LEARN OUR PROCESS: DRYERSDRYING
1) material handling process begins with dewatered sludge cake. Wet cake is withdrawn from a 2) tipping pit using 3) feeder screws and 4) weighed on a belt conveyor that discharges to a 5) recycle screw conveyor. The recycle screw feeds a 6) mixer with wet cake and with previously dried solids. The damp mix falls into the dryer throat (entrance). Inside the 7) dryer drum, the initial moisture is driven off through direct contact with hot air. The dried solids discharge upwards from the drum through a high velocity duct to a 8) cyclonic separator. These solids, which are now in the form of discrete granules, meet the Class A pathogen and vector attraction requirement. These granules are collected by the separator and discharged via an 9) airlock to a 10) screener, where they are screened into four fractions: trash, oversize, product, and fines. Trash, consisting of coarse plastics and other undesirable solids, is collected in a drum for disposal. Oversize granules drop into a 11) roll crusher and subsequently fall into the 12) recycle bin. Fines also fall into the recycle bin, which stores the dry material to be mixed with the wet biosolids as previously described. The remaining, properly sized granules – the finished product – are cooled and transported to storage.
The above is an example of a rotary drum drying process and is just one potential manufacturing option. There are several drying technology options.