Minimizing of foaming in digesters by pre-treatment of the surplus-sludge

2000 ◽  
Vol 42 (9) ◽  
pp. 235-241 ◽  
Author(s):  
M. Barjenbruch ◽  
H. Hoffmann ◽  
O. Kopplow ◽  
J. Tränckner
Keyword(s):  
High Pressure ◽  
Activated Sludge ◽  
Treatment Methods ◽  
Foaming Agents ◽  
Instance Reduction ◽  
Filamentous Microorganisms ◽  
Hydrophobic Substances ◽  
Pre Treatment ◽  
Heating Up ◽  
The Impact

Several reasons can lead to the emergence of foam in digesting tanks, for instance overloading or the impact of hydrophobic substances. Furthermore, the foaming is in regular periods going together with the emergence of filamentous microorganisms. Up to now, several strategies to avoid foaming have been tested out (for instance reduction of the sludge load in the activated sludge stage, lowering of the sludge level in the digestion tank, dosage of anti foaming agents), but these have been done relatively unsystematically and with more or less success. For our contribution, laboratory-scale digestion tests were run to analyse mechanical and thermal pre-treatment methods for the destruction of the surplus sludge. Whereas the disintegration by a high pressure homogeniser did only achieve a low reduction of the foam phase, the thermal pre-treatment at 121°C made for an effective subduing of the foam emergence. Both methods allowed for a cutting up of the filaments, but only the heating up effected the reduction of the hydrophobic substances; thus, the foaming is possibly caused by them.

scholarly journals EFFECT OF HYDROTHERMAL PRETREATMENT ON THE ACIDIFICATION OF THICKENED WASTE ACTIVATED SLUDGE AND SOURCE SEPARATED ORGANICS

2021 ◽  
Author(s):  
Farokh laqa Kakar
Keyword(s):  
Activated Sludge ◽  
Hydrothermal Pretreatment ◽  
Waste Activated Sludge ◽  
Pre Treatment ◽  
The Impact

The objective of this study was to investigate the impact of the hydrothermal pre-treatment (HTP) on solubilization and acidification of thickened waste activated sludge (TWAS) and source separated organics (SSO). The temperatures, retention times, and pressures used in this study ranges were 150-240°C, 5-30 min, and 69-488 psi, respectively. Mesophilic batch acidification tests were conducted for all pretreated and non-pretreated samples. For the TWAS, the highest overall COD solubilization due to HTP and acidification of 64% was observed at “200°C-10 min” compared to 30% for raw TWAS. The highest VFAs yield of 2856 mg VFAs/g VSS added was observed at “190°C-10 min” compared to 1251 for raw TWAS. For the SSO, the highest overall COD solubilization of 63% was observed at “210°C-20 min” compared to 17% for raw SSO. The highest VFAs yield of 1536 mg VFAs/g VSS added was observed at “210°C-20 min” compared to 768 for raw SSO.

scholarly journals EFFECT OF THERMAL PRETREATMENT ON THE SOLUBILIZATION OF ORGANIC MATTERS IN A MIXTURE OF PRIMARY AND WASTE ACTIVATED SLUDGE

2015 ◽  
Vol 9 (1) ◽  
pp. 82-88 ◽  
Author(s):  
Ahmed M. Aboulfotoh ◽  
E.H. El Gohary and O.D. El Monayeri
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Treatment Time ◽  
Chemical Properties ◽  
High Energy ◽  
Gas Production ◽  
Waste Activated Sludge ◽  
Thermal Pretreatment ◽  
Treatment Methods ◽  
Pre Treatment

The increased demand for advanced techniques in anaerobic digestion over the last few years has led to the employment of various pre-treatment methods prior to anaerobic digestion to increase gas production. These pre-treatment methods alter the physical and chemical properties of sludge in order to make it more readily degradable by anaerobic digestion. Although the thermal pre-treatment presents high energy consumption, the main part of this energy to heat can be recovered from the biogas produced in the anaerobic process. In this research a mixture of primary and waste activated sludge was thermally pretreated at 100, 125, 150, 175 and 200o C in order to determine the effect of thermal pretreatment on improving the solubilization of sludge by increasing the soluble organic fraction (expressed as soluble COD and VFA). Experimental results proved that the solubilization ratio of sludge is depends on the treatment time and the applied temperature and the optimal temperature ranged between 175 and 200o C. The COD solubilization ratio (at 175o C) increased from 11.2% to 15.1% and 25.1% when the time of treatment increased from 60 min to 120 and 240 min respectively. The experimental data could be fitted to obtain an empirical model (Known as the enzyme-kinetic equation) relating the COD solubilization ratio of sludge and VFA concentration to the applied temperature and the heating time.

