scholarly journals Coupling hydrothermal carbonization with anaerobic digestion: an evaluation based on energy recovery and hydrochar utilization

2021 ◽  
Vol 8 (3) ◽  
pp. 1444-1453
Author(s):  
Mahmood Al Ramahi ◽  
Gábor Keszthelyi-Szabó ◽  
Sándor Beszédes
Keyword(s):  
Anaerobic Digestion ◽  
Energy Recovery ◽  
Oxygen Demand ◽  
Hydrothermal Carbonization ◽  
Steam Gasification ◽  
Post Treatment ◽  
Point Of View ◽  
Yield Potential ◽  
Treatment Technique ◽  
Dairy Sludge

This work evaluates the effect of hydrothermal carbonization (HTC) as a pretreatment and post-treatment technique to anaerobic digestion (AD) of dairy sludge. HTC's effect on AD was evaluated based on energy recovery, nutrient transformation, and hydrochar utilization. The first approach was executed by performing HTC under a range of temperatures before mesophilic AD. HTC optimal pretreatment temperature was 210 °C for 30 min residence time. HTC pretreatment significantly increased the methane yield potential by 192%, the chemical oxygen demand removal by 18%, and the sludge biodegradability during AD by 30%. On the other hand, the application of HTC after AD (post-treatment) increased the total energy production, i.e., in addition to methane, a hydrochar with a caloric value of 10.2 MJ/kg was also obtained. Moreover, HTC post-treatment improved the steam gasification performance of the AD digestate. From the fertilizer quality point of view, HTC implementation generally boosted the concentrations of macro, micro, and secondary nutrients, suggesting its suitability for use as a liquid fertilizer. Overall, the findings of the present study indicate that if bioenergy production were the main target, HTC post-treatment following AD would lead to the most promising outcomes.

scholarly journals Mathematical model for evaluation of cost-effectiveness of waste treatment technique with energy recovery

2016 ◽  
Vol 20 (suppl. 5) ◽  
pp. 1573-1584
Author(s):  
Biljana Milutinovic ◽  
Gordana Stefanovic ◽  
Ksenija Dencic-Mihajlov ◽  
Petar Djekic ◽  
Aleksandra Boricic
Keyword(s):  
Mathematical Model ◽  
Cost Effectiveness ◽  
Anaerobic Digestion ◽  
Energy Recovery ◽  
Waste Treatment ◽  
Cost Effective ◽  
Operating Costs ◽  
Treatment Technique ◽  
Treatment Facility ◽  
The City

A cost-effectiveness of a specific waste treatment technique is very important factor when making the decision to invest in a waste treatment facility. Waste treatment can bring economic benefit through the value of product: recycled materials, the compost, the generated electricity, or heat. However, the expected economic benefits depend on many factors: the investment costs and operating costs of the waste treatment facility, revenues, the market price of the product obtained by waste treatment etc. The investment and operating costs and the revenue also depend on the amount of treated waste. This paper presents a mathematical model for evaluation of cost-effectiveness in the waste treatment technique with energy recovery depending on the amount of waste, i. e. evaluation the minimum amount of waste to be treated for a cost-effective waste treatment technique with energy recovery. To develop the mathematical model, a socio-economic analysis was used. The model is applied to calculate the lower limit of cost-effectiveness in the waste treatment techniques with energy recovery: incineration and anaerobic digestion, in the city of Nis, Serbia, as a case study. The obtained results show that the amount of waste currently generated in the city of Nis is not sufficient for the cost-effective incineration treatment, but with the currently available amount of waste, anaerobic digestion is the waste treatment that can be operated without losses in the city of Nis.

Anaerobic digestion technologies for closing the domestic water, carbon and nutrient cycles

2000 ◽  
Vol 41 (3) ◽  
pp. 203-211 ◽  
Author(s):  
F. Hammes ◽  
Y. Kalogo ◽  
W. Verstraete
Keyword(s):  
Anaerobic Digestion ◽  
Solid Waste ◽  
Life Support ◽  
Oxygen Demand ◽  
Post Treatment ◽  
Microbial Pathogens ◽  
Domestic Water ◽  
Black Water ◽  
Semi Solid ◽  
Treatment Alternatives

Sustainable wastewater treatment requires that household wastewater is collected and treated separately from industrial wastewater and rainwater run-offs. This separate treatment is, however, still inadequate, as more than 70% of the nutrients and much of the chemical oxygen demand (COD) and potential pathogens of a domestic sewage system are confined to the few litres of black water (faeces, urine and toilet water). Whilst grey water can easily be filter treated and re-used for secondary household purposes, black water requires more intensive treatment due to its high COD and microbial (pathogens) content. Recently developed vacuum/dry toilets produce a nutrient rich semi-solid waste stream, which, with proper treatment, offers the possibility of nutrient, carbon, water and energy recovery. This study investigates the terrestrial applicability of Life Support System (LSS) concepts as a framework for future domestic waste management. The possibilities of treating black water together with other types of human-generated solid waste (biowastes/mixed wastes) in an anaerobic reactor system at thermophilic conditions, as well as some post treatment alternatives for product recovery and re-use, are considered. Energy can partially be recovered in the form of biogas produced during anaerobic digestion. The system is investigated in the form of theoretical mass balances, together with an assessment of the current feasibility of this technology and other post-treatment alternatives.

