Reducing Disposal Costs for Waste and Sludge

For industrial sludge, disposal via private disposal companies, via municipal wastewater treatment plants (e.g. also co-digestion of energy-rich flotate sludge) or in approved biogas plants is common. After maximum mechanical dewatering, the sludge is often further treated thermally in drying plants and then thermally utilised or incinerated by these facilities. In the case of production sludge, reuse may also be possible.

The greatest potential for reducing disposal costs for sludge, apart from fundamental avoidance, is thickening or dewatering. In this process, the volumes and thus the quantities are reduced by removing water, while the solids content remains the same. Since billing is usually based on volume or tonnage, this reduces costs.

The maximum degree of dewatering can be determined analytically and is often referred to as the DS(A) value. This value refers to the maximum dry solids (DS) content that can be achieved by mechanical sludge treatment and, as mentioned above, depends on a variety of factors. Some types of sludge dewater to over 50 % DR, others only to 15 % DR or less.

The maximum dewatering or volume reduction depends on many factors regarding the sludge quality. For example, the loss on ignition (proportion of the mass of organic material to the total mass of the material), conductivity and, above all, the choice of the right polymeric flocculation aids play a major role. In laboratory or pilot tests, HUBER can determine the possible potentials in advance.

Biological surplus sludge, flotate sludge, primary sludge, but also other residual materials such as paper fibres, can be treated. Especially in the case of industrial sludge, however, a test should be carried out in the laboratory or with a pilot plant beforehand.