J+A Bache ClassifierTM Grit Washer

The demand for cleaner and biodegradable waste products, with reduced odor is growing. The J+A Bache Classifier® grit washer is highly effective equipment for the separation of grit from foul organic solids. The grit/solids and water mixture is received from the primary grit separating system located either upstream or downstream from the screening plant.
  • The potential for foul odor is removed
  • Abstraction of organic solids equal to or below 5%
  • Maximum capacity up to 23 liters per second
  • Few moving parts for maximum design life and durability

The grit solution is delivered to the J+A Bache Classifier® grit washer via a solids pump or, alternatively, an airlift pump system. Both systems can be provided by Ovivo. Normal pumping duties are carried out via 100mm nominal bore pipes and rated nominally for 15 liters per second.

The Ovivo® grit washer discharges a clean grit product, which translates into valuable volume reduction of waste removal from the site. The potential for foul odor is removed, especially in confined spaces. Under this environment, storage of the discharged product now becomes acceptable.

The classifiers are manufactured in carbon or grades of stainless steel.


  • Classified grit is free of putrescible solids, therefore volume reduction is achieved
  • No rotating parts in the washing area
  • A “no-wear” trough liner
  • High separation of fine and super-fine grits
  • Low energy consumption

There is a growing requirement in Europe to recycle and reuse collected grit. By washing the grit and removing the odor, it can be repurposed for roadways or other such enterprises.

The Bache Classifier® grit washer is the perfect product to remove pungent odors from highly sensitive sites such as those near residential areas. Removing organic material reduces objectionable odors, making the construction of a separate inlet works building unnecessary, further reducing installation costs by avoiding additional expenditure during the initial design phase.

Other suppliers for grit classification equipment use a shafted conveyor screw that rotates on a wearable liner. Due to the rotating action of the screw, the collected grit wears away the plastic liner, which if not regularly monitored, can lead to effluent seepage from the inclined trough. Additionally, these liners are located below the water line, which prevents any visual inspection to take place. To avoid this from occurring, the Ovivo conveyor screw is supported by two bearings with no metal-to-metal contact between the screw and trough.

The Bache Classifier drive units use no more than 0.75 Kw of electricity due to its intermittent operation, which keeps energy consumption low and Opex costs to a minimum.


Water/grit solution is transported to the classifier via a grit pumped system. Grit is deposited onto the floor of the tilting launder assembly. Washwater is injected into the launder for grit washing and organic separation. The organic solids are flushed out and into the works effluent channel. The launder is then inclined and the washed grit is transported down into the screw dewatering/conveyor positioned below. The grit is then elevated by means of an inclined screw for maximum dewatering and discharged into a collection receptacle, for off-site disposal.


  • Organic content is reduced to approximately 5%
  • Maximum capacity – up to 23 liters per second
  • Grit size – commonly 0.2 mm, 2.65 s.g.
  • Water supply – final effluent or potable water
  • Washwater supply – minimum capacity of 5 liters per second
  • Overall size – nominal 4.0 meters long x 1.6 meters wide x 2.85 meters high (launder trough inclined)
  • Motor power – Drive unit-0.75 Kw, Inclined launder-0.37 Kw
  • Materials of construction – painted mild steel, 304L and 316L stainless steel

What is the advantage of the J+A Bache Classifier®?

The Bache Classifier is an upgrade of the conventional screw classifier, which will not provide the level of cleanliness and reduced organic material of the Bache.

Can a conventional screw classifier be converted to a Bache Classifier?

Both designs of classifier do appear to be similar, however a conversion is not possible.

Can multiple grit traps feed into the Bache Classifier?

Yes. The Bache Classifier can accept pumped feeds from two grit traps. We recommend that each grit trap feeds the classifier independently, not at the same time.

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