scholarly journals Studies on the Gasification Performance of Sludge Cake Pre-Treated by Hydrothermal Carbonization

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1442 ◽  
Author(s):  
Sang Yeop Lee ◽  
Se Won Park ◽  
Md Tanvir Alam ◽  
Yean Ouk Jeong ◽  
Yong-Chil Seo ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Moisture Content ◽  
Energy Recovery ◽  
Calorific Value ◽  
Hydrothermal Carbonization ◽  
Treatment Technique ◽  
Gasification Process ◽  
Cold Gas Efficiency ◽  
Sludge Cake ◽  
Gas Efficiency

Proper treatment and careful management of sewage sludge are essential because its disposal can lead to adverse environmental impacts such as public health hazards, as well as air, soil, and water pollution. Several efforts are being made currently not only to safely dispose of sewage sludge but also to utilize it as an energy source. Therefore, in this study, initiatives were taken to valorize sewage sludge cake by reducing the moisture content and increasing the calorific value by applying a hydrothermal treatment technique for efficient energy recovery. The sludge cake treated at 200 °C for 1 h was found to be the optimum condition for hydrothermal carbonization, as, in this condition, the caloric value of the treated sludge increased by 10% and the moisture content removed was 20 wt.%. To recover energy from the hydrothermally treated sludge, a gasification technology was applied at 900 °C. The results showed that the product gas from hydrothermally treated sludge cake had a higher lower heating value (0.98 MJ/Nm3) and higher cold gas efficiency (5.8%). Furthermore, compared with raw sludge cake, less tar was generated during the gasification of hydrothermally treated sludge cake. The removal efficiency was 28.2%. Overall results depict that hydrothermally treated sewage sludge cake could be a good source of energy recovery via the gasification process.

scholarly journals Microbial Electrochemical Oxidation of Anaerobic Digestion Effluent From Treating HTC Process Water

2021 ◽  
Vol 3 ◽  
Author(s):  
Shixiang Dai ◽  
Benjamin Korth ◽  
Carsten Vogt ◽  
Falk Harnisch
Keyword(s):  
Anaerobic Digestion ◽  
Oxygen Demand ◽  
Community Analysis ◽  
Hydrothermal Carbonization ◽  
Cod Removal ◽  
Microbial Community Analysis ◽  
Process Water ◽  
Material Synthesis ◽  
Current Production ◽  
High Chemical Oxygen Demand

Hydrothermal carbonization (HTC) is a promising technology for chemical and material synthesis. However, HTC produces not only valuable solid coal-materials but also yields process water (PW) with high chemical oxygen demand (COD) that requires extensive treatment. Anaerobic digestion (AD) has been used for initial treatment of HTC-PW, but the AD effluent is still high in COD and particles. Here, we show that microbial electrochemical technologies (MET) can be applied for COD removal from AD effluent of HTC-PW. Bioelectrochemical systems (BES) treating different shares of AD effluent from HTC-PW exhibited similar trends for current production. Thereby, maximum current densities of 0.24 mA cm−2 and COD removal of 65.4 ± 4.4% were reached (n = 3). Microbial community analysis showed that the genus Geobacter dominated anode biofilm and liquid phase of all reactors indicating its central role for COD oxidation and current generation.

Enhanced anaerobic digestion as a sanitation and energy recovery technology

2013 ◽  
Vol 3 (4) ◽  
pp. 572-581 ◽  
Author(s):  
T. Garoma ◽  
C. Williams
Keyword(s):  
Anaerobic Digestion ◽  
Energy Recovery ◽  
Waste Treatment ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Total Coliform ◽  
Operational Parameters ◽  
Nitrogen And Phosphorus ◽  
Treatment Technology ◽  
Volatile Solids

The potential for using an enhanced anaerobic digestion (AD) process as a sanitation and energy recovery technology for communities that lack access to basic sanitation was evaluated. For the enhanced AD system to generate a reliable supply of biogas, so that it can be adopted and self-sustained by the community, the use of algal biomass as a supplementary feedstock was evaluated. In addition, the effects of operational parameters on waste mineralization and biogas production were investigated. The results show that the system has the potential to be developed into an effective waste treatment technology, and it has produced high biogas yields and digested waste low in fecal bacteria and high in nutrients. Reductions of 42 to 51% in volatile solids and 29 to 45% in chemical oxygen demand were achieved at 35 °C. On average, total coliform and fecal coliform concentrations of 7.6 × 105 and 1.4 × 104 CFU per gram of total solids, respectively, were measured in the digested waste. The total nitrogen and phosphorus content of the residual was determined to be in the range of 9–17% as N and 3–7% as P (7–16% as P2O5). The biogas yields varied in the range of 0.47–0.57 mL per mg of volatile solids digested.

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