Anaerobic digestion of sludge differing in inorganic solids content: performance comparison and the effect of inorganic suspended solids content on degradation

2016 ◽  
Vol 74 (9) ◽  
pp. 2152-2161 ◽  
Author(s):  
Nina Duan ◽  
Xiaohu Dai ◽  
Bin Dong ◽  
Lingling Dai
Keyword(s):  
Anaerobic Digestion ◽  
Suspended Solids ◽  
Degradation Process ◽  
Performance Comparison ◽  
Batch Experiments ◽  
Biogas Yield ◽  
Stirred Tank Reactors ◽  
Volatile Fatty Acid Concentration ◽  
Substrate Conversion ◽  
Solids Content

High inorganic suspended solids (ISS) content of sludge in many areas (especially with combined sewage systems) results in low VS/TS (volatile solids, VS; total solids, TS) levels and raises concerns about its effect on anaerobic digestion. The performances of sludge anaerobic digestion with different feeding VS/TS levels as well as the effect of ISS content on the anaerobic degradation process were investigated in completely stirred tank reactors by semi-continuous and batch experiments. In semi-continuous experiment with sludge at VS/TS of 61.4%, 45.0, 30.0% and 15.0%, biogas yield, VS reduction and methane content decreased logarithmically with the feeding VS/TS decreasing; slightly higher volatile fatty acid concentration was observed at VS/TS 15%. Results of the batch experiments suggested that acetogenesis and methanogenesis are obviously affected by high ISS addition, while hydrolysis is less affected. The retardment of substrate conversion rate is probably attributed to decreased mass transfer efficiency at high ISS content.

scholarly journals Effects of Hydrothermal Pretreatment and Hydrochar Addition on the Performance of Pig Carcass Anaerobic Digestion

2021 ◽  
Vol 12 ◽  
Author(s):  
Jie Xu ◽  
Hongjian Lin ◽  
Kuichuan Sheng
Keyword(s):  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Ammonia Concentration ◽  
Hydrothermal Pretreatment ◽  
Biogas Yield ◽  
Stirred Tank Reactors ◽  
Liquid Products ◽  
Pig Carcasses

Proper disposal and utilization of dead pig carcasses are problems of public concern. The combination of hydrothermal pretreatment (HTP) and anaerobic digestion is a promising method to treat these wastes, provided that digestion inhibition is reduced. For this reason, the aim of this work was to investigate the optimal HTP temperature (140–180°C) for biogas production during anaerobic digestion of dead pigs in batch systems. In addition, the effects of hydrochar addition (6 g/L) on anaerobic digestion of pork products after HTP in continuous stirred tank reactors (CSTR) were determined. According to the results, 90% of lipids and 10% of proteins present in the pork were decomposed by HTP. In addition, the highest chemical oxygen demand (COD) concentration in liquid products (LP) reached 192.6 g/L, and it was obtained after 170°C HTP. The biogas potential from the solid residue (SR) and LP was up to 478 mL/g-VS and 398 mL/g-COD, respectively. A temperature of 170°C was suitable for pork HTP, which promoted the practical biogas yield because of the synergistic effect between proteins and lipids. Ammonia inhibition was reduced by the addition of hydrochar to the CSTR during co-digestion of SR and LP, maximum ammonia concentration tolerated by methanogens increased from 2.68 to 3.38 g/L. This improved total biogas yield and degradation rate of substrates, reaching values of 28.62 and 36.06%, respectively. The acetate content in volatile fatty acids (VFA) may be used as an index that reflects the degree of methanogenesis of the system. The results of the present work may also provide guidance for the digestion of feedstock with high protein and lipid content.

Recovering biomethane and nutrients from anaerobic digestion of water hyacinth (Eichhornia crassipes) and its co-digestion with fruit and vegetable waste

2015 ◽  
Vol 73 (2) ◽  
pp. 355-361 ◽  
Author(s):  
M. A. Hernández-Shek ◽  
L. S. Cadavid-Rodríguez ◽  
I. V. Bolaños ◽  
A. C. Agudelo-Henao
Keyword(s):  
Anaerobic Digestion ◽  
Water Hyacinth ◽  
Biogas Production ◽  
Organic Loading Rate ◽  
Vegetable Waste ◽  
Fruit And Vegetable ◽  
Biogas Yield ◽  
Stirred Tank Reactors ◽  
Volatile Solids ◽  
Bmp Test

The potential to recover bioenergy from anaerobic digestion of water hyacinth (WH) and from its co-digestion with fruit and vegetable waste (FVW) was investigated. Initially, biogas and methane production were studied using the biochemical methane potential (BMP) test at 2 g volatile solids (VS) L−1 of substrate concentration, both in the digestion of WH alone and in its co-digestion with FVW (WH-FVW ratio of 70:30). Subsequently, the biogas production was optimized in terms of total solids (TS) concentration, testing 4 and 6% of TS. The BMP test showed a biogas yield of 0.114 m3 biogas kg−1 VSadded for WH alone. On the other hand, the biogas potential from the WH-FVW co-digestion was 0.141 m3 biogas kg−1 VSadded, showing an increase of 23% compared to that of WH alone. Maximum biogas production of 0.230 m3 biogas kg−1 VSadded was obtained at 4% of TS in the co-digestion of WH-FVW. Using semi-continuously stirred tank reactors, 1.3 m3 biogas yield kg−1 VSadded was produced using an organic loading rate of 2 kg VS m−3 d−1 and hydraulic retention time of 15 days. It was also found that a WH-FVW ratio of 80:20 improved the process in terms of pH stability. Additionally, it was found that nitrogen can be recovered in the liquid effluent with a potential for use as a liquid fertilizer.

