scholarly journals High-Rate Anaerobic Digestion of Waste Activated Sludge by Integration of Electro-Fenton Process

Molecules ◽  
2020 ◽  
Vol 25 (3) ◽  
pp. 626 ◽  
Author(s):  
Emna Feki ◽  
Audrey Battimelli ◽  
Sami Sayadi ◽  
Abdelhafidh Dhouib ◽  
Sonia Khoufi
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Volatile Fatty Acids ◽  
Continuous Fermentation ◽  
Removal Rate ◽  
High Rate ◽  
Organic Loading Rate ◽  
Waste Activated Sludge ◽  
Capillary Suction ◽  
Biogas Yield

Anaerobic digestion (AD), being the most effective treatment method of waste activated sludge (WAS), allows for safe disposal. The present study deals with the electro-Fenton (EF) pretreatment for enhancing the WAS biogas potential with low-cost iron electrodes. The effect of pretreatment on the physicochemical characteristics of sludge was assessed. Following EF pretreatment, the pH, conductivity, soluble chemical oxygen demand (SCOD), and volatile fatty acids (VFA) increased to 7.5, 13.72 mS/cm, 4.1 g/L, and 925 mg/L, respectively. Capillary suction time (CST) analysis highlighted the dewaterability effect of EF on WAS, as demonstrated by the decrease in CST from 429 to 180 s following 30 min of pretreatment. Batch digestion assays presented an increase in the biogas yield to 0.135 L/g volatile solids (VS) after 60 min of EF pretreatment in comparison to raw sludge (0.08 L/g VS). Production of biogas was also found to improve during semi-continuous fermentation of EF-pretreated sludge conducted in a lab-scale reactor. In comparison to raw sludge, EF-pretreated sludge produced the highest biogas yield (0.81 L biogas/g VS) with a high COD removal rate, reaching 96.6% at an organic loading rate (OLR) of 2.5 g VS/L. d. Results revealed that the EF process could be an effective WAS disintegration method with maximum recovery of bioenergy during AD.

scholarly journals Comparison between Thermo-Alkaline and Electro-Fenton Disintegration Effect on Waste Activated Sludge Anaerobic Digestion

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Emna Feki ◽  
Sami Sayadi ◽  
Slim Loukil ◽  
Abdelhafidh Dhouib ◽  
Sonia Khoufi
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Continuous Fermentation ◽  
Waste Activated Sludge ◽  
Sludge Reduction ◽  
Continuous Stirred Tank Reactor ◽  
Biogas Yield ◽  
Anaerobic Biodegradability ◽  
Continuous Stirred Tank ◽  
Better Than

Disintegration of municipal waste activated sludge (WAS) using thermo-alkaline (TA) and electro-Fenton (EF) methods was investigated and compared in terms of the efficiency of sludge solubilisation and enhancement of anaerobic biodegradability. Performance of organic matter solubilisation (soluble COD, proteins, polysaccharides) of sludge pretreated with EF was proved to be better than that with TA pretreatment, which resulted in the enhancement of anaerobic biodegradability. Comparison of results indicated that percentages of PN and PS release obtained after EF pretreatment (68.95 and 65.22%) were higher than those obtained by TA method (45.25 and 35.22%) respectively. An improvement of biogas potential about 2 and 1.6 times was achieved respectively by EF and TA pretreatment in comparison to raw sludge. During semi-continuous fermentation study in continuous stirred tank reactor, EF pretreated sludge gave the best biogas yield (0.6 L biogas/g COD) at an OLR of 2.5 g COD/L. d in comparison to TA pretreated sludge (0.3 L biogas/g COD), where low biogas yield about 0.1 L biogas/g COD was registered by raw sludge in the same CSTR. Therefore, the integration of EF process to anaerobic digestion might be a promising process for sludge reduction and biogas recovery.

