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dimensions (50-150 pm) steadily increased (Fig. 17) dimensions between 150 and 500 um; while, after the ultrasonic treatment, the number of flocs

Figure 17 dimensions (50-150 pm) steadily increased (Fig. 17) dimensions between 150 and 500 um; while, after the ultrasonic treatment, the number of flocs

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Table 1 On the other hand, the total area for agriculture in the EU is about one third of what is now
Table 1 On the other hand, the total area for agriculture in the EU is about one third of what is now
Table 2. Per capita sludge production (g/personxd) in different countries © sluUdse Proguculon Tablse Is qulle labee (24U — 2% siperson XxX GQ) WS MaICauNs Wie AUICTeN proach to WW treatment and sludge management in different countries. Sludge production more less directly depends on the pollutants removal efficiency and chemicals added for phospahte ecipitation and flocculation. Too high values, however, can indicate that the biologica rbilization process is not completed. We generally can say that the appropriate values should be ir > range of 45-65 g/(person x d), unless phosphorus removal process by chemical precipitation 1:
Table 2. Per capita sludge production (g/personxd) in different countries © sluUdse Proguculon Tablse Is qulle labee (24U — 2% siperson XxX GQ) WS MaICauNs Wie AUICTeN proach to WW treatment and sludge management in different countries. Sludge production more less directly depends on the pollutants removal efficiency and chemicals added for phospahte ecipitation and flocculation. Too high values, however, can indicate that the biologica rbilization process is not completed. We generally can say that the appropriate values should be ir > range of 45-65 g/(person x d), unless phosphorus removal process by chemical precipitation 1:
Table 3. Current disposal options in European countries (% of sludge produced) It may be seen that in many countries agricultural utilisation still plays an important role while in
Table 3. Current disposal options in European countries (% of sludge produced) It may be seen that in many countries agricultural utilisation still plays an important role while in
member state. The regulations of the 2000 working document are more specific towards pathogens
member state. The regulations of the 2000 working document are more specific towards pathogens
reduction, treatment processes and site restrictions in land application (Table 6).
reduction, treatment processes and site restrictions in land application (Table 6).
Frequency (minimum number per year) 8Dry and organic matter, pH, primary nutrients (N, PK), secondary nutrients (Ca, Mg, S), micro-nutrients (B, Co, Fe, Mn, Mo}
Frequency (minimum number per year) 8Dry and organic matter, pH, primary nutrients (N, PK), secondary nutrients (Ca, Mg, S), micro-nutrients (B, Co, Fe, Mn, Mo}
Fig. 2 Scheme of the anaerobic digestion process methanogenic bacteria. The following scheme (Fig. 2) shows the 4 steps involved in the anaerobic
Fig. 2 Scheme of the anaerobic digestion process methanogenic bacteria. The following scheme (Fig. 2) shows the 4 steps involved in the anaerobic
as reported in Table 8. representative sample. In the three WW treatment plants the sampling campaigns were carried out
as reported in Table 8. representative sample. In the three WW treatment plants the sampling campaigns were carried out
Table 9. Main characteristics of the WW treatment plants Table 9 shows the main characteristics of the treatment units of the three WW treatment plants. sludge in the excess sludge line.
Table 9. Main characteristics of the WW treatment plants Table 9 shows the main characteristics of the treatment units of the three WW treatment plants. sludge in the excess sludge line.
Throughout this study the octapole cell was pressurized with ultra high purity He gas. The
Throughout this study the octapole cell was pressurized with ultra high purity He gas. The
Table 10. Operating conditions adopted for ORS-ICP-MS analyses Error! Reference source not found.Tables 11, 12 and 13 Error! Reference source not analyzed sludges sampled at Roma Nord, Co.bis. and Fregene WWTPs.
Table 10. Operating conditions adopted for ORS-ICP-MS analyses Error! Reference source not found.Tables 11, 12 and 13 Error! Reference source not analyzed sludges sampled at Roma Nord, Co.bis. and Fregene WWTPs.
