Let’s take wastewater treatment as an example. Governments around the world are tightening environmental regulation, and many pulp and paper mills have stricter discharge limits over water pollutants in their permits. To ensure that the outlet effluent is within allowable discharge limits 24/7, the mills require continuous treatment process stability, which is not that easy to achieve.
“The loads of suspended solids, turbidity, and hard COD, which is particularly challenging for the mills, vary in the wastewater from hour to hour. The reality is that in many cases the treatment chemicals are fed into the process at a steady dosage flow. This leaves a lot of points in time where the chemicals are either underdosed or unnecessarily overdosed,” says Anders Ånäs, Manager for Water Quality and Quantity Management Applications in Kemira.
Adding to the challenge are the time-consuming quality control processes. Typically, basic monitoring and control requires manual work in collecting samples and analyzing them in a lab. This causes delays in the process.
“It can take several hours or even days before the plant personnel can react to a changed wastewater composition and take corrective actions to adjust the chemical dosage and optimize the treatment process performance. As a result, the mills face unstable and at times poor effluent quality and, on the other hand, chemical wastage and unnecessary costs.”
At many mills, there are a lot of points in time where the water treatment chemicals are either underdosed or unnecessarily overdosed.
The same goes for other water treatment applications at pulp and paper mills, starting from the incoming raw water treatment and internal process clarification all the way to sludge dewatering. Fresh water that is taken into the production from rivers and lakes contains varying levels of organic compounds, which makes maintaining a steady quality in the chemically purified water a challenge. Similarly, varying sludge composition makes it difficult to predict the performance of the dewatering process and to optimize both the sludge dryness and filtrate quality.
“Without an up-to-date view you are unable to adapt to the fluctuating process conditions. There’s a lot to gain with improved process control and efficiency.”
Digital services for optimized efficiency
Kemira has developed digital services that help optimize the performance of different water treatment processes at pulp and paper mills. The KemConnect™ Water Treatment solutions enable real-time measuring, monitoring, and control of different water treatment applications: wastewater, internal process water and raw water treatment, sludge dewatering, and odor and corrosion control.
“The real-time view helps in overcoming many challenges. In the customizable KemConnect dashboard, you can see at a glance the current levels of COD, suspended solids, turbidity or hydrogen sulfide (H2S) in your process and how the current treatment is performing. Based on the data, the mill personnel can make fact-based and timely decisions, leading to round-the-clock stable quality and optimized performance.”
The real-time view enables fact-based and timely decisions and leads to round-the-clock stable quality and optimized performance.
For example, poisonous hydrogen sulfide poses a serious health and safety risk for the wastewater treatment plant personnel and can damage pipelines, basins, and equipment. 24/7 visibility to the situation enables immediate automated alarms on process disturbances.
“Overall, thanks to the improved process control, there will be fewer of these situations where something goes unexpectedly wrong and a sudden remedy is needed,” Anders Ånäs points out.
Kemira’s portfolio of reliable online monitoring tools for chemical applications and the KemConnect platform are based on extensive chemistry and application expertise and process know-how.
“Determining the right measuring and chemical dosing points is an obvious key to getting the optimal results. Our experts work closely with the mill personnel for successful implementation and reliable service. Smart dosage control ensures that just the right dose of chemicals is used at the right time.”
Compliance, cost-savings, and safety improvements
Optimized and cost-efficient water treatment processes are built with a combination of best-in-class application expertise, high-performing chemistry, and the digital solutions for real-time monitoring. A mill producing specialty paper grades was able to further reduce suspended solids by 60% and COD by 30% in their wastewater treatment process after introducing treatment chemicals from Kemira together with the KemConnect solution for real-time monitoring.
“Continuous operation stability secures effluent quality and ensures that the mill stays compliant with the strict discharge limits of environmental permits at all times. The coagulation and flocculation performance is monitored and controlled at multiple points throughout the wastewater treatment process. Based on the real-time data, the operators can respond to changes without delay and with optimal use of chemistry,” Anders Ånäs explains and shares another case.
“Real-time data helped a board mill overcome high seasonal variations in the incoming fresh water. The mill achieved 50% increase in COD removal efficiency. Dissolved organic compounds cause issues e.g. with runnability and increase deposit risk at the paper machine, so stable raw water quality materializes as savings in operation costs.”
Improved process control can translate into significant savings also in sludge handling, where optimized dewatering process performance helps increase sludge dryness and thus reduce sludge disposal volumes. On the other hand, real-time monitoring can help reduce chemical wastage and cost – a Kemira customer was able to reduce the overall consumption of sludge dewatering chemicals by 20–30%.
“When you see your chemical applications in real-time, you can stay one step ahead and maintain optimized efficiency even in varying conditions. The process and performance data that cumulates over time provides additional insight and reveals opportunities for further improvement.”