scholarly journals Comparative Life Cycle Assessment of HTC Concepts Valorizing Sewage Sludge for Energetic and Agricultural Use

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 786 ◽  
Author(s):  
Kathleen Meisel ◽  
Andreas Clemens ◽  
Christoph Fühner ◽  
Marc Breulmann ◽  
Stefan Majer ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Ghg Emissions ◽  
Hydrothermal Carbonization ◽  
Additional Energy ◽  
Sludge Digestion ◽  
Water Recirculation ◽  
Agricultural Use ◽  
Agricultural Yields ◽  
Direct Use ◽  
Positive Effect

In many countries, sewage sludge is directly used for energy and agricultural purposes after dewatering or digestion and dewatering. In recent years, there has been a growing interest in additional upstream hydrothermal carbonization (HTC), which could lead to higher yields in the energetic and agricultural use. Twelve energetic and agricultural valorization concepts of sewage sludge are defined and assessed for Germany to investigate whether the integration of HTC will have a positive effect on the greenhouse gas (GHG) emissions. The study shows that the higher expenses within the HTC process cannot be compensated by additional energy production and agricultural yields. However, the optimization of the HTC process chain through integrated sewage sludge digestion and process water recirculation leads to significant reductions in GHG emissions of the HTC concepts. Subsequently, nearly the same results can be achieved when compared to the direct energetic use of sewage sludge; in the agricultural valorization, the optimized HTC concept would be even the best concept if the direct use of sewage sludge will no longer be permitted in Germany from 2029/2032. Nevertheless, the agricultural valorization concepts are not generally advantageous when compared to the energetic valorization concepts, as it is shown for two concepts.

scholarly journals Model-Based Evaluation of Hydrothermal Treatment for the Energy Efficient Dewatering and Drying of Sewage Sludge

Processes ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 1346
Author(s):  
Philipp Knötig ◽  
Hendrik Etzold ◽  
Benjamin Wirth
Keyword(s):  
Sewage Sludge ◽  
Energy Efficient ◽  
Energy Savings ◽  
Wastewater Treatment Plants ◽  
Positive Impact ◽  
Experimental Studies ◽  
Hydrothermal Carbonization ◽  
Phosphorus Recycling ◽  
Phosphorus Reduction ◽  
Positive Effect

This research paper evaluates hydrothermal carbonization (HTC) as a possible treatment for sewage sludge, including phosphorus recycling. German governmental requirements force a high number of wastewater treatment plants (WWTP) to recover phosphorus from sewage sludge above limits of 20 g kgTS−1 before further disposal (e.g., co-incineration). The results show that pH reduction has a positive effect on shifting phosphorus to the liquid phase during HTC. Although the experimental results of this research do not yet achieve the necessary phosphorus reduction, various calculations are made to achieve this goal in future experimental studies. In order to be able to assess the energy benefits of HTC, Aspen Plus modeling was used to show the positive impact of implementing this technology in a WWTP. It is shown that the mechanical dewaterability of sewage sludge (SS) increases after HTC enabling energy savings by means of subsequent thermal drying. A heat optimized HTC is able to cut energy expenses by half, further providing a phosphorus-depleted hydrochar for extensive energetic use.

scholarly journals Sewage Sludge Treatment by Hydrothermal Carbonization: Feasibility Study for Sustainable Nutrient Recovery and Fuel Production

Energies ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2697
Author(s):  
Gabriel Gerner ◽  
Luca Meyer ◽  
Rahel Wanner ◽  
Thomas Keller ◽  
Rolf Krebs
Keyword(s):  
Liquid Phase ◽  
Sewage Sludge ◽  
Hydrothermal Carbonization ◽  
Economic Feasibility ◽  
Phosphorus Recovery ◽  
High Yield ◽  
Nutrient Recovery ◽  
Waste Biomass ◽  
Sludge Treatment ◽  
Sewage Sludge Treatment

