Two combined techniques to enhance anaerobic digestion of sludge

2002 ◽  
Vol 46 (10) ◽  
pp. 167-172 ◽  
Author(s):  
G. Moeller-Chávez ◽  
S. González-Martínez
Keyword(s):  
Anaerobic Digestion ◽  
Yeast Extract ◽  
Methane Production ◽  
Influencing Factor ◽  
Removal Rates ◽  
Primary Sludge ◽  
Methanogenic Activity ◽  
Iron Nickel ◽  
Pre Treatment ◽  
Treatment Procedures

The rate-limiting step during anaerobic digestion is the hydrolysis of the particulate organic matter and methanogenesis. Certain elements, such as iron, nickel and cobalt and some growth factors such as coenzymes are needed for the adequate growth of the organisms. The main objective of this research was to enhance anaerobic digestion of primary sludge combining thermal and alkaline pre-treatment with stimulation of the methanogenic activity by adding yeast extract. Primary sludge was exposed, separately, to alkaline and thermal pre-treatment procedures. After this pre-treatment, different amounts of yeast extract were added to the sludge. The best COD, TSS and VSS removal rates were observed without pre-treatment and with the addition of 0.1% in weight of yeast extract. The highest specific methane production was obtained with thermal pre-treatment and 0.1% yeast addition. A second experimental stage was run for a closer analysis of the preliminary results. Thermal pre-treatment and 0.1% yeast addition was tested. The best results regarding both COD, TSS and VSS removal rates and methane production were obtained without thermal pre-treatment and with addition of yeast extract. The calculated F-values for the ANOVA-test show that the main influencing factor was the addition of yeast extract where the Biochemical Methane Production was doubled compared with the blank. The highest values for the hydrolysis constants were obtained at hydraulic retention times of six days after adding 0.1% of yeast extract.

scholarly journals Efficiency of integrated electrooxidation and anaerobic digestion of waste activated sludge

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
J. A. Barrios ◽  
A. Cano ◽  
F. F. Rivera ◽  
M. E. Cisneros ◽  
U. Durán
Keyword(s):  
Anaerobic Digestion ◽  
Current Density ◽  
Methane Production ◽  
Energy Recovery ◽  
Energy Analysis ◽  
Mathematical Optimization ◽  
Waste Activated Sludge ◽  
Bdd Electrode ◽  
Vs Removal ◽  
Pre Treatment

Abstract Background Most of the organic content of waste activated sludge (WAS) comprises microbial cells hard to degrade, which must be pre-treated for energy recovery by anaerobic digestion (AD). Electrooxidation pre-treatment (EOP) with boron-doped diamond (BDD) electrode have been considered a promising novel technology that increase hydrolysis rate, by the disintegrating cell walls from WAS. Although electrochemical oxidation could efficiently solubilize organic substances of macromolecules, limited reports are available on EOP of WAS for improving AD. In this endeavour, the mathematical optimization study and the energy analysis of the effects of initial total solids concentrations [TS] of WAS and current density (CD) during EOP on the methane production and removal of chemical oxygen demand (COD) and volatile solids (VS) were investigated. Because limited reports are available on EOP of WAS for improving biogas production, it is not well understood; however, it has started to attract interest of scientists and engineers. Results In the present work, the energy recovery as biogas and WAS conversion were comprehensively affected by CD and [TS], in an integrated EOP and AD system. When working with WAS at 3% of [TS] pre-treated at current density of 24.1 mA/cm2, the highest COD and VS removal were achieved, making it possible to obtain the maximum methane (CH4) production of 305 N-L/kg VS and a positive energy balance of 1.67 kWh/kg VS. Therefore, the current densities used in BDD electrode are adequate to produce the strong oxidant (hydroxyl radical, ·OH) on the electrode surface, allow the oxidation of organic compounds that favours the solubilization of particulate matter and VS from WAS. Conclusions The improvement of VS removal and COD solubilization were due to the effects of pre-treatments, which help to break down the microbial cells for faster subsequent degradation; this allows a decomposition reaction that leads to biodegrade more compounds during AD. The balance was positive, suggesting that even without any optimization the energy used as electricity could be recovered from the increased methane production. It is worth noting that this kind of analysis have not been sufficiently studied so far. It is therefore important to understand how operational parameters can influence the pre-treatment and AD performances. The current study highlights that the mathematical optimization and energy analysis can make the whole process more convenient and feasible.

