The commonly used indicators are often too slow to reflect the operating status in time.Confronted with lacking reliable early-warning indices in the single-phase anaerobic digestion for kitchen waste which is easy to decay

lab-scale experiments of start-up and continuous operation process of anaerobic digestion for kitchen waste were carried out in the single-phase anaerobic reactor which is self-designed under mesophilic conditions.Those values which reflect the capacity of acidity-basicity resistance

including the ratio of bicarbonate alkalinity to total alkalinity (BA/TA)

absolute testing value of volatile fatty acid (VFA) and the ratio of total concentration for volatile fatty acid to bicarbonate alkalinity (VFA/BA)

are determinated to be the early-warning indices for acidification and imbalance of single-phase anaerobic digestion for kitchen waste.It is considered that

when VFA/BA＞0.8

BA/TA＜0.4 and VFA＞3000mg/L

buffering capacity of the system is very poor

and the system might be out of control.Therefore

an immediately steps must be taken.While

when BA/TA≥0.7~0.8 and VFA/BA＜0.4

the alkalinity of system is relatively better and the process can be operated with higher organic volumetric loading

which can raise the biogas-producing efficiency and get economic benefit.