Industrial wastewater

Lesser costs, less fuel, more sustainability


Valmet has recently unveiled its Hs measurement system that enables stable and accurate measurements for industrial wastewater treatment and for other processes.

Headquartered in Espoo, Finland, Valmet recorded 3.1 billion net sales last year and employs some 12,000 professionals around the world. A significant part of this business comes from the energy and, of course, pulp, paper and tissue industries. These, together with water treatment, are the very segments that the company is planning to address with its newly launched solution, called Valmet HS. HS is an acronym and stands for High Solid Measurement System. The company, allegedly, is confident that these sectors will prove most profitable for HS in the near future, worldwide. As sources clearly stated, Valmet High Solids Measurement (Valmet HS) enables «stable and accurate measurements for industrial wastewater treatment, pulp and paper production and a wide range of other industrial processes. It measures for over 30% solids or 1-70% moisture» and was originally designed «for municipal waste water plants». Valmet HS builds upon the advantages of microwave technology and «features a patented sensor structure. It extracts a continuous sample flow from a downfall or drop leg section in the process and returns it back to the process after the solids content has been measured». Valmet, whose business was established in the 18th century, believes this new method of measurement can provide users with a number of unprecedented benefits. «It helps to minimize transport costs of sludge in waste water applications», as Valmet itself reported in a recent press release, «and reduce supplementary fuel use where sludge fuels a boiler, therefore improving the sustainability of industrial processes. Additionally, Valmet High Solids Measurement makes it possible to optimize total solids levels and follow up, in real time, the performance of dewatering or drying processes».


The HS technology was already installed and used after a high-consistency roll press; and the producer estimated that it can easily ensure «accurate pulp consistency control to refining and consequently more stable-quality pulp to the paper machine». Of course, these are only a few of the competitive advantages that the solution can display. «Benefits», as Valmet recalled, «also include lower press energy consumption, a reduced fibre crushing and», last but not least, «the prevention of excessive consistency, eventually damaging the process equipment». Furthermore, «other proven applications of Valmet HS include wastewater sludge solids measurement after dewatering in pulp and paper applications, measuring sawdust moisture before pelleting in the wood processing industry and sludge moisture monitoring before incineration». This is why managers at Valmet’s expect HS to become most successful in a variety of different business scenarios. «We see high potential for this solution», as Jarmo Havana, product manager at Valmet’s Automation division,pointed out, «especially in the pulp and paper industry where an accurate high solids measurement provides many benefits, such as improved high consistency control, cost savings and higher quality. The solution has been so successful», Jarmo Havana added, «that new applications are coming up all the time. Ongoing development work in various industries also includes the measurement of moisture with starch, sugar and gypsum as well as a complete control over thermal drying processes».

Technical specifications

The Valmet HS system builds upon the properties of microwave technology and this means that it requires no additional nor special certification «to make a stable and accurate solid measurement for dewatering controls in water treatment». In fact, it extracts «a continuous sample from the falling cake flow after a centrifuge or screw press and measures the solid content before returning the sample back to the process». The company also noticed that HS works as «an on-line measurement with continuous moisture output. When the customer’s process is on, Valmet HS is running and giving the customer accurate moisture information». Also, it was designed in order to operate in a fully interconnected 4.0 environment, since «in addition to full remote access of Valmet DS functions, measurement data, alarms and diagnostics via the Industrial Internet, the Valmet DS Ethernet connection can be used for local control with a laptop or tablet computer during commissioning». Valmet HS, as the Finnish company also recalled, «is installed where the material is dropping in chute or from conveyor to another conveyor. A sample retrieval screw feeds a return screw which compresses and pushes the sample through the microwave sensor chamber before being returned to the process. The Valmet HS measurement is based on a multi-variable microwave resonance, compensated for variations in material temperature and density; and finally calibrated during commissioning with samples taken from the screw; and, then, oven dried».

Case studies

Some of Valmet HS’s tested applications include the management of thermally dried municipal waste water sludge. In this very case, the target was that to precisely monitor the thermal dryer and stabilize the drier’s optimal output moisture. «A stable moisture output», is the comment, «brings many advances to the customer: Savings in energy consumption for not over drying the sludge; and a more stable moisture», which «improves process control after the dryer». In addition, the solution was implemented in order to ensure «the moisture measurement of saw dust before pelletizing». Here, the goal was that «to produce a stable moisture to saw dust and maximize a successful palletization process. Savings can be achieved through a lowered energy consumption and a more effective palletization process». As for dried pulp mill waste water sludge, the target of measurement was, again, that to optimize the drying process. «An optimal output», as Valmet noticed, «is maximal dryness in the sludge and therefore minimum amount of water to be transported further in the process. The optimization of polymer dosage is the other major factor here»; and an accurate moisture measurement «helps customers in finding the right chemical to their process and finding the optimal dosage of chemicals». Finally, Valmet’s recent release was also used in order to manage thermally dried municipal water sludge before incineration. In this circumstance users aimed to efficiently monitor the performance of the thermal drier and, at the same time, to minimize its output moisture. Sources at Espoo underlined that this methodology can offer customers a series of important advantages, assuming, in first place, that «a minimal moisture to the incineration plant results in lower side fuel expenses and smaller emissions».