Anaerobic waste activated sludge co-digestion with olive mill wastewater

2012 ◽  
Vol 65 (12) ◽  
pp. 2251-2257 ◽  
Author(s):  
E. Athanasoulia ◽  
P. Melidis ◽  
A. Aivasidis
Keyword(s):  
Activated Sludge ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Olive Mill Wastewater ◽  
System Stability ◽  
Waste Activated Sludge ◽  
Loading Rates ◽  
Soluble Chemical Oxygen Demand ◽  
Continuous Stirred Tank ◽  
Olive Mill

Co-digestion of waste activated sludge (WAS) with agro-industrial organic wastewaters is a technology that is increasingly being applied in order to produce increased gas yield from the biomass. In this study, the effect of olive mill wastewater (OMW) on the performance of a cascade of two anaerobic continuous stirred tank (CSTR) reactors treating thickened WAS at mesophilic conditions was investigated. The objectives of this work were (a) to evaluate the use of OMW as a co-substrate to improve biogas production, (b) to determine the optimum hydraulic retention time that provides an optimised biodegradation rate or methane production, and (c) to study the system stability after OMW addition in sewage sludge. The biogas production rate at steady state conditions reached 0.73, 0.63, 0.56 and 0.46 lbiogas/lreactor/d for hydraulic retention times (HRTs) of 12.3, 14, 16.4 and 19.7 d. The average removal of soluble chemical oxygen demand (sCOD) ranged between 64 and 72% for organic loading rates between 0.49 and 0.75 g sCOD/l/d. Reduction in the volatile suspended solids ranged between 27 and 30%. In terms of biogas selectivity, values of 0.6 lbiogas/g tCOD removed and 1.1 lbiogas/g TVS removed were measured.

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.

Effect of Aeration Rate on the Hydrolysis and Acidification of Waste Activated Sludge in Thermophilic Aerobic Conditions

2013 ◽  
Vol 664 ◽  
pp. 111-116
Author(s):  
Ya Nan Hou ◽  
Chun Xue Yang ◽  
Ai Juan Zhou ◽  
Ai Jie Wang
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Volatile Fatty Acids ◽  
Oxygen Demand ◽  
Ventilation Rate ◽  
Aeration Rate ◽  
Waste Activated Sludge ◽  
Digestion Process ◽  
Hydrolysis Process ◽  
Soluble Chemical Oxygen Demand

This study investigated the effect of aeration rates on the hydrolysis process of Waste Activated Sludge (WAS) with thermophilic aerobic microbes and explained by the change of solubilization of lipids, carbohydrates and proteins in sludge under different aeration rates (0.03 vvm, 0.05 vvm, 0.07 vvm, 0.09 vvm, 0.11 vvm). The results revealed that with the increase of aeration rate, the accumulation of volatile fatty acids (VFAs) in the treated sludge was decreased. Only 2 142 mg COD/L was accumulated at the ventilation rate of 0.11 vvm, while the highest accumulation which was 4 088 mg/L at the ventilation rate of 0.05 vvm. Further investigation showed that under optimal aeration rate which was 0.05 vvm, theromophilic aerobic microbes facilitated the organism hydrolysis and increased the biodegradability of WAS significantly. The concentration of carbohydrates was improved remarkably from 70 mg COD/L to 560 mg COD/L compared with the control (the process without aeration) at 65°C. Meanwhile, the concentration of protein was increased stably due to the high activity of protease, and reached the peak of 1 320 mg COD/L after 72h, then decline at the later period. The maximal soluble chemical oxygen demand (SCOD) was 5 600 mg/L and VFAs was 4 088 mg COD/L, which would be beneficial to the followed digestion process. Therefore, appropriate aeration is efficient to improve the accumulation of soluble organic matters and VFAs in WAS.

