Microbiological control in paper mill water circuits requires, in addition to effective products, careful process management. The evolution moves from traditional dosing to continuous and automated monitoring of chemical parameters, supported by sensors, data analysis and artificial intelligence tools. The objective is to improve efficiency and production continuity.
In the microbiological control of paper mill water circuits, monochloramine (MCA) is a well-known and now widely used solution. Its effectiveness is widely recognized, but operational experience shows that the real difficulty is not so much the chemistry itself, but the ability to manage it within the process. José Domingos Fernandes, tissue corporate accounts manager Emena & sales manager South Europe at Buckman, addressed precisely this aspect at Miac 2025, speaking not about chemical product innovation, but about the evolution of the method by which it is analyzed, monitored and regulated, in order to avoid the critical issues typical of traditional applications.
Managing monochloramine
“Monochloramine is often considered one of the best microbiological control agents available on the market,” explains Domingos Fernandes. “It is widely used both in the paper industry and in water treatment systems, because it offers several advantages.” Among these are, first of all, chemical stability and long residual activity. Unlike many traditional biocides, which act quickly but degrade just as fast, monochloramine can remain active in water systems for longer periods, allowing microbiological control to be maintained in the circuit and ensuring continuous protection against bacterial proliferation. Furthermore, “monochloramine is able to penetrate biofilms more effectively than many other chemical solutions, inactivating microorganisms even in the deepest layers and limiting regrowth.” This effectiveness also translates into greater control over the entire system.
“In many cases, traditional biocides must be used at high concentrations to achieve the same result, increasing costs and the risk of microbial resistance.” Monochloramine, instead, can be effective at relatively lower and more constant concentrations, making it particularly suitable for complex and large water circuits.
There is also an aspect to consider, continues Domingos Fernandes, related to regulatory acceptance and operational safety. The substance is widely used in drinking water treatment and other regulated areas, which facilitates its application also in the industrial sector.
However, the manager stresses that the use of monochloramine requires very careful management. “It is a complex chemistry and requires knowledge of specific parameters: maintaining optimal pH, the correct chlorine-to-ammonia ratio, and residual levels.” A task, he says, “far from simple.”
Improper management can compromise disinfection effectiveness or promote the formation of unwanted by-products. “If the system is not correctly controlled, monochloramine can contribute to the formation of nitrosamines and other disinfection by-products (DBPs), chlorinated or nitrogen-based. At the same time, it can promote corrosion phenomena in metal pipes and the release of metals into the circuit.”
Not only that, suboptimal application can lead to monochloramine degradation with “release of ammonia, loss of disinfecting effect and development of biofilm.” From an environmental and operational safety point of view as well, attention is required, adds Domingos Fernandes: “too high concentrations can be irritating to the eyes and respiratory tract, while chloramines released into surface waters can be toxic to aquatic organisms, even at low concentrations.”
The MCA approach
To manage these variables, the chemical sector has developed various operational methods over time. “In most cases, monochloramine control is based on periodic laboratory procedures carried out on site.” These activities include, for example, verification of the quality of sodium hypochlorite (HYPO) used as a precursor, adjustment of the chlorine-to-ammonia ratio, and measurement of residual chlorine levels in the circuit. “However, this is an approach heavily dependent on human intervention and the frequency of checks. The critical aspect is precisely this strong dependence on people and on the periodicity of analyses,” explains Domingos Fernandes. Consistency and precision are required, because if monitoring is not continuous, process variations may go unnoticed.
Another widespread practice is batch dosing, i.e., the introduction of monochloramine into the system in predefined quantities and at regular intervals. This method, although simple to implement, “inevitably introduces a certain variability in the process and can lead to high MCA levels.” It is a widely adopted solution by chemical suppliers, the manager explains, but it has some limitations. In addition to generating concentration fluctuations, it can lead to higher consumption and increased costs.
Another approach developed in recent years concerns improvements in the design and operation of equipment supplied by chemical product manufacturers. However, even in this case, “there is wide variability among the solutions offered by different suppliers, both in terms of design and functionality as well as safety levels and costs.”
