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As the name suggests thermal sludge drying is a process where the dewatered sludge from a wastewater treatment plant is dried using external heat to produce a Class A sludge in accordance with USA EPA Rule 503. The dried product is a sterile granular biosolids with a greater than 90% solids content that has a potential for beneficial reuse as an organic fertilizer or soil conditioner.
The Flo-Dry Drier works by directly heating air in a combustion chamber and passing it though a rotation barrel. As the barrel rotates, the wet material is continually lifted and cascaded through the hot air stream as it makes it way towards the discharge. A feature of the Flo-Dry Drier is that a large proportion of the combustion air is recycled thus reducing the volume of exhaust gases.
Thermal drying of sludge has been used in Europe and the USA for some time and is gaining in popularity as one of the technologies available to overcome the increasing problems associated with sludge treatment, disposal and the question of beneficial re-use. The product is promoted and being sold as an organic fertilizer that potentially has a commercial commodity value that is able to provide for operational cost recovery or for full commercialisation.
The advantage of thermal drying is that it very easily satisfies the criteria required for sludge treatment and beneficial reuse as the disposal option. The high drying temperatures sterilize, deodorize and change the nature of the sludge making it acceptable to a wider range of end users and cultural groups. Other benefits include the reduced volume of material to be handled and being able to use existing agricultural equipment such as spreaders or loaders for land disposal options.
In summary this plant will:
Produce a sterile and pathogen free product that will comply with a Class A Biosolids.
Produce no offensive odour
Dry dewatered sludge to 90-95% solids content
Produce a biosolids that is granular in nature and has been subjected to temperatures of 500-600ēC
Provide options for a variety of beneficial disposal options such as fertiliser. |
