case study on paper mill

Tapping digital’s full potential in pulp and paper process optimization

In recent years, the pulp and paper industry has looked to digital to further optimize operations. This is driven, in part, by three market trends: continued price pressure on paper manufacturers as the market for traditional paper products declines, growing demand for paper packaging as a more sustainable alternative to plastic, and growing demand for tissue products globally.

About the authors

This article is a collaborative effort by Christer Gerdin, Oskar Lingqvist , Andy Luse, Lapo Mori , Kunwar Singh , and Greg Vainberg.

Digital technologies—machine connectivity, intelligent automation, and advanced analytics—enable new levels of productivity in pulp and paper operations by leveraging large quantities of production data to deliver better insights and outcomes. Successful digital innovators are seeing throughput gains of 5 to 10 percent, yield gains of up to five percentage points, and significant savings on materials, chemicals, and energy. For the industry, this represents a $4 billion to $6 billion opportunity, and the value is achievable here and now. Over 25 unique use cases are already generating value across the full pulp and paper value chain (Exhibit 1).

In forestry and logistics, we see the benefit of applications that track real-time material flow from harvester to mill to help optimize delivery and planning. In pulp mills, companies are using advanced analytics to improve kappa control and boost fiber yield. In paper mills, energy optimization, AI-driven root-cause problem solving, and speed optimization boost profit per hour. And finally, in finishing, advanced analytics is driving improved quality.

Companies that are maximizing their return on investment in digital do three things well:

• Develop a strategic value-capture road map and put the right technology enablers in place. Companies need to clearly articulate the total value potential from digital and how they plan to capture that value over time. A strategic road map helps anchor the organization on the sequence of value-capture initiatives as well as the technology enablers that need to be put in place (such as sensors, data pipelines, and storage) to capture the opportunity. The goal should be to manage the program to a well-defined business case with target key performance indicators (KPIs) and avoid running technology experiments.
• Build new capabilities in-house. Successful digital transformation requires new skills and new ways of working. Companies can supplement their workforce with external contractors to start and build momentum; however, they must build these new capabilities in-house if they want the digital transformation to scale and be sustained. To capture the full value and improve implementation outcomes, companies need to combine technology and data expertise with core process and operational know-how. This requires a major focus on hiring and upskilling people in a systematic way.
• Master change management. The greatest digital solutions drive no value unless they are adopted and used every day in the workplace. To make this happen, organizations must obsessively focus on the end users of technology and invest time to understand their needs and incorporate their feedback. Equal focus and attention must be applied both to training and reinforcing new behaviors and to deploying new applications.

Case example: Maximizing value from existing assets by leveraging advanced analytics

Despite significant investment in Lean and Six Sigma, a top-quartile, multi-asset pulp and paper company was still struggling to make a step change in profitability; it was experiencing significant variability in major KPIs, leading the company to explore opportunities in digital. The resulting advanced-analytics transformation increased throughput by 8 to 10 percent in the pulp mill, decreased costs by 15 to 20 percent across use cases, and enabled a sustained four- to five-percentage-point increase in earnings before interest, taxes, depreciation, and amortization (EBITDA) overall.

Below is an overview of what the company did well to achieve those benefits, illustrating best practices.

Putting the right technology enablers and road map in place

The company developed an exciting and aspirational analytics transformation program with a clearly linked data strategy. It executed use cases in sequence to demonstrate value, build momentum, and develop capabilities. The vast quantity of data (20+ GB) available was stitched together from multiple repositories, cleaned, and analyzed through the deployment of over 50 analytics models across more than 20 use cases, with a focus on optimizing KPIs such as throughput, quality, and cost reduction throughout the operations.

New capability building

Close interaction between domain and advanced-analytics experts was key to unlocking the full potential of the assets. There was a focus on capability building within the organization rather than resorting to massive external recruitment. This included designing and setting up an academy within the organization that touched more than 20 percent of the workforce in the first year, ensuring skills were developed at all levels from senior management to line managers, while a set of high-performing people was identified to run the center of excellence, including data engineering, development, process optimization, and change management.

Processes and change management

Adopting agile ways of working coupled with a rapid implementation mindset was crucial for driving change. The company put in place multidisciplinary teams including designers, technologists, operators, and process owners to implement the analytics solution with clearly defined improvement KPIs. Exhibit 2 shows how short sprints by these multidisciplinary teams led to a significant reduction in chemical use in as little as 20 days.

The gap between digital frontrunners and laggards is expected to grow over the coming years, and companies that get their digital transformations right will have a distinct competitive advantage. A no-regrets first step for pulp and paper companies that have not yet started this journey is to explore opportunities and align the senior team on a vision and ambition for digital, and to lay out a strategic road map that considers critical business KPIs, harnesses the strengths of the organization, and is aligned with business priorities.

Christer Gerdin is an associate partner in McKinsey’s Stockholm office, where Oskar Lingqvist is a senior partner; Andy Luse is an associate partner in the Philadelphia office; Lapo Mori is a partner in the Denver office; Kunwar Singh is a partner in the Delhi office; and Greg Vainberg is a senior partner in the Montréal office.

The authors wish to thank Freddie Briggs, Matt Castello, Abhinav Goel, Amélie Nicolay, Abhik Tandon, Asad Ul Haq, and Zach Warren for their contributions to this article, with special thanks to Xavier Morin.

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Case study: Drives and retrofits on paper mill slitter-rewinder

The United States, according to The Federal Network for Sustainability, uses approximately 8 million tons of office paper annually. That’s enough to build a wall 20 feet high and 6,815 miles long. To keep up with demand, paper mills constantly are looking for ways to improve efficiency and quality. While there are many different machines and processes involved with papermaking, a vital part of any paper mill is the slitter-rewinder.

A slitter-rewinder machine is responsible for unwinding huge, newly made rolls from the main papermaking machine, cutting them into smaller sections, and rewinding them as more manageable rolls for distribution. As one of the final production points in a paper mill, any problem with the slitter-rewinder can halt production for the entire mill.

Consisting of multiple motors and controls, the slitter-rewinder is one of the most advanced pieces of equipment in a mill. At the heart of this machine’s process is tension, which determines the quality of the paper rolls. Accurate and consistent forces need to be applied throughout the process to ensure perfect web tracking, precise slitting and proper roll density profiles.

Except for nip control, the quality of the roll is governed, largely, by the performance of the drives. The winder must run as a coordinated system and provide tight control of speed and torque through the continual cycles – from stop-to-full-speed and back-down-to-zero-speed. Even small inaccuracies in performance can cause problems, such as sheet breaks, rough edges, telescoping, offsets and tie-ups, resulting in downtime, rejected rolls and, ultimately, lost profit.

Objective: Continuous High-speed Production To increase productivity and efficiency, one leading paper mill facility in the southeastern United States decided to rebuild its slitter-rewinder and incorporate the latest technology. The goal of the upgrade was to improve roll quality, increase machine speed to the highest possible level and eliminate costly shutdowns.

The mill turned to SDS Inc, a U.S.-based systems integrator that specializes in control designs for paper and web handling industries. SDS analyzed the existing system and provided a cost-effective solution that utilized existing motors and components, integrated ABB's state-of-the-art ACS800 AC drives and new DCS800 DC drives – the most advanced DC drive of its kind. The drive hardware was rounded out with SDS’s Intelli-Wind, a popular two-drum winder HMI that provides TNT control, recipes, numeric and graphical set points, permissives and diagnostics.

