A Review of Sludge-to-Energy Recovery Methods

Oladejo, Jumoke; Shi, Kaiqi; Luo, Xiang; Yang, Gang; Wu, Tao

doi:10.3390/en12010060

Cited by 209 publications

(183 citation statements)

References 150 publications

(242 reference statements)

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“…Typically, a MWWTP consumes a large amount of energy for aeration, pumping, and sludge management; however, a MWWTP can be a net energy producer by extracting energy from the wastewater and sludge [1]. Several sludge-to-energy technologies are available today such as combustion, pyrolysis, gasification, and anaerobic digestion (AD) [2]. Among these, AD is a proven technology to reduce the footprint of and produce bioenergy, in the form of methane (CH 4 )-rich biogas, from sewage sludge [3].…”

Section: Introductionmentioning

confidence: 99%

Performance and Microbial Community Dynamics in Anaerobic Digestion of Waste Activated Sludge: Impact of Immigration

et al. 2019

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Waste activated sludge (WAS) is a byproduct of municipal wastewater treatment. WAS contains a large proportion of inactive microbes, so when it is used as a substrate for anaerobic digestion (AD), their presence can interfere with monitoring of active microbial populations. To investigate how influent cells affect the active and inactive microbial communities during digestion of WAS, we operated model mesophilic bioreactors with conventional conditions. Under six different hydraulic retention times (HRTs;25,23,20,17,14, and 11.5 d), the chemical oxygen demand (COD) removal and CH 4 production of the AD were within a typical range for mesophilic sludge digesters. In the main bacteria were proteobacteria, bacteroidetes, and firmicutes in both the WAS and the bioreactors, while in main archaeal methanogen group was Methanosarcinales in the WAS and methanomicrobiales in the bioreactors. Of the 106 genera identified, the estimated net growth rates were negative in 72 and positive in 34. The genera with negative growth included many aerobic taxa. The genera with positive growth rates included methanogens and syntrophs. In some taxa, the net growth rate could be positive or negative, depending on HRT, so their abundance was also affected by HRT. This study gives insights into the microbial dynamics of a conventional sludge anaerobic digester by distinguishing potentially active (growing) and inactive (non-growing, dormant) microbes and by correlating population dynamics with process parameters.

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Section: Introductionmentioning

confidence: 99%

Performance and Microbial Community Dynamics in Anaerobic Digestion of Waste Activated Sludge: Impact of Immigration

et al. 2019

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“…Until very recently, the almost unique form of energy recovery from these facilities consisted of the anaerobic post-digestion of process residuals (waste activated sludge, WAS) by which chemical energy in the form of biogas (mostly methane) is obtained. This is still one of the main energy recovery options applied, generally sufficient to cover about half of total plants requirements, but with low (30% to 60%) conversion efficiency of the organically embedded chemical energy into a readily usable source [16]. However, implementation of new process technologies is nowadays making possible more efficient strategies of energy recovery from sewage [17].…”

Section: Introductionmentioning

confidence: 99%

Energy Issues in Sustainable Urban Wastewater Management: Use, Demand Reduction and Recovery in the Urban Water Cycle

2019

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Urban water systems and, in particular, wastewater treatment facilities are among the major energy consumers at municipal level worldwide. Estimates indicate that on average these facilities alone may require about 1% to 3% of the total electric energy output of a country, representing a significant fraction of municipal energy bills. Specific power consumption of state-of-the-art facilities should range between 20 and 45 kWh per population-equivalent served, per year, even though older plants may have even higher demands. This figure does not include wastewater conveyance (pumping) and residues post-processing. On the other hand, wastewater and its byproducts contain energy in different forms: chemical, thermal and potential. Until very recently, the only form of energy recovery from most facilities consisted of anaerobic post-digestion of process residuals (waste sludge), by which chemical energy methane is obtained as biogas, in amounts generally sufficient to cover about half of plant requirements. Implementation of new technologies may allow more efficient strategies of energy savings and recovery from sewage treatment. Besides wastewater valorization by exploitation of its chemical and thermal energy contents, closure of the wastewater cycle by recovery of the energy content of process residuals could allow significant additional energy recovery and increased greenhouse emissions abatement.

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“…In the context of effectively implementing circular economy objectives, particular importance should be attributed to sludge management, due to the possibility of recovering valuable raw materials from sewage sludge and the use of its energy potential [15]. The importance of energy recovery in contemporary waste management practices remains assured due to its impact on global waste minimization, resource optimization and alternative energy generation [16].…”

Section: Introductionmentioning

confidence: 99%

Towards Circular Economy: Evaluation of Sewage Sludge Biogas Solutions

et al. 2019

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Today it is obvious that the existing linear model of the economy does not correlate with the principles of sustainable development. The circular economy model can replace the current linear economy whilst addressing the issues of environmental deterioration, social equity and long-term economic growth. In the context of effectively implementing circular economy objectives, particular importance should be attributed to wastewater treatment sludge management, due to the possibility of recovering valuable raw materials and using its energy potential. Anaerobic digestion is one of the methods of recovering energy from sewage sludge. The main goal of this study is to make a preliminary evaluation of possible sewage sludge biogas and biomethane solutions using a computation model called MCBioCH4 and compare its results with laboratory tests of sewage sludge fermentation from the northern wastewater treatment plant (WWTP) of Ekaterinburg (Russian Federation). Laboratory experiments were conducted to determine the volume and qualitative composition of biogas produced throughout anaerobic fermentation of raw materials coming from the WWTP. The specific productivity of samples ranged between 308.46 Nm3/tvs and 583.08 Nm3/tvs depending if mesophilic or thermophilic conditions were analyzed, or if the experiment was conducted with or without sludge pre-treatment. Output values from the laboratory were used as input for MCBioCH4 to calculate the flow of biogas or biomethane produced. For the case study of Ekaterinburg two possible energy conversion options were selected: B-H (biogas combustion with cogeneration of electrical and thermal energy) and M-T (biomethane to be used in transports). The results of the energy module showed a net energy content of the biogas between 6575 MWh/year and 7200 MWh/year. Both options yielded a favorable greenhouse gas (GHG) balance, meaning that avoided emissions are higher than produced emissions. The results discussion also showed that, in this case, the B-H option is preferable to the M-T option. The implementation of the biogas/biomethane energy conversion system in Ekaterinburg WWTP necessitates further investigations to clarify the remaining technical and economic aspects

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A Review of Sludge-to-Energy Recovery Methods

Cited by 209 publications

References 150 publications

Performance and Microbial Community Dynamics in Anaerobic Digestion of Waste Activated Sludge: Impact of Immigration

Performance and Microbial Community Dynamics in Anaerobic Digestion of Waste Activated Sludge: Impact of Immigration

Energy Issues in Sustainable Urban Wastewater Management: Use, Demand Reduction and Recovery in the Urban Water Cycle

Towards Circular Economy: Evaluation of Sewage Sludge Biogas Solutions

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