What parameters must be controlled for optimal anaerobic digestion performance?

Anaerobic digestion optimization requires controlling multiple parameters: 1) Temperature - mesophilic (35-37C) or thermophilic (55-57C); higher temperatures increase reaction rates but require more energy and are less stable. 2) pH - optimal range 6.8-7.4; VFA accumulation causes acidification; alkalinity buffering (2000-4000 mg/L as CaCO3) maintains stability. 3) C:N ratio - optimal 20-30:1; too much nitrogen causes ammonia inhibition; too little limits microbial growth. 4) Organic loading rate (OLR) - kg VS/m3/day; higher loading increases productivity but risks overload; typical range 1-6 kg VS/m3/day. 5) Hydraulic retention time (HRT) - must exceed microbial doubling time; typically 15-30 days for mesophilic. 6) Mixing - ensures substrate-microbe contact and temperature uniformity without disrupting floc structure. 7) Toxics/inhibitors - heavy metals, sulfide, ammonia at high levels inhibit methanogens. Monitoring includes gas production, composition, VFA/alkalinity ratio, and effluent quality.