Disintegration of excess activated sludge – evaluation and experience of full-scale applications

2006 ◽  
Vol 53 (12) ◽  
pp. 229-236 ◽  
Author(s):  
J. Zábranská ◽  
M. Dohányos ◽  
P. Jeníček ◽  
J. Kutil
Keyword(s):  
Organic Matter ◽  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Activated Sludge ◽  
Biogas Production ◽  
Full Scale ◽  
Energy Yield ◽  
Operational Experience ◽  
Digested Sludge

Anaerobic digestion of sewage sludge can be improved by introducing a disintegration of excess activated sludge as a pretreatment process. The disintegration brings a deeper degradation of organic matter and less amount of output sludge for disposal, a higher production of biogas and consequently energy yield, in some cases suppression of digesters foaming and better dewaterability. The full-scale application of disintegration by a lysate-thickening centrifuge was monitored long term in three different WWTPs. The evaluation of contribution of disintegration to biogas production and digested sludge quality was assessed and operational experience is discussed. Increment of specific biogas production was evaluated in the range of 15–26%, organic matter in digested sludge significantly decreased to 48–49%. Results proved that the installation of a disintegrating centrifuge in WWTPs of different sizes and conditions would be useful and beneficial.

Improvement of anaerobic digestion of sludge

2004 ◽  
Vol 49 (10) ◽  
pp. 89-96 ◽  
Author(s):  
M. Dohányos ◽  
J. Zábranská ◽  
J. Kutil ◽  
P. Jeníček
Keyword(s):  
Particulate Matter ◽  
Anaerobic Digestion ◽  
Energy Balance ◽  
Activated Sludge ◽  
High Resistance ◽  
Biogas Production ◽  
Treatment Plant ◽  
Process Conditions ◽  
Digested Sludge ◽  
Acceptable Method

Anaerobic digestion improvement can be accomplished by different methods. Besides optimization of the process conditions, pretreatment of input sludge and increase of process temperature is frequently used. The thermophilic process brings a higher solids reduction and biogas production, a high resistance to foaming, no problems with odour, better pathogens destruction and an improvement of the energy balance of the whole treatment plant. Disintegration of excess activated sludge in a lysate centrifuge was proved to cause increase of biogas production in full-scale conditions. The rapid thermal conditioning of digested sludge is an acceptable method of particulate matter disintegration and solubilization.

Ultrasonic sludge treatment for enhanced anaerobic digestion

2004 ◽  
Vol 50 (9) ◽  
pp. 25-32 ◽  
Author(s):  
F. Hogan ◽  
S. Mormede ◽  
P. Clark ◽  
M. Crane
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
New Technology ◽  
Downstream Processing ◽  
Full Scale ◽  
Waste Stream ◽  
Site Conditions ◽  
Digested Sludge ◽  
Sludge Treatment ◽  
Primary Sludge

Ultrasound is the term used to describe sound energy at frequencies above 20 kHz. Highpowered ultrasound can be applied to a waste stream via purpose-designed tools in order to induce cavitation. This effect results in the rupture of cellular material and reduction of particle size in the waste stream, making the cells more amenable to downstream processing. sonixTM is a new technology utilising high-powered, concentrated ultrasound for conditioning sludges prior to further treatment. This paper presents recent results from a number of demonstration and full-scale plants treating thickened waste activated sludge (TWAS) prior to anaerobic digestion, therefore enhancing the process. The present studies have proved that the use of ultrasound to enhance anaerobic digestion can be achieved at full scale and effectively result in the TWAS (typically difficult to digest) behaving, after sonication, as if it were a “primary” sludge. The technology presents benefits in terms of increased biogas production, better solids reduction, improved dewatering characteristics of the digested sludge mixture and relatively short payback periods of two years or less subject to the site conditions and practices applicable at that time.

scholarly journals Digested Sludge Quality in Mesophilic, Thermophilic and Temperature-Phased Anaerobic Digestion Systems

