The rheological behaviour of anaerobic digested sludge

Baudez, Jean-Christophe; Markis, Flora; Eshtiaghi, Nicky; Slatter, Paul

doi:10.1016/j.watres.2011.08.035

Cited by 132 publications

(91 citation statements)

References 18 publications

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“…The viscosity of the reactor sludge in the control reactor (R2) ranged between 2.0 ± 0.2 and 7.7 ± 0.3 mPa*s throughout the experiment (Fig. 1h), which was in the same range as previously reported values for reactor liquids of processes digesting sewage sludge (Baudez et al 2011(Baudez et al , 2013. It should also be noted that in addition to TS, changes in parameters such as, e.g., particle size, polymeric substances, and ion concentrations, may have contributed to changes in viscosity of the R1 upon codigestion of OFMSW as an additional substrate (Nges et al 2012;Moestedt et al 2016;Lindorfer and Demmig 2016).…”

Section: Resultssupporting

confidence: 84%

Feasibility of OFMSW co-digestion with sewage sludge for increasing biogas production at wastewater treatment plants

Björn

Yekta

Ziels

et al. 2017

Euro-Mediterr J Environ Integr

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Sweden has the ambition to increase its annual biogas production from the current level of 1.9 to 15 TWh by 2030. The unused capacity of existing anaerobic digesters at wastewater treatment plants is among the options to accomplish this goal. This study investigated the feasibility of utilizing the organic fraction of municipal solid waste (OFMSW) as a co-substrate, with primary and waste-activated sewage sludge (PWASS) for production of biogas, corresponding to 3:1 ratio on volatile solid (VS) basis. The results demonstrated that co-digestion of OFMSW with PWASS at an organic loading rate of 5 gVS l −1 day −1 has the potential to increase the biogas production approximately four times. The daily biogas production increased from 1.0 ± 0.1 to 3.8 ± 0.3 l biogas l −1 day −1 , corresponding to a specific methane production of 420 ± 30 Nml methane gVS −1 during the laboratory experiment. Co-digestion of OFMSW with PWASS showed a 50:50 distribution of hydrogenotrophic and aceticlastic methanogens in the digester and enhanced the turnover kinetics of intermediate products (acetate, propionate, and oleate). Practical limitations potentially include the need for sludge dewatering to maintain a sufficient hydraulic retention time (17 days in this study), as well as additional energy consumption for mixing due to an increased sludge apparent viscosity (from 1.8 ± 0.1 to 45 ± 4.8 mPa*s in this study) at elevated OFMSW-loading rates.

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Section: Resultssupporting

confidence: 84%

Feasibility of OFMSW co-digestion with sewage sludge for increasing biogas production at wastewater treatment plants

Björn

Yekta

Ziels

et al. 2017

Euro-Mediterr J Environ Integr

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“…Several factors that potentially influence N losses by NH 3 volatilization during and after field spreading are affected by anaerobic digestion: Reduction of dry matter content (e.g., Asmus et al 1988) and viscosity Baudez et al 2011) can increase the infiltration of liquid manure into the soil, thereby decreasing the exchange surface of slurry with the atmosphere thus lowering NH 3 volatilization (Rubaek et al 1996;Sommer and Hutchings 2001). However, digestion leads simultaneously to an increase in manure pH (by 0.5-2.0 U) and of the ammonium concentration (relative increase of >20 %) (Möller and Müller 2012); both factors promote N losses via NH 3 volatilization (e.g., Gericke et al 2012;Ni et al 2012;Sommer and Hutchings 2001 In concordance with the described potential effects, contradictory results regarding the effects of anaerobic digestion on NH 3 volatilization after field application of digestates have been reported in literature: Some researchers report a decrease of NH 3 losses after soil application of digested animal manures, others report an increase of losses, and others did not found any or ambiguous effects (Table 3).…”

Section: Impact Of Anaerobic Digestion On Ammonia Volatilization Frommentioning

confidence: 99%

Effects of anaerobic digestion on soil carbon and nitrogen turnover, N emissions, and soil biological activity. A review

Möller¹

2015

Agron. Sustain. Dev.