Table 11. Solid and nutrient content of Roma Nord sludges Table. 12 Solid and nutrient content of Co.bis. sludges
Table 11. Solid and nutrient content of Roma Nord sludges Table. 12 Solid and nutrient content of Co.bis. sludges
the very prolonged sludge age and probably the inefficiency of the degritting unit.
the very prolonged sludge age and probably the inefficiency of the degritting unit.
Table 15. Heavy metals content (mg/kg) of Co.bis. sludges
Table 15. Heavy metals content (mg/kg) of Co.bis. sludges
Primary sludge is always richer in EOX content than the activated one.
Primary sludge is always richer in EOX content than the activated one.
utilization in agriculture, are mostly adsorbed in primary sludge. These results show that anionic surfactants, which are one of the focus pollutant affecting sludge
utilization in agriculture, are mostly adsorbed in primary sludge. These results show that anionic surfactants, which are one of the focus pollutant affecting sludge
Fig. 6 Anionic surfactants (one of the focus pollutant because inserted in the third draft of the proposed new directive on sludge utilization in agriculture) are mostly adsorbed in primary sludge (MBAS = methylene blue active substances)
Fig. 6 Anionic surfactants (one of the focus pollutant because inserted in the third draft of the proposed new directive on sludge utilization in agriculture) are mostly adsorbed in primary sludge (MBAS = methylene blue active substances)
Fig. 7. Typical SCOD increase pattern at different specific energy inputs
Fig. 7. Typical SCOD increase pattern at different specific energy inputs
gravity thickened for 24 h at 4°C before carrying out the sonication experiments. Fig. 8 .View of Roma Nord treatment plant avoid the addition of polyelectrolyte, which can alter the charge density determinations. It was
gravity thickened for 24 h at 4°C before carrying out the sonication experiments. Fig. 8 .View of Roma Nord treatment plant avoid the addition of polyelectrolyte, which can alter the charge density determinations. It was
Fig. 9. Microscopic photographs of untretaed and sonicated sludge, at 10 and 40 min. plateau value. The DDcop trend can be described with a logarithmic curve. Nith energy input of 3000-4000 kJ/kgTS, a low disintegration degree (around 5%) can be obtaine: as reported also by Lehne et al, 2001). This low DDcod indicated therefore the disruption of sludge flocs into smaller aggregates, without significant organic material release. With increasing
Fig. 9. Microscopic photographs of untretaed and sonicated sludge, at 10 and 40 min. plateau value. The DDcop trend can be described with a logarithmic curve. Nith energy input of 3000-4000 kJ/kgTS, a low disintegration degree (around 5%) can be obtaine: as reported also by Lehne et al, 2001). This low DDcod indicated therefore the disruption of sludge flocs into smaller aggregates, without significant organic material release. With increasing
resulted almost constant. varying the sludge sample volume, the sonication time and the power of the ultrasonic devic« the sludge, different series of sonication experiments were performed at fixed specific energy anc To confirm that the disintegration degree is strictly dependent on the specific energy delivered to
resulted almost constant. varying the sludge sample volume, the sonication time and the power of the ultrasonic devic« the sludge, different series of sonication experiments were performed at fixed specific energy anc To confirm that the disintegration degree is strictly dependent on the specific energy delivered to
Fig. 11. Dimensional distribution of the particles in the sludge supernatatant increasing the disintegration degree, the solubilisation of the smaller particles occurred. This may be explained because for DDcop lower than 10%, the release of the colloidal extracellular polymeric substances and the fine intracellular colloidal and supracolloidal (>1.2 tm) material occurred. At higher disintegration degrees, the dimensions of these particles are significantly ge eee, occurred. At higher disintegration degrees, the dimensions of these particles are significantly
Fig. 11. Dimensional distribution of the particles in the sludge supernatatant increasing the disintegration degree, the solubilisation of the smaller particles occurred. This may be explained because for DDcop lower than 10%, the release of the colloidal extracellular polymeric substances and the fine intracellular colloidal and supracolloidal (>1.2 tm) material occurred. At higher disintegration degrees, the dimensions of these particles are significantly ge eee, occurred. At higher disintegration degrees, the dimensions of these particles are significantly
The trend of the surface charge contribution due to the particles smaller than 0.45 um was different:
The trend of the surface charge contribution due to the particles smaller than 0.45 um was different:
were found to be almost constant. On the contrary, a significant effect of the solids on DDcop was observed for higher TS contents (in the range 21-27.7 g/L): delivering the same specific energy input, the disintegration degrees were much higher with respect to those obtained pretreating sludge
were found to be almost constant. On the contrary, a significant effect of the solids on DDcop was observed for higher TS contents (in the range 21-27.7 g/L): delivering the same specific energy input, the disintegration degrees were much higher with respect to those obtained pretreating sludge
Fig. 15. CST as function of the specific energy
Fig. 15. CST as function of the specific energy
Table 17 Dimensional distribution of the untreated and sonicated sludge (10 min) (a):flocs number; (b): percentage of flocs number
Table 17 Dimensional distribution of the untreated and sonicated sludge (10 min) (a):flocs number; (b): percentage of flocs number
untreated sample (Table 18). Based on these results the disintegration degree was 2.9%
untreated sample (Table 18). Based on these results the disintegration degree was 2.9%
Table 19. Dimensional distribution of the untreated and sonicated sludge (40 min) (a):flocs number; (b): percentage of flocs number time. The specific energy delivered to the sludge sample was 44444 kJ/kgTS.
