Sludge Physics Analyser (SPA)

Description

The SPA unit is a new innovative solution that enables wastewater treatment plants to measure the physical properties of sludge and thereby optimize operations based on this data:

• SETTLING VELOCITY
• SVI/DSVI INDEX
• DEWATERING PROPERTIES 

EFFICIENT AND AUTOMATED ANALYSIS

DMR’s SPA unit is fully automated and only requires a sludge sample to be placed in the equipment, after which a few sample-specific data are entered and the start button is pressed. The SPA unit is optimized for both activated sludge and digested sludge. The measurements consist briefly of the following:

• A laser that scans the sludge surface with millimeter accuracy for precise data collection on settling.
• A scale to monitor how much water is filtered (dewatered) over time.

A filter is inserted into the sample cylinder, making it possible to monitor and document the filtration properties. The SPA unit automatically adjusts the necessary filtration pressure and simultaneously measures the filtration flow.

 

EMBEDDED CALCULATIONS AND ADVANCED SOFTWARE

Model calculations are performed, developed in collaboration with the Department of Chemistry at Aalborg University. The software automatically calculates the parameters:

SETTLING:

• SVI30/DSVI (Sludge Volume Index/Diluted Sludge Volume Index)
• Settling Velocity

DEWATERING PROPERTIES:

• Specific filter resistance (which is an expression of dewatering properties)

STANDARDIZED MONITORING OF SETTLING

Until now, only manual measurements of SVI/DSVI have been performed at treatment plants. The SPA unit enables automatic digital measurements of the unrestricted settling velocity, which is a parameter that can be more directly related to the operation of the treatment plant. Settling velocity is a more direct measure of settling properties than SVI/DSVI.

Depending on the properties of the sludge, SVI/DSVI can reflect both something about settling velocity and the sludge’s compaction ability. It can thus be difficult to separate these parameters from each other. But with the SPA unit, it is possible to separate the settling velocity from the compaction ability and thus better translate it into how it will affect the plant’s operation.

 

MONITORING AND OPTIMIZATION OF SLUDGE DEWATERING

The dewatering properties of sludge can be monitored and optimized by measuring the sludge’s specific filter resistance. Effective dewatering can be achieved through the correct dosing of polymers, which is known to be a significant cost factor.

Savings on polymer consumption can ensure a payback period for the SPA unit ranging from weeks to a few months, as shown in the example below.

EXAMPLE OF POLYMER OPTIMIZATION:

A treatment plant with 50,000 PE (population equivalents), producing 30 grams TS (total solids) per PE per day, generates approximately 1.5 tons TS daily. With a polymer consumption of 30 kg per ton TS and a price of 70 DKK/kg polymer, this amounts to an annual expense of over 1 million DKK. A reduction of just a few percent in polymer consumption can lead to significant savings.

Additionally, savings are achieved if the sludge needs to be transported, which is cheaper the less water the sludge contains. Furthermore, optimizing polymer dosing can lead to lower costs for any drying before subsequent incineration.

 

AUTOMATED MONITORING AND DATA SHARING

The automated SPA equipment (Sludge Physics Analyzer) provides improved monitoring of the physical properties of sludge. With online access and data sharing, your plant can benchmark its performance against other plants.

In case of problems with sludge dewatering or settling, you can view data from other plants and get inspiration for the choice of polymer or dosage, etc.

If you also participate in the MIDAS database at the Department of Biotechnology at Aalborg University, it will be possible to link the physical properties of the sludge with the bacterial composition in the sludge.

 

CONTINUOUS DEVELOPMENT WITH ADDITIONAL MEASUREMENTS

The SPA unit is prepared to be supplemented over time with more measurement parameters, thus providing even more detailed characterization of the sludge. This could include digital image processing for characterizing particles in the water phase after settling or the introduction of a new parameter that quantifies floating sludge. Both can be measured with a microscope camera prepared for mounting on the scanner in the equipment. This is still under development but will be introduced gradually.

 

The SPA unit requires that the location where it is installed has access to compressed air with a minimum output pressure of 6 bars.

 

If you need more information please contact our experts.