Sludge produced by industrial trade waste plants generally arises from dissolved air flotation (DAF), sedimentation or biological processes. Liquid sludge requires tankers to remove and dispose of the waste. Disposal involves either soil injection or further processing at industrial or sewerage treatment plants. Depending on the location of the plant, transport and disposal costs can amount to significant levels.
The installation of a mechanical sludge dewatering plant, however, can produce a reduction of up to 97% in the volume of waste. The final cake produced is in a spadable form that can be beneficially reused, composted or sent to landfill. How can this be achieved?
Technologies available for dewatering liquid sludges include:
- Belt filter presses
- Plate filter presses
- Decanter centrifuges
- Inclined sludge presses
The selection of dewatering technology is dependent upon the sludge properties and volume to be treated. In general, belt filter presses will treat sludge generated from a variety of industrial applications, including food processing facilities, dairy facilities, meat facilities and abattoirs.
Applications include DAF sludges, digested sludges, clarifier underflows
sand slurry, biological sludges, metal hydroxides, waste-activated sludges, coal tailings, primary sludges and food processing sludges.
To cater for the range of different applications, AJM/Eimco Water Technologies has a range of sludge dewatering equipment to suit, including belt filter presses, plate filter presses, centrifuges and inclined sludge presses.
When considering capital, maintenance and operating costs, sludge dewatering with belt filter presses yields payback periods as little as three months and rarely exceeding 16 months.
Feasibility and assessment
The suitability of various technologies available for sludge dewatering is based on experience. In some instances it may be necessary to carry out on-site assessment to review the plant, followed by bench trials to assess the properties of the sludge.