Veolia to treat a 3-million-person wastewater load at Arauco's Brazil pulp mill

Arauco is developing Sucuriú, a US$4.6 billion pulp mill in Inocência, in Brazil's Mato Grosso do Sul state. The global pulp producer has selected Veolia to design and implement the mill's industrial effluent treatment plant, which will be built to treat 10,600 cubic meters of wastewater an hour.

The mill is Arauco's first in Brazil, and the company describes it as the largest industrial facility in the world built in a single phase.

That single-phase build is what makes the water contract worth a closer look. It suggests the treatment side has to be sized for the full mill from the start, not expanded later alongside new production lines. Veolia's answer is a hybrid biological process chosen to fit as much treatment as possible onto a compact site.

A city's worth of organic load

The mill's planned output is 3.5 million tonnes of short-fibre pulp a year, with operations expected by late 2027. Veolia estimates that the organic load its plant will handle matches what a municipality of 3 million people generates.

The 3-million-person comparison is the more telling of the two. Veolia frames it on organic load rather than volume, and organic load is what the bacteria in a biological plant actually have to break down.

Put simply, the hourly volume tells an engineer how much water has to pass through. The population equivalent tells them how much work the biomass has to do while the water is there. On a single industrial site, the second number is usually the harder one to fit.

The stated purpose is local. According to Filtration and Separation's account of the announcement, the capacity is meant to help prevent pollution of natural water sources and protect freshwater resources for local communities. Veolia also presents the system as support for the mill's environmental compliance.

Biofilm carriers and a smaller footprint

The process Veolia chose for Sucuriú is biofilm activated sludge, or BAS, which pairs a moving bed bioreactor (MBBR) with conventional activated sludge treatment.

The point of the pairing is intensification. Veolia says the integrated approach aims to maximize treatment capacity within a compact footprint while delivering operational flexibility and efficiency. Water & Waste Water Asia's report on the contract adds reliable treatment and efficient resource use to the design goals.

Most of the footprint savings come from the MBBR half. In AnoxKaldnes MBBR technology, which Veolia Water Solutions & Technologies has supplied, biofilm grows on plastic carriers that move freely through an aerated reactor. A Water & Wastes Digest case study notes that nearly all of the effective biomass lives on that media. The design aims for a reactor that doesn't clog, has low headloss and high surface area, and never needs backwashing.

Running several reactors in series lets operators establish a specialized bacterial population in each one, the case study adds. That is how the process handles staged removals such as biological nutrient removal. The same logic helps explain the hybrid: the carriers hold a dense, attached population, and the activated sludge component brings conventional suspended-growth treatment into the same line.

The Linden precedent, at a different scale

Veolia supplied an MBBR system for International Specialty Products' groundwater remediation plant in Linden, N.J. It's designed for extremely high loading conditions and typically occupies about one-fourth of the space of a conventional plant.

ISP installed it to replace an aged conventional groundwater remediation plant, using a single-train, single-stage MBBR to remove volatile and semi-volatile organics. The reactor is a 13-ft-diameter tank with a 21-ft water depth, holding about 21,000 gallons, and was designed for an average flow of 0.186 million gallons per day. It was built to cut soluble BOD5 by 82% at average monthly load, and the case study reports more than 95% removal of targeted contaminants.

In MBBR systems, the share of the reactor filled with biofilm carriers can range from 10% to 67%, depending on the application.

That fill rate is one of the main design levers. Designers optimize the reactor by sizing the amount of carriers correctly and choosing the most effective mixing pattern. That keeps nutrients, pollutants and oxygen reaching the biofilm and holds its thickness uniform. The technology had a track record by then, too: more than 500 major AnoxKaldnes MBBR installations worldwide, over 15% of them in U.S. industrial and municipal facilities since its U.S. introduction in 1995.

That benchmark needs a caution. One-fourth was a typical figure for standalone MBBR systems, the Linden job treated groundwater rather than pulp mill effluent, and Sucuriú's line adds an activated sludge stage, so the ratio shouldn't be read as a spec for this mill. What carries over is the principle. Carriers let a tank hold more working biomass than suspended growth alone, which suggests why a hybrid suits a plant facing city-scale load on a single industrial site.

The scale gap makes the same point. Linden's design flow was a fraction of a million gallons a day. Sucuriú's is 10,600 cubic meters every hour.

Belt presses and the sludge bill

Biological treatment leaves sludge behind, and the contract treats it as a design item in its own right. Veolia will install its proprietary belt presses to dewater the sludge, with the stated goal of optimizing both sludge production and final disposal, according to METissue's account of the announcement.

The carrier mechanism connects directly to that step. Biofilm that sloughs off the media leaves with the effluent, which suggests the biology and the presses work as one system rather than two separate purchases. The more biomass the reactors grow, the more solids the dewatering stage has to handle.

Water as a condition of running the mill

Leonardo Crociati, Arauco's executive manager of implementation for Sucuriú, framed the choice around scale and compliance. A project this size, he said in the announcement, needs partners who share Arauco's commitment to sustainability, and Veolia's selection is meant to keep the mill operating to the highest environmental compliance standards while creating shared value for Mato Grosso do Sul. He also called the project "a historic milestone for Arauco."

Anne Le Guennec, CEO of Veolia's water technology activities, went further. Securing water resources and protecting local ecosystems, she said, have become essential to business continuity and sovereignty. She tied the contract to GreenUp, Veolia's strategic program focused on sustainable industrial production and water resource protection, and said Veolia was proud to support Arauco's "journey toward more efficient and environmentally responsible operations." For capital project teams at any plant with concentrated organic effluent and limited space, that framing puts the treatment plant on the same critical path as the production line.

Veolia is selling repeatability as well. Filtration and Separation describes the offer as pre-engineered solutions designed to meet the operational and environmental requirements of next-generation mills. For producers weighing their own builds, that wording suggests Sucuriú is meant to work as a reference design as much as a one-off contract.

The next marker is the mill's start-up, expected by late 2027. After that, the useful figure for other producers planning large single-phase builds will be how quickly Sucuriú's BAS line reaches its design load once pulp starts flowing.