Table 19. Dimensional distribution of the untreated and sonicated sludge (40 min) (a):flocs number; (b): percentage of flocs number time. The specific energy delivered to the sludge sample was 44444 kJ/kgTS.
Fig. 18. Soluble COD of the untreated and sonicated sludge (40 min) experiments carried out during different periods of the work, on different sludge samples. the soluble COD increment observed after the ultrasonic treatment at 200 kHz in the 5 differet
Fig. 18. Soluble COD of the untreated and sonicated sludge (40 min) experiments carried out during different periods of the work, on different sludge samples. the soluble COD increment observed after the ultrasonic treatment at 200 kHz in the 5 differet
Table 20. EPS (proteins and carbohydratres ) content of the untreated and sonicated sludge (40 min. Because EPS, and the proteins in particular, are the main responsible for the negative charge of the of sludge, before and after the ultrasonic treatment. also monitored. Table 20 reports the proteins and carbohydrates concentrations in the soluble phase
Table 20. EPS (proteins and carbohydratres ) content of the untreated and sonicated sludge (40 min. Because EPS, and the proteins in particular, are the main responsible for the negative charge of the of sludge, before and after the ultrasonic treatment. also monitored. Table 20 reports the proteins and carbohydrates concentrations in the soluble phase
Fig. 19. Surface charge density of untreated and sonicted sludge (40 min) which can was observed for the sonicated sludge of two different experiments with respect to the
Fig. 19. Surface charge density of untreated and sonicted sludge (40 min) which can was observed for the sonicated sludge of two different experiments with respect to the
resulted in an increase of the sludge flocs having smaller dimensions (50 to 150 and 0 to 50 um)
resulted in an increase of the sludge flocs having smaller dimensions (50 to 150 and 0 to 50 um)
Fig. 21. Microscopic photographs of untreated and sonicted sludge sludge solids to the liquid phase, as it was demonstrated by an increase of soluble COD after
Fig. 21. Microscopic photographs of untreated and sonicted sludge sludge solids to the liquid phase, as it was demonstrated by an increase of soluble COD after
of about 40%) for sludge sonication at 207 kHz (Tiehm et al., 2001). energy input of 44’667 kJ/kgTS. This value was much higher than that reported by Tiehm (DDcop
of about 40%) for sludge sonication at 207 kHz (Tiehm et al., 2001). energy input of 44’667 kJ/kgTS. This value was much higher than that reported by Tiehm (DDcop
EPS (mainly proteins and carbohydrates) represent a considerable fraction of the organic material in
EPS (mainly proteins and carbohydrates) represent a considerable fraction of the organic material in
Fig. 24 EPS content of the untreated and sonicated sludge the high sludge age of the activated sludge plant) the increase of soluble protein in the liquid phas
Fig. 24 EPS content of the untreated and sonicated sludge the high sludge age of the activated sludge plant) the increase of soluble protein in the liquid phas
treatment at a specific energy of 23894 kJ/kgTS, the proteic COD incresead to 34%.
treatment at a specific energy of 23894 kJ/kgTS, the proteic COD incresead to 34%.
