Conference Papers | 2009 Conference Papers

ATAD PROCESS FOR THE TREATMENT OF BIOSOLIDS FOR BENEFICIAL RE-USE

Tim Giffin, Treatment Coordinator – Wastewater, CAMS

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ABSTRACT

The operating principles of the Autothermal Thermophilic Aerobic Digestion (ATAD) process and its field of application with respect to the beneficial reuse of biosolids are explained with particular reference to the plant in use at the Bendigo Water Reclamation Plant.

The ATAD process is widely used in the USA and Europe for the stabilisation of biosolids. It is a thermophilic process operating in a temperature range of 50-70°C without external heat input, this provides for pathogen inactivation and volatile solids reduction sufficient to meet EPA guidelines for beneficial reuse. Advantages of the process include rapid treatment, stable process with minimal supervision, ability to accommodate widely varying loads, and a small land foot print. Downsides to the process include high energy use, need for odour collection and treatment and a moderately difficult sludge to dewater.

The plant in use at the Bendigo WRP is supplied with thickened sludge from DAF’s, employs a range of different aeration and mixing techniques, supplements aeration with pure oxygen and finally produces a 20% solids product using centrifuges. The plant is capable of meeting Victorian EPA Treatment Grade 1 (T1) specifications.

KEYWORDS

Biosolids, ATAD, re-use, thermophilic, odour, sludge