Wastewater as a resource
Anaerobic reactors pay off for paper manufacturers
2014-01-20 - The installation of a modern wastewater treatment system is an investment that pays off for paper manufacturers. They are perfectly aligned to the respective paper mill, operating reliably and securely within the prescribed limit values. An additional benefit is the reduced operating cost for wastewater treatment.
Voith offers two types of anaerobic reactors: the R2S reactor, which is especially suitable for wastewater containing a lot of calcium with a high COD content, and the E2E reactor which is suitable for diluted low-calcium wastewater. The first anaerobic reactor which Voith installed in the Italian town of Lucca in 2007 is an R2S reactor. From the beginning the reactor has always worked very well as the operator confirms to Voith technicians who regularly service it on site.
At its newly constructed mill in Partington, Great Britain, the paper manufacturer Saica has chosen a wastewater treatment system with an R2S reactor from Voith. That one reliably breaks down approx. 80% of the load. Each day up to 25,000 Nm3 of biogas is produced. The secret behind this success is the rugged design and very exact adaptation to the specific conditions of the paper mill, which produces 1,400 metric tons of corrugated board base paper daily from 100% recovered paper and generates up to 6,000 m3 of wastewater.
The start-up at the Partington site was difficult, because the coordination of processes was not as simple as initially assumed. Nonetheless, the goals that were set were achieved. The customer is very satisfied today as Federico Asensio, the Deputy General Manager and R&D Group Director at Saica, is happy to confirm: “For a customer, it is important to rely on the technical know-how and commitment of the supplier, especially if there is an unexpected situation. Thanks to the strong collaboration between Voith and Saica, the initial problems have been solved and the wastewater treatment system finally achieved our original expectations. Its operation is smooth and stable.”
This constant stable behavior is one of the advantages of the integrated approach. Axel Gommel, a Voith engineer, confirms from a manufacturer’s perspective that integrated process designs such as those at Saica generally lead to noticeably more stable operating behavior than is seen with conventional systems. There are other advantages: there are fewer dissolved substances in the circulating water during production, the legal limit values for the wastewater are reliably adhered to with low personnel requirements and the excess sludge accumulated is reduced by 70%. Depending on the paper grade, it is possible to reduce the fresh water consumption of the paper mill by reusing purified water.