Dark fermentation of cheese whey - supplement materials control the conversion pathways.

Area of Science:

• Biotechnology
• Environmental Science
• Chemical Engineering

Background:

• Cheese whey is a dairy industry byproduct with potential for bioenergy production.
• Dark fermentation (DF) is a biological process for converting organic matter into biohydrogen (bioH₂).
• Additives can influence DF efficiency and bioH₂ yield.

Purpose of the Study:

• To investigate the impact of various additives (fly ash, biochar, geopolymer) on cheese whey conversion pathways.
• To optimize biohydrogen production using dark fermentation with selected additives.
• To understand the mechanisms behind additive-mediated changes in biohydrogen yield and conversion pathways.

Main Methods:

• Cheese whey was used as a substrate for dark fermentation.
• Additives including fly ash (FA), biochar (BC), and geopolymer (GP) were supplemented at specific concentrations.
• Biohydrogen production was measured, and physicochemical parameters (pH, EC, VFAs, VS) were analyzed.
• Additive characterization was performed using XRD, SEM, XRF, and BET analysis.

Main Results:

• Fly ash (10 g/L) supplementation resulted in the highest biohydrogen yield (316.68 ml/g), an 86% increase compared to the control.
• FA's buffering capacity maintained pH, preventing significant drops observed in the control.
• Geopolymer supplementation led to low biohydrogen production due to high electrical conductivity, shifting pathways from butyric to acetate production.

Conclusions:

• Fly ash is an effective additive for enhancing biohydrogen production from cheese whey via dark fermentation.
• The release of metallic elements and buffering capacity of FA contribute to improved microbial activity and pH regulation.
• Understanding the influence of additive properties like electrical conductivity is crucial for optimizing biohydrogen production pathways.