Mark II Process Description

Chemical Dosing

An Or-Tec Blend emulsion polymer feed system automatically makes up and delivers the polymer and water solution to the injection site. As an alternate, a solution of suitable polymer is made up in a stainless steel chemical mixing / storage tank. The tank is usually designed with a capacity for one day operation of the system.


Sludge is pumped to a stainless steel flocculation tank by a variable capacity pump. Prepared polymer is simultaneously injected to the inlet of the flocculation tank by a variable speed chemical dosing pump. Here a thorough mixing occurs that is aided by a variable speed flocculator fitted in the tank. Speed adjustments are manual.

Gravity Drainage Area

Flocculated sludge flows from the flocculator down a sludge feed chute. This chute provides a gentle and even distribution of sludge over the gravity drainage section and a uniform thickness on the dewatering belt. The drainage area allows for the separation of the free water contained within the sludge and its consequent discharge into the drainage tray. Capillary action takes place as the dewatering belt moves across tracking and pressure rollers. The drainage area is sealed by polypropylene skirting that is bolted to the top trays and rests on the filter cloth.

Roller Pressure Dewatering Zone

Further liquid removal is achieved as the belt and sludge are pressed between a series of rubber covered rollers. Gradually the sludge is squeezed by adjustable rollers that have been preset during commissioning.

Sludge Discharge

Dewatered sludge is continuously removed by a fixed scraper blade acting against the final roller and allowed to fall into a horizontal stainless steel conveyor. The conveyor can transport the sludge cake to the outside of the building. Sludge cake can also be elevated with a stainless steel inclined screw auger for discharge to a waste hauling vehicle for off-site removal. A dry cake pump can be used as an alternative to the conveyor or auger.

Filter Belt Washing

The filter belt is continually washed by pump generated high pressure water sprayed through fine nozzles. Belt wash water and filtrate are collected in a stainless steel drainage tray. This runoff is funneled to the customer drainage system via the supplied 4" diameter flanged outlet in the tray. In most cases, the filtrate is acceptable as reuse for wash water, as is the final effluent of the W.W.T.P.


The system can be automatically controlled. Start-up is simple and requires a minimum of time. The unit's design, incorporating variations in both speed of the main elements and in roller pressure, offer a high degree of flexibility to the end user.