System Integrator personnel paid several visits to the facility to survey the situation. They learned there were a variety of issues with the existing slitter-rewinder.

“It’s imperative to get the perspective of everyone who is affected by that rewinder,” says John Parker, senior sales engineer for SDS. “The maintenance crew had concerns regarding component failure and a drive room that required precise temperature control to keep analog components from drifting. The production department wanted to increase uptime, improve roll quality and provide their customers with a cost-effective product, and they wanted to use technologically advanced equipment. Our partnership with ABB allowed us to address and achieve these advantages.”

Outdated Equipment: Inefficient and Costly to Maintain This paper mill, according to both ABB and system integrator experts, was among an increasing number of manufacturers that are still operating with drive systems that are 25 to 30 years old. The drive system on the slitter-rewinder was getting increasingly expensive to repair and maintain. A number of components had become obsolete and could not be replaced. Some of the analog equipment needed constant attention due to drift, and old wiring started showing signs of fracture and insulation breakdown at hinged points. The mechanical assemblies that held the thyristor assemblies and fuses in place were beyond repair; and, on top of everything else, there were issues with the structural integrity of the power modules.

Craig Tierno, senior application engineer with SDS, explains that, with these multiple problems, a retrofit that would replace analog regulators with digital counterparts, while maintaining their existing power bridge, was not practical. The SCRs inside the power modules would not be dependable. So the integrator recommended a complete drive and control system upgrade to improve reliability and performance.

“Often, if a company’s DC power modules are still within their life cycle, we will recommend retrofitting them with new digital, high-performance front ends (DFE) to enhance the regulation performance while firing the existing SCRs,” says Tierno, “In this case, we could not do that.”

New Technology, in Concert with Drives, Provide Valuable Synergy In its search for a drive solution, the integrator found an answer in ABB.

“Our biggest concern was that drive suppliers were not doing anything new with DC. Most of the suppliers were sitting on products that were near 10 to 20 years old,” says Tierno.

ABB, he learned, was developing a new DC drive, designed with some of the same software tools and communication modules as its AC products. That made it feasible to use and integrate both DC and AC products in the project.

There is still a large installed base of DC motors throughout North America with a wide variety of horsepower and speed ranges.

“These motors have a long life with proper maintenance and occasional repairs, so customers are not anxious, necessarily, to replace them,” says Tierno. “Finding a supplier such as ABB, which continues to invent and introduce new technology to control these motors, gave us an advantage from the beginning.”

For this system, four ABB DCS800 drives were installed. The first drive controls the 500-horsepower unwind motor that provides tension regulation for the jumbo parent roll. The second DCS800 drive was installed on the 50-horsepower lead-in paper roll which is used to transport the paper to the slitter section. The third and fourth drives were installed on the 250HP front and rear drums – components that are responsible for providing machine speed reference and profiling torque to the re-wound roll.

Due to the size of the rolls and the demanding torque required to accelerate and decelerate, all the DC drives were sized to handle 200 percent current limit for one minute.

Two ACS800 AC drives and motors rated at 15HP were connected to the two ends of the rider roll to provide vertical force for acceleration and deceleration torque. From a mechanical viewpoint, the motor frame size was based on the application horsepower and ventilation style since the motors are mounted within a moving rider-roll frame.

New Load Cells for Tension Control The load cells, which measure web tension on the unwind section of the machine, were replaced with ABB PillowBlock style Pressductor transducers. The PFTL units selected where based on system requirements and the fact that they were a direct physical replacement for the old load cells. The new technology load cells from ABB, which came pre-calibrated for the application, enhance tension control and reduced installation time and cost.

Compatible Platforms; Retrofit and Use Existing DC Motors Integrator personnel felt the DCS800 was a perfect fit for the paper mill’s Engineering and IT staff, who were already familiar with the operating and commissioning functions of DC drives. ABB’s complementary ACS800, with a look and feel similar to the DC product, made it easy for the mill to transition to AC.

“Making sure that the DC drives were fully complementary – hand-in-hand, step-in-step – with what we were going to do with the AC product, that was really important; having those two on the same platform,” says Tierno.

He explains that the new DC drives enable retrofitters to provide up-to-date technology and outstanding regulation at a fraction of the cost of replacing the entire power system. “A lot of our customers aren’t looking to change out motors and go through a huge installation process. If there is a more cost-effective method, they want to hear about it.”

Master Control via Winder-Operating Software In coordination with the drives, the system integrator installed their own winder-operating software, called iWind, which is designed to optimize roll profile and quality while offering automatic stopping, product recipes, numeric and graphical set-points, permissives and full diagnostics. An elegant and easy-to-use interface, iWind merges the various control equipment directly with the drive hardware, resulting in a less complex system that provides increased performance. It is easier to troubleshoot and maintain as well.

Primarily focused on tension, nip, and torque (TNT), SDS was able to create an architecture that met the customer’s need for improved roll quality. The automatic stopping feature solved the mill’s problem of product length and diameter. Permissive and diagnostic pages provided operators quick help in keeping the winder running, and reduced support calls to maintenance. The recipe system allowed operations to set up orders quickly and maintain product consistency.

Pre-Built Elevated Panels Speed Five-Day Installation The retrofit utilized existing construction – an open-panel design that required minimal real estate and clearance in the control room. Instead of using floor-mounted cabinets, all of the power modules, circuit breakers and other components were laid out on elevated panels. This enabled the integrator to prebuild a separate sub-panel for each drive, allowing time before demolition of the old equipment to test the drives individually and as a group! This made it possible for all communications between the drives and much of the application software and drive functionality to be tested thoroughly before installing and commissioning.

The setup and commissioning of the application program was a smooth process. It took the system integrator team approximately four weeks to engineer the schematics, create the drive and controller software and build the panels. After a thorough two-week testing process, the team was able to install the new equipment within the five-day contingency the mill required. Engineers remained on site for a few days after start-up to ensure a seamless transition for the plant operators.

Winning Combination Enables Optimum Uptime Since the installation of the DCS800 and ACS800 drives, in complement with iWind software, the mill has been able to realize their goals of increased production, top-speed efficiency, better roll quality, reduced maintenance and minimal shutdowns. In fact, they have been able to virtually eliminate shutdowns that happened previously because of component malfunction.

“We are pleased with the ABB products and support, and plan to continue using ABB products for future projects,” Parker said. “And, at the moment, we have eight paper manufacturing projects in front of us for which we are recommending ABB, either ACS800, DCR- or DCS-800 for various applications.”

Tierno adds, “Our relationship with ABB and the people in New Berlin has been very rewarding. They have been most helpful with product delivery and with training on the new products, especially the DCS800.”

ABB products offer the system integrator the resources and flexibility they need to help satisfy each customer according to their specific needs and budget.

ABB and SDS have another reason to celebrate: The paper mill installation marks the first time that a DCS800 has been integrated into a total systems package in the United States. With the almost unlimited scalability of the DCS800, the entire team is looking forward to supplying customers with drives and software for many years to come.

To learn more about this subject, visit www.abb.us/drives or contact Thomas Junger, product line manager, ABB Inc., at 262-785-3377 or [email protected].

(844) 251-7823

Case Study:

Paper Mill Upgrade

75-year-old single line paper machine using outdated methods was ready for an overhaul.

• Upgrade and update paper machine to improve speed, flexibility, and safety.
• Sectionalized the drives from the wet end to the reel.
• Installed an AC coordinated drive lineup featuring a master controller.
• Installed two HMIs to provide a centralized location to monitor and control processes.
• Added an I/O, safety processor, and safety-rated VFDs to boost safety.

