A novel pretreatment biotechnology for increasing methane yield from lipid-rich wastewater based on combination of hydrolytic enzymes with Candida rugosa fungus

Abstract

Lipid-rich wastewater from the local dairy industry (cheese whey) in the Galilee, Israel was hydrolyzed by using two different sources of lipase as hydrolytic enzymes: fungal (Candida rogusa lipase-AY) and animal porcine pancreatic lipase(PPL). Pretreatment efficiency was verified by comparative biodegradability tests of raw and treated wastewater samples. Simultaneous hydrolysis and anaerobic digestion in the same reactors were also tested. Enzymatic pretreatment of these samples at a concentration of 0.05 w v⁻¹ showed organic matter removal of 90% and methane formation increases of 140% for the fungal source enzyme (i.e., AY), while for the animal source enzyme (i.e., PPL) was 86 and 130%, respectively. Enzymatic pretreatment led to significant methane formation which was obtained only for moderate substrate concentration (initial chemical oxygen demand of 15 gL⁻¹); While in high concentrated lipid-rich wastewater led to methane yield inhibition. The main finding was that the combination of AY enzyme with Candida rugosa fungus (i.e., enzyme mixture) led to a high efficiency in methane production (+152%) and organic materials removal (more than 90%). In summary, the use of fungal hydrolytic lipase mixed with Candida rugosa fungus is a promising method for enhancing methane production during the biodegradation of fat and grease-rich wastewaters.

Keywords:

• Anaerobic digestion
• Candida rugosa fungus
• enzymatic pretreatment
• fat oil and grease
• lipids-rich wastewater
• long-chain fatty acids

Acknowledgment

The Ministry of Environmental Protection, Israel [project agreement 142-4-1 and 192-3-1]. The authors gratefully acknowledge this financial support. Also they would like to thank the Ministry of Science and Technology (MOST), Israel, for their supporting SA., MH, and RE in his Post-doctorate fellowship [3-15422]. The author would like to thank, also, the European Union Peacebuilding Initiative (EUPI) under “Unity and Diversity in Nature and Society” project [project agreement ENI/2019/412-148].

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article [and/or] its supplementary materials.

Additional information

Funding

Israeli Ministry of Environmental Protection [project agreement 142-4-1 and 192-3-1]. European Union Peacebuilding Initiative (EUPI) under “Unity and Diversity in Nature and Society” [ENI/2019/412-148].