scholarly journals EFFECT OF THERMAL PRETREATMENT ON THE SOLUBILIZATION OF ORGANIC MATTERS IN A MIXTURE OF PRIMARY AND WASTE ACTIVATED SLUDGE

2015 ◽  
Vol 9 (1) ◽  
pp. 82-88 ◽  
Author(s):  
Ahmed M. Aboulfotoh ◽  
E.H. El Gohary and O.D. El Monayeri
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Treatment Time ◽  
Chemical Properties ◽  
High Energy ◽  
Gas Production ◽  
Waste Activated Sludge ◽  
Thermal Pretreatment ◽  
Treatment Methods ◽  
Pre Treatment

The increased demand for advanced techniques in anaerobic digestion over the last few years has led to the employment of various pre-treatment methods prior to anaerobic digestion to increase gas production. These pre-treatment methods alter the physical and chemical properties of sludge in order to make it more readily degradable by anaerobic digestion. Although the thermal pre-treatment presents high energy consumption, the main part of this energy to heat can be recovered from the biogas produced in the anaerobic process. In this research a mixture of primary and waste activated sludge was thermally pretreated at 100, 125, 150, 175 and 200o C in order to determine the effect of thermal pretreatment on improving the solubilization of sludge by increasing the soluble organic fraction (expressed as soluble COD and VFA). Experimental results proved that the solubilization ratio of sludge is depends on the treatment time and the applied temperature and the optimal temperature ranged between 175 and 200o C. The COD solubilization ratio (at 175o C) increased from 11.2% to 15.1% and 25.1% when the time of treatment increased from 60 min to 120 and 240 min respectively. The experimental data could be fitted to obtain an empirical model (Known as the enzyme-kinetic equation) relating the COD solubilization ratio of sludge and VFA concentration to the applied temperature and the heating time.

scholarly journals Pre-treatment dips to enhance the removal of apple leafcurling midge from apples using high pressure washing

2017 ◽  
Vol 70 ◽  
pp. 315
Author(s):  
N.E.M. Page-Weir ◽  
L.E. Jamieson ◽  
A.J. Hawthorne ◽  
S.P. Redpath ◽  
A. Chhagen ◽  
...  
Keyword(s):  
High Pressure ◽  
Acetic Acid ◽  
Lactic Acid ◽  
Citric Acid ◽  
Hot Water ◽  
Hot Water Treatment ◽  
Pre Treatment ◽  
The Impact ◽  
Uv C ◽  
Improve Access

The presence of apple leafcurling midge (ALCM) on apples is of concern for many of New Zealand’s export apple markets. High pressure washing (HPW) systems have been implemented in export packhouses to reduce the risks associated with various pests; however, higher removal rates of ALCM are required to improve access to challenging markets. A range of pre-treatment dips to improve ALCM removal efficacy when applied before HPW were tested, and the impact of these pre-treatment dips on pest viability determined. Removal of ALCM cocoons by HPW alone was 41%, compared with pre- treatments of hot water at 51˚C (66%), Saturate® (58%), Prospect oil® (57%), malic acid (53%), citric acid (48%), lactic acid (46%), acetic acid (39%), HarvestCide® (37%) or sodium bicarbonate (37%). However, only the hot-water treatment significantly enhanced removal compared with HPW alone. In a second trial, removal of ALCM cocoons with HPW was 69% and hot water + UV-C increased removal to 76%, although this difference was not statistically significant. Overall, none of the pre-treatment dips was found to reduce ALCM viability significantly compared with HPW alone.

scholarly journals EFFECT OF HYDROTHERMAL PRETREATMENT ON THE ACIDIFICATION OF THICKENED WASTE ACTIVATED SLUDGE AND SOURCE SEPARATED ORGANICS

2021 ◽  
Author(s):  
Farokh laqa Kakar
Keyword(s):  
Activated Sludge ◽  
Hydrothermal Pretreatment ◽  
Waste Activated Sludge ◽  
Pre Treatment ◽  
The Impact