Results and Benefits

• The customer enjoys higher operational efficiencies, improved sectional control of the machine, and easier thread up.
• By automating processes previously completed manually by operators, a more inexperienced workforce can operate the machines and focus on value-adding areas of operation.
• The paper mill will enjoy less downtime for maintenance of the machine.
• Centralized monitoring and controls will allow for more efficient, flexible operations.
• Workplace safety conditions are improved.

The Quad Plus gauging team was called for a TPO Roofing manufacturer who was looking to upgrade their current gauge system to detect delamination between plys of product while keeping an eye on the cost of the improvement. Their current system was not only inaccurate, but also scanning very slowly. The customer also complained that their automatic profile control (APC) never worked correctly and was removed years ago.

Quad Plus Solution

The Quad Plus team started with a thorough analysis of existing equipment and careful consideration of the paper mill’s customers. Our experts have years of experience sizing the coordinated drives of a paper machine according to TAPPI standards, and our solution included sectionalizing the drives from the wet end to the reel and installed an AC coordinated drive lineup with a master controller supplied by the mill’s preferred PLC vendor.

We then provided a system to aid in the speed regulation of the entire machine and its various sections. With the addition of two HMIs (computer screens with graphical representations of the machine), operators could utilize a single, centralized location to monitor and control the process. To improve safety, we also added an additional I/O, safety processor, and safety-rated VFDs.

Before the upgrade, the speed and draws of the machine were performed manually by operators using potentiometers. By automating the line, the current workforce is able to focus on value-added areas rather than operation, and the younger, more inexperienced workforce can come on board as the automation helps to ease training concerns. Lastly, the line shaft and the DC motor replacement will help the mill enjoy less downtime for maintenance.

Meeting Market Demands

For most manufacturers, the demands of the market determine how your operations must be managed. When market demands exceed the capabilities of your equipment, it’s time for a change.

The Quad Plus team has years of experience working with manufacturers to make smart upgrades to get the most from their existing equipment while taking advantage of new technologies to improve productivity and remain flexible for the future.

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Please note you do not have access to teaching notes, economics of a nordic paper mill: case study.

Industrial Management & Data Systems

ISSN : 0263-5577

Article publication date: 2 February 2010

The purpose of this paper is to reveal how the prices, costs, and logistics develop in the case mill and how these variables correlate with profits, and finally to give suggestions for improvements.

Design/methodology/approach

A typical Finnish paper mill is selected for the basis of the case study. The complete data for the mill for the years 2001 to 2007 at a monthly level are used. The data are obtained from the mill's financial management system and transferred to Excel. Statistica 4.1 software is used to run the statistical correlation analyses. The results can be generalized with certain limitations to paper manufacturing located at a long distance from its customers.

This paper gives an important insight into the economics of the Finnish paper industry. From theory‐building point of view, the empirical process data show that the variation in production lines is minimal, but there are important variations in paper deliveries. A lot can be gained in the logistics processes. Larger volumes delivered in tons also tend to increase profits. From the mill to the consignees, fluctuations in the process and paper sales grow substantially, which indicates longer storage times.

Research limitations/implications

The results of the case study are based on the data of a single large integrated paper mill in Finland covering the years 2001‐2007, so the results cannot be directly generalized to concern all Nordic paper mills. In May 2005, there was an industrial blackout, which considerably affected the production and deliveries of all Finnish paper mills in that year.

Practical implications

The competitive advantages of the Finnish paper industry are undermined by low paper prices and costly logistics. The mill managers should increasingly focus on overcapacity and cost issues and also deliver volumes, which all could contribute to higher profits.

Originality/value

In this paper, the Finnish paper industry is studied through a time series, economic geography, and statistical tools. This approach is a novel method and gives new insights into this research object. The mill's economic variables, such as paper prices, profits, and logistics and manufacturing costs, and the characteristics of these issues in a spatial context are studied.

• Paper industry
• Distribution management

Hämäläinen, E. and Tapaninen, U. (2010), "Economics of a Nordic paper mill: case study", Industrial Management & Data Systems , Vol. 110 No. 1, pp. 5-23. https://doi.org/10.1108/02635571011008371

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Copyright © 2010, Emerald Group Publishing Limited

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INTRODUCTION

Methodology, results and discussion, conclusions and future perspectives, data availability statement, life cycle assessment of paper mill wastewater: a case study in viet nam.

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Hiep Nghia Bui , Yi-Ching Chen , Anh Thi Pham , Si Ling Ng , Kun-Yi Andrew Lin , Ngan Quang Viet Nguyen , Ha Manh Bui; Life cycle assessment of paper mill wastewater: a case study in Viet Nam. Water Sci Technol 1 March 2022; 85 (5): 1522–1537. doi: https://doi.org/10.2166/wst.2022.049

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Although in a critical position in the economy, the paper industry releases a lot of wastewater that requires adequate treatment for sustainable development. This study presents an application of Life cycle assessment (LCA) with the ReCiPe tool on the wastewater treatment plant (WWTP) of a paper factory in Vietnam to evaluate the environmental effect of the individual techniques in WWTP, especially the internal circulation (IC) reactor, a pioneer and practical anaerobic technology. Both Midpoint and Endpoint categories results demonstrated that chemical use and electricity consumption mainly contributed to the environmental impact in the WWTP. The Dissolved air flotation (DAF) and Moving bed biofilm reactor (MBBR) are classified as effective techniques to reduce the impacts on the environment. Moreover, the comparison of LCA between IC and up-flow anaerobic sludge bed (UASB) shows that IC is the better practically green technique for the environment.

Life cycle assessment was applied in a paper mill wastewater treatment plant.

Midpoint and Endpoint indicators were employed to evaluate environmental impact.

Two scenarios of electricity generating from biogas between Internal circulation and up-flow anaerobic sludge bed were investigated.

Chemicals use and energy consumption were determined to be the most factors to damage indicators.