Anaerobic digestion of waste activated sludge combined with ozone post-treatment and recycling

2003 ◽  
Vol 48 (4) ◽  
pp. 61-68 ◽  
Author(s):  
A. Battimelli ◽  
C. Millet ◽  
J.P. Delgenès ◽  
R. Moletta
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Removal Rate ◽  
Operating Conditions ◽  
Cod Removal ◽  
Process Efficiency ◽  
Recycling Rate ◽  
Waste Activated Sludge ◽  
Digested Sludge ◽  
Combined Process

The aim of the study was to determine the performances of a combined ozone/anaerobic digestion system for waste activated sludge reduction. The objective was the estimation of the process efficiency and stability when keeping constant influent flow while increasing recycled chemically treated flow. The ozonation step consisted in a partial oxidation (0.16 g O3/g SS) of the anaerobic mesophilic digested sludge. Chemical treatment of digested sludge resulted in a threefold COD solubilization and a decrease of SS of 22%. Some of the advantages of digested sludge ozonation were: deodorization, better settlement and a reduction in viscosity. However there were drawbacks: foaming during ozonation and, at high ozone doses, poorer filterability. The anaerobic digestion was carried out over 6 months with an increasing recycling of ozonated flow. Suspended solids removal rate and COD removal rate were compared with initial operating conditions for the biological reactor and the whole combined process. The optimum recycling rate was 25% with increases of SS removal and COD removal of 54% and 66% respectively when considering the combined process; corresponding to a decrease of the hydraulic retention time from 24 days to 19 days.

Extracellular polymeric substances and dewaterability of waste activated sludge during anaerobic digestion

2014 ◽  
Vol 70 (9) ◽  
pp. 1555-1560 ◽  
Author(s):  
Fenxia Ye ◽  
Xinwen Liu ◽  
Ying Li
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Extracellular Polymeric Substance ◽  
Extracellular Polymeric Substances ◽  
Waste Activated Sludge ◽  
Sludge Dewatering ◽  
Capillary Suction ◽  
Relationship Analysis ◽  
The Relationship ◽  
Insight Into

Anaerobic digestion of waste activated sludge was conducted to gain insight into the mechanisms underlying change in sludge dewaterability during its anaerobic digestion. Unexpectedly, the results indicated that sludge dewatering properties measured by capillary suction time only deteriorated after 10 days of anaerobic digestion, after which dewaterability recovered and remained stable. The loosely bound extracellular polymeric substance (LB-EPS) content increased three-fold after 20 days of anaerobic digestion, and did not change significantly during the remaining 30 days. The tightly bound EPS (TB-EPS) content reduced slightly after 20 days of anaerobic digestion, and stabilized during the last 30 days. Polysaccharides (PS) and proteins (PN) content in LB-EPS increased after 10 days of anaerobic digestion. However, PS and PN contents in TB-EPS decreased slightly. The relationship analysis showed that only LB-EPS correlated with dewaterability of the sludge during anaerobic digestion.

scholarly journals Methanosarcinaceae and Acetate-Oxidizing Pathways Dominate in High-Rate Thermophilic Anaerobic Digestion of Waste-Activated Sludge

2013 ◽  
Vol 79 (20) ◽  
pp. 6491-6500 ◽  
Author(s):  
Dang P. Ho ◽  
Paul D. Jensen ◽  
Damien J. Batstone
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Retention Time ◽  
Elevated Temperatures ◽  
Stable Carbon Isotope ◽  
High Rate ◽  
Continuous Reactor ◽  
Waste Activated Sludge ◽  
Acetate Oxidation ◽  
Syntrophic Acetate Oxidation

