Energy Utilization Assessment of Municipal Sewage Sludge Based on SWOT-FAHP Analysis
2. Materials and Methods
2.1. Treatment and Disposal of MSS in Jiangsu, China
2.2. Composition and Characteristics of MSS
2.3. Treatment and Disposal of MSS
2.3.1. Anaerobic Digestion
3. Legislation of MSS Management in China and Jiangsu, China
4. The Energy Recovery Potential Assessment
4.1. Energy Recovery Potential Assessment of Anaerobic Digestion
4.2. Energy Recovery Potential Assessment of Incineration
4.3. Energy Recovery Potential Assessment of Pyrolysis
4.4. Energy Recovery Potential Assessment of Gasification
5. Comparative Evaluation by SWOT-FAHP Analysis
5.1. SWOT Analysis
- Problem solving: Was the relevant energy utilization method sufficient to treat sewage sludge or is additional treatment required?
- Ecological environment: Were greenhouse gas emissions produced under the background of carbon neutrality, and could a reduction in greenhouse gas emissions be achieved?
- Technological development: Has the method been applied in Jiangsu Province, and at what stage is it currently in (site scale, pilot scale or laboratory scale)?
- Laws and regulations: Were there any corresponding laws and regulations related to this method? Was it a national standard or an industry standard?
5.2. Fuzzy Hierarchy Model and the Introduction of the Trapezoidal Fuzzy Function Method
5.3. Results of SWOT-FAHP Analysis
6. Potential Deployment Barriers to Sludge Pyrolysis
- Sales of pyrolysis products: The market for pyrolysis products needs to be further expanded to effectively utilize pyrolysis products.
- Technical risk issues: If the technology is not applied on a large scale before implementation, the relevant parties would be generally unwilling to bear any unknown risks.
- Financial support issues: It was difficult to obtain project funding due to the lack of operational experience.
- Countermeasures to manage the market problems of pyrolysis products: pygas and bio-oil could be applied for boiler power generation, fuel production, chemical raw materials, etc. Biochar could be employed to produce activated carbon, for soil remediation, in situ adsorption of pollutants in sewage plants, etc.
- Countermeasures to manage large-scale application problems: the government could be the initiator and invest a certain amount of research funds and establish sludge pyrolysis pilots.
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
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|Scheme||Issue||Internal Advantages (S)||Internal Disadvantages (W)||External Opportunities (O)||External Threats (T)|
|Anaerobic digestion||Problem solving||(1) No need to dry or dewater.|
(2) Produces biogas with high energy potential (natural gas, fuel and fertilizer production) .
(3) Low external input energy requirements.
(4) Sludge stabilization and reduction.
|(1) Long reaction time: >14 days .|
(2) Toxicity of exogenous pollutants at high levels .
(3) Biogas requires subsequent treatment before it can be utilized .
(4) High system operation requirements.
|(1) The biogas produced could replace fossil fuels.|
(2) The organic fertilizers could replace nitrogen and phosphate fertilizers.
|(1) Needs large amount of land.|
(2) Competition with other methods.
(3) Affected by the seasons.
|Ecological environment||(1) Emission control system available.||(1) CO2 emissions.||-||-|
|Technological development||(1) Mature technology.|
(2) Could be coordinated with biomass anaerobic digestion.
|(1) High investment costs.|
(2) Low energy conversion efficiency.
(3) Heavy metals, persistent organic pollutants, etc., could not be eliminated and require subsequent treatment.
|(1) Wider applicability than other energy utilization technologies.||(1) The economic environment is unstable.|
|Laws and regulations||-||(1) There are no complete laws or regulation framework.||(1) Environmental awareness is gradually increasing.|
(2) The support of policy.
|Incineration||Problem solving||(1) Sludge is completely reduced and harmless.|
(2) Heat could be recycled for power generation and heating .
(3) Minimizes odor generation.
(4) Ash residue could be used for building materials and the production of phosphoric acid .
|(1) The sludge needs to be dewatered/dried .|
(2) Energy efficiency is low, and mono-incineration had corresponding requirements for the heating value of sludge .
|(1) Government subsidies are available.||(1) Competition with other thermal technologies.|
(2) Higher investment.
|Ecological environment||(1) Emission control system is available.||(1) Production of chloro-compounds.|
(2) Air pollution problems (NOX, N2O, SOX, dioxin and furan emissions) .
(3) Increased demand for gas treatment and strict environmental emission control.
|(1) Environmental problems due to high-risk emissions.|
|Technological development||(1) Mature technology.|
(2) Coordinated incineration could utilize a variety of solid wastes.
|(1) Pretreatment of the sludge required.|
(2) Generally suitable for large sewage plants to ensure economic viability.