Graphical Abstract

The pulp and paper mills are among the most critical industries in Vietnam. Approximately 300 pulp and paper mill factories have been established in Vietnam since 1920. The paper industry contributes around 1.5% of Vietnam's gross domestic product with over 1.97 billion $ in 2020 and is expected to reach 2.89 billion $ in 2026 ( ReportLinker 2021 ). However, it discharges large volumes of waste into the environment and is considered the third-largest industrial waste source in the world ( Liang et al. 2021 ). Afzal et al. (2008) indicated that each ton of produced paper releases approximately 60 m 3 of wastewater. The massive pulp wastewater contains a large number of organic and inorganic compounds expressed in high color, chemical oxygen demand (COD), biological oxygen demand (BOD), suspended solids (SS), xenobiotic compounds, heavy metals, and so on, which may cause long-term adverse effects on living creatures; therefore, wastewater treatment is needed to prevent pollution ( Tiku et al. 2007 ; Farooqi & Basheer 2017 ). Most pulp and paper mill treatment plants integrate an innovative biological treatment with physical or chemical to eliminate the wastewater's contaminants ( Liang et al. 2021 ). While physical or chemical units; that is, dissolved air flotation (DAF), sedimentation, oxidation tank, and so on remove most color, SS, heavy metals or decompose xenobiotic compounds in the wastewater, biological treatment is considered a key unit to eradiate organic compounds in the pulp and paper mill wastewater ( Farooqi & Basheer 2017 ). The conventional biological method in a paper mill wastewater treatment plant is an up-flow anaerobic sludge bed (UASB) reactor, which has a higher organic load rate (OLR) than aerobic techniques ( Larsson et al. 2015 ; Bakraoui et al. 2020 ). Larsson et al. (2015) had applied UASB to treat alkaline bleaching wastewater from a kraft mill. They stated that approximately 65% TOC was eliminated after 120 days of operation with OLR ranging from 0.9 to 2.2 g TOC/day and a stable treatment process was obtained at hydraulic retention time (HRT) of 7–14 h. While Bakraoui et al. (2020) engaged UASB to mitigate recycled paper mill wastewater in Morocco, this system eliminated around 80.6% COD with OLR ranging from 1.7 to 2.2 g VS/ day at HRT 15.14 h and operated for 130 days without any overload problems. Even UASB could be applied for treating the organic content of wastewater from paper mill plants; however, the exceptionally high organic content (over 20,000 mg/L of COD) in this wastewater had limited UASB systems ( Tiku et al. 2007 ). The high organic content in the influent required high OLR during the operational phase or required more area for bigger UASB to eliminate the wastewater; therefore, some improvement should be conducted in the UASB system to successfully treat pollutants from paper mill wastewater ( Ruan et al. 2017 ; Ha & Ha 2019 ). Recently, one of the successors to the UASB, the internal circulation (IC) reactor, has been developed to treat various high organic content influents such as refineries ( Wang et al. 2020 ), breweries ( Chen et al. 2021 ), dairy ( Charalambous et al. 2020 ), molasses ( Li & Li 2019 ) and paper mill ( Ruan et al. 2017 ). With two sets of separator modules and internal circulation as compared with one set of a separator of UASB, the granular sludges in the IC reactor could efficiently mix with and expeditiously dilute influent; therefore, the IC reactor could retain high biomass or operate at high OLR with low HRT that significantly improve the organic treatment performance compared to UASB ( Liu et al. 2020 ). Moreover, the IC reactor entails lower investment costs and requires less ground space; hence, the IC reactor has gradually begun replacing the UASB in the wastewater treatment field ( Ha & Ha 2019 ; Wang et al. 2020 ). Even there have been studies of IC reactors in some wastewaters ( Charalambous et al. 2020 ; Wang et al. 2020 ; Chen et al. 2021 ), the application of IC reactors on real paper mill wastewater treatment plants is still limited ( Ruan et al. 2017 ; Ha & Ha 2019 ).

Beyond the importance of technical feasibility, the environmental impacts of the treatment method should be evaluated to determine the practical application of these techniques. Recently, several studies have focused on life cycle assessment (LCA), an approach to qualify the environmental impacts of the wastewater treatment process in both design and operation phases; therefore, the application of LCA could reduce the adverse effects on the environment ( Corominas et al. 2020 ). Although some authors have given studies on the application of LCA in industrial wastewater treatment plants ( Naushad 2018 ; Tabesh et al. 2019 ; Corominas et al. 2020 ), there is only a few authors attempted on specific wastewaters such as petroleum ( Vlasopoulos et al. 2006 ), agro-industrial ( Chen et al. 2020b ) and olive mill ( Chatzisymeon et al. 2013 ). Up to now, there have been no previous LCA studies on paper mill wastewater treatment plants.

This work aims to evaluate the environmental impacts of a paper mill wastewater treatment plant in Vietnam using the ReCiPe, a harmonized life cycle impact assessment method at Midpoint and endpoint level ( Huijbregts et al. 2017 ). The scenarios of IC and UASB in anaerobic stages were also carried out to elucidate the environmental role of the IC reactor in the treatment plant.

The LCA was conducted according to the ISO14040-44 guidelines with four steps ( Klöpffer 2012 ). The assumptions and data are detailed in the following sections, starting with the goal and scope definition, the inventory analysis, the impact assessment and interpretation for treatment routes. The round outline of the LCA procedure in this study is displayed in Figure 1 .

The framework of the LCA performed in this study.

Goal and scope definition

This LCA study aims to assess the environmental benefits and drawbacks of a paper mill wastewater treatment plant (Ba Ria – Vung Tau Province, Vietnam). All effects of each treatment stage at the wastewater treatment plant (WWTP) and secondary emissions were valorized through chemical consumption and transportation. The comparison scenario between IC reactor and reference UASB at the anaerobic treatment unit was also investigated.

Functional unit

The daily average influent flow at the WWTP is 7,500 m 3 /d; therefore, the functional unit can also be converted to 1 m 3 of wastewater treated by a scaling factor of 1/7,500 ( Rebello et al. 2021 ).

Descriptive of influent characteristic

There are included two producing procedures in this mill paper factory; that is, testliner paper and tissue paper (Fig. S1). The full capacity of the paper mill could reach 2,73,000 tons of paper a year. Moreover, approximately 60% of ‘white water’ in the pulp washing influent is reused daily to save chemicals and water ( Hubbe 2007 ). Therefore, the influent's characteristic was varied compared to traditional paper mill factories and it was not suitable for applying to biological treatment directly (BOD 5 /COD ratio<0.3) ( Dubey et al. 2012 ). To eliminate the contaminants from this mill paper, the WWTP was built in 2018 based on the estimated flow rate of 17,000 m 3 /day and total COD (tCOD) of 15,000 mg/L to meet column A of Vietnam National technical regulation on the effluent of pulp and paper mills (QCVN 12:2015/BTNMT). After the acclimatization period, the soluble COD (sCOD) treatment capacity was always stable above 75% when the organic load fluctuated from 5 to 20 kg/m 3 /day. When the organic load is lower than 5 kg/m 3 /day, sCOD treatment efficiency will decrease gradually. The output sCOD of the IC system is the input of the moving bed biofilm reactor (MBBR) system. Usually, the MBBR inlet sCOD should be less than 1,000 mg/L for optimum performance ( Hansen et al. 1999 ). Therefore, IC systems are designed with loads of 15–18 kg/m 3 /day, with lower loads not taking full advantage of the system's capabilities. However, due to the covid-19 pandemic, the paper production is low and the organic load only reached an average of 10.5 kg/m 3 /day (approximately flow rate of 7,500 m 3 /day) with tCOD value of 7,000 mg/L since the beginning of 2021. Some other average influent components of the wastewater were tabulated in Table 1 .

Influent and effluent quality of the paper mill WWTP

a Vietnam National technical regulation on the effluent of pulp and paper mills, column A (QCVN12:2015/BTNMT), pH unit is not specific.

The wastewater treatment processes shown in Figure 2 include physical, chemical and biological treatments through primary and secondary treatment stages. While equalization is used to remove SS partially in the influent, the primary dissolved air flotation (DAF) tank have applied chemicals (mixed of Polyaluminium Chloride -PAC and Polyacrylamide -PAM) to eliminate most SS and insoluble COD. The key treatment function in this WWTP is the internal circulating anaerobic (IC) reactor, which degrades most soluble COD (the regular operation of HRT fluctuates about 4–5 hours with COD: N: P =800: 5: 1 pollutant ratio ( Li & Li 2019 ). This retention time is 2–4 times lower than that of a traditional UASB tank ( Chen et al. 2020a ; Liu et al. 2020 ). According to operational data from the WWTP, this IC reactor solely eliminates approximately 77% of sCOD from the influent before it lets in another biological unit, aerobic activated sludge (MBBR), which could remove 82% of the remaining sCOD. The wastewater then goes to the final DAF to separate the activated sludge; the sludge-free wastewater is disinfected and finally filtrated by a pressure filter before reusing or discharging to the environment. The treatment performance of each mentioned stage is listed in Table S1.