The objective of this study was to investigate the impact of the hydrothermal pre-treatment (HTP) on solubilization and acidification of thickened waste activated sludge (TWAS) and source separated organics (SSO). The temperatures, retention times, and pressures used in this study ranges were 150-240°C, 5-30 min, and 69-488 psi, respectively. Mesophilic batch acidification tests were conducted for all pretreated and non-pretreated samples. For the TWAS, the highest overall COD solubilization due to HTP and acidification of 64% was observed at “200°C-10 min” compared to 30% for raw TWAS. The highest VFAs yield of 2856 mg VFAs/g VSS added was observed at “190°C-10 min” compared to 1251 for raw TWAS. For the SSO, the highest overall COD solubilization of 63% was observed at “210°C-20 min” compared to 17% for raw SSO. The highest VFAs yield of 1536 mg VFAs/g VSS added was observed at “210°C-20 min” compared to 768 for raw SSO.

Variation in Sludge Settleability with Temperature

1980 ◽  
Vol 15 (1) ◽  
pp. 73-82 ◽  
Author(s):  
J.G. Henry ◽  
E.E. Salenieks
Keyword(s):  
Activated Sludge ◽  
Effect Of Temperature ◽  
Organic Load ◽  
Limiting Factor ◽  
Appreciable Effect ◽  
Loading Rates ◽  
Bench Scale ◽  
Filamentous Bulking ◽  
Filamentous Microorganisms ◽  
Sludge Settleability

Abstract This study examined the effect of temperature on the settleabi1ity of activated sludge at various organic loading rates. Five completely mixed, bench-scale, activated sludge plants, operating under similar conditions at 5, 10 and 19°C, were continuously fed diluted, settled sewage supplemented with carbohydrate (sucrose). Hydraulic loading rates, MLSS and pH were maintained at constant levels during the experiments to eliminate these factors are variables. Dissolved oxygen was kept in excess of 3 mg/1 so that it would not be a limiting factor. Sludge Volume Indices (SVI ) and zone settling velocities were used to indicate changes in sludge settleability. Microscopic examination of the activated sludge indicated significant differences in the morphological features of filamentous microorganisms present at the two temperature extremes. At 19°C, the predominant forms were characterized by long curving trichomes, occasionally falsely branching, containing short cylindrical cells. At 5 °C, much smaller straight filaments, composed of long, narrow, rod-shaped cells appeared to be the principal microorganisms responsible for bulking. Various other filamentous forms were always present at each of the temperatures studied. Stirred sludge settling tests of moderately bulking sludges generally exhibited much higher settling velocities and lower SVI's than unstirred bulking samples. However, extremely filamentous bulking sludge exhibited comparable stirred and unstirred settling velocity and SVI values. The standard SVI test was found to be an inadequate indicator of the extent of bulking when trying to correlate the SVI failures from bench-scale performance with the results from continuous units. Lower temperature had no appreciable effect on COD removal efficiency as long as bulking did not cause a loss of solids in the effluent. However, results suggested that less than half the organic load could be accepted at 5°C, that could be handled at 19°C, before filamentous bulking occurred. A plot of loading versus temperature for various SVI's provided a visual indication of the safe loading limit below which bulking was unlikely to occur. The study clearly demonstrated that temperature can have a significant effect on sludge settleability.

The Impact of a Chemostat Discharge Containing Oil Degrading Bacteria on the Biological Kinetics of a Refinery Activated Sludge Process

1988 ◽  
Vol 20 (11-12) ◽  
pp. 131-136 ◽  
Author(s):  
A. D. Wong ◽  
C. D. Goldsmith
Keyword(s):  
Activated Sludge ◽  
Retention Time ◽  
Waste Treatment ◽  
Treatment Plant ◽  
Utilization Rate ◽  
Activated Sludge Process ◽  
Kinetic Evaluation ◽  
Degrading Bacteria ◽  
Waste Treatment Plant ◽  
The Impact