Water ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 2839
Author(s):  
Iryna Lanko ◽  
Jakub Hejnic ◽  
Jana Říhová-Ambrožová ◽  
Ivet Ferrer ◽  
Pavel Jenicek
Keyword(s):  
Organic Matter ◽  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Energy Demand ◽  
Calorific Value ◽  
Single Stage ◽  
Digested Sludge ◽  
Final Disposal ◽  
Temperature Regimes ◽  
Mesophilic Conditions

Anaerobic digestion (AD) technology is commonly used to treat sewage sludge from activated sludge systems, meanwhile alleviating the energy demand (and costs) for wastewater treatment. Most often, anaerobic digestion is run in single-stage systems under mesophilic conditions, as this temperature regime is considered to be more stable than the thermophilic one. However, it is known that thermophilic conditions are advantageous over mesophilic ones in terms of methane production and digestate hygienisation, while it is unclear which one is better concerning the digestate dewaterability. Temperature-phased anaerobic digestion (TPAD) is a double-stage AD process that combines the above-mentioned temperature regimes, by operating a thermophilic digester followed by a mesophilic one. The aim of this study is to compare the digestate quality of single-stage mesophilic and thermophilic AD and TPAD systems, in terms of the dewaterability, pathogenic safety and lower calorific value (LCV) and, based on the comparison, consider digested sludge final disposal alternatives. The research is conducted in lab-scale reactors treating waste-activated sludge. The dewaterability is tested by two methods, namely, centrifugation and mechanical pressing. The experimental results show that the TPAD system is the most beneficial in terms of organic matter degradation efficiency (32.4% against 27.2 for TAD and 26.0 for MAD), producing a digestate with a high dewaterability (8.1–9.8% worse than for TAD and 6.2–12.0% better than for MAD) and pathogenic safety (coliforms and Escherichia coli were not detected, and Clostridium perfringens were counted up to 4.8–4.9 × 103, when for TAD it was only 1.4–2.5 × 103, and for MAD it was 1.3–1.8 × 104), with the lowest LCV (19.2% against 15.4% and 15.8% under thermophilic and mesophilic conditions, respectively). Regarding the final disposal, the digested sludge after TAD can be applied directly in agriculture; after TPAD, it can be used as a fertilizer only in the case where the fermenter HRT assures the pathogenic safety. The MAD digestate is the best for being used as a fuel preserving a higher portion of organic matter, not transforming into biogas during AD.

scholarly journals Demand-Driven Biogas Production from Anaerobic Digestion of Sewage Sludge: Application in Demonstration Scale

2021 ◽  
Author(s):  
Mauro Lafratta ◽  
Rex B. Thorpe ◽  
Sabeha K. Ouki ◽  
Achame Shana ◽  
Eve Germain ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Biogas Production ◽  
Pilot Scale ◽  
Full Scale ◽  
Operational Environment ◽  
Biogas Yield ◽  
Feeding Regimes ◽  
Generation Capacity ◽  
Flexible Generation

Abstract The power system needs flexible electricity generators. Whilst electricity generation from anaerobic digestion (AD) of sewage sludge has traditionally been baseload, transforming the generation capacity into a modern flexible operator is an opportunity to further valorise the resource. This work aims to demonstrate that AD of sewage sludge can support flexible generation and be operated dynamically in a relevant operational environment, to promote full scale implementation. A demonstration scale plant (20 m3 conventional AD reactors) was used to test several feeding regimes designed to return a biogas production rate that matches the demand. Two demand profiles are defined, either by common corporate power purchase agreements or by the main balancing mechanism used by the grid operator in UK. Demand-driven biogas production is demonstrated in this relevant operational environment, and the flexibilisation performance is positive in all scenarios. The value of the biogas increases by up to 2%, which outperforms the results obtained at pilot scale. Additionally, an increase in biogas yield is observed. Whilst transitional imbalances are recorded, they last for few hours and the overall stability is not affected. In conclusion, these trials demonstrate demand-driven biogas production is a feasible operational solution and full-scale implementation is possible. Graphical Abstract