The schematic flow diagram of WWTP and its system LCA boundaries (upper) with two comparison scenarios IC and UASB at the anaerobic treatment system (lower). The colored lines represent the input chemicals (red), sludge flow (orange), energy-saving (green), electricity flow (blue), and wastewater and emissions (black), gas flow (pink). Please refer to the online version of this paper to see this figure in colour: http://dx.doi.org/10.2166/wst.2022.049 .

System boundaries

In the WWTP, there are three processes; that is, construction, operation, and demolition, which could embody high energy and material consumption and fugitive emissions. In this study, construction and demolitiion impacts were not included in the boundaries since there was insufficient data. As such, this was a gate-to-gate study beginning with the entry of wastewater into the primary dissolved air flotation (DAF) and ending with the effluent after pressure filter ( Figure 2 ). In this case, the assumption is that the process inputs are stable, the pollutants are different according to COD removal efficiency, and the WWTP's electricity is supplied from the government grid. The sludge from the physical and the biological units is collected, dewatered, and dried before transferring to the local sludge incineration company. The incineration process

achieves a complete stabilization of the sludge and delivers thermal energy and a solid residue in ash; subsequently, the sludge is involved in LCA calculation at the Midpoint. Moreover, a UASB operating scenario instead of IC in the biological unit is calculated and compared through the environmental impacts and the conversion of biogas generated into electricity to highlight the IC performance.

Life cycle inventory

Following the goal and scope step, a life cycle inventory analysis was performed regarding all the energy, chemicals, and materials flows into or out across the system boundaries. In this study, the database on several processes such as power generation, chemical production, transportation, etc. was taken from Ecoinvent 3 ( Raghuvanshi et al. 2017 ), while remaining wastewater treatment stages, i.e., UASB, IC, MBBR, etc. which could not find from the tool were retrieved from EMEP standard ( Adams et al. 2013 ) or provided from WWTP source data and lab analysis.

The energy was inventoried through the form of electricity, which involved total purchased electricity from the Vietnamese national grid, power consumption of main equipment and generation of biogas (mostly CH 4 ) to heat and energy (CHP) from anaerobic digestion (IC or UASB) every day. The biogas emissions are determined using a flowrate measurement controlled by SCADA software and stored at a balloon gas tank. Approximately 12,000 m 3 biogas emissions come from the WWTP every day. According to research by Carnevale & Lombardi (2015) , the power generation efficiency of CHP is about 32% and generates about 2.1 kWh of electricity for every cubic meter of biogas. In addition, they also assume that 1% CH 4 will be lost from the engine and emission air NOx, SO 2 , PM and CO of 1.89, 0.00638, 0.0191 and 0.829 g per cubic meter of biogas, respectively.

Chemicals used as coagulants, flocculants, nutrients or disinfectants in the WWTP were determined and the secondary impacts from these chemicals were also assessed using the Ecoinvent database ( Raghuvanshi et al. 2017 ). All used chemicals are produced by the same plant, located 42 km from the WWTP. The dewatered sludge (approximately 3 tons/day) was collected and burned at a local sludge incineration company far away (30 km) from the WWTP. The transportation of chemicals and the sludge was carried out by lorry with a capacity of 16 tons with Euro 4 emission standards, while the transportation background data were also analyzed using this Ecoinvent database. The inventory database of this study since the beginning of 2021 is summarized in Table 2 ( Akbarjon et al. 2019 ). The Covid-19 pandemic has interfered with the regular operation of the WWTP; therefore, it could not operate at full capacity, which could lead to a slight difference in wastewater or dewatered sludge characteristics.

Summary of LCI of WWTP per functional unit

‘–’: nonapplicable.

This Life Cycle Impact Assessment (LCIA) step identifies and describes the environmental relevance and significance of the treatment system through the input and output data from the previous LCI process. Before analyzing, the collected data were classified into different categories (impact categories) according to their environmental contribution ( Pennington et al. 2004 ; Ahmed 2010 ) by several widely standardized methods; that is, CML-IA, TRACI, ReCiPe, IMPACT 2002+, Eco-Indicator99, etc. ( Hauschild et al. 2018 ). Unlike the CML-IA methods, TRACI focuses on assessing the environmental impacts at the middle stage through different individual influences (Midpoint). Then typical techniques such as IMPACT 2002+, Eco-Indicator99, evaluate environmental impacts through groups of end effects (endpoints) attributed or calculated from individual impacts ( Hauschild et al. 2018 ). Regarding the choice of LCA method, CML-IA is the widely used LCA model, one of the oldest and most popular methods and it is still one of the preferred approaches. However, if research is directed towards applying the endpoint approach, this method is not suitable, especially when applied to WWTPs. Also, note that the ReCiPe method comes in second position (Fig. S2). The method dominantly reflects the environmental impact of WWTP both at the middle (Midpoint) and the end (Endpoint), based on CML-IA and Eco-Indicator99 ( de Oliveira Schwaickhardt et al. 2017 ; Lutterbeck et al. 2017 ). Therefore, the ReCiPe method with midpoint version 2016 (H) was implemented to evaluate the environmental impact of this WWTP. This method categorized LCI data into two main groups: the potential impacts (Midpoint) and the potential damage (Endpoint). The Midpoint category involved 18 environmental impacts such as Global warming (GW), Stratospheric ozone depletion (SOD), Ionizing radiation (IR), Ozone formation – Human Health (OHH), Fine particulate matter formation (FPMF), Ozone formation-Terrestrial ecosystems (OTE), Terrestrial acidification (TA), Freshwater eutrophication (FE), Marine eutrophication (ME), Terrestrial ecotoxicity (TET), Freshwater ecotoxicity (FET), Marine ecotoxicity (MET), Human carcinogenic toxicity (HCT), Human non-carcinogenic toxicity (HNT), Land use (LU), Mineral resource scarcity (MRS), Fossil resource scarcity (FRS), Water consumption (WC). At the Endpoint, the final three impact categories are Human health (HH), Ecosystems (E), Resources (R). Figure 3 illustrates the categories and pathways of action covered in the ReCiPe methodology in this study. Midpoint indicators focus on individual environmental issues, such as climate change, eutrophication. Endpoint indicators show environmental impact across the three higher aggregate levels. Converting the Midpoint to the Endpoint simplifies the interpretation of the LCIA.

Representation of the relationships between impact categories (Midpoint) and the areas of protection (Endpoint) in ReCiPe 2016.

Interpretation

This is the final phase of an LCA study in which the results are presented. Thereby, the main types of impacts selected to replace or minimize are presented. Interpretation involves consideration of all stages of the LCA. From there, the quality of the data and the consistency of the hypotheses can be checked. Two of the three principal steps of the interpretation according to the ISO 14043 standard are identifying critical issues based on the inventory and LCA impact assessment stages, testing and conclusions, recommendations, and reporting ( Ahmed 2010 ).

Mid assessment

The environmental impacts at 18 different categories for the WWTP processes at individual components are described in Figure 4 . For most types of effects, the primary DAF stage is the predominant factor. The primary DAF was used in WWTP of the paper industry to eliminate the high SS content in the influent; however, the process consumes a lot of electricity and chemicals. Therefore, the primary DAF should be the most critical indicator for environmental evaluation ( Sharaai et al. 2009 ). Related to eutrophication impact, the sterilization phase contributes 70.36% for all the stages, proving the critical roles of the WWTP process in disinfecting and reusing the wastewater. However, the most identified stratospheric ozone depletion and water consumptions are 89.79% and 63.62% for the IC process. The findings could be explained that a high amount of nutrients is required and high sludge generation during the IC phase could increase the water consumption for nutrient production and stratospheric ozone depletion from handling and decomposing the generated sludge ( Yang et al. 2020 ). The environmental impacts of each treatment stage can be shown in Table 3 and Fig. S3.

