Characteristics of Biogas Production and Synergistic Effect of Primary Sludge and Food Waste Co-Digestion

• Published in: Bioenergy research Vol. 17; no. 1; pp. 646 - 659
• Main Authors: Rakić, Nikola, Šušteršič, Vanja, Gordić, Dušan, Jovičić, Nebojša, Bošković, Goran, Bogdanović, Ivan
• Format: Journal Article
• Language: English
• Published: New York Springer US 05-06-2023; Springer Nature B.V
• Subjects: Biodegradability; Biodegradable wastes; Biodegradation; Biogas; Biomedical and Life Sciences; Chemical oxygen demand; Digestion; Food; Food waste; Life Sciences; Mathematical models; Microorganisms; Plant Breeding/Biotechnology; Plant Ecology; Plant Genetics and Genomics; Plant Sciences; Primary sludge; Sewage sludge; Sludge; Sludge digestion; Substrates; Synergistic effect; Wastewater treatment; Wastewater treatment plants; Wood Science & Technology; Food waste; Primary sludge; Synergy; Chemical oxygen demand balance; Co-digestion
• ISSN: 1939-1234; 1939-1242; 1939-1242
• DOI: 10.1007/s12155-023-10620-8

  
Co-digestion implementation in wastewater treatment plants enhances biogas yield, so this research investigated the optimal ratio of biodegradable waste and sewage sludge. The increase in biogas production was investigated through batch tests using basic BMP equipment, while synergistic effects were evaluated by chemical oxygen demand (COD) balance. Analyses were performed in four volume basis ratios (3/1, 1/1, 1/3, 1/0) of primary sludge and food waste with added low food waste: 3.375%, 4.675%, and 5.35%, respectively. The best proportion was found to be 1/3 with the maximum biogas production (618.7 mL/g VS added) and the organic removal of 52.8% COD elimination. The highest enhancement rate was observed among co-digs 3/1 and 1/1 (105.72 mL/g VS). A positive correlation between biogas yield and COD removal is noticed while microbial flux required an optimal pH, value of 8 significantly decreased daily production rate. COD reductions further supported the synergistic impact; specifically, an additional 7.1%, 12.8%, and 17% of COD were converted into biogas during the co-digestions 1, 2, and 3, respectively. Three mathematical models were applied to estimate the kinetic parameters and check the accuracy of the experiment. The first-order model with a hydrolysis rate of 0.23–0.27 indicated rapidly biodegradable co-/substrates, modified Gompertz confirmed immediate commencement of co-digs through zero lag phase, while the Cone model had the best fit of over 99% for all trials. Finally, the study points out that the COD method based on linear dependence can be used for developing relatively accurate model for biogas potential estimation in anaerobic digestors.