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Accurate sludge conditioning for good dewatering results

Flow and density are key parameters for quality

Control of sludge conditioner mixing procedure through continuous density and mass measurement improves dewatering results for polymer and lime solutions.

Band filter for dewatering sludge from a municipal wastewater plant. ©Endress+Hauser

The results

  • Improvement of sludge dewatering resulting in a better continuous quality of the dewatered sludge

  • Less maintenance due to longer filter life up to 25%

  • Cost savings effect due to less consumption of conditioner (15…20% achieved)

Customer challenge

Where should I put the sludge? There is a positive consensus among wastewater plant operators and other groups on the marketplace that the subject of sludge will take on more importance in the future. Reasons are the increasingly strict controls on discharge methods and the obvious cost burden of every cubic meter of sludge. Since charges for sludge disposal are volume-based, it is indispensable to know exactly what happens during sludge dewatering.

Correct mixing or dosing of additives which facilitate the dewatering process is crucial for long filter life and good drainage results.

Sludge dewatering needs to be operated efficient, that means:

  • High sludge dewatering results

  • Long dewatering cycles

  • Optimized conditioner consumption.

The preparation of the conditioner solution only controlled by volume flow results in changing solution concentrations which makes an optimal dosage difficult. Plant operators are also facing non-optimal sludge concentration in the dewatered sludge as well as short dewatering cycles causing additional maintenance effort.

Our solution

Coriolis mass flow measurement provides not just pure flow rate values but further parameters like density, temperature, concentration and viscosity. Therefore, this measuring principle is a neat and reliable solution for many applications. The following applications in waste water treatment plants have already been realized to improve sludge dewatering result, operation time of the dewatering machine and optimize the conditioner usage:


  1. Density measurement of lime milk in order to detect concentration variations

  2. Density measurement in the working solution to control dilution process of the parent solution of polymers

More exotic solution for one of our customers: Density measurement of precipitating agents (Fe(III) salt) in the biology:

  • Detection of the transition from saturated to unsaturated parent solution and automatic ordering of precipitants (light inventory management)

  • Assuring the limit values

Solution components

  • Instrumentation: Promass 80I

  • Optionally we offer support for complete dosage solutions


  • Optimizing the plant safety of your wastewater treatment plant

  • Managing the chemicals cost efficiently

  • Reduce the production of sludge