Midpoint environmental impacts in various phases of the WWTP

The contribution of each activity to the environmental impact indicators midpoint.

Primary DAF stage

According to Figure 4 , primary DAF accounts for a relatively large proportion of factors affecting the environment in the WWTP. More than 80% of the primary DAF effect comes from the used chemicals (PAC and PAM), while electricity only accounts for approximately 15%. The primary DAF itself affects land use with only 47.4% contribution ( Figure 5 ). The significant impact of the DAF process may come from the emissions in the production of chemicals and energy ( Sharaai et al. 2009 ). Although in the previous studies, it was presented that DAF will create many impacts on the environment, actually, the DAF technique was comprehended compared with the ultrafiltration (UF) membrane technique.

Most significant processes for environmental impacts during the primary DAF process.

The effect of the IC process on the environment in WWTP can be depicted in Figure 6 . The most influential factors to the environment could be determined as the used chemicals (NaOH, Diammonium Phosphate and Urea) for the anaerobic process. The start-up of the IC reactor requires a lot of nutrients (Diammonium Phosphate and Urea) to cultivate anaerobic bacteria that form granular sludges and release organic acid that has to be controlled by dosing NaOH ( Charalambous et al. 2020 ; Wang et al. 2020 ; Chen et al. 2021 ). This chemical consumption accounts for approximately 60% of the environmental impact of the IC process, while the IC stage only significantly contributes to land use, global warming, and stratospheric ozone depletion. High greenhouse gas emissions could be explained by these contributions (approximately 27%) during anaerobic treatment and the land for building IC systems or capturing gas. The significant effect of the greenhouse gas from the anaerobic process on the environment has been mentioned elsewhere ( Lopes et al. 2018 ; Gallego-Schmid & Tarpani 2019 ).

Most significant processes for environmental impacts during the IC process.

MBBR is a biological treatment that uses plastic carriers covered in biofilm to decompose waste with aeration conditions. In this process, the bacteria consume oxygen, while a large amount of N 2 O is released from denitrification ( Sabba et al. 2018 ). Revell et al. (2012) stated that N 2 O is the essential ozone-depleting gas. This is in line with our findings in Figure 7 ; MBBRs contribute approximately 74.04% to stratospheric ozone depletion, are dominant (79.86%) in land use and contribute in a minor way to global warming (0.21%). Surprisingly, the highest impact on the environment at the MBBR stage is the power consumption for generating and distributing oxygen in the systems. High electricity consumption in the MBBR process was also obtained by Teow et al. (2021) in a palm oil mill WWTP.

Most significant processes for environmental impacts during the MBBR process.

Secondary DAF stage

In the WWTP, the secondary DAF plays a role in removing decayed or excess sludge generated from previous biological treatment units. This process used the same equipment and chemicals as primary DAF. It is not surprising that the chemicals (PAC and PAM) are the greatest environmental impact followed by electricity; in contrast, transportation is considered neglectable environmental impact ( Figure 8 ). The secondary DAF only significantly causes land use (51.8%) due to the high required area for operating ( Sharaai et al. 2009 ). However, compared with primary DAF, the percentage contribution of chemicals in the DAF process is slightly lower and the energy consumption is a little higher. The results may come from the lower pollutant concentration, especially SS in the effluent of secondary DAF and, therefore, a reduction in chemical usage.

Most significant processes for environmental impacts during the secondary DAF process.

Disinfection stage

The disinfection in this WWTP is required for effluent wastewater to reach as defined by the WWTP safely. This process applied the most widely used disinfectant, sodium hypochlorite (NaOCl), as a disinfectant to eliminate viruses, bacteria, fungi or mycobacterium. The concentration of 0.008 mg/L of NaOCl was directly injected into the disinfection tank and mixed by continuous pumping. Major percentage contributors to the environment are NaOCl, electricity production followed by the transportation and disinfection stage ( Figure 9 ). However, the predomination of disinfection stage to freshwater eutrophication (98.77%) could be related to the untreated nutrients, which cause eutrophication, as mentioned by Remy et al. (2014) .

Most significant processes for environmental impacts during the disinfection process.

Endpoint damage indicator

At this stage, the results of the mid-point indicators are combined using the ReCiPe Endpoint (H) V.1.11 tool to address three distinct areas of protection (Endpoint indicators); that is, human health, ecosystems and resources. Figure 10 describes the results of three Endpoint effect indicators for all treatment processes divided into chemicals, electricity, transportation, and self effect in WWTP. As seen in Figure 10 , the highest impact contributor in the WWTP was Human health, which accounted for 116.95 mPt, followed by Ecosystems (9.76 mPt) and Resources (0.99 mPt). The dominant impact of Human health is mainly associated with the use of chemicals (75.33 mPt) and electricity (31.9 mPt); the contribution of the technology's characteristics and transportation are insignificant (below 10 mPt).

Endpoint assessment results of chemicals, energy, technology and transportation operating from WWTP.

The highest impact of chemicals and electricity on human health or the environment could be confirmed in Figure 11 , which displays the contributions of the different treatment processes in the WWTP regardless of the impact category. Most chemical and electricity consumption is attributed appreciably to DAFs, IC and MBBR, while the disinfection stage has a minor contribution to the overall impact. These results reflect the primary function of the WWTP, which is the eliminating of SS and organic pollutants in the influent. As presented in Fig. S4, as much as 48.62% of chemicals and 62.38% of electricity are attributed to primary DAF and MBBR, respectively. This finding suggests the improvement or change of these techniques could reduce the total environmental impact of WWTP. Moreover, the high share of these environmental impacts ( Figure 11 ) and a moderate contribution to chemicals and electricity consumption (Fig. S4) of the IC phase represents a suitable technique to paper mill WWTP, as stated in many previous studies ( Ruan et al. 2017 ; Ha & Ha 2019 ).

Endpoint assessment results in the different stages of WWTP.

IC and UASB scenarios environmental analysis

To evaluate how the results changed by using the traditional UASB treatment process, mid-point indicators at two scenarios with electricity generated directly from the biogas, are shown in Table 4 and Fig. S5. According to the table, both IC and UASB have positive contributions (negative values) on five environmental indicators: fine particulate matter formation, terrestrial acidification, human carcinogenic toxicity, human non-carcinogenic toxicity and fossil resource scarcity. These occurred due to the anaerobic bacteria growth stage in both IC and UASB using wastewater, reducing the pollutants and releasing green energy, then decreasing the impacts of these 05 life cycle indicators ( Yang et al. 2020 ).

