From municipal associations to industry: Anyone involved in purifying wastewater faces massively escalating costs for disposing of the sludge that is produced. Stricter regulations (for example, the Düngemittelverordnung (Fertiliser Ordinance) in Germany) and more and more restrictions are sending the prices of thermal recycling through the roof, partly because existing disposal capacities are limited. Experts consider costs of up to 200 euros per tonne to be realistic in the near future.
Optimum dewatering, which reduces the weight of the sludge requiring disposal, is therefore becoming increasingly important – after all, no one wants to transport water for incineration. This is where the VTA mudinator® comes in. In this technology developed by VTA, the sludge is treated with ultrasound immediately before the polymer is added. In contrast with disintegration, the energy input is significantly lower. The structure of the sludge is changed in a way that enhances the effect of the flocculants (polymers).
‘The more effective charge balance results in a more shear stable floc from which the interstitial water is also released. This increases the dewatering result by up to five percentage points’, explains VTA biologist, Andreas Gabriel MSc. In terms of quantity, this means significantly less sludge requiring disposal. Polymer consumption is reduced at the same time.
‘The VTA mudinator® can be used in combination with all conventional dewatering units. Thanks to the compact design, retrofitting on existing plants is easy and can be done without changing the existing infrastructure’, stresses Robert Reitinger (VTA Technical Field Service). Due to its flexible, modular design, the VTA mudinator® can be precisely configured for the respective requirements (sludge volume, dewatering time). This is achieved through an informative process starting with sludge analyses and a zero sample that has not been treated with ultrasound in the VTA mobile laboratory directly on site at the plant.
This is followed by extensive tests using standardised presses and vibrating modules in the VTA laboratory, including determination of dry residue in the discharge. The reported results are discussed with the plant operator before an accompanying practical test is started at the
This is also quite simple: A test mudinator of the required size is coupled as a bypass into the inflow of the dewatering unit. VTA specialists determine the basic setting, the parameters of which can be adapted and adjusted by the operator in the following two to three weeks. An objective payback calculation puts the achievable economic advantages in a nutshell.
Synergy effects are utilised
The effectiveness of the VTA mudinator® is further increased by VTA Biocitran®. This high-performance product for sludge conditioning based on citric acid is mixed directly into the feed line of the VTA mudinator® and improves the result. But not only that – it binds organic substances, ensures a clearer filtrate (or centrate) thus reducing backcharge on the treatment plant ecosystem. In addition, VTA Biocitran® facilitates a reduction in polymer consumption of up to 20%.
The positive effects of the VTA mudinator®, with or without VTA Biocitran®, are now also evident in day-to-day practice at wastewater treatment plants. They are backed up by current investigations by an external analysis laboratory at the Piding treatment plant, for example, like many others.
Field report from the VTA Group’s scientific journal ‘The Tree Frog’, Issue 85