navel orange residue, waste activated sludge, pre-treatment, co-digestion, volatile fatty acids
D-limonene, Waste activated sludge, Anaerobic fermentation, Volatile fatty acids
Partial nitrification, Low intensity ultrasound, Organic load rate, extracellular polymeric substances, Microbial community
Low-intensity ultrasound, Partial nitrification, Organic loading, Oxygen competition, Microbial community structure