Mid-point impact indicators per m 3 wastewater for the two scenarios

However, both techniques have caused environmental damage (positive values) in stratospheric ozone depletion, ionizing radiation, freshwater eutrophication, terrestrial ecotoxicity, mineral resource scarcity and water consumption due to the required nutrients, minerals for growing bacteria and also release greenhouse gas which impacts toward to these categories. The advancement of IC compared to UASB techniques is clearly evidenced in the seven remaining indicators (global warming, ozone formation- human health, ozone formation- terrestrial ecosystems, marine eutrophication, freshwater ecotoxicity, marine ecotoxicity and land use). IC is characterized by a lower environmental impact (negative values) than the UASB (positive values) in all these indicators. A possible explanation of this discrepancy finding is two reasons. Firstly, IC has a higher treatment capacity than UASB, as the same conditions of this WWTP, IC generates approximately 7,895 m 3 biogas/day ( Driessen et al. 2000 ) as compared with 6,090 m 3 biogas/day of UASB ( Metcalf et al. 2004 ); the biogas could become energy (3,088 kWh and 2,382 kWh for IC and UASB, respectively); therefore, IC could hugely reduce the energy or reduce the global warming, ozone formation- human health, ozone formation- terrestrial ecosystems ( Driessen et al. 2000 ; Zhang et al. 2015 ). Secondly, both IC and UASB are anaerobic techniques; however, the chemical balance for COD: N: P in IC is 800:5:1 while UASB is 350:5:1, which means the IC process uses fewer chemicals with lower HRT compared to UASB. Arshad et al. (2011) and Ali et al. (2009) also emphasized that IC has efficient mixing, which reduces the HRT 4 times and with organic loading six times higher than UASB. The above explanations imply less land use and marine eutrophication, freshwater ecotoxicity, and marine ecotoxicity and even give the green effect to these indicators of IC technique.

This work presented an environmental assessment of a paper mill wastewater treatment plant (WWTP) in Vietnam. Midpoint and Endpoint assessments by ReCiPe 2016 were applied to measure environmental indicators of the WWTP. The obtained Midpoint results indicated that the DAF and IC phase's chemical use and energy consumption were key contributors to the total impact category. Among the categories, terrestrial ecotoxicity carried the majority impact in this 5.786 kg 1,4-DCB/m 3 wastewater, followed by Human non-carcinogenic toxicity and Global warming with 2.61 kg 1,4-DCB/m 3 wastewater and 2.068 kg CO 2eq , respectively. The DAF was also the most significant phase impact to three Endpoint categories (44.02 mPt). Moreover, the DAF's chemical use was still the highest contribution to the three Endpoint categories with 80.02 mPt. MBBR was determined as the highest energy consumption (62.38%), which significantly contributed to human health indicators (31.90 mPt). The comparative scenario between IC and UASB (a traditional anaerobic technique) revealed that UASB carries the most significant impact as compared to IC by all the categories. The IC technique even contributes negatively impacts (greener technique) to seven categories within 18 Midpoint categories. These findings highlighted the efficiency of IC on the environmental aspect for this kind of high organic pollutants as paper mill wastewater. The limitation of this study lies in the inventory data; Vietnam does not have the LCIs. The European and OECD data used may not represent 100% LCA cases in other region-specific locations. More system improvement should focus on biological and physical techniques to reduce contaminant and power consumption.

All relevant data are included in the paper or its Supplementary Information.

Supplementary data

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CASE STUDY: LOUISIANA PAPER MILL RECOVERY OF VALUE STREAMS

DOWNLOAD CASE STUDY

The monitoring system was installed on the effluent of primary clarification. The solution included calibrations for BOD and black liquor, as well as other materials and compounds including white liquor, weak wash, soap, tall oil, turpentine, and foul condensate Real Tech’s most robust primary wastewater-grade system was selected for the site to cope with the harsh primary effluent wastewater conditions and Real Tech’s high-resolution UV-VIS PL-Series sensor was used to obtain the data needed for accurate and reliable parameter and contaminant calibrations.

The system continues to learn the mill’s effluent, adding more strength to the calibrations and confidence for the plant over time. As the mill experiences new events, event time and characteristics information is relayed to Real Tech. This information is then matched with the sensor’s real-time data and used for improving the event detection algorithms employed. Once installed and commissioned the system delivered continuous information to the mill on BOD and black liquor spill events, alarming when set concentrations are exceeded. By implementing real-time monitoring, the plant was able to see results in two key areas:

Recovery of Value Streams

Site specific thresholds for black liquor have been established and real-time information is relayed from the Real Tech system to a graph on the operator’s screen. This allows staff to track and monitor effluent loading, alarming when problems arise, or upsets occur. Providing an early warning allows the operators to respond to events in a timely manner and reduce black liquor loss to drain.

Process Optimization

The real-time BOD information captured by the monitoring system is used to supplement data collected from DO probes in the aeration basins. This way the plant is able to confirm the required aeration rate from two independent sources, which increases the operator confidence. In addition, when high BOD loads are detected, upstream processes are investigated for potential upsets which expedites decision making for corrective action. The real-time BOD data is also used to aid in nutrient dosing optimization for an effective biological treatment in the aeration basins.

Paper and pulp sludge dewatering

An introduction to this case study.

The global production of paper was 400 million tons in 2015 and is expected to reach 550 million tons in 2050. About 40–50 kg of sludge (dry) is generated in the production of 1 ton of paper at a paper mill. Various wastes are generated in pulp and paper mills, such as ash, dregs, grits, lime mud and pulp mill sludge. Traditionally, these wastes were typically sent to landfills or incinerated. This type of disposal can have a significant impact on the environment, damaging the water, soil, and air. The way we can assist the industry is by using the Fournier Rotary Press TM dewatering technology to treat the sludge in such a way that it can be used to create new value-added products.

Technologies used in this case study:

• Dewatering technology

Look at how we deal with the following challenge:

1. Paper and pulp sludge dewatering

‍ Challenge: ‍

Paper and pulp mills generate various types of sludge that result from wastewater treatment procedures used in the mills: primary sludge (fibre sludge), biological sludge, mixed sludge, de-inking sludge, hydroxide (chemical precipitation) sludge and coating sludge.  

The first step in the management of paper and pulp sludge is the separation of the sludge into liquid and solid fractions. For many years the belt press and the screw press have been the standard sludge dewatering devices in the paper industry.

However, the environmental legislation of recent years has forced many mills to install secondary or biological treatment for the wastewater to reduce trade effluent charges by reducing chemical oxygen demand (COD) levels.

The addition of surplus biological sludge to the primary sludge for dewatering can be problematic for the belt press and the screw press.

Solution: ‍

Sinowatek offers a dewatering method to reduce the moisture content of the cake. This presents options in terms of handling the solids in boilers, landfill, or new products. ‍

When using the Fournier Rotary Press TM dewatering technology the high capture rate of solids results in a relatively clean filtrate (low TSS) that allows water to be treated effectively for release or reuse.

Benefits for the client: ‍

• Sinowatek offers full-scale pilot testing of the Fournier Rotary Press TM . The 6 m containerized unit is quickly connected to the client’s source of sludge to give real-time results.
• By having access to real on-site results the risk of non-performing capital purchase is eliminated.
• Accurate production figures per channel are obtained from the test. This allows for accurate sizing of equipment with the correct number of channels.
• For possible future expansion, a press can be ordered with extended shafts to accommodate up to 8 channels.
• The Fournier Rotary Press TM is tolerant of feed sludge concentration changes.
• Modularity, interchangeable channels, and the ability to expand capacity by adding single channels are attractive from a capital investment standpoint.
• Quiet operation, effective containment of odour and suitability for automation with an unattended operation are big advantages.
• High performance, easy operation, reduced polymer usage, low power consumption and low maintenance.
• An automated 5 min self-cleaning procedure ensures a 24-hour continuous operating cycle.

Let's talk  about your specific challenges in this field.

At Sinowatek we apply our comprehensive engineering, business, and management skills to enable producers to change to more sustainable production practices.

