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The high moisture content present in sewage sludge hinders the use of sewage sludge in incineration or energy application. This limitation of moisture present in sewage sludge can be obviated by using the hydrothermal carbonization (HTC) process. In sewage sludge management, the HTC process requires less energy compared to other conventional thermo–chemical management processes. The HTC process produces energy-rich hydrochar products and simultaneously enables phosphorus recovery. This study investigates the influence of organic acids, inorganic acid, and alkali as additives on phosphorus transformation, yield, proximate analysis and the heating value of subsequently produced hydrochar. The analysis includes various process temperatures (200 °C, 220 °C, and 240 °C) in the presence of deionized water, acids (0.1 M and 0.25 M; H2SO4, HCOOH, CH3COOH), and alkali (0.1 M and 0.25 M; NaOH) solutions as feed water. The results show that phosphorus leaching into the process-water, hydrochar yield, proximate analysis, and the heating value of produced hydrochar is pH- and temperature-dependent, and particularly significant in the presence of H2SO4. In contrast, utilization of H2SO4 and NaOH as an additive has a negative influence on the heating value of produced hydrochar.
Vicky Shettigondahalli Ekanthalu; Satyanarayana Narra; Jan Sprafke; Michael Nelles. Influence of Acids and Alkali as Additives on Hydrothermally Treating Sewage Sludge: Effect on Phosphorus Recovery, Yield, and Energy Value of Hydrochar. Processes 2021, 9, 618 .
AMA StyleVicky Shettigondahalli Ekanthalu, Satyanarayana Narra, Jan Sprafke, Michael Nelles. Influence of Acids and Alkali as Additives on Hydrothermally Treating Sewage Sludge: Effect on Phosphorus Recovery, Yield, and Energy Value of Hydrochar. Processes. 2021; 9 (4):618.
Chicago/Turabian StyleVicky Shettigondahalli Ekanthalu; Satyanarayana Narra; Jan Sprafke; Michael Nelles. 2021. "Influence of Acids and Alkali as Additives on Hydrothermally Treating Sewage Sludge: Effect on Phosphorus Recovery, Yield, and Energy Value of Hydrochar." Processes 9, no. 4: 618.
A persistent topic of the anaerobic digestion of biowaste is the efficient use of co-substrates. According to Renewable Energy Sources Act the co-substrate input is limited to 10 percent of the average daily substrate feed in Germany. In this concern, the primary focus of this paper is to understand the suitability of crude glycerol in anaerobic digestion of biowaste. Two identical lab-scale anaerobic digester units were added with crude glycerol, and each unit was equipped with four identical fermenters. Unit A was fed with an average organic loading rate of 4.5 kg VS m−3 d−1, and the average organic loading rate of unit B was set at 5.5 kg VS m−3 d−1. The share of crude glycerol in the total feed was 0.77 percent of the fresh matter. The abort criterion is a ratio of the volatile organic acids and buffer capacity (FOS/TAC) in the fermenter above 1.2. The abort criterion was reached after 16 days. In summary, the results lead us to the conclusion crude glycerol is not suitable as a co-substrate for anaerobic digestion for several reasons.
Jan Sprafke; Vicky Shettigondahalli Ekanthalu; Michael Nelles. Continuous Anaerobic Co-Digestion of Biowaste with Crude Glycerol under Mesophilic Conditions. Sustainability 2020, 12, 9512 .
AMA StyleJan Sprafke, Vicky Shettigondahalli Ekanthalu, Michael Nelles. Continuous Anaerobic Co-Digestion of Biowaste with Crude Glycerol under Mesophilic Conditions. Sustainability. 2020; 12 (22):9512.
Chicago/Turabian StyleJan Sprafke; Vicky Shettigondahalli Ekanthalu; Michael Nelles. 2020. "Continuous Anaerobic Co-Digestion of Biowaste with Crude Glycerol under Mesophilic Conditions." Sustainability 12, no. 22: 9512.