Phosphorus recovery from waste biomass is becoming increasingly important, given that phosphorus is an exhaustible non-renewable resource. For the recovery of plant nutrients and production of climate-neutral fuel from wet waste streams, hydrothermal carbonization (HTC) has been suggested as a promising technology. In this study, digested sewage sludge (DSS) was used as waste material for phosphorus and nitrogen recovery. HTC was conducted at 200 °C for 4 h, followed by phosphorus stripping (PS) or leaching (PL) at room temperature. The results showed that for PS and PL around 84% and 71% of phosphorus, as well as 53% and 54% of nitrogen, respectively, could be recovered in the liquid phase (process water and/or extract). Heavy metals were mainly transferred to the hydrochar and only <1 ppm of Cd and 21–43 ppm of Zn were found to be in the liquid phase of the acid treatments. According to the economic feasibility calculation, the HTC-treatment per dry ton DSS with an industrial-scale plant would cost around 608 USD. Between 349–406 kg of sulfuric acid are required per dry ton DSS to achieve a high yield in phosphorus recovery, which causes additional costs of 96–118 USD. Compared to current sewage sludge treatment costs in Switzerland, which range between 669 USD and 1173 USD, HTC can be an economically feasible process for DSS treatment and nutrient recovery.

scholarly journals Does Revitalizing the Center of Mid-Sized French Cities Reduce GHG Emissions from Commuting?

2021 ◽  
Vol 13 (4) ◽  
pp. 1851
Author(s):  
Alexis Poulhès ◽  
Angèle Brachet
Keyword(s):  
Land Use Planning ◽  
Statistical Models ◽  
Total Population ◽  
Ghg Emissions ◽  
Low Carbon ◽  
Trip Distance ◽  
Working People ◽  
Shrinking City ◽  
The Relationship ◽  
Positive Effect

Mid-sized cities are usually considered in the literature to be shrinking cities. Some policies promote right-sizing and others promote revitalization. The relationship between land-use planning and mobility having been established, the present research issue is focused on whether a policy of revitalizing the centers of mid-sized cities is favorable to low-carbon mobility. Our study investigates commuting trips through two indicators: commuting trip distance and car modal share. The increase in total population, the increase in the number of jobs per resident, the decrease in the unemployment rate, the increase in the rate of executives, the increase in the rate of working people in the population and the decrease in the residential vacancy rate all come from the censuses of 2006 and 2016. Statistical models based on individuals in 113 mid-sized cities, in which sociodemographic variables are introduced, show that at the level of agglomerations, no indicator has a simultaneously positive effect in the center and in the urban periphery. No indicator is entirely positive or negative on GHG emissions from commuting trips. While the increase in GHG emissions from commuting trips between 2006 and 2016 is significant in mid-sized cities (18%), a shift toward shrinking city centers is insufficient to change this trajectory.

scholarly journals Sewage Sludge as a Tool in Limiting the Content of Trace Elements in Avena sativa L. on the Soil Polluted with Diesel Oil

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4003
Author(s):  
Mirosław Wyszkowski ◽  
Jadwiga Wyszkowska ◽  
Agata Borowik ◽  
Natalia Kordala
Keyword(s):  
Trace Elements ◽  
Sewage Sludge ◽  
Soil Contamination ◽  
Avena Sativa ◽  
Negative Impact ◽  
Diesel Oil ◽  
Average Content ◽  
Nickel Copper ◽  
Copper Manganese ◽  
Positive Effect

The aim of the research was to determine the effect of soil contamination with diesel oil (0; 5; 10 and 15 cm3 kg−1 of soil) on the content of trace elements in the aboveground parts of oat (Avena sativa L.). Stabilised sewage sludge was used to mitigate the likely negative impact of diesel oil on the plant. Growing soil contamination with diesel oil had a significant impact on the content of trace elements in the aboveground biomass of oat. In the series without sewage sludge, the contents of the analysed elements, except for chromium, zinc, copper and cobalt, were positively correlated with the increasing doses of diesel oil. The largest increase in the content was recorded in the case of manganese. The sewage sludge used to reduce the influence of diesel oil on the chemical composition of oat had a positive effect on the content of the analysed trace elements. Compared to the series without the addition of a stabilised sewage sludge, it contributed to a reduction in the average content of chromium, nickel, copper, manganese and cobalt in the aboveground parts of oat plants. No significant effect of the applied remediation treatment was noted for cadmium, and the results were equivocal for iron.

scholarly journals Application of Hydrochar, Digestate, and Synthetic Fertilizer to a Miscanthus x giganteus Crop: Implications for Biomass and Greenhouse Gas Emissions

2020 ◽  
Vol 10 (24) ◽  
pp. 8953
Author(s):  
Toby Adjuik ◽  
Abbey M. Rodjom ◽  
Kimberley E. Miller ◽  
M. Toufiq M. Reza ◽  
Sarah C. Davis
Keyword(s):  
Greenhouse Gas ◽  
Nutrient Management ◽  
Agricultural Land ◽  
Biomass Yield ◽  
Ghg Emissions ◽  
Hydrothermal Carbonization ◽  
Control Treatment ◽  
Miscanthus X Giganteus ◽  
Synthetic Fertilizer ◽  
Ghg Fluxes

