scholarly journals Energy-Positive Disintegration of Waste Activated Sludge—Full Scale Study

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 555
Author(s):  
Monika Zubrowska-Sudol ◽  
Katarzyna Sytek-Szmeichel ◽  
Piotr Krawczyk ◽  
Agnieszka Bisak
Keyword(s):  
Activated Sludge ◽  
Organic Compounds ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Full Scale ◽  
Positive Energy ◽  
Anaerobic Sludge ◽  
Waste Activated Sludge ◽  
Mechanical Disintegration ◽  
Positive Disintegration

This study aimed to evaluate the effects of mechanical disintegration of waste activated sludge (WAS) on full scale anaerobic digestion, considering the possibility of obtaining a positive energy balance. The results showed that an increase in energy density (εL) used in disintegration was accompanied by an increase in the release of organic compounds from sludge (SCOD increased from 211 ± 125 mg O2/L for εL = 0 kJ/L to 6292 ± 2860 mgO2/L for εL = 180 kJ/L). Some of them were volatile fatty acids. The percentage share of WAS subject to disintegration was also documented as a crucial parameter affecting the efficiency of biogas production. An increase in the value of this parameter from 25% to 100%, even at much lower εL used in disintegration (therefore with much smaller amounts of organic compounds released from sludge flocs) resulted in an increase in biogas production. Conducting disintegration of the entire stream of WAS directed to the fermentation tank at εL 30 kJ/L resulted in an increase in biogas production by 14.1%. Such a surplus would allow production of approximately 360 kWh/d net electricity. Mechanical disintegration of thickened WAS therefore may be an economically justifiable strategy for the intensification of anaerobic sludge stabilisation.

Production of volatile fatty acids by fermentation of waste activated sludge pre-treated in full-scale thermal hydrolysis plants

2011 ◽  
Vol 102 (3) ◽  
pp. 3089-3097 ◽  
Author(s):  
F. Morgan-Sagastume ◽  
S. Pratt ◽  
A. Karlsson ◽  
D. Cirne ◽  
P. Lant ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Volatile Fatty Acids ◽  
Full Scale ◽  
Waste Activated Sludge ◽  
Thermal Hydrolysis

Causes and effects of foaming in anaerobic sludge digesters

1997 ◽  
Vol 36 (6-7) ◽  
pp. 463-470 ◽  
Author(s):  
Krishna R. Pagilla ◽  
Kent C. Craney ◽  
Wendell H. Kido
Keyword(s):  
Activated Sludge ◽  
Full Scale ◽  
Anaerobic Sludge ◽  
Waste Activated Sludge ◽  
Foam Layer ◽  
Anaerobic Digesters ◽  
Primary Sludge ◽  
Total Solids ◽  
Volatile Solids ◽  
Different Depths

Full scale anaerobic digesters treating mixed sludge containing primary sludge and thickened waste activated sludge were investigated for causes and effects of foaming. Sludge samples were collected from different depths of two full scale digesters, one gas-mixed, and the other mechanically-mixed, to determine the extent of foaming and its effects on anaerobic digestion; both digesters were fed the same feed sludge (3.4% TS) and at the same feed rate (about 2.2 kg TS/m3.day). The average depth of the surface foam layer in the gas-mixed and mechanically-mixed digester were 2.4 and 1.3 m respectively. Higher total solids concentrations were found at the surface (about 5% TS) than those found at the bottom (about 2% TS) in both gas-mixed and mechanically-mixed digesters, indicating an inverse total solids profile. Presence of excessive levels of Nocardia filaments (>106 number/g VSS) in the activated sludge caused thicker foam layer at the surface, and this effect was more pronounced in the gas-mixed digester than in the mechanically-mixed digester. Gas-mixed digester (0.74 m3/kg VS destroyed) produced less sludge gas than the mechanically-mixed digester (0.93 m3/kg VS destroyed), however, gas-mixed digester (62% VS reduction) destroyed more volatile solids than the mechanically-mixed digester (54% VS reduction). These results indicate that gas-mixed digesters are more prone to foaming than mechanically-mixed digesters, and that the foaming can increase when excessive levels of Nocardia filaments are present in the feed sludge causing decreased digester performance.

scholarly journals Investigation of Heavy Metal Effects on the Anaerobic Co-Digestion Process of Waste Activated Sludge and Septic Tank Sludge

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Quang-Minh Nguyen ◽  
Duy-Cam Bui ◽  
Thao Phuong ◽  
Van-Huong Doan ◽  
Thi-Nham Nguyen ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Activated Sludge ◽  
Removal Efficiency ◽  
Biogas Production ◽  
Cod Removal ◽  
Septic Tank ◽  
Waste Activated Sludge ◽  
Digestion Process ◽  
Cod Removal Efficiency