Renewable energies – especially wind and solar – have grown remarkably in recent years, but bioenergy is still the most important renewable resource worldwide and in Germany. In contrast to the situation in many other countries, bioenergy in Germany is often based on energy crops. As a result of changing political frameworks, the German bioenergy industry has to use alternative substrates as biogenic waste and residues and to implement more efficient utilization pathways. Biogenic waste and residues can cover in Germany 7 to 9% of the current total primary energy consumption. In the federal state of Mecklenburg-Western Pomerania, more electricity is produced than consumed. This means that the federal state exports electricity to other German regions or abroad, assuming grid bottlenecks do not prevent this. The share of fluctuating wind and solar power is still increasing. Without stabilization by coal power plants, the electrical network could be destabilized by those sources. The presented case study of Mecklenburg-Western Pomerania shows that there are opportunities to contribute to a stable network through the use of bioenergy. Besides the supply of electricity, thermal energy at different temperature levels, as well as fuels for transportation, are also provided by biomass. Around 22% of the annual energy consumption of the federal state could be covered by biogenic waste and residues (based on the technical fuel potential). The figure is currently 7.3%. This shows that there is room to extend bioenergy generation and the use of biogenic waste and residues in the bioeconomy without impacting food production.
Andrea Schüch; Jan Sprafke; Michael Nelles. Role of biogenic waste and residues as an important building block towards a successful energy transition and future bioeconomy – results of a site analysis. Detritus 2020, 109 -117.
AMA StyleAndrea Schüch, Jan Sprafke, Michael Nelles. Role of biogenic waste and residues as an important building block towards a successful energy transition and future bioeconomy – results of a site analysis. Detritus. 2020; (10):109-117.
Chicago/Turabian StyleAndrea Schüch; Jan Sprafke; Michael Nelles. 2020. "Role of biogenic waste and residues as an important building block towards a successful energy transition and future bioeconomy – results of a site analysis." Detritus , no. 10: 109-117.
This paper presents a survey to determine the influence of impurities and green waste on anaerobic biowaste treatment, comparing the current common biowaste management system with a proposed future system. The results imply that it is possible to increase the specific biogas yield and the baseload capacity by means of an adapted biowaste management system. To analyse a possible correlation between biogas yield and biowaste composition from urban or rural areas the quality and quantity of biowaste was evaluated in a long-term research programme. August was the month with the maximum percentage of 69% green waste in biowaste, compared to February with a minimum proportion of 14%. The specific biogas yield of biowaste is in the range of 91 to 160 m³/tOS. The evaluation showed that, as expected, seasonal fluctuations in weather affected the proportion of garden and park waste (green waste) as well as impurities. Moreover, the proportion of green waste and impurities affects the substrate quality and degradability of biowaste. The investigated biowaste fermentation plant is not able to generate sufficient baseload for the reasons described above. Other reasons for this limitation include maintenance work, plant operation in part-load range and plant capacity limitations concerning the CHP module, digester capacity and pipes for gas transportation. The best ratio between organic fraction and impurities is obtained from biowaste from rural areas, while gas yields from urban areas are more constant and less volatile. Based on these findings, the increasing of the baseload capacity of waste fermentation plants can be achieved by: Optimisation of process flows (substrate management, preparation, post-treatment); Use of co-substrates in compliance with legal requirements; Determination and consideration of key figures.
Jan Sprafke; Nils Engler; Qahtan Thabit; Michael Nelles; Andrea Schuech. INCREASING THE BASELOAD CAPACITY OF BIOWASTE FERMENTATION PLANTS THROUGH OPTIMISED SUBSTRATE MANAGEMENT. Detritus 2020, 68 -75.
AMA StyleJan Sprafke, Nils Engler, Qahtan Thabit, Michael Nelles, Andrea Schuech. INCREASING THE BASELOAD CAPACITY OF BIOWASTE FERMENTATION PLANTS THROUGH OPTIMISED SUBSTRATE MANAGEMENT. Detritus. 2020; (9):68-75.
Chicago/Turabian StyleJan Sprafke; Nils Engler; Qahtan Thabit; Michael Nelles; Andrea Schuech. 2020. "INCREASING THE BASELOAD CAPACITY OF BIOWASTE FERMENTATION PLANTS THROUGH OPTIMISED SUBSTRATE MANAGEMENT." Detritus , no. 9: 68-75.