Miscanthus x giganteus (miscanthus), a perennial biomass crop, allocates more carbon belowground and typically has lower soil greenhouse gas (GHG) emissions than conventional feedstock crops, but best practices for nutrient management that maximize yield while minimizing soil GHG emissions are still debated. This study evaluated the effects of four different fertilization treatments (digestate from a biodigester, synthetic fertilizer (urea), hydrochar from the hydrothermal carbonization of digestate, and a control) on soil GHG emissions and biomass yield of an established miscanthus stand grown on abandoned agricultural land. Soil GHG fluxes (including CH4, CO2, and N2O) were sampled in all treatments using the static chamber methodology. Average biomass yield varied from 20.2 Mg ha−1 to 23.5 Mg ha−1, but there were no significant differences among the four treatments (p > 0.05). The hydrochar treatment reduced mean CO2 emissions by 34% compared to the control treatment, but this difference was only statistically significant in one of the two sites tested. Applying digestate to miscanthus resulted in a CH4 efflux from the soil in one of two sites, while soils treated with urea and hydrochar acted as CH4 sinks in both sites. Overall, fertilization did not significantly improve biomass yield, but hydrochar as a soil amendment has potential for reducing soil GHG fluxes.

Biolixiviation des métaux lourds et stabilisation des boues d'épuration : essai en bioréacteur opéré en mode cuvée

1993 ◽  
Vol 20 (1) ◽  
pp. 57-64 ◽  
Author(s):  
R. D. Tyagi ◽  
J. F. Blais ◽  
N. Meunier ◽  
D. Kluepfel
Keyword(s):  
Heavy Metals ◽  
Sewage Sludge ◽  
Suspended Solids ◽  
Elemental Sulfur ◽  
Batch Reactor ◽  
Fecal Coliforms ◽  
Sludge Stabilization ◽  
Sludge Digestion ◽  
Batch Time ◽  
Phosphorus And Potassium

A biological process of heavy metals solubilization and sewage sludge stabilization was studied in a batch reactor of 30-L capacity. The acclimatized leaching microflora was composed of two major groups of thiobacilli: less acidophilic and acidophilic. A batch time of 10 days allows a substantial metal solubilization: cadmium (100%), copper (80%), manganese (80%), nickel (46%), and zinc (100%). The bioleaching process also causes a significative decrease in sludge total suspended solids (25%) and volatile suspended solids (32%), and a considerable reduction (under the detection limit of 10 cfu∙mL−1) of indicator bacteria (total coliforms, fecal coliforms, fecal streptococci). After filtration or centrifugation of the leached sludge, the solubilized metals were precipitated by lime neutralization. The phosphorus and potassium sludge contents were not affected by bioleaching process. These results indicate that the process of sludge digestion and metal leaching can be conducted in parallel in the same reactor. Key words: sewage sludge, heavy metals, bioleaching, stabilization, thiobacilli, elemental sulfur.

Potential of activated sludge disintegration

2006 ◽  
Vol 53 (12) ◽  
pp. 207-216 ◽  
Author(s):  
M. Boehler ◽  
H. Siegrist
Keyword(s):  
Sewage Sludge ◽  
Cost Evaluation ◽  
Anoxic Zone ◽  
Excess Sludge ◽  
Solid Retention Time ◽  
Biological Sludge ◽  
Operating Stability ◽  
Agricultural Use ◽  
Sludge Ash ◽  
Sludge Production

The disposal of sewage sludge and the agricultural use of stabilised sludge are decreasing due to more stringent regulations in Europe. An increasing fraction of sewage sludge must therefore be dewatered, dried, incinerated and the ashes disposed of in landfills. These processes are cost-intensive and also lead to the loss of valuable phosphate resources incorporated in the sludge ash. The implementation of processes that could reduce excess sludge production and recycle phosphate is therefore recommended. Disintegration of biological sludge by mechanical, thermal and physical methods could significantly reduce excess sludge production, improve the settling properties of the sludge and reduce bulking and scumming. The solubilised COD could also improve denitrification if the treated sludge is recycled to the anoxic zone. However, disintegration partly inhibits and kills nitrifiers and could therefore shorten their effective solid retention time, thus reducing the safety of the nitrification. This paper discusses the potential of disintegration on sludge reduction, the operating stability of nitrification, the improvement of denitrification and also presents an energy and cost evaluation.

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