Fig. 26. Comparison of DD cop 20K, and DD cop 200, pattern as function of the specific energy
Fig. 26. Comparison of DD cop 20K, and DD cop 200, pattern as function of the specific energy
Table 22 Characterization of the mixtures with untreated and sonicated sludge, and of the anaerobic inoculum: (F/I=0.5) *= CODpan is calculated as difference between COD, and COD.) **= COD,, 1s calculated using the formula (COD,,/VS=1,5) particulate and total) for the components of both mixtures are reported in Table 22.
Table 22 Characterization of the mixtures with untreated and sonicated sludge, and of the anaerobic inoculum: (F/I=0.5) *= CODpan is calculated as difference between COD, and COD.) **= COD,, 1s calculated using the formula (COD,,/VS=1,5) particulate and total) for the components of both mixtures are reported in Table 22.
Table 23 Anaerobic digestion trend of the untreated and sonicated mixture (F/I=0.5
Table 23 Anaerobic digestion trend of the untreated and sonicated mixture (F/I=0.5
Table 24 volatile solids degradation efficiency and biogas productions of untreated and sonicated sludge during the digestion process. (F/I=0.5) (+16%) than the one obtained from the digestion of the same sludge, untreated. digestion process. The biogas produced from the digestion of the sonicated sludge is resulted higher
Table 24 volatile solids degradation efficiency and biogas productions of untreated and sonicated sludge during the digestion process. (F/I=0.5) (+16%) than the one obtained from the digestion of the same sludge, untreated. digestion process. The biogas produced from the digestion of the sonicated sludge is resulted higher
Table 25 Characterization of seconadry sludge and inoculums (F/I=1) For both mixtures, the total and volatile solids and the COD trends during the anaerobic digestion i ee oo oe i ae
Table 25 Characterization of seconadry sludge and inoculums (F/I=1) For both mixtures, the total and volatile solids and the COD trends during the anaerobic digestion i ee oo oe i ae
For the untreated mixture, the volatile solids and the COD, soluble and particulate, showed the same
For the untreated mixture, the volatile solids and the COD, soluble and particulate, showed the same
Table 27 volatile solids degradation efficiency and biogas productions of untreated and sonicated sludge during the digestion process. (F/I=1)
Table 27 volatile solids degradation efficiency and biogas productions of untreated and sonicated sludge during the digestion process. (F/I=1)
Table 28 Characterization of secondary sludge an of inoculums (F/I=2) The untreated and sonicated mixtures at F/I = 2 contained 60% of secondary sludge, untreated or sonicated, and 40% of inoculum. The batch anaerobic reactors were stopped at 55h, 5, 12 and 25 day. Table 29 reports the total and volatile solids content and the COD trends of untreated and sonicated mixtures during the anaerobic digestion. kJ/kg TS, obtaining a disintegration degree of 10.6%.
Table 28 Characterization of secondary sludge an of inoculums (F/I=2) The untreated and sonicated mixtures at F/I = 2 contained 60% of secondary sludge, untreated or sonicated, and 40% of inoculum. The batch anaerobic reactors were stopped at 55h, 5, 12 and 25 day. Table 29 reports the total and volatile solids content and the COD trends of untreated and sonicated mixtures during the anaerobic digestion. kJ/kg TS, obtaining a disintegration degree of 10.6%.
In the digestion of the untreated mixture, a significant degradation of the VS in the first 55h was onicated mixtures during the anaerobic digestion.
In the digestion of the untreated mixture, a significant degradation of the VS in the first 55h was onicated mixtures during the anaerobic digestion.
Table 30 volatile solids degradation efficiency and biogas productions of untreated and sonicated sludge during the digestion process. (F/I=2)
Table 30 volatile solids degradation efficiency and biogas productions of untreated and sonicated sludge during the digestion process. (F/I=2)
fable 31 shows VS degradation efficiency for both untreated and sonicated sludge: the beneficial
fable 31 shows VS degradation efficiency for both untreated and sonicated sludge: the beneficial
Also the digestion experiments of the sonicated mixture (Fig. 28) appear to follow the first-order Statistically different: the highest F/I experiment is characterized by the highest hydrolysis constant
Also the digestion experiments of the sonicated mixture (Fig. 28) appear to follow the first-order Statistically different: the highest F/I experiment is characterized by the highest hydrolysis constant
and 1, respectively.
and 1, respectively.