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High Pressure Grinding Roll and Magnetic Separation for Energy Saving in Grinding and Simultaneously Improving Processing Capacity: A Case Study of a Magnetite Ore

• Published: 31 May 2024

Cite this article

• Jianwen Yu 1 , 2 , 3 ,
• Yaxiong An   ORCID: orcid.org/0000-0002-6310-7644 1 , 3 ,
• Peng Gao 1 , 2 , 3 &
• Yuexin Han 1 , 2 , 3  

This paper presents an industrial verification test, adding a high pressure grinding roll and magnetic separation operation after the third-stage fine crushing operation to reduce the particle size of ball mill feed and improve the processing capacity of grinding operation. The optimal process parameters of high pressure grinding roll and magnetic separation were determined to be a 10 mm of roller surface spacing, a 10.5 Mpa of roller surface pressure, a 14 r/min of roller surface speed, a particle feed size to the magnetic separator of P 100 3 mm, and a 3000 Oe of magnetic field intensity. Under the above optimized conditions, the iron grade of magnetic pre-enriched concentrate increased significantly from 28.27% to 36.30%, and the iron recovery was 87.59%. Meanwhile, the yield of coarse tailings was 36.16%, which significantly reduced the amount of ore entering the subsequent ball mill-magnetic separation operation. The ball mill Bond work index W ib of raw materials and the pre-enriched concentrate were 11.76 kW•h/t and 10.46 kW•h/t, respectively. The relative grindability of the pre-enriched concentrate was increased by 34%.

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The authors were grateful for the funding provided by the National Natural Science Foundation of China (Grant No. 52074067, 51974063, 52130406).

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Jianwen Yu, Yaxiong An, Peng Gao & Yuexin Han

State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang, 110819, PR China

Jianwen Yu, Peng Gao & Yuexin Han

National-Local Joint Engineering Research Center of High-Efficient Exploitation Technology for Refractory Iron Ore Resources, Shenyang, 110819, PR China

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Yu, J., An, Y., Gao, P. et al. High Pressure Grinding Roll and Magnetic Separation for Energy Saving in Grinding and Simultaneously Improving Processing Capacity: A Case Study of a Magnetite Ore. Mining, Metallurgy & Exploration (2024). https://doi.org/10.1007/s42461-024-01015-0

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The eyebrow-raising legal theory behind Alvin Bragg’s case against Trump

It took a jury two days to find former president Donald Trump guilty of all 34 counts of falsifying business records in the first degree, proving that Manhattan District Attorney Alvin Bragg's somewhat risky approach to prosecuting the hush money case was a sound choice.

Soon after Bragg's office brought the first indictment against Trump in April 2023, three other felony indictments were returned in three other jurisdictions: Florida, Georgia and the District of Columbia. As the cases wound their way through their respective state and federal court systems, the expectation was that Trump’s D.C. federal election interference case would go to trial before any of the others. Many were therefore surprised when it was announced that Bragg’s case would be the first to go. And the (somewhat delayed) scrutiny into the New York election interference case kicked into overdrive.

It’s the added element of the “another crime” that raised eyebrows.

When the indictment was unsealed in April 2023, it revealed 34 felony counts of falsifying business records in the first degree, in violation of New York Penal Law, Section 17-152. It’s important to take a minute to digest what the prosecution had to prove, beyond a reasonable doubt: Trump, with the intent to defraud, made (or caused to be made) false entries in an enterprise’s business records, and his “intent to defraud included an intent to commit another crime or to aid or conceal the commission thereof.” What is the other crime that the prosecution said Trump intended to commit or to aid or conceal the commission of? According to Assistant District Attorney Joshua Steinglass, that would be New York Election Law Section 17-152: “Conspiracy to promote or prevent election. Any two or more persons who conspire to promote or prevent the election of any person to a public office by unlawful means.”

The Manhattan DA’s office has prosecuted a number of falsification of business records cases. These are usually straightforward, run-of-the-mill paper crimes. Bragg has even referenced them as the “bread and butter” of his office’s white-collar work. But it’s the added element of the “another crime” that raised eyebrows. And this is the heart of the novel legal theory that Bragg chose to employ in this trial. The Washington Post reviewed the New York State Law Reporting Bureau as far back as 2000 for any relevant case law regarding this specific statute. The report found “two entries in which a judge issued legal opinions on the statute. Both were from [Judge Juan] Merchan last year   in rejecting Trump’s motions to have the case dismissed.” That’s how rarely Section 17-152 is prosecuted in New York. And that fact makes Bragg’s decision to primarily premise the prosecution of a former president of the United States on that statute even more novel.

Bragg is an experienced prosecutor. He graduated from Harvard Law School, clerked for a federal judge, worked in the New York attorney general’s office as a federal prosecutor in the Southern District of New York, and was a law professor at New York Law School. While at the SDNY, his case focus was on fraud and money laundering cases, as well as public corruption. He knows his way around the courtroom and is no stranger to Trump prosecutions: He led the team at the AG’s office that successfully prosecuted the Trump Foundation, for which it was dissolved and Trump made to pay $2 million in restitution. 

Bragg had the right combination of book smarts and street smarts to bring this indictment against Trump, and the wisdom to see this case for what it truly was. In an interview with WNYC , he declared: “The core is not money for sex. ... it’s about conspiring to corrupt a presidential election.”

As you may recall, Bragg’s predecessor, Cyrus Vance Jr., began investigating Trump as far back as 2019. Vance has advised that his investigation began in and around the same time as that of the Southern District of New York. In fact, he says that the SDNY told him to stand down, which he did for over a year. Vance ultimately decided not to prosecute Trump — or any of his confederates — on any charges. One reason : due to concerns about “novel issues around using the false statements statute in connection with committing a crime that violates federal election laws.” Vance did indict, in July 2021, former Trump Organization CFO Allen Weisselberg, the Trump Corp. (doing business as Trump Organization) and the Trump Payroll Corp. (doing business as Trump Organization) on, among other offenses, charges of criminal tax fraud, grand larceny and falsification of business records in the first degree. That prosecution resulted in a guilty plea to perjury from Weisselberg and a guilty verdict after trial for the remaining defendants.

Initially, Bragg, himself, showed doubts about pursuing a prosecution.

Initially, Bragg, himself, showed doubts about pursuing a prosecution. Two top prosecutors, Carey Dunne and Mark Pomerantz, who were brought in by Vance to run the Trump investigation and stayed on when Bragg took the reins, abruptly resigned in early 2022 . Pomerantz, in his resignation letter that was made public , harshly criticized Bragg for his inaction. Pomerantz said in the letter that he believed that Trump was “guilty of numerous felony violations” and that Bragg’s decision not to prosecute Trump was “contrary to the public interest.” Fast-forward 13 months, and Trump was indicted by Bragg.

The inside baseball on prosecuting cases is that even if the facts meet all of the elements of the crime, and even if there is a good faith basis to prosecute, that doesn’t necessarily mean there aren’t other factors considered before deciding to move forward with a case. Part of that calculation includes a likelihood of success with a jury. In this instance, Bragg and his prosecution team must have considered if there was a chance of jury nullification and if the jury would be able to understand the theory of the prosecution and care enough about this case. With a guilty verdict now reached, I guess we know the answer.

Katie S. Phang is the host of "The Katie Phang Show," which airs Saturdays and Sundays at 8 a.m. ET on MSNBC. She is a legal contributor for NBC News and MSNBC based in Miami. She leverages her significant trial attorney experience to provide analysis and commentary on the latest legal issues.