Techno-economic Assessment of Thermal Co-pretreatment and Co-digestion of Food Wastes and Sewage Sludge for Heat, Power and Biochar Production

The paper deals with the performances of the mesophilic anaerobic digestion treatment of sewage sludge from a full scale BNR process without primary settling (nominally 300,000 PE). A relation between the activated sludge observed yields, Yobs, and the anaerobic digester performance was preliminarily found: for values of Yobs of 0.25 kgVSS/kgCOD the anaerobic digester specific gas production showed the best performances (0.22 m3/kgVSfed). This has to be confirmed with wider future studies. It was also shown the level of sludge pre-thickening to be reached for the self-sustaining warming of the digester also in wintertime. According to the energetic balance and to a comparison with an aerobic stabilisation process, it was pointed out as when a co-generation unit for heat and energy production was introduced about 3.4 kWh/PE y of energy were produced in the anaerobic digestion process. On the other hand, 4.3 kWh/PE y were spent if an aerobic stabilisation process was applied. The economic assessment, carried out on the basis of the energy balances, showed that the anaerobic digestion is always economically advantageous if compared to aerobic stabilisation processes, also for small WWTPs. According to the energetic evaluations an environmental balance was assessed, in terms of CO2 emissions. The difference between anaerobic and aerobic processes was about 5.3 kgCO2/PE y in favour of anaerobic processes application.

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Technical and Economic Assessment of Biogas and Liquid Energy Systems from Sewage Sludge and Industrial Waste

Renewable Energy Systems from Biomass ◽

10.1201/9781315153971-4 ◽

2018 ◽

pp. 57-73

Author(s):

Hossain M. Anawar ◽

Vladimir Strezov

Keyword(s):

Sewage Sludge ◽

Industrial Waste ◽

Energy Systems ◽

Economic Assessment

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Economic assessment of food waste co-digestion with sewage sludge in five Asian cities

Journal of Material Cycles and Waste Management ◽

10.1007/s10163-019-00844-2 ◽

2019 ◽

Vol 21 (4) ◽

pp. 872-884 ◽

Cited By ~ 1

Author(s):

Yi-Shin Wang ◽

Nae-Wen Kuo

Keyword(s):

Sewage Sludge ◽

Food Waste ◽

Economic Assessment ◽

Asian Cities

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Biotechnology of intensive aerobic conversion of sewage sludge and food waste into fertilizer

Water Science & Technology ◽

10.2166/wst.2004.0631 ◽

2004 ◽

Vol 49 (10) ◽

pp. 147-154 ◽

Cited By ~ 8

Author(s):

J.-Y. Wang ◽

O. Stabnikova ◽

S.T.-L. Tay ◽

V. Ivanov ◽

J.-H. Tay

Keyword(s):

Sewage Sludge ◽

Organic Carbon ◽

Food Waste ◽

Bacterial Culture ◽

Food Wastes ◽

Coenzyme F420 ◽

Plant Seeds ◽

Volatile Solids ◽

Anaerobic Biomass ◽

Closed Reactor

Biotechnology for intensive aerobic bioconversion of sewage sludge and food waste into fertilizer was developed. The wastes were treated in a closed reactor under controlled aeration, stirring, pH, and temperature at 60¡C, after addition of starter bacterial culture Bacillus thermoamylovorans. The biodegradation of sewage sludge was studied by decrease of volatile solids (VS), content of organic carbon and autofluorescence of coenzyme F420. The degradation of anaerobic biomass was faster than biodegradation of total organic matter. The best fertilizer was obtained when sewage sludge was thermally pre-treated, mixed with food waste, chalk, and artificial bulking agent. The content of volatile solid and the content of organic carbon decreased at 24.8% and 13.5% of total solids, respectively, during ten days of bioconversion. The fertilizer was a powder with moisture content of 5%. It was stable, and not toxic for the germination of plant seeds. Addition of 1.0 to 1.5% of this fertilizer to the subsoil increased the growth of different plants tested by 113 to 164%. The biotechnology can be applied in larger scale for the recycling of sewage sludge and food wastes in Singapore.

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MBR-Assisted VFAs Production from Excess Sewage Sludge and Food Waste Slurry for Sustainable Wastewater Treatment

Applied Sciences ◽

10.3390/app10082921 ◽

2020 ◽

Vol 10 (8) ◽

pp. 2921 ◽

Cited By ~ 3

Author(s):

Mohsen Parchami ◽

Steven Wainaina ◽

Amir Mahboubi ◽

David I’Ons ◽

Mohammad J. Taherzadeh

Keyword(s):

Wastewater Treatment ◽

Sewage Sludge ◽

Food Waste ◽

Volatile Fatty Acids ◽

Wastewater Treatment Plants ◽

Biogas Production ◽

Economic Assessment ◽

Ph Control ◽

Daily Basis ◽

Solids Concentration

The significant amount of excess sewage sludge (ESS) generated on a daily basis by wastewater treatment plants (WWTPs) is mainly subjected to biogas production, as for other organic waste streams such as food waste slurry (FWS). However, these organic wastes can be further valorized by production of volatile fatty acids (VFAs) that have various applications such as the application as an external carbon source for the denitrification stage at a WWTP. In this study, an immersed membrane bioreactor set-up was proposed for the stable production and in situ recovery of clarified VFAs from ESS and FWS. The VFAs yields from ESS and FWS reached 0.38 and 0.34 gVFA/gVSadded, respectively, during a three-month operation period without pH control. The average flux during the stable VFAs production phase with the ESS was 5.53 L/m2/h while 16.18 L/m2/h was attained with FWS. Moreover, minimal flux deterioration was observed even during operation at maximum suspended solids concentration of 32 g/L, implying that the membrane bioreactors could potentially guarantee the required volumetric productivities. In addition, the techno-economic assessment of retrofitting the membrane-assisted VFAs production process in an actual WWTP estimated savings of up to 140 €/h for replacing 300 kg/h of methanol with VFAs.

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