Table 32 Soluble COD variation during the digestion process, for the untreated and sonicated slugde Table 32 shows the soluble COD variation during the digestion experiments for both untreated anc sonicated mixture. than that of the untreated sludge, demonstrating the effectiveness of the ultrasonic pretreatment. For the untreated sludge, during the digestion at low F/I (0,5 and 1) soluble COD slightly increases in the first 55 hours of the process and it remains almost constant. At high F/I the COD increment ir the first phase is higher, probably due to the lower amount of inoculum. In such a situation the activity of hydrolytic bacteria at the beginning of the digestion is likely to be prevalent respect tc methanogen bacteria. The trend of the soluble COD was different for the sonicated sludge: the higk than that of the untreated sludge, demonstrating the effectiveness of the ultrasonic pretreatment.
Table 32 Soluble COD variation during the digestion process, for the untreated and sonicated slugde Table 32 shows the soluble COD variation during the digestion experiments for both untreated anc sonicated mixture. than that of the untreated sludge, demonstrating the effectiveness of the ultrasonic pretreatment. For the untreated sludge, during the digestion at low F/I (0,5 and 1) soluble COD slightly increases in the first 55 hours of the process and it remains almost constant. At high F/I the COD increment ir the first phase is higher, probably due to the lower amount of inoculum. In such a situation the activity of hydrolytic bacteria at the beginning of the digestion is likely to be prevalent respect tc methanogen bacteria. The trend of the soluble COD was different for the sonicated sludge: the higk than that of the untreated sludge, demonstrating the effectiveness of the ultrasonic pretreatment.
Fig. 29 Hydrolysis constants as function of the food/inoculums ratio, for the untreated and sonicated sludge F/I and sonication (Tomei, 2008).
Fig. 29 Hydrolysis constants as function of the food/inoculums ratio, for the untreated and sonicated sludge F/I and sonication (Tomei, 2008).
hydrolysis and conversion, with prevalent effect of hydrolysis in the first phase of the process. because of the high amount of available volatile solids. Fig. 33 shows that the cumulative
hydrolysis and conversion, with prevalent effect of hydrolysis in the first phase of the process. because of the high amount of available volatile solids. Fig. 33 shows that the cumulative
The low value found in these experiments may be attributable to the high sludge age, which can t
The low value found in these experiments may be attributable to the high sludge age, which can t
Fig. 34 Cumulative biogas production of the sonicated sludge in the three digestion tests high amount of available substrate with respect to the inoculum (Fig. 34). The biogas production of the sonicated sludge at F/I = 2 shows a slowdown in the first 55 h: this is due to the initial accumulation of soluble organic substances suggesting a kinetic decoupling between hydrolysis (i.e. solubilisation of organic substances) and methanogenesis (i.e. biogas production). Nevertheless, in the second phase the biogas production increase and overtakes the other ones. The produced biogas volume per unit of degraded substrate is 280 Nm*/kg VS degraded,
Fig. 34 Cumulative biogas production of the sonicated sludge in the three digestion tests high amount of available substrate with respect to the inoculum (Fig. 34). The biogas production of the sonicated sludge at F/I = 2 shows a slowdown in the first 55 h: this is due to the initial accumulation of soluble organic substances suggesting a kinetic decoupling between hydrolysis (i.e. solubilisation of organic substances) and methanogenesis (i.e. biogas production). Nevertheless, in the second phase the biogas production increase and overtakes the other ones. The produced biogas volume per unit of degraded substrate is 280 Nm*/kg VS degraded,
*= biogas increment at increasing F/I for untreated/sonicated sludge **= biogas increment of sonicated sludge with respect to the untreated one at the same F/I
*= biogas increment at increasing F/I for untreated/sonicated sludge **= biogas increment of sonicated sludge with respect to the untreated one at the same F/I
Fig. 35 Cumulative biogas production as function of the F/I ratio, for the untreated and sonicated sludge om the energy point of view, Fig. 35 shows that the ultrasound pretreatment has a positive effec
Fig. 35 Cumulative biogas production as function of the F/I ratio, for the untreated and sonicated sludge om the energy point of view, Fig. 35 shows that the ultrasound pretreatment has a positive effec
Fig. 36. Proteic and soluble COD pattern of the untreated sludge in the digestion tests at F/I=0.5 and 2 carbohydrates (Wang et al., 1999; Novak et al., 2003).