scholarly journals Enriched Renewable Methane from the Anaerobic Digestion of Petrochemical Wastewater: A Bio-Remediation Structure

2021 ◽  
Vol 4 (1) ◽  
pp. 1-7
Author(s):  
M.N.I. Siddique ◽  
M.F. Ishak ◽  
A.W. Zularisam
Keyword(s):  
Anaerobic Digestion ◽  
Industrial Application ◽  
Ammonium Bicarbonate ◽  
Stirred Tank ◽  
Petrochemical Wastewater ◽  
Biogas Yield ◽  
Stirred Tank Reactors ◽  
Optimal Dosing ◽  
Continuous Stirred Tank ◽  
Mathematical Calculation

Scarcity of nitrogenous resource and buffering capability were recognized as reverting failure in earlier research treating petrochemical wastewater in anaerobic continuous stirred tank reactors. The purpose of this work is to explore the use of ammonium bicarbonate (NH4HCO3) as supplementation ensuring nitrogenous supply and buffering requirement. With a view to measure the effect of NH4HCO3 on the anaerobic process, a set of dosing up to 40 mg L-1 was examined. The result was evaluated in terms of biogas yield. It was found that 10 mg L-1 dosing was the optimal dosing without affecting methanogenesis. Moreover, mathematical calculation explained that this optimum dosing can enhance biogas yield up to 27.77% compared to control PWW digestion. Results showed an obvious financial advantage to make the industrial application feasible.

scholarly journals Performance of a Full-Scale Anaerobic Digestion on Bakery Wastewater Treatment : Effect of Modified Distribution System

2020 ◽  
Vol 11 (1) ◽  
pp. 12-18
Author(s):  
Hanny Vistanty ◽  
Rizal Awaludin Malik ◽  
Aris Mukimin
Keyword(s):  
Anaerobic Digestion ◽  
Distribution System ◽  
Suspended Solids ◽  
Loading Rate ◽  
Oxygen Demand ◽  
Degradation Process ◽  
Full Scale ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
External Circulation

The effectiveness of a full-scale anaerobic digestion pretreatment was evaluated and the effect of wastewater distribution system was determined on the performance of bakery wastewater (BW) treatment. The BW was fed to 3 series of anaerobic compartments as the main degradation process. The distribution system of first compartment was modified and circulated to enhance contact and efficiency. While the effluent of last compartment was partly returned to the first compartment as an external circulation and the other part was further processed in activated sludge under aerobic conditions. The overall system was able to remove chemical oxygen demand (COD), total suspended solids (TSS), and biochemical oxygen demand (BOD) up to 97.7%, 99.7%, and 99.6%, respectively, at maximum organic loading rate of 6.3 kg COD/m3day. High removal of pollutants indicated that modified distribution of circulation is advantageous to the BW treatment

Solubilization of organic sludge by thermophilic aerobic bacteria as a pretreatment for anaerobic digestion

2000 ◽  
Vol 41 (3) ◽  
pp. 163-169 ◽  
Author(s):  
S. Hasegawa ◽  
N. Shiota ◽  
K. Katsura ◽  
A. Akashi
Keyword(s):  
Anaerobic Digestion ◽  
Continuous Flow ◽  
Volatile Fatty Acids ◽  
Suspended Solids ◽  
Extracellular Enzymes ◽  
Thermophilic Bacteria ◽  
Aerobic Bacteria ◽  
Batch Experiments ◽  
Microaerobic Conditions ◽  
Flow Experiments

Solubilization of organic sludge by thermophilic aerobic bacteria as a pretreatment for anaerobic digestion was investigated. The thermophilic bacteria which solubilized organic sludge were isolated from the thermophilic aerobic digestion reactor. The bacterium type SPT2-1 could grow at pH ranging from 5.0 to 8.5 with optimal temperature at 60–70°C. In batch experiments, 25–30% of volatile suspended solids (VSS) in the pre-heated sludge were solubilized on inoculating with the isolated bacteria although little was solubilized without inoculation. The isolated bacteria appeared to secret the extracellular enzymes including proteases and amylases. In continuous flow experiments, sludge solubilization rate (VSS removal) was around 40% under aerobic as well as microaerobic conditions. No accumulation of volatile fatty acids in the treated sludge was observed under aerobic conditions while significant amounts of them were accumulated under microaerobic conditions. Production of biogas on anaerobic digestion of the microaerobically-pretreated sludge was increased by 1.5 when compared with the sludge without pretreatment.