The effect of discharging specific oil degrading bacteria from a chemostat to a refinery activated sludge process was determined biokinetically. Plant data for the kinetic evaluation of the waste treatment plant was collected before and during treatment. During treatment, the 500 gallon chemostatic growth chamber was operated on an eight hour hydraulic retention time, at a neutral pH, and was fed a mixture of refinery wastewater and simple sugars. The biokinetic constants k (days−1), Ks (mg/L), and K (L/mg-day) were determined before and after treatment by Monod and Lineweaver-Burk plots. Solids discharged and effluent organic concentrations were also evaluated against the mean cell retention time (MCRT). The maximum utilization rate, k, was found to increase from 0.47 to 0.95 days−1 during the operation of the chemostat. Subsequently, Ks increased from 141 to 556 mg/L. Effluent solids were shown to increase slightly with treatment. However, this was acceptable due to the polishing pond and the benefit of increased ability to accept shock loads of oily wastewater. The reason for the increased suspended solids in the effluent was most likely due to the continual addition of bacteria in exponential growth that were capable of responding to excess substrate. The effect of the chemostatic addition of specific microbial inocula to the refinery waste treatment plant has been to improve the overall organic removal capacity along with subsequent gains in plant stability.

scholarly journals Pre-treatment clinical and gene expression patterns predict developmental change in early intervention in autism

2021 ◽  
Author(s):  
Michael V. Lombardo ◽  
Elena Maria Busuoli ◽  
Laura Schreibman ◽  
Aubyn C. Stahmer ◽  
Tiziano Pramparo ◽  
...  
Keyword(s):  
Gene Expression ◽  
Treatment Outcome ◽  
Early Intervention ◽  
Developmental Change ◽  
Expression Patterns ◽  
Gene Expression Patterns ◽  
Time In Treatment ◽  
Pre Treatment ◽  
Blood Leukocyte ◽  
The Impact

AbstractEarly detection and intervention are believed to be key to facilitating better outcomes in children with autism, yet the impact of age at treatment start on the outcome is poorly understood. While clinical traits such as language ability have been shown to predict treatment outcome, whether or not and how information at the genomic level can predict treatment outcome is unknown. Leveraging a cohort of toddlers with autism who all received the same standardized intervention at a very young age and provided a blood sample, here we find that very early treatment engagement (i.e., <24 months) leads to greater gains while controlling for time in treatment. Pre-treatment clinical behavioral measures predict 21% of the variance in the rate of skill growth during early intervention. Pre-treatment blood leukocyte gene expression patterns also predict the rate of skill growth, accounting for 13% of the variance in treatment slopes. Results indicated that 295 genes can be prioritized as driving this effect. These treatment-relevant genes highly interact at the protein level, are enriched for differentially histone acetylated genes in autism postmortem cortical tissue, and are normatively highly expressed in a variety of subcortical and cortical areas important for social communication and language development. This work suggests that pre-treatment biological and clinical behavioral characteristics are important for predicting developmental change in the context of early intervention and that individualized pre-treatment biology related to histone acetylation may be key.

scholarly journals Time-to-Treatment in Oral Cancer: Causes and Implications for Survival

Cancers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1321
Author(s):  
Constanza Saka-Herrán ◽  
Enric Jané-Salas ◽  
Antoni Mari-Roig ◽  
Albert Estrugo-Devesa ◽  
José López-López
Keyword(s):  
Oral Cancer ◽  
Previous Treatment ◽  
Diagnostic Procedures ◽  
Original Data ◽  
Primary Treatment ◽  
Medical Attention ◽  
Time Interval ◽  
Pre Treatment ◽  
The Impact ◽  
Lack Of Knowledge

The purpose of this review was to identify and describe the causes that influence the time-intervals in the pathway of diagnosis and treatment of oral cancer and to assess its impact on prognosis and survival. The review was structured according to the recommendations of the Aarhus statement, considering original data from individual studies and systematic reviews that reported outcomes related to the patient, diagnostic and pre-treatment intervals. The patient interval is the major contributor to the total time-interval. Unawareness of signs and/or symptoms, denial and lack of knowledge about oral cancer are the major contributors to the process of seeking medical attention. The diagnostic interval is influenced by tumor factors, delays in referral due to higher number of consultations and previous treatment with different medicines or dental procedures and by professional factors such as experience and lack of knowledge related to the disease and diagnostic procedures. Patients with advanced stage disease, primary treatment with radiotherapy, treatment at an academic facility and transitions in care are associated with prolonged pre-treatment intervals. An emerging body of evidence supports the impact of prolonged pre-treatment and treatment intervals with poorer survival from oral cancer.

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