Energy recovery from thermal treatment of dewatered sludge in wastewater treatment plants

2016 ◽  
Vol 74 (3) ◽  
pp. 672-680 ◽  
Author(s):  
Qingfeng Yang ◽  
Karla Dussan ◽  
Rory F. D. Monaghan ◽  
Xinmin Zhan
Keyword(s):  
Wastewater Treatment ◽  
Thermal Treatment ◽  
Moisture Content ◽  
Energy Recovery ◽  
Municipal Wastewater ◽  
Municipal Wastewater Treatment ◽  
Gas Temperature ◽  
Total Energy Consumption ◽  
Syngas Combustion ◽  
Dewatered Sludge

Sewage sludge is a by-product generated from municipal wastewater treatment (WWT) processes. This study examines the conversion of sludge via energy recovery from gasification/combustion for thermal treatment of dewatered sludge. The present analysis is based on a chemical equilibrium model of thermal conversion of previously dewatered sludge with moisture content of 60–80%. Prior to combustion/gasification, sludge is dried to a moisture content of 25–55% by two processes: (1) heat recovered from syngas/flue gas cooling and (2) heat recovered from syngas combustion. The electricity recovered from the combined heat and power process can be reused in syngas cleaning and in the WWT plant. Gas temperature, total heat and electricity recoverable are evaluated using the model. Results show that generation of electricity from dewatered sludge with low moisture content (≤ 70%) is feasible within a self-sufficient sludge treatment process. Optimal conditions for gasification correspond to an equivalence ratio of 2.3 and dried sludge moisture content of 25%. Net electricity generated from syngas combustion can account for 0.071 kWh/m3 of wastewater treated, which is up to 25.4–28.4% of the WWT plant's total energy consumption.

scholarly journals Modelling the bioenergy potential of municipal wastewater treatment plants

2018 ◽  
Vol 77 (11) ◽  
pp. 2613-2623 ◽  
Author(s):  
Kerstin Schopf ◽  
Johannes Judex ◽  
Bernhard Schmid ◽  
Thomas Kienberger
Keyword(s):  
Wastewater Treatment ◽  
Sewage Sludge ◽  
Energy Recovery ◽  
Municipal Wastewater ◽  
Energy Content ◽  
Treatment Plant ◽  
High Energy ◽  
Recovery Efficiency ◽  
Municipal Wastewater Treatment ◽  
Self Sufficiency

Abstract A municipal wastewater treatment plant accounts for a large portion of the total energy consumption of a municipality. Besides their high energy demand, the plants also display a significant bioenergy potential. This is due to the utilisation of the energy content of digester gas and sewage sludge if there exist suitable units. To maximise the energy recovery efficiency of wastewater treatment systems (WWTS), it is important to analyse the amount of digester gas and sludge produced in different types of plants. Therefore, the present paper deals with designing a tool to answer the following research questions: Which bioenergy potentials occur in different plant types? Which mass and energy flows are related to the specific potentials? Which utilisation processes for the potentials can lead to a high energy recovery efficiency of WWTS? Preliminary analyses with the designed tool were focused on estimating the level of electric and thermal energy self-sufficiency of different plant configuration scenarios including or excluding digester gas and/or sludge utilisation units. First results based on the level of self-sufficiency and associated energy and disposal costs show that a digester gas and sewage sludge utilisation should be considered when designing future WWTS.

Benchmarking energy consumption in municipal wastewater treatment plants in Japan

2010 ◽  
Vol 62 (10) ◽  
pp. 2256-2262 ◽  
Author(s):  
Kentaro Mizuta ◽  
Masao Shimada
Keyword(s):  
Wastewater Treatment ◽  
Energy Consumption ◽  
Power Consumption ◽  
Electric Power ◽  
Municipal Wastewater ◽  
Ghg Emissions ◽  
Electric Power Consumption ◽  
Specific Power ◽  
Municipal Wastewater Treatment ◽  
Total Energy Consumption

Reduction of greenhouse gas (GHG) emissions is one of the most important tasks facing municipal WWTPs. Electric power consumption typically accounts for about 90% of the total energy consumption. This study presents a benchmarking analysis of electric power consumption. The specific power consumption (SPC) ranged from 0.44 to 2.07 kWh/m3 for oxidation ditch plants and from 0.30 to 1.89 kWh/m3 for conventional activated sludge plants without sludge incineration. Observed differences of the SPC can be attributed to the difference in the scale of plants rather than to different kinds of wastewater treatment processes. It was concluded that economical benefits by centralizing treatment had contributed significantly to the reduction of energy consumption. Further analysis was carried out on the plant that had shown an extremely small SPC value of 0.32 kWh/m3. In this WWTP, a large amount of digestion gas was generated by anaerobic digestion. In particular, it was used to generate power using phosphoric acid fuel cells to generate approximately 50% of the energy consumed in the plant. It was calculated that this plant had reduced the overall SPC by 0.17 kWh/m3. The effect of power generation using digestion gas demonstrated clearly the advantage of implementing energy recovery schemes.

STUDIES REGARDING THE PERFORMANCES OF MUNICIPAL WASTEWATER TREATMENT PROCESSES

2006 ◽  
Vol 5 (4) ◽  
pp. 685-692
Author(s):  
Elisabeta Chirila ◽  
Ionela Carazeanu Popovici ◽  
Techin Ibadula ◽  
Alice Iordache
Keyword(s):  
Wastewater Treatment ◽  
Municipal Wastewater ◽  
Municipal Wastewater Treatment ◽  
Treatment Processes
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