Sewage dewatering

Washing and dewatering by air displacement of cakes are possible. AppHcations are in the treatment of minerals, in the sugar industry, and in the treatment of municipal sewage sludge and fillers like talc, clay, whiting, etc. 

The vertical recessed plate automatic press, shown schematically in Figure 15 and described previously, is another example of a horizontal belt pressure filter. Cycle times ate short, typically between 10 and 30 minutes, and the operation is fully automated. The maximum cake thickness is about 35 mm washing and dewatering (by air displacement) of cakes is possible. Apphcations include treatment of mineral slurries, sugar, sewage sludge, and fillers like talc, clay, and whiting. 

Screw presses (Fig. 2) do not produce a clear liquid product. Frequendy, the product is further filtered in a filter press to give a clear Hquid product. Press aids are added to feed materials containing fine particles or particles that can deform and plug the slots in the edge of a screw press. Typical press aids include sawdust, rice hulls, perlite, and diatomaceous earth (see Diatomite). A vertical screw press is a continuous press that has been used for dewatering sewage sludge (2). 

Rhenipal A sewage sludge treatment process. One of three proprietary additives is used be-fore dewatering. The resulting filter cake is smaller in volume, has less odor, and its heavy metals are insoluble. Offered by Rhenipal, UK, a joint venture between National Power and Dirk European. 

The N-Viro process for alkaline stabilization of municipal sewage sludge combines dewatered sludge with one or more alkaline industrial by-products. The process destroys pathogens by a... 

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