(3) Low energy conversion efficiency.
(4) The problem of heavy metal content in ash treatment .
|(1) Technological progress and safety factor improved.||(1) The economic environment was unstable.|
(2) High cost of blended fuels.
|Laws and regulations||(1) Laws and regulations exist and have been adopted.||(1) Sludge incineration requires strict legal control.||(1) Environmental awareness is gradually increasing.||(1) Strengthen legal controls.|
|Gasification||Problem solving||(1) No additional energy required after stable operation.|
(2) Syngas could be used as a feedstock for the production of natural gas, hydrogen and chemical synthesis .
(3) Ash residue could be used for building materials.
|(1) The moisture content of the sludge should be less than 30%.|
(2) The composition and efficiency of the gasification products may vary depending on the operating parameters, and improper handling could produce a large number of by-products such as tar .
|(1) Increased research and investment.||(1) Financing difficulties.|
(2) Competition with other thermal processing processes.
|Ecological environment||(1) Avoids NOX, SOX, dioxin and furan emissions.||(1) Releases large amounts of organic pollutants.||-|
|Technological development||(1) High energy efficiency and carbon balance achieved.|
(2) Could be co-treated with biomass.
|(1) Heavy metal content in ash treatment .|
(2) At present, it has not been promoted and applied.
(3) High investment and operating costs.
(4) The synthesized gas contains tar, coke and hydrogen carbon that may contaminate the device.
|(1) Renewable technology research and development cooperation.||(1) The economic environment was unstable.|
(2) Commercial feasibility is unknown.
|Laws and regulations||-||(1) There are no perfect laws or regulations.||(1) Environmental awareness is gradually increasing.||(1) Lack of environmental standards.|
|Pyrolysis||Problem solving||(1) Bio-oil, pyrolysis gas and biochar have market potential.|
(2) Short processing cycle, large equipment processing capacity and small footprint.
(3) Sludge is completely reduced and harmless .
|(1) Need to be dewatered or dried.|
(2) The composition and efficiency of the pyrolysis product depends on the operating parameters and sludge characteristics .
|(1) Increased research and investment.||-|
|Ecological environment||(1) Reduced greenhouse gas emissions.|
(2) Avoids NOX, SOX, dioxin and furan emissions.
|(1) CO and CO2 emissions.|
|Technological development||(1) High energy efficiency and carbon balance achieved.||(1) It has not been promoted and applied.|
(2) Most of the technologies are proprietary abroad.
|(1) Renewable technology research and development cooperation.||(1) The economic environment is unstable.|
(2) Commercial feasibility needs to be further studied.
|Laws and regulations||(1) There are no perfect laws or regulations.||(1) Environmental awareness is gradually increasing.||(1) Lack of environmental standards.|
|0.5||Equally important||i was equally important to j|
|0.6||Moderately important||i was slightly more important than j|
|0.7||Obviously important||i was obviously more important than j|
|0.8||Strongly important||i was much more important than j|
|0.9||Extremely important||i was extremely important than j|
|0.1, 0.2, 0.3, 0.4||Compare instead||The two elements i and j are compared in reverse, rij = 1−rji|
|Standard||Weight Value||Energy Utilization Methods||Weight|
|Problem solving (a)||0.4945||AD (1)||0.3366|
|Ecological environment (b)||0.2336||Incineration (2)||0.1443|
|Technological developments (c)||0.1665||Gasification (3)||0.1756|
|Laws and regulations (d)||0.1054||Pyrolysis (4)||0.3435|
|Problem Solving (A)||Ecological Environment (B)||Technological Developments (C)||Laws and Regulations (D)||Weight Value|
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Xiang, L.; Li, H.; Wang, Y.; Qu, L.; Xiao, D. Energy Utilization Assessment of Municipal Sewage Sludge Based on SWOT-FAHP Analysis. Water 2023, 15, 260. https://doi.org/10.3390/w15020260
Xiang L, Li H, Wang Y, Qu L, Xiao D. Energy Utilization Assessment of Municipal Sewage Sludge Based on SWOT-FAHP Analysis. Water. 2023; 15(2):260. https://doi.org/10.3390/w15020260Chicago/Turabian Style
Xiang, Lu, He Li, Yizhuo Wang, Linyan Qu, and Dandan Xiao. 2023. "Energy Utilization Assessment of Municipal Sewage Sludge Based on SWOT-FAHP Analysis" Water 15, no. 2: 260. https://doi.org/10.3390/w15020260