Claudio Mudadu Silva Universidade Federal de Vicosa 7th - - PowerPoint PPT Presentation

Environmental Management in the Pulp and Paper Industry: Future Challenges and Tendencies

Claudio Mudadu Silva Universidade Federal de Vicosa

7th International Colloquium on Eucalyptus Pulp

Presentation Outline

• Kraft pulp mill environmental aspects
• End-of-pipe versus Pollution Prevention approaches
• Water and wastewater

– Water use, effluent use (closed-cycle systems), treatment technologies, effluent discharge

• Solid waste or valuable by-products

– Landfill, land application, energy recovery, other uses

• Final considerations

Integrated Pulp and Paper Mill

wood water chemicals effluent air emissions pulp paper

Pulp Mill

solid residues

Paper Mill

effluent water vapour chemicals solid residues

Environmental Aspects

• bark
• effluent
• rejects
• effluent
• acidic and alkaline effluent
• air emmisions
• contaminated condensates
• air emmisions
• dregs
• grits
• air emission
• whitewater
• air emmisions
• ashes

Causticizing Recovery boiler lime kiln Evaporation Wood yard Digester Fiberline Bleaching Drier wood cooking liquor Paper mill pulp paper

Black liquor

Cooking liquor chemicals Biomass boiler

End-of-Pipe versus Pollution Prevention

General scheme

Raw material water chemicals Effluent Air emmisions Final product Solid residues

Mill

End-of-pipe approach

Raw material water chemicals Effluent Air emmisions Final product Solid residues

Mill

Filter CHIMENEA

LANDFILL

WWTP

End-of-pipe approach

• Classical sanitary/environmental control

approach

• Generally accepted
• Little attraction to industry ($)

Effluent Treatment Plant

Landfill

Gas emmisions treatment

Pollution Prevention Approach

Any action that reduces or eliminates contaminants at the source, where they are generated, through process modification

Advantages of Pollution Prevention over end-of-pipe approach

• Cost reduction
• Lower environmental impact risks
• Legislation reinforcement (Best available

technologies)

Source reduction Final disposal Treatment Recycling/Reuse 1 4 3 2 Hierarchy

Water consumption in the pulp industry Year 1959 1969 1975 1979 1985 1988 1999 2015 m3/adt 240 156 111 96 79 72 60 20-25

REEVE, 1999

Equivalent population compared to water consumption in the pulp industry

Considering :

• average water consumption of 1 person is around 200 L/d.
• a new mill with a production of 3,000 adt/d and a specific

water consumption of 30 m3/adt.

• Total water consumption = 3,000 * 30 = 90,000 m3/d
• Population equivalent = 90,000/0.2 = 450,000 people

Water closed-cycle systems

Closed cycle systems for manufacture of wood pulp of low lignin content, high brightness, strength and cleanliness, that is, bleached chemical pulp, are systems using processes wherein water and other chemicals are recycled and reused and thus waste for disposal is minimized without jeopardizing processing cost or value of saleable products.

Non process elements

Negative effects Element deposits corrosion fouling RB bleach plant effects Ca, Al, Si K, Cl, Mg K, Cl Mn, Fe

Examples of potential problems due to effluent reuse

How to tackle these problems ?

One approach is to remove the contamination through an in-plant effluent treatment processes prior to water reuse

Effluent Treatment Processes/Technologies

• removal of suspended solids (sedimentation,

flotation, filtration)

• removal of dissolved biodegradable organic matter

(biological treatment)

• removal of recalcitrant organic matter

(coagulation/flocculation, membrane filtration, AOP)

• removal of ions (membranes, ion exchange)

How much it would cost to remove contaminants and enable recycling?

• Hardly the economic analysis will be favorable to

water reuse except if other chemicals are also recovered

• Water is still relatively cheap
• STILL…

Other driving forces ?

• Water shortage
• Restrict effluent quality discharge regulations

– COD – Color – Nutrients – Toxicity (acute and cronic) – ? ? ? ? ?

Solid wastes or Valuable by-products?

Main by-products generated on a kraft pulp mill

NON-HAZARDOUS MATERIAL

• Organic

– Primary, secondary and sometimes tertiary sludge, dirt bark

• Inorganic/Alkaline

– Dregs – Grits – Lime mud – Power boiler ashes

Wood yard Digester Fiberline

Bleach plant

Dryer Bark

100-200

Evaporation

Recovery Boiler Caust. Lime kiln

10 - 15

dregs

2 - 5

grits Biomass Boiler

5 - 10

ashes Primary treatment Secondary treatment

Primary sludge

40 - 60

Secondary sludge

5 - 15

Solid by-products (kg/adt)

Landfill: an environmentally sound solution or an enviromental passive?

Main use tendencies

• Soil amendment (pH, organic matter, nutrients)

– composting

Main use tendencies

• Soil amendment (pH, organic matter, nutrients)

– By-product central

Main use tendencies

• Energy production

– Biomass boiler, briquetting, anaerobic digestion

Fine wood Biological sludge Dry residues (15%) Mixture of residues Briquettes production Briquettes Donation Commercialization Power boiler Exit gas Other energy sources

Main use tendencies

• Commercialization (primary sludge for recycling paper

production, lime mud, etc.)

• Road construction, ceramics, cement

Main legislation tendencies

• Avoid landfilling (very high costs)
• Gradually more restrictive

– BAT - best available technologies

CHALLENGES

Education

Educate mill personnel and environmental legislators and authorities about potential of transforming actual “wastes” into “by-products” of commercial interest and environmental sound

• Review the current concept of residue or waste and

describe a legal way to use as a by-product according to its composition and not only according to its

• rigin.
• Review constantly the international legislation and

foreing experience on this issue

Legislation

Investigation

• Continually

investigate

• ptions

to improve environmentally and economically the use, treatment and/or disposal of the by-product

Final considerations

• Water use minimization and reuse

– In-plant process modifications – In-plant treatment to remove contaminants – Closed-cycle systems – Water shortage and legislation restrictions

• Solid by-products

– Find new opportunities for uses (industrial ecology)

THANK YOU!