Purac - Customized Water and Wastewater Treatment Plants and Solutions

Purac have supplied more than 500 water and wastewater treatment plants to the pulp and paper industry. The company is recognized as one of the world leaders providing water and wastewater treatment for this industry. The know-how embraces the fields of process water treatment, fibre separation in recycling internal process water and various methods of wastewater treatment.

Purac is a part of the Läckeby Water Group, which is an independent, privately-owned Swedish group, offering contracting, products and servicing for water treatment and biogas production. We are established on three continents and have to date completed contracts in 67 countries worldwide.

BIOLOGICAL TREATMENT OF WASTEWATER BY ANAEROBIC OR AEROBIC PROCESSES

Wastewater can be treated anaerobically (ANAMET) followed by an activated sludge stage, or by a biofilm aerobic method alone or in combination with an activated sludge stage.

Local conditions – sludge disposal costs and potential utilization of biogas – together with the organic load determine the choice between anaerobic and biofilm aerobic treatment.

Biofilm technology means that the biomass - micro-organisms - grows as a film on a surface in contact with liquid. The best technical solution proved to be use of mobile carriers in the form of small plastic elements, free-floating in liquid and with a large specific surface. The process, which requires minimal space, is today a proved and well-documented method with about 100 reference installations in the pulp and paper industry.

The suspended carrier biofilm process offers many benefits compared with traditional biological treatment:

• Increased treatment capacity in existing plants
• Flexible design adaptable to existing basin volumes
• Less sensitivity to load increases and toxic discharges
• A more stable treatment process
• Unaffected by sludge age

PROCESS WATER TREATMENT WITH DAF, FLOOFILTER™ OR LAMELLA SEDIMENTATION

Process water requires high-quality treatment to control parameters such as suspended solids, hardness, colour, aluminium, iron and magnesium. Purac can offer various solutions, depending on the source of raw water and the space available for the treatment plant:

• Dissolved Air Flotation (DAF)
• Sand filtration
• Floofilter™, combining flotation and filtration in one unit
• Lamella sedimentation
• High-loaded pressure sand filtration
• Membrane filtration
• Each process is customized to fit local demands

NEXT GENERATION OF DISSOLVED AIR FLOTATION, PURAC DAFRapide™

The Purac DAFRapide™ is an improved Dissolved Air Flotation (DAF) system, which increases the surface loading by four to six times - while still reducing capital costs. The new DAF technology was first installed at Fiskeby Board AB in Sweden as a final chemical precipitation treatment after a biological treatment plant. The second installation of DAFRapide™ was successfully started at the beginning of 2004 for production of 1,300m³/h of raw water for Stora Enso Nymölla's production of pulp and fine paper.

DISSOLVED AIR FLOTATION, DAF, KIDNEY FOR INTERNAL WATER RECIRCULATION IN THE RECYCLED PAPER PRODUCTION PLANTS

Purac and its sister company Flootek WTS have supplied DAF for internal water recirculation to the major producers of recycled paper around the world. The Dissolved Air Flotation (DAF) system is installed both for fibre / sludge recovery and for water reuse.

LÄCKEBY PRODUCTS - SOLUTIONS FOR MECHANICAL TREATMENT OF WATER AND SLUDGE AND PULP AND PAPER HANDLING

We offer products that are important for well-functioning plants. In-house design, development and production ensure a high level of quality and innovation, and our long experience guarantees products that can be adapted to the unique requirements of each plant.

Läckeby Products supplies machinery and systems for reject handling (pulper reject, heavy and light reject) in DIP as well as for virgin pulp handling (knot handling, pulp conveying, screening reject and debarking water filtration). Some of our products are: Roto-Sieve™ drum screens, shaftless screw conveyors, classifiers and compactors.