Sludge accumulation and methanogenic activity in an anaerobic lagoon

2000 ◽  
Vol 42 (10-11) ◽  
pp. 247-255 ◽  
Author(s):  
J. Paing ◽  
B. Picot ◽  
J. P. Sambuco ◽  
A. Rambaud
Keyword(s):  
Anaerobic Digestion ◽  
Methane Production ◽  
Anaerobic Degradation ◽  
Volatile Fatty Acids ◽  
Anaerobic Fermentation ◽  
Methanogenic Activity ◽  
Start Up ◽  
Anaerobic Lagoon ◽  
Methane Production Rate ◽  
Sludge Accumulation

Sludge accumulation and the characteristics of anaerobic digestion in sludge had been investigated in a primary anaerobic lagoon. Methanogenic potential of sludge was evaluated by an anaerobic digestion test which measured the methane production rate. Sludge was sampled at several points in the lagoon to determine spatial variations and with a monthly frequency from the start-up of the lagoon to observe the development of anaerobic degradation. Maximum amounts of sludge accumulated near the inlet. The mean methane production of sludge was 2.9 ml gVS–1 d–1. Sludge near the outlet presented a greater methanogenic activity and a lesser concentration of volatile fatty acids than near the inlet. The different stages of anaerobic degradation were spatially separated, acidogenesis near the inlet and methanogenesis near the outlet. This staged distribution seemed to increase efficiency of anaerobic fermentation compared with septic tanks. Methane release at the surface of the lagoon was estimated to be very heterogeneous with a mean of 25 l m–2 d–1. The development of performance and sludge characteristics showed the rapid beginning of methanogenesis, three months after the start-up of the anaerobic lagoon. Considering the volume of accumulated sludge, it could however be expected that methanogenic activity would further increase.

Anaerobic digestion of macroalgae: methane potentials, pre-treatment, inhibition and co-digestion

2011 ◽  
Vol 64 (8) ◽  
pp. 1723-1729 ◽  
Author(s):  
H. B. Nielsen ◽  
S. Heiske
Keyword(s):  
Anaerobic Digestion ◽  
Methane Production ◽  
Organic Content ◽  
Saccharina Latissima ◽  
Green Tides ◽  
Volatile Solids ◽  
Continuously Stirred Tank Reactor ◽  
Pre Treatment ◽  
Centralized Biogas Plant ◽  
Chaetomorpha Linum

In the present study we tested four macroalgae species – harvested in Denmark – for their suitability of bioconversion to methane. In batch experiments (53 °C) methane yields varied from 132 ml g volatile solids−1 (VS) for Gracillaria vermiculophylla, 152 ml g VS−1 for Ulva lactuca, 166 ml g VS−1 for Chaetomorpha linum and 340 ml g VS−1 for Saccharina latissima following 34 days of incubation. With an organic content of 21.1% (1.5–2.8 times higher than the other algae) S. latissima seems very suitable for anaerobic digestion. However, the methane yields of U. lactuca, G. vermiculophylla and C. linum could be increased with 68%, 11% and 17%, respectively, by pretreatment with maceration. U. lactuca is often observed during ‘green tides’ in Europe and has a high cultivation potential at Nordic conditions. Therefore, U. lactuca was selected for further investigation and co-digested with cattle manure in a lab-scale continuously stirred tank reactor. A 48% increase in methane production rate of the reactor was observed when the concentration of U. lactuca in the feedstock was 40% (VS basis). Increasing the concentration to 50% had no further effect on the methane production, which limits the application of this algae at Danish centralized biogas plant.