Fig. 36. Proteic and soluble COD pattern of the untreated sludge in the digestion tests at F/I=0.5 and 2 carbohydrates (Wang et al., 1999; Novak et al., 2003).
Fig. 37 Specific charge density of sonicated sludge particles in the digestion tests at F/I=0.5 and 2 Surface charge density of the sludge increased noticeably in the first days of digestion at high F/I,
Fig. 37 Specific charge density of sonicated sludge particles in the digestion tests at F/I=0.5 and 2 Surface charge density of the sludge increased noticeably in the first days of digestion at high F/I,
Fig. 38 Proteic and soluble COD pattern of the sonicated sludge in the digestion tests at F/I=0.5 and 2 COD (and protein concentration) was evident (Fig. 38). regards the digestion in presence of low content of inoculum, a marked degradation of the soluble
Fig. 38 Proteic and soluble COD pattern of the sonicated sludge in the digestion tests at F/I=0.5 and 2 COD (and protein concentration) was evident (Fig. 38). regards the digestion in presence of low content of inoculum, a marked degradation of the soluble
Table 34 CST determination for the digestion at F/I=0.5 Table 35 CST determination for the digestion at F/I=2
Table 34 CST determination for the digestion at F/I=0.5 Table 35 CST determination for the digestion at F/I=2
Fig. 39 Specific charge density of sonicated sludge particles in the digestion tests at F/I=0.5 and 2
Fig. 39 Specific charge density of sonicated sludge particles in the digestion tests at F/I=0.5 and 2
Table 37 Anaerobic digestion trend for the untreated sludge at F/I=0.5 Table 38 Anaerobic digestion trend for the sonicated sludge at F/I=0.5 carbohydrates) in the digestion of the untreated and sonicated sludge, respectively.
Table 37 Anaerobic digestion trend for the untreated sludge at F/I=0.5 Table 38 Anaerobic digestion trend for the sonicated sludge at F/I=0.5 carbohydrates) in the digestion of the untreated and sonicated sludge, respectively.
Fig. 40 Proteins content of the untreated and sonicated sludge Fig. 41Soluble COD pattern of the untreated and sonicated one
Fig. 40 Proteins content of the untreated and sonicated sludge Fig. 41Soluble COD pattern of the untreated and sonicated one
Fig. 42 Carbohydates content of the untreated and sonicated sludge
Fig. 42 Carbohydates content of the untreated and sonicated sludge
fate of carbohydrates during sludge digestion seemed different, for untreated but also for sonicated
fate of carbohydrates during sludge digestion seemed different, for untreated but also for sonicated
Table 39 Cumulative biogas production of the untreated sonicated sludge
Table 39 Cumulative biogas production of the untreated sonicated sludge
Fig. 43 Cumulative biogas production of the untretated and sonicated sludge The sonicated mixture digestion is characterized by constantly higher biogas production with
Fig. 43 Cumulative biogas production of the untretated and sonicated sludge The sonicated mixture digestion is characterized by constantly higher biogas production with
Table 40 Characterization of the untreated and sonicated sludge, and of the anaerobic inoculum the untreated and sonicated sludge and of the inoculum used in this digestion test. was performed as described for the previous experiment. Table 40 summarizes the characteristics of
Table 40 Characterization of the untreated and sonicated sludge, and of the anaerobic inoculum the untreated and sonicated sludge and of the inoculum used in this digestion test. was performed as described for the previous experiment. Table 40 summarizes the characteristics of
Fig. 44 LAS degradation pattern in the digestion test at F/I =0.5
Fig. 44 LAS degradation pattern in the digestion test at F/I =0.5
Table 42 Anaerobic digestion trend for the sonicated sludge at F/I=1
Table 42 Anaerobic digestion trend for the sonicated sludge at F/I=1
Table 41 Anaerobic digestion trend for the untreated sludge at F/I=1