Continuous control and process stability
In light of these issues, according to Domingos Fernandes, to fully exploit the potential of monochloramine, the solution is twofold: “the objective must be to maintain optimal control at all times and, at the same time, stabilize the system,” he states. This means moving from periodic monitoring to automated and continuous monitoring. The ratio between monochloramine precursors—particularly sodium hypochlorite and ammonia—must be automatically controlled, and the correct balance of the two substances must be kept constant. In addition, pH checks must be performed and the system must be monitored online via sensors providing real-time data, enabling control of biocide dosing in the closed circuit and process parameters. “In this way, doses are automatically adjusted to operating conditions.” The most advanced dosing technologies, explains Domingos Fernandes, include smart pumps, control valves placed on all application lines, and thermal sensors capable of detecting temperature variations, thereby highlighting possible anomalies.
Another important element concerns preventive maintenance. “Thanks to integrated sensors, it is possible to monitor the status of critical system components and know in advance when they need to be replaced, avoiding sudden failures and process interruptions.”
Overall, the manager explains, this approach aims to stabilize the wet end of the paper machine and keep under control phenomena such as microbiological deposits, pH variations or calcium build-up, all factors that can affect paper quality and operational continuity.
Between chemistry and artificial intelligence
In this area of analysis, monitoring and control of chemical parameters in water treatment in paper mills, the most recent evolution consists in the integration of chemistry with digital data analysis tools. In this regard, Domingos Fernandes presents the Buckman Ackumen MCA-i system, which combines the use of monochloramine with digital monitoring platforms and predictive models.
“Ackumen MCA-i goes beyond simple data collection,” the expert explains. In industrial applications, the configuration may include multiple independent dosing points distributed along the paper machine circuit. “The system then produces simple and intuitive operational visualizations of the process; the collected data are transformed into easily interpretable graphs and indicators. The system also manages alarms and notifications in real time, allowing operators to monitor plant performance both from desktop and mobile devices via the Buckman Ackumen platform,” and to intervene promptly in case of anomalies. Cloud connectivity also enables remote monitoring of different operational parameters and the development of predictive models that can anticipate changes in the circuit.
Application in the paper mill
In July 2023, Buckman launched a biocide trial with Ackumen MCA-i at a tissue plant, initially on one of the site’s machines, TM5, with the intention of extending the trial also to PM3.
“Our main objective,” explains Domingos Fernandes, “was to reduce breaks linked to suboptimal microbiological control.” Secondly, the study aimed at “maintaining machinability above 95%, reducing microbial loads measured through ATP tests and dip slides (immersion slides), and using online monitoring of parameters such as oxidation-reduction and total chlorine to improve system control.”
Monitoring results, the manager reports, showed a progressive stabilization of total chlorine levels in the clarified white water circuit. At the same time, microbiological analyses showed a decrease in bacterial load measured via dip slides, an indicator of microbiological contamination.
The most significant parameter for the mill, however, was breaks. According to Buckman’s findings, the introduction of the new management system led to a 46% reduction in breaks, with a consequent improvement in operational continuity and production costs.
Process stability and operational benefits
According to Domingos Fernandes, the combination of monochloramine-based chemistry, advanced sensors and data analysis allows a more structured approach to microbiological control in paper systems. “With this solution we have implemented a data-based approach supported by artificial intelligence, which provides operational indications directly during the process,” he states. Continuous data analysis makes it possible to quickly identify system variations and adjust biocide dosing accordingly. Expected benefits, he adds, include process stabilization, increased operability and improved effluent quality. Furthermore, more precise control of process parameters helps improve the performance of other functional chemistries used in the wet end and protects equipment from corrosion and deposits. Not only that, continuous monitoring also helps reduce unplanned downtime thanks to preventive maintenance and optimize chemical consumption, while increasing operational safety.
In conclusion, accurate microbiological dosing is increasingly required in the current context of the paper industry, where, on the one hand, the increased use of recycled or variable-quality fibers directly affects microbiological control in water systems, and on the other hand, mills are required to reduce water consumption while maintaining unchanged paper quality standards. Biocide dosing thus becomes an even more delicate balance than in the past.
“Systems like Ackumen MCA-i aim to manage this complexity through continuous monitoring of water microbiological quality and automatic adjustment of monochloramine dosing throughout the entire process, from stock preparation to the paper machine,” he concludes. The objective, says Domingos Fernandes, is to find “the right dosage in the right places,” with a system that combines chemistry, advanced sensors and predictive data analysis.