Aquaflow - Minimising environmental impacts with cutting-edge effluent treatment

A new wastewater treatment plant is currently underway at Metsä Fibre's Kemi Bioproduct Mill, Finland
Successfully introducing new and more sustainable water treatment technology and processes to the bioproducts industry requires more than technical expertise. “You need trust”.
Mikko Lonka
Sales Director of Aquaflow.

Building Trust in Bioproducts

For the pulp, paper, and related bioproducts industry, system reliability is simply non-negotiable. Guaranteed reliability is of primary importance and is the key deliverable for enterprises that supply the sector. In the pulp and paper industry, even short stoppages may cost millions of euros, and processes and equipment must deliver on promises of extremely high availability. At the same time, resource-intensive sectors like pulp and paper are under increasing pressure to modernise, reduce their environmental impact and become more sustainable. This requires adopting strategies consistent with the circular economy in order to minimise the consumption of raw resources like water and energy.

For Finland-based Aquaflow, Veolia’s Technology Center for pulp and paper industry effluent treatment, bringing new technologies to market starts with proven results. Aquaflow works in collaborative industry partnerships with pulp mills, pulp line main suppliers, R&D institutes, and universities as part of its R&D programme to build the data that in turn allows customers a high degree of confidence. Alongside intensive R&D with the supply chain and customers, active in-house research - as well as in partnership with academic institutions - is key to introducing new ideas and process developments. Even the continuous process of fine-tuning existing systems requires ongoing research and development activities.

However, equally important to a successful industrial partnership is extensive experience in the pulp and paper industry. Aquaflow engineers are fully conversant with the relevant technical terms and expressions and understand the production processes and the sources of different effluent fractions. This intimate sector knowledge extends to elements such as the main wood species and raw materials, and the details of pulp and bleaching processes. That knowledge allows the company to invariably make optimal technology choices for any particular process and feedstock. With its extensive portfolio of tailored pulp and paper industry processes and equipment, is it possible to select the most appropriate process and equipment while taking into account specific demands and local climate conditions.

The Kemi Bioproduct Mill

A breakthrough project highlighting these capabilities is currently underway at Metsä Fibre’s Kemi bioproduct mill project in northern parts of Finland near the Swedish border. This EUR 2.02 billion project is being built to replace an existing pulp mill that has reached the end of its service life. The new mill will produce 1.5 million tonnes of softwood and hardwood pulp a year, as well as many other bioproducts. It will use approximately 7.6 million m3 of pulpwood a year, 4.5 million m3 more than the current pulp mill in Kemi. The new bioproduct mill will be started-up as planned in the third quarter of 2023. In addition to pulp, it will produce other bioproducts from side streams such as tall oil, tree bark, as well as products like sulphuric acid. 

Under the terms of a detailed delivery contract between Metsä Fibre and Aquaflow, a new wastewater treatment plant is being developed at the site which features Aquaflow’s proprietary multi-stage biological treatment process and which is followed by a further chemical treatment process. 

The wastewater treatment plant represents even more advanced technology than required by BAT (Best Available Technique) standards and helps to ensure that we will achieve the best environmental performance possible, whatever the conditions, says Jari-Pekka Johansson, Project Director, Metsä Fibre.

Aquaflow also delivered the wastewater treatment plant of Äänekoski bioproduct mill which began production in 2017. The plant in Kemi is implemented with equivalent technology. 

We have brought the good experiences achieved with a skilled partner from the Äänekoski bioproduct mill project to Kemi and we are going to achieve ambitious environmental targets, adds Johansson.

Aquaflow’s multi-stage biological treatment process (MBP)

The Aquaflow’s multi-stage biological treatment process (MBP) is the most economical and environmentally friendly way to reduce effluent loads like COD and BOD and uses a wider, more diverse population of biological elements and a longer food chain than normally seen in effluent treatment plants. The organisms include bacteria but also higher multi-cellular organisms that allow the best approach for a particular wastewater stream to be deployed as required. This aerobic process creates lower levels of suspended biomass solids than a conventional system and they settle easily in the secondary clarifier. The procedures produce fewer biosolids, which contain less water than other approaches and hence require fewer chemicals, dewatering, and energy to dispose of.

Following the biological treatment, Aquaflow’s AF-Float chemical tertiary treatment process is used to remove hard COD, phosphorus, color, etc. AF-Float process includes many in-house developed equipment and component which reduces the chemical volumes needed to get the best possible treated effluent quality. The heart of the process is the tailor-made Dissolved Air Flotation (DAF). 

The AF-Float tertiary treatment process is designed especially for the pulp and paper industry with large flows and high loads. 

Minimising Environmental Impacts with Cutting-Edge Effluent Treatment

Once operational the plant will treat the entire effluent from the bioproduct mill in a continuous operation with guaranteed extremely high availability. While the mill is being built using the Best Available Techniques (BAT) the wastewater treatment plant goes even beyond that high standard and is designed to minimise environmental impact, energy use, and material efficiency.
Wastewater discharges are minimised primarily by closing the water cycle as much as possible and as part of its environmental efficiency, some of the treated effluents will be returned to the plant for use in the process. In the Metsä Fibre Kemi bioproduct mill, the nominal water consumption is less than half that of existing pulp mills. This represents significant savings on the core process water use but also on the water treatment side where effluent volumes are far lower. The advanced wastewater treatment process means the Kemi mill will have an extremely low burden on the waterways and is considered exceptionally low by both Finnish and international standards. Indeed, despite the significant increase in production, the new bioproduct mill will have very low discharge.

Furthermore, as an example of Metsä Group’s commitment to sustainability, the bioproduct mill will not use any fossil fuels as it will produce around 2 TWh of renewable electricity per year. Mill’s electricity self-sufficiency is 250% and it produces roughly 2.5% of the total national electricity use.


Building Sustainable Processes on Trust

With the availability of these much more efficient effluent treatment processes, the development of similar parallel projects in the future is anticipated as bioproduct mills look to reduce their environmental footprint and existing assets reach the end of their service life. The 2020 delivery contract for the effluent treatment system at Kemi follows the delivery of the wastewater treatment plant at the Äänekoski bioproduct mill which began production in 2017. 

Improving sustainability and reducing water consumption while simultaneously increasing throughput is the goal, but introducing new processes demands a trusted partner that can prove exceptional reliability. For Aquaflow, this extends beyond R&D, reams of reference projects, and solid results. It also includes experience in project execution and a specific approach to this key industry that has been developed and fine-tuned over decades. We speak the same language and, above all else, that means peace of mind.