Table 41 Anaerobic digestion trend for the untreated sludge at F/I=1
material due to the ultrasound disintegration. Fig. 45 Proteins content of the untreated and sonicated sludge
material due to the ultrasound disintegration. Fig. 45 Proteins content of the untreated and sonicated sludge
Fig. 46 soluble COD paternt of the untreated and sonicated sludge
Fig. 46 soluble COD paternt of the untreated and sonicated sludge
Fig. 47 Carbohydrates content of the untreated and sonicated sludge
Fig. 47 Carbohydrates content of the untreated and sonicated sludge
Fig. 49 LAS degradation pattern in the digestion test at F/I = 1
Fig. 49 LAS degradation pattern in the digestion test at F/I = 1
Fig. 50 LAS homologues pattern during anaerobic digestion tests; U=untreated mixture, S=sonicated mixture The degradation pathway in the case of F/I=1 seemed completely different, both for untreated and
Fig. 50 LAS homologues pattern during anaerobic digestion tests; U=untreated mixture, S=sonicated mixture The degradation pathway in the case of F/I=1 seemed completely different, both for untreated and
Fig. 51 EPS content of untreated sludge during anaerobic digestion at F/I=0.5 (a) and F/I=1 (b)
Fig. 51 EPS content of untreated sludge during anaerobic digestion at F/I=0.5 (a) and F/I=1 (b)
; important to note that protein and carbohydrates concentrations at the end of the digestion were
; important to note that protein and carbohydrates concentrations at the end of the digestion were
and to a scarce consume of these substances by the methanogens. slightly higher than the initial one. This can be ascribed to the intense hydrolysis in the first pha
and to a scarce consume of these substances by the methanogens. slightly higher than the initial one. This can be ascribed to the intense hydrolysis in the first pha
removal increases by decreasing F/I, both for untreated and sonicated sludge digestion. ludge, in the tests at different F/I ratios. Biogas production of the untreated sludge was, as
removal increases by decreasing F/I, both for untreated and sonicated sludge digestion. ludge, in the tests at different F/I ratios. Biogas production of the untreated sludge was, as
Fig. 54 Surface charge trend during anaerobic digestion tests; U=untreated sludge S=sonicated sludge improvement compared to non-pretreatment. For the test at F/I=1 the beneficial effect of ultrasound
Fig. 54 Surface charge trend during anaerobic digestion tests; U=untreated sludge S=sonicated sludge improvement compared to non-pretreatment. For the test at F/I=1 the beneficial effect of ultrasound
Fig. 55 Cumulative biogas production of the untreated and sonicated sludge at F/I=0.5 and 1 Table 46 Biogas gain
Fig. 55 Cumulative biogas production of the untreated and sonicated sludge at F/I=0.5 and 1 Table 46 Biogas gain
disintegration degree of the 20 kHz sonicated samples. and digested in the same conditions. The ultrasound treatment at higher frequency provided good gains in VS removals, and surprisingly at F/I=1 the improvement was significantly higher than the one obtained at the conventional 20 kHz.
disintegration degree of the 20 kHz sonicated samples. and digested in the same conditions. The ultrasound treatment at higher frequency provided good gains in VS removals, and surprisingly at F/I=1 the improvement was significantly higher than the one obtained at the conventional 20 kHz.
Fig. 56 Biogas gain of the 20 and 200 kHz pretreated sludge at F/I =0.5 and 1 comparable with the biogas gained pretreating the sludge at 20 kHz (Fig. 56). anaerobic digestion performances, as regards to solubilisation and removal of organic substances
Fig. 56 Biogas gain of the 20 and 200 kHz pretreated sludge at F/I =0.5 and 1 comparable with the biogas gained pretreating the sludge at 20 kHz (Fig. 56). anaerobic digestion performances, as regards to solubilisation and removal of organic substances
contaminants in water, is assigned to the AOPs.
contaminants in water, is assigned to the AOPs.
