures at the top of the column were relatively constant with values ranging in between 22,1 to 25,1°C and an overall average temperature of 23,4 ± 0,3°C which was a little higher than the average collection tank temperature of 22,6°C. The slightly difference in temperature can be explained by energy conservation as stated by the first law of thermodynamics where some of the mechanical energy provided by the pump gets converted into thermal energy and thus increasing the temperature of the fluid.

98 4.5.3. Batch No. 3 in SFBBR-1

Batch No. 3 was operated for a total of 6 days at a HLR of 13,8 m/h and the approximated air flow rate of 10,1 L/h. The total volume of sludge water treated in this batch was equal to 20,0 L and the pH was adjusted by using the 0,7 M K2CO3 solution.

The daily change in the volume of treated sludge water was calculated as indicated for batch No. 1 where the calculated loss rate value was equal to 165,5 mL/d and a total volume of 240,0 mL were sampled from the collection tank.

The operational condition values monitored during the treatment period are given in appendix C. The graphical representation of the collected data is given in figure 70.

Figure 70. Operational conditions measured during Batch No. 3 in SFBBR-1 system

Figure 70 shows that the temperature in the collection tank varied in between 20,0 to 22,0 °C during the process with an average value of 21,6°C. The volume of the treated sludge water was calculated for day 6 as approximately 19,5 L which represented a decrease of about 500,0 mL from the initial volume of 20,0 L.

The pH values ranged in between 7,5 to 8,5 with a total consumed volume of the 0,7 M K2CO3 solution of 750,0 mL. The moles of hydrogen ions that reacted with the added carbonate ions, the acid capacity of the treated sludge water and the total acid capacity of the system were calculated as already described for the batch No. 1 case with values equal to 1,1 mol H⁺, 1,4 mol H⁺ and 2,5 mol H⁺ respectively. These values corresponded to the same values calculated for the batch No. 2 process.

Furthermore, the DO concentration was measured and recorded at top of the packed bed biofilm. The data analysis for these data was done in the same way as already

0,0

Vol_SW pH TK-T Vol. K2CO3 Cons.

99

described in batch No. 1. The calculated values and raw data are given in appendix C for batch No. 3. The graphical representation of the calculated values are illustrated in figure 71.

Figure 71. DO conc. & T values measured during Batch No. 3 in SFBBR-1 system

As observed in figure 71, during this treatment process the average DO concentrations at the top of the column reached a highest value of 11,61 mg O2/L with a lowest point of 7,81 mg O2/L for days 2 and 4 respectively. The overall average DO value was equal to 9,49 ± 0,52 which was slightly higher than the saturation value of 9,09 mg O2/L at 20°C. The oversaturated recorded values were probably due to the relative high HLR and air flow rate used during this treatment process which resulted in strong foaming formation at the top of the column. Furthermore, the larger than 5 mg O2/L DO values registered during the process at the top of the packed bed biofilm considerable reduced the oxygen limitations in the growth of the AOB and NOB within the biofilm, hence an efficient ammonium and nitrite oxidation was expected for this treatment process.

The temperatures at the top of the column were found to be in between 22,0 to 23,0°C with an average value of 22,6 ± 0,1°C. This value was slightly higher than the average value of 21,6°C registered during the treatment process in the collection tank.

4.5.4. Batch No. 4 in SFBBR-1

This batch was operated for a total of 14 days at HLR of 4,9 m/h and a constant air flow rate of 1,5 L/h. The initial volume of sludge water treated was approximately equal to 20,0 L and the pH was adjusted by using the 0,7 M K2CO3 solution. The daily change

100

in volume of the treated sludge water was calculated in the same way as already described for Batch No.1 in the SFBBR-1 system. The calculated loss rate value was equal to 58,9 mL/d and a total volume of 720,0 mL were sampled from the collection tank.

The operational condition values monitored during the treatment period are given in appendix C and their graphical representation is given in figure 72.

Figure 72. Operational conditions measured during Batch No. 4 in SFBBR-1 system

As illustrated in figure 72, the temperature in the collection tank varied in between 20,0 to 24,0°C with an average value of 22,4°C. The daily volume of the treated sludge water was calculated to a final volume of approximately 19,2 L by day 14 which represented a decrease of approximately 800,0 mL from the initial volume of 20,0 L.

The pH values ranged in between 7,5 to 8,5 during the treatment period with a total consumed volume of 760,0 mL corresponding to the 0,7 M K2CO3 solution. The moles of hydrogen ions that reacted with the added carbonate ions, the acid capacity of the treated sludge water and the total acid capacity of the system were calculated as already described in the batch No. 1 section with values equal to 1,1 mol H⁺, 1,4 mol H⁺ and 2,5 mol H⁺ respectively.

The DO concentration was measured in the collection tank and at top of the packed bed biofilm. The data analysis for the raw data recorded at the top of the packed bed biofilm was done in the same way as already described in batch No. 1. The calculated values and raw data are given in appendix C for batch No. 4.

The graphical representation of the calculated values are given in figure 73.

0,0

Vol_SW pH TK-T Vol. K2CO3 Cons.

