Phase 2     Hydromechanical Pre-treatment

The front wet pre-treatment system is what differentiates the BTA® Process from other organics processing systems. Inert contaminants such as plastics, glass, metals, small format batteries, cutlery and fine grit are stripped away at the front end to ensure downstream product quality. Removing the contaminants upfront also allows for higher organic capture rates.

Step 2: Waste Pulping

The primary device that removes the non-biodegradable fraction of the incoming waste is BTA’s patented Waste Pulper. The waste pulper produces three fractions:

 

BTA®  Waste Pulper
         Disco Road - 75,000 Metric Tonnes

 

1. Clean, Homogenous Pulp Fraction: The pulpers process the waste in batch cycles. The waste is charged into the pulper where the hydraulic shear forces de-fibre the organic waste into a “pulp fraction”. Not shredding the waste preserves the structural integrity of the organic fibres, improves digestion and avoids releasing toxins in items such as small format batteries.

 

            Hydraulic Shear Forces Inside
            Homogenous Pulp Fraction

 

2. Light Fraction Residual: A mechanically operated rake captures floating debris that is classified as the “light fraction,” and is made up of primarily mixed plastics. It is discarded into a dewatering press. An auger conveys the rake discard into dewatering press and then into a bin that is typically shipped to land fill.

 

            Light Fraction Routine
            Dewatered Mixed Plastics

 

3. Heavy Fraction Residual: The “heavy fraction” is collected in a flush trap located on the bottom of the pulper. A trap is configured with an upper and a lower gate. Process water flushing prevents organic build-up and cleans the collected material. This fraction is typically land filled.

 

            Heavy Fraction Trap
            Dewatered Heavy Fraction

Step 3: Grit Removal

The organic suspension that is pumped off from the pulper is transferred to the patented BTA® Grit Removal System (GRS). The GRS removes tiny pieces of sand and grit from the organic suspension using centrifugal forces. 

 

Grit Fraction Residual: A grit box is discharged whenever grit reaches a pre-set level. The grit falls into a screw conveyor and is transferred into a bin, typically for disposal. 

 

            BTA® Grit Removal System (GRS)
            Dewatered Grit Fraction

Step 4:  Suspension Buffer

 After the separation of the inert contaminants, the de-gritted pulp is pumped continuously into the pulp buffer tank to even out the hydraulic loading and maintain a homogeneous suspension. The digestion phase is fed from this buffer. 

Step 5: Residuals Management

All non-processable materials captured in the front end hydromechanical pre-treatment are typically land filled as non hazardous waste. Alternative uses in a local market could exist.