ABSTRACTThis study investigated the process of high-rate, high-temperature methanogenesis to enable very-high-volume loading during anaerobic digestion of waste-activated sludge. Reducing the hydraulic retention time (HRT) from 15 to 20 days in mesophilic digestion down to 3 days was achievable at a thermophilic temperature (55°C) with stable digester performance and methanogenic activity. A volatile solids (VS) destruction efficiency of 33 to 35% was achieved on waste-activated sludge, comparable to that obtained via mesophilic processes with low organic acid levels (<200 mg/liter chemical oxygen demand [COD]). Methane yield (VS basis) was 150 to 180 liters of CH4/kg of VSadded. According to 16S rRNA pyrotag sequencing and fluorescence in situ hybridization (FISH), the methanogenic community was dominated by members of theMethanosarcinaceae, which have a high level of metabolic capability, including acetoclastic and hydrogenotrophic methanogenesis. Loss of function at an HRT of 2 days was accompanied by a loss of the methanogens, according to pyrotag sequencing. The two acetate conversion pathways, namely, acetoclastic methanogenesis and syntrophic acetate oxidation, were quantified by stable carbon isotope ratio mass spectrometry. The results showed that the majority of methane was generated by nonacetoclastic pathways, both in the reactors and in off-line batch tests, confirming that syntrophic acetate oxidation is a key pathway at elevated temperatures. The proportion of methane due to acetate cleavage increased later in the batch, and it is likely that stable oxidation in the continuous reactor was maintained by application of the consistently low retention time.

High rate mesophilic, thermophilic, and temperature phased anaerobic digestion of waste activated sludge: A pilot scale study

2012 ◽  
Vol 32 (6) ◽  
pp. 1196-1201 ◽  
Author(s):  
David Bolzonella ◽  
Cristina Cavinato ◽  
Francesco Fatone ◽  
Paolo Pavan ◽  
Franco Cecchi
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Pilot Scale ◽  
High Rate ◽  
Waste Activated Sludge

scholarly journals Effect Of Hydrothermal Pre-Treatment On Methane Production During Anaerobic Digestion Of Thickened Waste Activated Sludge

2021 ◽  
Author(s):  
Suleman Khan
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Anthropogenic Sources ◽  
Organic Loading Rate ◽  
Waste Activated Sludge ◽  
Optimum Conditions ◽  
Solid Retention Time ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Pre Treatment

The effects of hydrothermal pre-treatment on the production of methane and biogas on thickened waste activated sludge was investigated. This paper reviews the anaerobic digestion process and its complexities, provides an overview of the different stages of the anaerobic digestion process, different kinds of feedstocks and the essential and influential operating parameters such as temperature, pH, organic loading rate, solid retention time and particle size. This paper also demonstrates an overview of the natural and anthropogenic sources contributing to methane in the atmosphere. It further provides a recommendation on essential practices and methods required to enhance methane capture in the atmosphere. Furthermore, an experimental setup consisting of batch anaerobic digestion was employed for the sample analysis the purpose of this experimental research was to conduct a comprehensive assessment of the effect of the hydrothermal pre-treatment on thickened waste activated sludge and to determine the most optimum conditions to produce methane. Keywords: Anaerobic digestion, Thickened waste-activated sludge, Hydrothermal Pre-treatment

Anaerobic codigestion of waste activated sludge and OFMSW: the experiences of Viareggio and Treviso plants (Italy)

2006 ◽  
Vol 53 (8) ◽  
pp. 203-211 ◽  
Author(s):  
D. Bolzonella ◽  
P. Battistoni ◽  
C. Susini ◽  
F. Cecchi
Keyword(s):  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Biogas Production ◽  
Organic Loading Rate ◽  
Waste Activated Sludge ◽  
Municipal Solid Wastes ◽  
Biogas Yield ◽  
Payback Time ◽  
Low Energy Consumption ◽  
Anaerobic Codigestion

The paper presents the results of two full-scale applications of the anaerobic co-digestion process of waste activated sludge together with the organic fraction of municipal solid wastes. The experiences were carried out at Viareggio and Treviso wastewater treatment plants (Italy). In the first plant, 3 tons per day of source sorted OFMSW were co-digested with waste activated sludge, increasing the organic loading rate from 1.0 to 1.2 kgTVS/m3d. This determined a 50% increase in biogas production. At Treviso WWTP, which has been working for 2 years, some 10 tons per day of separately collected OFMSW are treated using a low-energy consumption sorting line, which allows the removal of 99% and 90% of metals and plastics respectively. In these conditions, the biogas yield increased from 3,500 up to 17,500 m3/month. Industrial costs were evaluated less than 50 € per ton of organic waste, while the payback time was calculated as two years.