scholarly journals Effects of Thickened Excess Sludge Pre-Treatment Using Hydrodynamic Cavitation for Anaerobic Digestion

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2483 ◽  
Author(s):  
Agnieszka Garlicka ◽  
Monika Zubrowska-Sudol ◽  
Katarzyna Umiejewska ◽  
Otton Roubinek ◽  
Jacek Palige ◽  
...  
Keyword(s):  
Methane Production ◽  
Pilot Scale ◽  
Hydrodynamic Cavitation ◽  
Excess Sludge ◽  
Maximum Increase ◽  
Primary Sludge ◽  
Sludge Flocs ◽  
Pre Treatment ◽  
Flocculation Process ◽  
Different Levels

The main purpose of this study was the assessment of the possibility of increasing the production of biogas through the pre-treatment of thickened excess sludge (TES) by means of the hydrodynamic cavitation (HC) conducted at different levels of energy density (EL) i.e., 70, 140 and 210 kJ/L. The experiments were performed on a pilot scale, and a mixture of thickened primary sludge (TPS) and TES was used as digester feed. The results documented that an important parameter determining the possibility of obtaining an enhanced methane production is the value of energy input in the HC process. This parameter determines the changes occurring in sludge as a result of disintegration (i.e., sludge floc deagglomeration, lysis of cells, re-flocculation process and the related release of compounds susceptible to biodegradation from sludge flocs). The maximum increase in methane yield (MY) of 152% was obtained for EL = 140 kJ/L. In this case, HC mainly caused sludge floc deagglomeration. An increase in MY was also recorded when TES was subject to the disintegration process at EL = 210 kJ/L. However, it was 4.3 times lower than that observed for EL = 140 kJ/L. Pre-treatment of TES at EL = 70 kJ/L did not contribute to an increase in methane production.

Anaerobic digestion of aerobic granular biomass: effects of thermal pre-treatment and addition of primary sludge

2013 ◽  
Vol 89 (5) ◽  
pp. 690-697 ◽  
Author(s):  
Ángeles Val Del Río ◽  
Tania Palmeiro-Sanchez ◽  
Mónica Figueroa ◽  
Anuska Mosquera-Corral ◽  
José L Campos ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Primary Sludge ◽  
Granular Biomass ◽  
Pre Treatment

scholarly journals Evaluation of acidogenic sludge from anaerobic reactors running at low solids retention times to reduce sludge generation and enhance biogas production

Water SA ◽  
2019 ◽  
Vol 45 (4 October) ◽  
Author(s):  
Wilza Da Silva Lopes ◽  
Ysa Helena Diniz Morais de Luna ◽  
Jose Tavares de Sousa ◽  
Wilton Silva Lopes ◽  
Valderi Duarte Leite
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Kinetic Constant ◽  
Oxygen Demand ◽  
Gas Production ◽  
Primary Sludge ◽  
Anaerobic Reactors ◽  
Solids Retention ◽  
Improved Performance ◽  
Pre Treatment

ABSTRACT   Sludges generated in the biological processing of sewage are complex mixtures, the constituents of which pose risks to public health and the environment. Anaerobic digestion is considered the most sustainable option for treating sludge because it offers the possibility of generating biogas. The aim of this study was to compare the quantities, properties, biodegradabilities and biochemical methane potentials (BMP) of primary sludge (PS) generated by a primary decanter with acidogenic sludges produced by upflow anaerobic (UA) reactors operating at solids retention times (SRTs) of 2, 4, 6 and 8 days (Samples S2, S4, S6 and S8, respectively). Sludges from both pre-treatments were submitted to alkaline solubilization in order to determine the efficiency of the process in disrupting extracellular complexes. Based on the levels of total solids (TS) present, the primary decanter was found to generate higher quantities of excess sludge (yield of 3.1 gTS∙d-1) than UA reactors operating at low SRTs (yields in the range 1.69 to 0.64 gTS∙d-1). The concentrations of dissolved materials in PS and Samples S2 and S8 were considerably higher after alkaline solubilization, with respective increases of 8, 14 and 28-fold in dissolved organic carbon, 12, 20 and 40-fold in chemical oxygen demand, 25, 31 and 59-fold in proteins, and 17, 21 and 63-fold in carbohydrates. In addition, the BMP value for S8 was some 13% higher than that recorded for PS while the kinetic constant for gas production by S8 was 1.8-fold greater than that of PS. It is concluded that a pre-treatment combining anaerobic digestion at low SRT and alkaline solubilisation would lead to improved performance in subsequent stages of anaerobic digestion and, consequently, increased efficiency in biogas production.