101

Figure 73. DO conc. & T values measured during Batch No. 4 in SFBBR-1 system

As seen in figure 73, the average DO concentration values measured at the top of the column varied from 1,0 to 4,0 mg O2/L in between days 0 and 2. For days 3 through 7 the DO concentration was at the lowest points being smaller than 1,0 mg O2/L. Then, the DO concentration increased in between days 8 to 12 with values in between 1,0 to 2,0 mg O2/L and during the last two days of treatment the DO concentration was greater than 5,0 mg O2/L. The overall DO concentration average value was equal to 2,02 ± 0,52 mg O2/L, this value was smaller than the calculated theoretical value of 2,7 mg O2/L required for optimal growth of AOB and was less than half the value corresponding to the suggested DO concentration value of 5 mg O2/L. Furthermore, the DO concentration in the collection tank varied in between 2,22 to 6,86 mg O2/L with an average value of 4,46 mg O2/L.

Based on the measured values and considering the fact that in average the DO concentration of the system was smaller than 5 mg O2/L. Then, oxygen limitations on AOB and NOB growth were expected during this process and thus affecting ammonium and nitrite oxidation and the overall efficiency of the treatment process.

The temperatures at the top of the column varied in between 21,3 to 24,7°C with an overall average temperature of 23,3 ± 0,2°C which was a little higher than the average collection tank temperature of 22,4°C.

The formation of foaming at the top of the column was not observed at the process conditions.

102 4.5.5. Batch No. 5 in SFBBR-1

This batch was operated for a total of 11 days at HLR of 10,1 m/h and a constant air flow rate of 1,5 L/h. The initial volume of sludge water treated was approximately equal to 20,0 L and the pH was adjusted by using the 0,7 M K2CO3 solution. The daily change in volume of the treated sludge water was calculated in the same way as already described for Batch No.1 in the SFBBR-1 system. The calculated loss rate value was equal to 121,4 mL/d and a total volume of 720,0 mL were sampled from the collection tank.

The operational condition values monitored during the treatment period are given in appendix C and their graphical representation is illustrated in figure 74.

Figure 74. Operational conditions measured during Batch No. 5 in SFBBR-1 system

As illustrated in figure 74, the temperature in the collection tank varied in between 21,0 to 24,0°C with an average value of 22,9°C. The daily volume of the treated sludge water was calculated to a final volume of approximately 18,7 L corresponding to the last day which represented a decrease of approximately 1,3 L from the initial volume of 20,0 L.

The pH values ranged in between 7,5 to 8,6 during the treatment period with a total consumed volume of 710,0 mL corresponding to the 0,7 M K2CO3 solution. The moles of hydrogen ions that reacted with the added carbonate ions, the acid capacity of the treated sludge water and the total acid capacity of the system were calculated as already described in the batch No. 1 section with values equal to 1,0 mol H⁺, 1,4 mol H⁺ and 2,4 mol H⁺ respectively.

Vol_SW pH TK-T Vol. K2CO3 Cons.

103

The DO concentration was measured in the collection tank and at top of the packed bed biofilm. The data analysis for the raw data recorded at the top of the packed bed biofilm was done in the same way as already described in batch No. 1. The calculated values and raw data are given in appendix C for batch No. 5. The graphical representation of the calculated values are given in figure 75.

Figure 75. DO conc. & T values measured during Batch No. 5 in SFBBR-1 system

Figure 75 shows that the average DO concentration values measured at the top of the column were below 1,0 mg O2/L in between days 0 to 7. For days 8 through 10 the DO concentration was in between 2,0 to 3,0 mg O2/L and by day 11 the DO concentration had increased to 6,1 mg O2/L.

The overall DO concentration average value at the top of the packed bed biofilm was equal to 1,29 ± 0,53 mg O2/L and the DO concentration in the collection tank varied in between 2,52 to 6,68 mg O2/L with an average value of 3,92 mg O2/L. The average DO concentration values are lower than the calculated theoretical value of 2,7 mg O2/L required for the optimal growth of AOB and are so much less than the suggested DO concentration value of 5 mg O2/L. For that reason, the same oxygen limitation as previously described for the batch No. 4 case was expected for this treatment process.

The temperatures at the top of the column varied in between 22,0 to 25,2°C with an overall average temperature of 24,2 ± 0,3°C which was a little higher than the average collection tank temperature of 22,9°C.

The formation of foaming at the top of the column was not observed at the process conditions.

104 4.5.6. Batch No. 6 in SFBBR-1

This batch was operated for a total of 10 days at a HLR of 11,6 m/h and at a constant air flow rate of 1,5 L/h. The initial volume of sludge water treated was approximately equal to 20,0 L and the pH was adjusted by using the 0,7 M K2CO3 solution. The daily change in volume of the treated sludge water was calculated in the same way as already described for the Batch No.1 process. The calculated loss rate value was equal to 139,8 mL/d and a total volume of 640,0 mL were sampled from the collection tank.

The operational condition values monitored during the treatment period are given in appendix C and their graphical representation is shown in figure 76.