240

139

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Sustainability in agriculture means the inclusion of several aspects, as sustainable agriculture systems must not compromise not only their ability to satisfy future needs by undermining soil fertility and the natural resource base but also sustainable agriculture has had to address a range of other issues including energy use, efficient use, and recycling of nutrients, the effects on adjacent ecosystems including the effects on water bodies and climate change. Organic manures are an important factor to keep the soil fertility level of soils. However, their management is often related to large emissions. In this context, anaerobic digestion is-similarly to composting-a treatment option for stabilization of biogenic wastes leading to a residual product called digestates, enabling the sanitation and the recycling and use as fertilizer. It is also a means to obtain energy from wastes as well as from dedicated energy crops. Therefore, anaerobic digestion potentially addresses several aspects of agricultural sustainability. This review discusses the current state of knowledge on the effects of anaerobic digestion on organic compounds in digestates and the most important processes influencing N emissions in the field, as well as the possible longterm effects on soil microbial biomass and soil fertility. The main findings are that (1) the direct effects of anaerobic digestion on long-term sustainability in terms of soil fertility and environmental impact at the field level are of minor relevance. (2) The most relevant effects of anaerobic digestion on soil fertility as well as on N emissions will be expected from indirect effects related to cropping system changes such as changes in crop rotation, crop acreage, cover cropping, and total amounts of organic manures including digestates. Furthermore, (3) the remaining organic fraction after anaerobic digestion is much more recalcitrant than the input feedstocks leading to a stabilization of the organic matter and a lower organic matter degradation rate after field application, enabling a similar reproduction of the soil organic matter as obtained by direct application of the feedstock or by composting of the feedstock. (4) Regarding emissions, the main direct effect of anaerobic digestion on a farm level is the influence on gaseous emissions during manure or digestate treatment and handling, whereas the direct effects of anaerobic digestion on a field level on emissions (NH 3 − and N 2 O − emissions, NO 3 -leaching) are negligible or at least ambiguous. (5) The main direct effects of anaerobic digestion on the field level are short-term effects on soil microbial activity and changes in the soil microbial community. Therefore, in terms of the effects on agricultural sustainability, potential cropping system-based changes induced by introduction of biogas plants are probably much more relevant for the overall performance and sustainability of the cropping system than the direct effects triggered by application of digestates in comparison to the undigested feedstock...

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“…Monteiro (1997) showed that anaerobic digested sludge rheology can be described using the Herschel-Bulkley model, for which the rheological characteristics decreased with the degree of fermentation. More recently, Baudez et al (2011a) highlighted a more complex behaviour with shear banding at low shear rates and a viscosity plateau at very high shear rates. However, these studies did not focus on the temperature dependence of the rheology of digested sludge, which would fundamentally affect the flow properties and consequent operating conditions of the digester.…”

Section: Introductionmentioning

confidence: 99%

The impact of temperature on the rheological behaviour of anaerobic digested sludge

Baudez

Slatter

Eshtiaghi

2013

Chemical Engineering Journal

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The rheological properties of municipal anaerobic digested sludge rheology are temperature dependent. In this paper, we show that both solid and liquid characteristics decrease with temperature. We also show that the yield stress and the high shear (Bingham) viscosity are the two key parameters determining the rheological behaviour. By normalising the shear stress with the yield stress and the shear rate with the yield stress divided by the Bingham viscosity, a master curve was obtained, independent of both temperature and concentration. We also show that the rheological behaviour is irreversibly altered by the thermal history. Dissolution of some of the solids may cause a decrease of the yield stress and an increase of the Bingham viscosity. This result suggests that the usual laws used to describe the thermal evolution of the rheological behaviour of fluids are no longer valid with anaerobic digested sludge. Finally, the impact of temperature and thermal history have to be taken into account for the design of engineering hydrodynamic processes such as mixing and pumping.

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The rheological behaviour of anaerobic digested sludge

Cited by 132 publications

References 18 publications

Feasibility of OFMSW co-digestion with sewage sludge for increasing biogas production at wastewater treatment plants

Feasibility of OFMSW co-digestion with sewage sludge for increasing biogas production at wastewater treatment plants

Effects of anaerobic digestion on soil carbon and nitrogen turnover, N emissions, and soil biological activity. A review

The impact of temperature on the rheological behaviour of anaerobic digested sludge

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