Giant salvinia is a nuisance aquatic plant that poses a threat to aquatic ecosystems and disruption to human activities due to its rapid growth and invasive nature. Thus, this research aimed to utilize giant salvinia as substrate for co-digestion with waste activated sludge to improve CH4 production. The effects of varying initial pH and biomass loading (C/N ratio) on CH4 production were investigated. The composition of the headspace gases and the formation of volatile fatty acids were monitored. DNA extraction and 16S rRNA analysis were done to verify the composition of the microbial consortium. Results showed that CH4 production is mainly affected by initial pH, biomass loading (C/N ratio), and their interaction. After 14 days of incubation, the highest CH4 produced was 43.91 mL/g VS at pH=7 and GS loading=50% (C/N ratio=13.46). Gompertz model was used for modeling the kinetics of CH4 production. Optimization via response surface methodology revealed that the highest CH4 production of 46.7 (mL/g VS) can be achieved at initial pH=6.75 and GS loading=33.23% (C/N=11.28). These findings highlight the potential of giant salvinia as substrate for anaerobic co-digestion with waste activated sludge in enhancing CH4 production that could address the environmental and social concerns associated with giant salvinia.