Table 49 LAS physical chemical characteristics After application, LAS are usually discharged to the sewer systems and appear in municipal
Table 49 LAS physical chemical characteristics After application, LAS are usually discharged to the sewer systems and appear in municipal
Fig. 59. Transport of surfactants in WWTP properties, sediment nature and environmental parameters. Among surfactants characteristics, the
Fig. 59. Transport of surfactants in WWTP properties, sediment nature and environmental parameters. Among surfactants characteristics, the
Fig. 60. Sorption isotherm for LAS.S is the sorbed surfactant concentration and C is the surfactant concentration in solution concentrations may provoke the formation of monomer
Fig. 60. Sorption isotherm for LAS.S is the sorbed surfactant concentration and C is the surfactant concentration in solution concentrations may provoke the formation of monomer
of microorganisms (ultimate biodegradation). The complete biodegradation of surfactants requires a mixture of bacteria because of the limitec
of microorganisms (ultimate biodegradation). The complete biodegradation of surfactants requires a mixture of bacteria because of the limitec
and some common applications of ultrasound.
and some common applications of ultrasound.
energy. Without energy input, bubbles implode ( Fig. 63): Fig. 63 Formation, growth and implosion of a cavitation bubble
energy. Without energy input, bubbles implode ( Fig. 63): Fig. 63 Formation, growth and implosion of a cavitation bubble
Fig. 65. The three sonochemical regions
Fig. 65. The three sonochemical regions
Zlass sonication cell is covered and water jacketed for cooling sonicated sludge mixture. Fig. 66. US reactor and generator (200 kHz) The transducer is made up of a piezo-ceramic element with an active area of approx. 25 cm”. Tt
Zlass sonication cell is covered and water jacketed for cooling sonicated sludge mixture. Fig. 66. US reactor and generator (200 kHz) The transducer is made up of a piezo-ceramic element with an active area of approx. 25 cm”. Tt
presented and discussed in this section. ultrasound at 600 kHz (Fig. 70); on the contrary, the removal efficiency of sonolysis at 200 kHz is plant at two different frequencies, 200 and 600 kHz. No LAS degradation was observed with
presented and discussed in this section. ultrasound at 600 kHz (Fig. 70); on the contrary, the removal efficiency of sonolysis at 200 kHz is plant at two different frequencies, 200 and 600 kHz. No LAS degradation was observed with
Table 50 Sluge characteristics and operating conditions of the six experiments
Table 50 Sluge characteristics and operating conditions of the six experiments
Table 51. LAS concentration (mg/Lyuagey and LAS degradation (%) in the six experiments experiments LAS content is higher, 5,9 and 3,9 mg/Lstudge for experiment | and 2, respectively. input, to render the process more sustainable. The initial LAS concentration of the untreated sludge
Table 51. LAS concentration (mg/Lyuagey and LAS degradation (%) in the six experiments experiments LAS content is higher, 5,9 and 3,9 mg/Lstudge for experiment | and 2, respectively. input, to render the process more sustainable. The initial LAS concentration of the untreated sludge
Fig. 71. LAS concentration in the untreated and sonicated sludge
Fig. 71. LAS concentration in the untreated and sonicated sludge
Table 52. eigenvalues and the percentage of variance for the first three component: Fig. 72 (a) shows the distribution of the variables in the space formed by the first two components
Table 52. eigenvalues and the percentage of variance for the first three component: Fig. 72 (a) shows the distribution of the variables in the space formed by the first two components
Table 52 reports the eigenvalues and the percentage of variance for the first three components.
Table 52 reports the eigenvalues and the percentage of variance for the first three components.
Fig. 74 LAS homologues degradation pattern
Fig. 74 LAS homologues degradation pattern
Fig. 75 Average percentage of the different homologues for untreated and sonicated samples (experiment # 5 and 6) combined role in the degradation of surfactants mixture. like reactivity of each homologue with OH radicals, surface excess and surface tension may play a
Fig. 75 Average percentage of the different homologues for untreated and sonicated samples (experiment # 5 and 6) combined role in the degradation of surfactants mixture. like reactivity of each homologue with OH radicals, surface excess and surface tension may play a
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