scholarly journals Process Optimization of Waste Activated Sludge in Anaerobic Digestion and Biogas Production by Electrochemical Pre-Treatment Using Ruthenium Oxide Coated Titanium Electrodes

2021 ◽  
Vol 13 (9) ◽  
pp. 4874
Author(s):  
Gan Chin Heng ◽  
Mohamed Hasnain Isa ◽  
Serene Sow Mun Lock ◽  
Choon Aun Ng
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Chemical Oxygen Demand ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Ruthenium Oxide ◽  
Parameters Optimization ◽  
Waste Activated Sludge ◽  
Capillary Suction ◽  
Pre Treatment

Anaerobic digestion (AD) appears to be a popular unit operation in wastewater treatment plant to treat waste activated sludge (WAS) and the produced methane gas can be harvested as renewable energy. However, WAS could inhibit hydrolysis stage during AD and hence pre-treatment is required to overcome the issue. This paper aimed to study the effect of electrochemical pre-treatment (EP) towards efficiency of AD using titanium coated with ruthenium oxide (Ti/RuO2) electrodes. The investigation has been carried out using in-house laboratory batch-scale mesophilic anaerobic digester, mixed under manipulation of important operating parameters. Optimization was performed on EP using response surface methodology and central composite design to maximize sludge disintegration and dewaterability. By operating at optimal conditions (pH 11.65, total solids 22,000 mg/L, electrolysis time 35 min, current density 6 mA/cm2, and 1000 mg/L of sodium chloride), the pre-treated WAS in terms of mixed liquor volatile suspended solids (MLVSS) removal, soluble chemical oxygen demand (sCOD), capillary suction time (CST) reduction, and extracellular polymeric substance (EPS) were 38%, 4800 mg/L (increased from 935 mg/L), 33%, and 218 mg/L, respectively. Following AD, the volatile solids (VS) removal and chemical oxygen demand (COD) removal by EP were enhanced from 40.7% and 54.7% to 47.2% and 61.5%, respectively, at steady-state. The biogas produced from control and electrochemical pre-treated WAS were in the ranges of 0.12 to 0.17 and 0.2 to 0.24 m3/kg VSfed, respectively, and the volume of biogas produced was 44–67% over the control. Based on the results obtained, suitability of EP for WAS prior to AD was confirmed.

Evaluation of anaerobic digestion processes for short sludge-age waste activated sludge combined with anammox treatment of digestate liquor

2015 ◽  
Vol 73 (5) ◽  
pp. 1052-1060 ◽  
Author(s):  
Huoqing Ge ◽  
Damien Batstone ◽  
Jurg Keller
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Removal Rate ◽  
Ammonia Solution ◽  
High Rate ◽  
Meat Processing ◽  
Sludge Digestion ◽  
Volatile Solids ◽  
Anammox Activity ◽  
Solids Retention

The need to reduce energy input and enhance energy recovery from wastewater is driving renewed interest in high-rate activated sludge treatment (i.e. short hydraulic and solids retention times (HRT and SRT, respectively)). This process generates short SRT activated sludge stream, which should be highly degradable. However, the evaluation of anaerobic digestion of short SRT sludge has been limited. This paper assesses anaerobic digestion of short SRT sludge digestion derived from meat processing wastewater under thermophilic and mesophilic conditions. The thermophilic digestion system (55°C) achieved 60 and 68% volatile solids destruction at 8 day and 10 day HRT, respectively, compared with 50% in the mesophilic digestion system (35°C, 10 day HRT). The digestion effluents from the thermophilic (8–10 day HRT) and mesophilic systems were stable, as assessed by residual methane potentials. The ammonia rich sludge dewatering liquor was effectively treated by a batch anammox process, which exhibited comparable nitrogen removal rate as the tests using a control synthetic ammonia solution, indicating that the dewatering liquor did not have inhibiting/toxic effects on the anammox activity.

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