The effect of copper, zinc, chromium, and lead on the anaerobic co-digestion of waste activated sludge and septic tank sludge in Hanoi was studied in the fermentation tests by investigating the substrate degradation, biogas production, and process stability at the mesophilic fermentation. The tested heavy metals were in a range of concentrations between 19 and 80 ppm. After the anaerobic tests, the TS, VS, and COD removal efficiency was 4.12%, 9.01%, and 23.78% for the Cu(II) added sample. Similarly, the efficiencies of the Zn(II) sample were 1.71%, 13.87%, and 16.1% and Cr(VI) efficiencies were 15.28%, 6.6%, and 18.65%, while the TS, VS, and COD removal efficiency of the Pb(II) added sample was recorded at 16.1%, 17.66%, and 16.03% at the concentration of 80 ppm, respectively. Therefore, the biogas yield also decreased by 36.33%, 31.64%, 31.64%, and 30.60% for Cu(II), Zn(II), Cr(VI), and Pb(II) at the concentration of 80 ppm, compared to the raw sample, respectively. These results indicated that Cu(II) had more inhibiting effect on the anaerobic digestion of the sludge mixture than Zn(II), Cr(VI), and Pb(II). The relative toxicity of these heavy metals to the co-digestion process was as follows: Cu (the most toxic) > Zn > Cr > Pb (the least toxic). The anaerobic co-digestion process was inhibited at high heavy metal concentration, which resulted in decreased removal of organic substances and produced biogas.

Anaerobic co-digestion of winery waste and waste activated sludge: assessment of process feasibility

2013 ◽  
Vol 69 (2) ◽  
pp. 269-277 ◽  
Author(s):  
C. Da Ros ◽  
C. Cavinato ◽  
F. Cecchi ◽  
D. Bolzonella
Keyword(s):  
Activated Sludge ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Waste Activated Sludge ◽  
Organic Loading ◽  
Operational Conditions ◽  
Loading Rates ◽  
Thermophilic Conditions ◽  
Soluble Chemical Oxygen Demand

In this study the anaerobic co-digestion of wine lees together with waste activated sludge in mesophilic and thermophilic conditions was tested at pilot scale. Three organic loading rates (OLRs 2.8, 3.3 and 4.5 kgCOD/m3d) and hydraulic retention times (HRTs 21, 19 and 16 days) were applied to the reactors, in order to evaluate the best operational conditions for the maximization of the biogas yields. The addition of lee to sludge determined a higher biogas production: the best yield obtained was 0.40 Nm3biogas/kgCODfed. Because of the high presence of soluble chemical oxygen demand (COD) and polyphenols in wine lees, the best results in terms of yields and process stability were obtained when applying the lowest of the three organic loading rates tested together with mesophilic conditions.

scholarly journals The Concept of Wastes to Energy Using Sugary Wastes

2012 ◽  
Vol 9 ◽  
pp. 57-62
Author(s):  
Fiza Sarwar ◽  
Wajeeha Malik ◽  
Muhammad Salman Ahmed ◽  
Harja Shahid
Keyword(s):  
Volatile Fatty Acids ◽  
Loading Rate ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Uasb Reactor ◽  
Organic Loading Rate ◽  
Anaerobic Sludge ◽  
Loading Rates ◽  
Sugar Mills ◽  
Anaerobic Sludge Blanket

Abstract: This study was designed using actual effluent from the sugary mills in an Up-flow Anaerobic Sludge Blanket (UASB) Reactor to evaluate treatability performance. The reactor was started-up in step-wise loading rates beginning from 0.05kg carbon oxygen demand (COD)/m3-day to 3.50kg-COD/m3-day. The hydraulic retention time (HRT) was slowly decreased from 96 hrs to eight hrs. It was observed that the removal efficiency of COD of more than 73% can be easily achieved at an HRT of more than 16 hours corresponding to an average organic loading rate (OLR) of 3.0kg-COD/m3-day, at neutral pH and constant temperature of 29°C. The average VFAs (volatile fatty acids) and biogas production was observed as 560mg/L and 1.6L/g-CODrem-d, respectively. The average methane composition was estimated as 62%. The results of this study suggest that the treatment of sugar mills effluent with the anaerobic technology seems to be more reliable, effective and economical.DOI: http://dx.doi.org/10.3126/hn.v9i0.7075 Hydro Nepal Vol.9 July 2011 57-62

Sign in / Sign up

Export Citation Format

Share Document