Anaerobic degradation of palm oil mill effluent with aluminum bauxite residue for methane production

2020 ◽  
pp. 0958305X2092312
Author(s):  
Anwar Ahmad ◽  
Salam S AlDawey ◽  
SS Reddy
Keyword(s):  
Anaerobic Digestion ◽  
Palm Oil ◽  
Methane Production ◽  
Bauxite Residue ◽  
Oxygen Demand ◽  
Palm Oil Mill Effluent ◽  
Methane Yield ◽  
Yield Coefficient ◽  
Methanogenic Activity ◽  
Palm Oil Mill

Experimental study of the anaerobic digestion of palm oil mill effluent (POME) was carried out in an anaerobic upflow sludge blanket reactor (UASBR) with bauxite residue. The production rate of methane 114 L/gCOD/d and CH4 concentration was 205 L gCOD/d at 8.5 g/L of bauxite residue in UASBR. The results showed that the highest methane yield was 37.5 L gCODadded/h; CO2 reduction 1.5 L gCODadded and chemical oxygen demand (COD) removal reached 98.3% at 8.5 g/L of bauxite residue, respectively. The results the best by the modified kinetic model and Umax was 100 mg/L. The kinetic of methane production was also studied. The methane yield coefficient, YM, was 0.69 L CH4/gCODremoved. Anaerobic digestion of acetate was the dominant soluble metabolites in development and specific methanogenic activity results showed that high observed between stoichiometric and experimental higher methane production.

scholarly journals Inter-stage thermophilic aerobic digestion may increase organic matter removal from wastewater sludge without decreasing biogas production

2017 ◽  
Vol 77 (3) ◽  
pp. 721-726
Author(s):  
Sasha D. Hafner ◽  
Johan T. Madsen ◽  
Johanna M. Pedersen ◽  
Charlotte Rennuit
Keyword(s):  
Anaerobic Digestion ◽  
Methane Production ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Wastewater Sludge ◽  
Aerobic Digestion ◽  
Anaerobic Digesters ◽  
Stage System ◽  
Thermophilic Aerobic Digestion ◽  
Pre Treatment

Abstract Combining aerobic and anaerobic digestion in a two-stage system can improve the degradation of wastewater sludge over the use of either technology alone. But use of aerobic digestion as a pre-treatment before anaerobic digestion generally reduces methane production due to loss of substrate through oxidation. An inter-stage configuration may avoid this reduction in methane production. Here, we evaluated the use of thermophilic aerobic digestion (TAD) as an inter-stage treatment for wastewater sludge using laboratory-scale semi-continuous reactors. A single anaerobic digester was compared to an inter-stage system, where a thermophilic aerobic digester (55 °C) was used between two mesophilic anaerobic digesters (37 °C). Both systems had retention times of approximately 30 days, and the comparison was based on measurements made over 97 days. Results showed that the inter-stage system provided better sludge destruction (52% volatile solids (VS) removal vs. 40% for the single-stage system, 44% chemical oxygen demand (COD) removal vs. 34%) without a decrease in total biogas production (methane yield per g VS added was 0.22–0.24 L g−1 for both systems).

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