Figure 76. Operational conditions measured during Batch No. 6 in SFBBR-1 system

As illustrated in figure 76, the temperature in the collection tank varied in between 21,0 to 23,0°C with an average value of 22,3°C. The daily volume of the treated sludge water was calculated to a final volume of approximately 18,8 L which corresponded to day 10 and represented a decrease of approximately 1,2 L from the initial volume of 20,0 L.

The pH values ranged in between 7,5 to 8,6 during the treatment period with a total consumed volume of 795,0 mL of the 0,7 M K2CO3 solution. The moles of hydrogen ions that reacted with the added carbonate ions, the acid capacity of the treated sludge water and the total acid capacity of the system were calculated as already described for batch No. 1 with values equal to 1,1 mol H⁺, 1,4 mol H⁺ and 2,5 mol H⁺ respectively.

Vol_SW pH TK-T Vol. K2CO3 Cons.

105

The DO concentration was measured in the collection tank and at top of the packed bed biofilm. The data analysis for the raw data recorded at the top of the packed bed biofilm was done in the same way as already described in batch No. 1. The calculated values and raw data are given in appendix C for batch No. 6. The graphical representation of the calculated values are given in figure 77.

Figure 77. DO conc. & T values measured during Batch No. 6 in SFBBR-1 system

Figure 77 shows that the average DO concentration values measured at the top of the column were equal to 1,0 mg O2/L for day 0 but in between days 1 to 6 the average value was lower than 1,0 mg O2/L and in between days 7 to 10 the DO concentration increased from 1,3 to 6,9 mg O2/L respectively.

The overall DO concentration average value at the top of the packed bed biofilm was equal to 1,60 ± 0,69 mg O2/L and the DO concentration in the collection tank varied in between 3,0 to 7,0 mg O2/L with an average value of 4,53 mg O2/L. As already discussed in batches No. 4 and 5, the average low concentrations of oxygen in the system are indications of possible oxygen limitation in the growth of the AOB and leading to lower ammonium consumption rates.

The temperature at the top of the column varied in between 22,4 to 24,5°C with an overall average temperature of 23,3 ± 0,2°C which was a little higher than the average collection tank temperature of 22,3°C.

0,0

106 4.5.7. Semi-Batch operation in SFBBR-1

The daily change in volume of the treated sludge water was calculated as described in the batch No. 1 section. The loss rate value was estimated as 150,0 mL/d as indicated in table 29 and a total of 400,0 mL were sampled from the collection tank.

The operational condition values measured during this treatment process are given in appendix D and their graphical representation is illustrated in figure 78.

Figure 78. Operational conditions measured during the semi-batch process in SFBBR-1 system

As seen in figure 78, the temperature in the collection tank was maintained in between 20,0 to 24,0°C with an average temperature of 22,1°C and by day 25 the volume of the treated sludge water had decreased to a value of 17,8 L representing a total liquid loss of approximately 2,2 L from the initial volume of 20,0 L.

The pH was maintained during the process within 7,5 to 8,5 with a total consumption of the 0,9 M sodium carbonate solution of 1995,0 mL. The consumption of the pH adjust solution was almost equal during the daily sludge water renewal period with values ranging from 75,0 to 85,0 mL corresponding to an acid capacity range of 0,1 to 0,2 mol H⁺. Furthermore, the 3,0 L of the sludge water contained approximately an alkalinity equal to 0,2 mol H⁺ leading to a daily total acid capacity range of 0,3 to 0,4 mol H⁺. Additionally, on the weekends, 9,0 L of the sludge water were renewed which represented a 3 day treatment. The consumptions of the pH adjust solution during the two weekends were 230,0 and 240,0 mL with a daily average consumption of 76,6

Vol_SW pH TK-T Vol. Na2CO3 Cons.

107

and 80,0 mL respectively, these values were found to be within the range observed during the daily treatment renewal. The acid capacity values were calculated as indicated in the batch No. 1 section but by using the 0,9 M concentration of the sodium carbonate solution.

The DO concentration and temperature values measured at the top of the packed bed biofilm and the DO concentration measured in the collection tank are illustrated in figure 79. The values are given in appendix D.

Figure 79. DO conc. & T values measured during the semi-batch process in SFBBR-1 system

As illustrated in figure 79, the DO concentration measured at the top of the column followed the same trend as already described for batches No. 4 through 6 with approximately the same constant air flow rate of 1,5 L/h. In general, during the daily treatment the concentration of DO in the top column decreased to values lower than 1,0 mg O2/L and then increased to values greater than 1,0 mg O2/L with a total average of 0,95 mg O2/L. The same trend was observed for the DO concentration in the collection tank but at higher values. In general, during the daily treatment the DO

As illustrated in figure 79, the DO concentration measured at the top of the column followed the same trend as already described for batches No. 4 through 6 with approximately the same constant air flow rate of 1,5 L/h. In general, during the daily treatment the concentration of DO in the top column decreased to values lower than 1,0 mg O2/L and then increased to values greater than 1,0 mg O2/L with a total average of 0,95 mg O2/L. The same trend was observed for the DO concentration in the collection tank but at higher values. In general, during the daily treatment the DO

Im Dokument The Master Thesis was not used in the same or in a similar version to achieve an academic grading or is being published elsewhere (Seite 111-0)