IDENTIFYING ANAEROBIC DIGESTION MODELS USING SIMULTANEOUS BATCH EXPERIMENTS

2010 ◽  
Vol 9 (3) ◽  
pp. 313-318 ◽  
Author(s):  
Xavier Flotats ◽  
Jordi Palatsi ◽  
Belen Fernandez ◽  
M. Angels Colomer ◽  
Josep Illa
Keyword(s):  
Anaerobic Digestion ◽  
Batch Experiments

Behaviour of Mechanically Blended Return-Sludge in Absence of Substrate

1970 ◽  
Vol 5 (1) ◽  
pp. 34-54
Author(s):  
Shyam D. Bokil ◽  
Jatinder K. Bewtra
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Treatment Plant ◽  
Aeration Rate ◽  
Batch Experiments ◽  
Sludge Treatment ◽  
Waring Blender ◽  
Settling Characteristics

Abstract Nine sets of batch experiments, each of ten to twelve days duration, were conducted in the laboratory on return-sludge samples collected from activated sludge treatment plant at Windsor. The thickened sludge samples were blended daily in a waring blender and were continuously aerated in twelve-litres capacity jars. Parallel runs were made on control sludge samples which were not blended. Amongst the parameters varied were the speed and frequency of blending and the aeration rate. The effects of these variables on progressive bio-degradation of volatile suspended solids and the settling characteristics of the sludge were determined. Blended sludge showed significant improvement in the rate of bio-degradation and its settling characteristics as compared to the control unblended sludge

Surface charge and extracellular polymer of sludge in the anaerobic degradation process

1996 ◽  
Vol 34 (5-6) ◽  
pp. 309-316 ◽  
Author(s):  
X. S. Jia ◽  
Herbert H. P. Fang ◽  
H. Furumai
Keyword(s):  
Surface Charge ◽  
Growth Phase ◽  
Anaerobic Degradation ◽  
Degradation Process ◽  
Anaerobic Sludge ◽  
Batch Experiments ◽  
High Substrate Concentration ◽  
Negative Surface ◽  
Negative Surface Charge ◽  
Extracellular Polymer

Changes of surface charge and extracellular polymer (ECP) content were investigated in batch experiments for three anaerobic sludges, each of which had been enriched at 35°C and pH 639-7.3 for more than 40 batches using propionate, butyrate and glucose, individually, as the sole substrate. Results showed that both ECP and the negative surface charge were dependent on the growth phase of microorganisms. They increased at the beginning of all batches when the microorganisms were in the prolific-growth phase, having high substrate concentration and food-to-microorganisms ratio. Both later gradually returned to their initial levels when the microorganisms were in the declined-growth phase, as the substrate became depleted. The negative surface charge increased linearly with the total-ECP content in all series with slopes of 0.0187, 0.0212 and 0.0157 meq/mg-total-ECP for sludge degrading propionate, butyrate and glucose, respectively. The change of surface charge for the first two sludges was mainly due to the increase of proteinaceous fraction of ECP; but, for glucose-degrading sludge, that could be due to the increases of both proteinaceous and carbohydrate fractions of ECP. The negative-charged nature of anaerobic sludge implies that cations should be able to promote granulation of anaerobic sludge.

scholarly journals Improving the Anaerobic Digestion of Swine Manure through an Optimized Ammonia Treatment: Process Performance, Digestate and Techno-Economic Aspects

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 787
Author(s):  
Anna Lymperatou ◽  
Niels B. Rasmussen ◽  
Hariklia N. Gavala ◽  
Ioannis V. Skiadas
Keyword(s):  
Anaerobic Digestion ◽  
Large Scale ◽  
Treatment Process ◽  
Aqueous Ammonia ◽  
Swine Manure ◽  
Batch Experiments ◽  
Ammonia Treatment ◽  
Aqueous Ammonia Soaking ◽  
High Ammonia ◽  
Reduction Efficiency

Swine manure mono-digestion results in relatively low methane productivity due to the low degradation rate of its solid fraction (manure fibers), and due to the high ammonia and water content. The aqueous ammonia soaking (AAS) pretreatment of manure fibers has been proposed for overcoming these limitations. In this study, continuous anaerobic digestion (AD) of manure mixed with optimally AAS-treated manure fibers was compared to the AD of manure mixed with untreated manure fibers. Due to lab-scale pumping restrictions, the ratio of AAS-optimally treated manure fibers to manure was only 1/3 on a total solids (TS) basis. However, the biogas productivity and methane yield were improved by 17% and 38%, respectively, also confirming the predictions from a simplified 1st order hydrolysis model based on batch experiments. Furthermore, an improved reduction efficiency of major organic components was observed for the digester processing AAS-treated manure fibers compared to the non-treated one (e.g., 42% increased reduction for cellulose fraction). A preliminary techno-economic analysis of the proposed process showed that mixing raw manure with AAS manure fibers in large-scale digesters could result in a 72% increase of revenue compared to the AD of manure mixed with untreated fibers and 135% increase compared to that of solely manure.

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