Anaerobic processes have been used in wastewater treatment systems for more than a century. Initially they were used to stabilise the solids produced, and generally consisted of simple concrete tanks in which the solids were placed as thin slurry and allowed to decompose anaerobically. However, using advanced pre-treatment processes in conjunction with traditional anaerobic digesters has not only enabled the HRTs to be reduced to about 15 days, the digesters can be operated with a solids loading as high as 4-6 kg VS/m3/d, biogas yields have increased, and reliable pathogen inactivation can now be achieved.
This paper discusses the operation of three variants of advanced anaerobic digestion using biological hydrolysis, and reinforces the sustainability benefits of biological hydrolysis when compared with more energy intensive thermal hydrolysis processes.
Operational Experience of Advanced Anaerobic Digestion