Recycling livestock manure provides energy and prevent pollution, yet actual transformation processes are limited in terms of performance and cost. Here we review inorganic additives used to improve anaerobic digestion. Additives include minerals such as zeolite and magnetite, metals such as bulk and nanoparticles, industrial wastes; and pH-regulating additives. We focus on microbial mechanisms in terms of microbial growth, enzymes, interspecies electron transfer and microbial community, instead of the often reported physico-chemical mechanisms. Porous additives such aszeolites are well suited to removing ammonium. Iron-based metal additives are highly influencing microbial mechanisms.
- Anaerobic digestion
- Livestock manure
- Iron-based metal additives
- Microbial community
- Interspecies electron transfer