Treatment of waste activated sludge together with agro-waste by anaerobic digestion: focus on effluent quality

2013 ◽  
Vol 69 (3) ◽  
pp. 525-531 ◽  
Author(s):  
C. Cavinato ◽  
C. Da Ros ◽  
P. Pavan ◽  
F. Cecchi ◽  
D. Bolzonella
Keyword(s):  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Point Of View ◽  
Waste Activated Sludge ◽  
Organic Substrates ◽  
Economic Point ◽  
Energetic Balance

Waste activated sludge production and management plays an important role in wastewater treatment plants (WWTPs), especially from an economic point of view. One possible approach is the anaerobic co-digestion of waste activated sludge with others organic substrates in mesophilic and thermophilic conditions in order to exploit the spare volume of existing reactors, recover energy from biogas production, and obtain a fertilizer as final product. The anaerobic trials were carried out at pilot scale, applying two organic loading rates (2.8 and 4.5 kg chemical oxygen demand (COD)/(m3·d)) with a hydraulic retention time of 16 and 21 days. Among agro-wastes, wine lees were chosen because of their continuous availability throughout the year, and their high COD content (up to 200–300 g/l, 70% soluble, on average). The addition of wine lees to activated sludge determined a higher biogas production (best yield was 0.40 Nm3/kgCODfed) improving the energetic balance of the sludge line of the WWTP. The characterization of both substrates fed and digester effluents was carried out in terms of heavy metals; comparison with EC proposed limits showed that, due to high content of Cu in wine lees, the loading rate of this agro-waste should be limited to maintain good characteristics of final biosolids.

scholarly journals Alkaline solubilisation of waste activated sludge (WAS) for soluble organic substrate – (SCOD) production / Tworzenie się rozpuszczalnego substratu organicznego podczas zasadowego rozpuszczania osadów ściekowych

2015 ◽  
Vol 41 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Jan Suschka ◽  
Eligiusz Kowalski ◽  
Jerzy Mazierski ◽  
Klaudiusz Grübel
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Volatile Fatty Acids ◽  
Construction Material ◽  
Oxygen Demand ◽  
Organic Substrate ◽  
Waste Activated Sludge ◽  
Condition Effect ◽  
Hydrolysis Process ◽  
Soluble Chemical Oxygen Demand

Abstract Improving the effects of hydrolysis on waste activated sludge (WAS) prior to anaerobic digestion is of primary importance. Several technologies have been developed and partially implemented in practice. In this paper, perhaps the simplest of these methods, alkaline solubilization, has been investigated and the results of hydrolysis are presented. An increase to only pH 8 can distinctively increase the soluble chemical oxygen demand (SCOD), and produce an anaerobic condition effect favorable to volatile fatty acids (VFA) production. Further increases of pH, up to pH 10, leads to further improvements in hydrolysis effects. It is suggested that an increase to pH 9 is sufficient and feasible for technical operations, given the use of moderate anti-corrosive construction material. This recommendation is also made having taken in consideration the option of using hydrodynamic disintegration after the initial WAS hydrolysis process. This paper presents the effects of following alkaline solubilization with hydrodynamic disintegration on SCOD

Evaluation of non-thermal effects by microwave irradiation in hydrolysis of waste-activated sludge

2014 ◽  
Vol 70 (4) ◽  
pp. 742-749 ◽  
Author(s):  
I. G. Byun ◽  
J. H. Lee ◽  
J. M. Lee ◽  
J. S. Lim ◽  
T. J. Park
Keyword(s):  
Microwave Irradiation ◽  
Activated Sludge ◽  
Thermal Effect ◽  
Oxygen Demand ◽  
Conventional Heating ◽  
Waste Activated Sludge ◽  
Molecular Formula ◽  
First Order Kinetics ◽  
Soluble Chemical Oxygen Demand ◽  
Hydrolysis Of

The activation energy (Ea) for waste-activated sludge (WAS) hydrolysis was compared between microwave irradiation (MW) and conventional heating (CH) methods to evaluate the non-thermal effect of MW. The microwave-assisted hydrolysis of WAS was assumed to follow the first-order kinetics on the basis of volatile suspended solids (VSS) conversion to soluble chemical oxygen demand (SCOD) for different initial VSS concentrations. By comparing the VSS decrement and the SCOD increment between MW and CH at different absolute temperatures of 323, 348 and 373 K, the average ratio of VSS conversion to SCOD was determined to range from 1.42 to 1.64 g SCOD/g VSS. These results corresponded to the theoretical value of 1.69 g SCOD/g VSS based on the assumption that the molecular formula of sludge was C10H19O3N. Consequently, the Ea of the MW-assisted WAS hydrolysis was much lower than that of CH for the same temperature conditions. The non-thermal effect of MW in the hydrolysis of WAS could be identified with the lower Ea than that of CH.