Sludge minimization by disintegration at different wastewater treatment plants

2008 ◽  
Vol 3 (1) ◽  
Author(s):  
Luchien Luning ◽  
Paul Roeleveld ◽  
Victor W.M. Claessen
Keyword(s):  
Organic Matter ◽  
Wastewater Treatment ◽  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
New Technologies ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Biological Degradation ◽  
Ongoing Research ◽  
Sludge Minimization

In recent years new technologies have been developed to improve the biological degradation of sewage sludge by anaerobic digestion. The paper describes the results of a demonstration of ultrasonic disintegration on the Dutch Wastewater Treatment Plant (WWTP) Land van Cuijk. The effect on the degradation of organic matter is presented, together with the effect on the dewatering characteristics. Recommendations are presented for establishing research conditions in which the effect of sludge disintegration can be determined in a more direct way that is less sensitive to changing conditions in the operation of the WWTP. These recommendations have been implemented in the ongoing research in the Netherlands supported by the National Institute for wastewater research (STOWA).

scholarly journals Biogas potential of organic waste onboard cruise ships — a yet untapped energy source

2021 ◽  
Author(s):  
Kai Schumüller ◽  
Dirk Weichgrebe ◽  
Stephan Köster
Keyword(s):  
Energy Source ◽  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Food Waste ◽  
Energy Demand ◽  
Organic Waste ◽  
Biogas Production ◽  
Biogas Yield ◽  
Cruise Ships ◽  
Detailed Presentation

AbstractTo tap the organic waste generated onboard cruise ships is a very promising approach to reduce their adverse impact on the maritime environment. Biogas produced by means of onboard anaerobic digestion offers a complementary energy source for ships’ operation. This report comprises a detailed presentation of the results gained from comprehensive investigations on the gas yield from onboard substrates such as food waste, sewage sludge and screening solids. Each person onboard generates a total average of about 9 kg of organic waste per day. The performed analyses of substrates and anaerobic digestion tests revealed an accumulated methane yield of around 159 L per person per day. The anaerobic co-digestion of sewage sludge and food waste (50:50 VS) emerged as particularly effective and led to an increased biogas yield by 24%, compared to the mono-fermentation. In the best case, onboard biogas production can provide an energetic output of 82 W/P, on average covering 3.3 to 4.1% of the total energy demand of a cruise ship.

Mesophilic and Thermophilic Digestion of Thickened Waste Activated Sludge: A Comparative Study

2010 ◽  
Vol 113-116 ◽  
pp. 450-458 ◽  
Author(s):  
Yong Zhi Chi ◽  
Yu You Li ◽  
Min Ji ◽  
Hong Qiang ◽  
Heng Wei Deng ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Municipal Wastewater ◽  
Treatment Plant ◽  
Methane Content ◽  
Waste Activated Sludge ◽  
Digested Sludge ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Significant Difference

This paper presents an experimental study over 204 days on anaerobic degradation of thickened waste activated sludge (TWAS) from a municipal wastewater treatment plant (WWTP). The experiments were conducted under thermophilic (55°C) and mesophilic (35°C) condition, respectively, by using the semi-continuous flow completely mixed reactors. The influent total solids (TS), hydraulic retention time (HRT) and chemical oxygen demand (COD) loading levels were around 4%, 30 days and 1.67 kg-CODCr•m-3•d-1 , respectively. During the opration period, the thermophilic anaerobic digestion process (TADP) and the mesophilic anaerobic digestion process (MADP) were stable and well-functioned without ammonia inhibition. Particulate organic matters reduction of TADP was superior to that of MADP. This result implies that TADP has higher sludge reduction efficiency than MADP. According to the simulated chemical formula of TWAS, C5.85H9.75O3.96N, and the stoichiometric equation, the methane content and the ammonia yield in the anaerobic process could be calculated, which were consistent with the experimental results. The methane yield of TADP was a little higher than that of MADP. The statistical mean values of methane content for TADP and MADP were 60.97% and 62.38%, respectively.According to paired t-test, there was a significant difference in methane content between TADP and MADP(α=0.01, n=62). Compared with the mesophilic digested sludge, the dewaterability of thermophilic digested sludge was lower.

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.

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