Influence of the heavy metals concentration on the anaerobic co-digestion performance of activated sludge and Olive mill wastewater

2021 ◽  
Author(s):  
khalideh Al bkoor Alrawashdeh
Keyword(s):  
Heavy Metals ◽  
Activated Sludge ◽  
Removal Efficiency ◽  
Biogas Production ◽  
Olive Mill Wastewater ◽  
Organic Load ◽  
High Concentration ◽  
Digestion Process ◽  
The Impact ◽  
Olive Mill

Abstract The influence of heavy metals (HMs) on the anaerobic co-digestion process (AD) of activated sludge and olive mill wastewater (50% v/v) was studied. Biogas production, methane CH4 concentration, and removal efficiency of the TS, VS, and TCOD were investigated in mesophilic conditions. The toxicity and inhibitory effects of HMs at different concentrations (15–60 ppm) on the digestion process were specified.A high concentration of HMs has resulted in a significant decrease in AD performance in terms of organic load degradation, biogas production, CH4 content, TCOD removal efficiency, and inhibition of hydrogenotrophic-methanogenic bacteria. The toxicity of HMs can be arranged according to TS removal: Cu > Zn ≈ Cr > Pb, according to TCOD removal efficiency: Cu > Cr > Zn > Pb, biogas production: Cu > Zn ≈ Cr > Pb, CH4 content: Cu > Zn > Cr > Pb. Also, the results showed that the methanogenic stage was influenced negatively and more than the acetogenic stage, where Pb < 30 ppm had a lower inhibitor effect on the digestion, while the lowest concentration of Cu(II) leads to the significant inhibition of the AD process is ≥ 10 ppm. At the concentration of 60 ppm of Pb, Zn, Cr, and Cu, the COD removal efficiency was 17.07%, 15.64%, 19.13%, and 20.53% respectively, TS removal was 17.31%, 13.44%, 16.28%, and 10.37 respectively, the VS removal was 19.4%, 14.445, 7.94% and 5.17%, respectively. Also, at the concentration of 60 ppm, biogas production has decreased by 51.55%, 66.46%, 68.1%, and 73.91%, respectively.Novelty statement This study provides new data specifying the inhibitor HMs concentration and the impact of HMs at the various concentrations on the anaerobic co-digestion of active sludge and olive mill wastewater

Use of Combined NaOH-Microwave Pretreatment for Enhancing Mesophilic Anaerobic Digestibility of Thickened Waste Activated Sludge

2010 ◽  
Vol 113-116 ◽  
pp. 459-468 ◽  
Author(s):  
Yong Zhi Chi ◽  
Yu You Li ◽  
Min Ji ◽  
Hong Qiang ◽  
Heng Wei Deng ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Uniform Design ◽  
Oxygen Demand ◽  
Holding Time ◽  
Waste Activated Sludge ◽  
Methane Potential ◽  
Soluble Chemical Oxygen Demand ◽  
Anaerobic Digestibility ◽  
Relationship Of ◽  
The Mathematical Model

A combined NaOH-microwave (MW) pretreatment process was studied in order to investigate the effects of NaOH-MW pretreated thickened waste activated sludge (TWAS) on anaerobic digestion. In the NaOH-MW pretreatment studies, Uniform design was successfully applied to determine the relationship of TWAS solubilization to environmental conditions (NaOH dose, target temperature, and MW holding time) and to establish the mathematical model describing the solubilization degree to changes in these variables. The maximum solubilization ratio (85.1%) of volatile suspended solids (VSS) could be achieved at 210°C with 0.2 g-NaOH/g-SS and 35 min holding time. The biochemical methane potential (BMP) tests showed that all digesters fed with pretreated TWAS improved the methane production compared to control system, and the optimal conditions, at 170°C with 0.05 g-NaOH/g-SS and 1 min holding time, were suggested for NaOH-MW pretreatment of TWAS. In spite of the increase in the soluble chemical oxygen demand concentration and decrease in the dewaterability of digested sludge, the semi-continuous reacter fed with the pretreated TWAS without neutralization was stable and gave higher organics reductions and methane yields compared to the control.

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