viewWaste management from pulp and paper production in the European Union
Introduction
Different processes in the pulp and paper industry result in the formation of different solid wastes and sludge. Solid waste is mainly generated from pulping, deinking unit operations and wastewater treatment. The amount and the composition of the solid waste depend on the paper grade produced, the raw materials used, the process techniques applied and the paper properties to be achieved. The significant residual waste streams from pulp and paper mills include wastewater treatment sludges, lime mud, lime slaker grits,1 green liquor dregs,2 boiler and furnace ash, scrubber sludges and wood processing residuals. In terms of volume, most solids or liquids are those from the treatment of effluents, although waste from wood is also produced in large quantities (IPPC, 2001, EPA, 2002, CANMET, 2005).
In general, solid wastes from pulp production and paper mill operations are humid and contain some organic compounds in the form of wood or recycled paper fibres, chlorinated organic compounds and pathogens, significant amounts of ash and trace quantities of heavy metals.
Whereas the solid waste composition from pulp and paper mills is known and constant, as a result of the current, highly controlled production processes, sludge compositions, on the other hand, vary widely throughout the industry and are dependent on the type of operations carried out at the mill. The wastes can be reused and valorised in a safe and environmental way, so landfill is strongly being reduced as their final destination. In fact, in countries such as Germany, Spain and The Netherlands, certain waste streams cannot be disposed at landfill sites. In addition, current legislation and increased taxes have resulted in research on non-conventional methods for the management or new uses of pulp and paper industry solid wastes. However, the difficult physical form of these wastes poses problems in waste handling and disposal, with the biosludge formed during biological effluent treatment being particularly problematic. These sludges have a low dry solid content requiring conditioning before they can be properly handled. Such sludges are usually thickened, and then either burned in a bark-fired boiler together with bark from wood handling, or used for landfilling. The problems associated with the landfilling of sludges and other wastes are the large volumes involved and the possibility of hazardous substances leaking into the environment. The share of residues disposed of in landfills has constantly decreased in Europe in recent years as shown in Fig. 1, in favour of the use as secondary raw material in other industries and other applications (e.g., soil improvers, in road construction, land reconstruction applications and for co-combustion in heat or power generating plants). This justifies the high number of studies carried out during the last decade focused on the research of alternative waste treatments, to minimize their possible adverse effects and on new waste applications such as, for example, road building, the brick industry, forestry and horticulture (Van Horn, 1997, Hynninen, 1998, Christmas, 2002, Cernec and Zule, 2005).
Through the increased use of recycled paper, the increased application of water treatment, tightening legislation and increasing costs of landfill, the pulp and paper industry is forced to place more and more emphasis on waste management (http://www.aspapel.es).
Section snippets
Legislation
The basis of the European Waste Legislation is the Framework Directive on Waste that is set out in the Directive on Waste 75/442, xxxx, Directive 91/156, xxxx, Directive on Hazardous Waste 91/689, xxxx. The Waste Framework includes two categories of directives: those setting requirements for the permission and operation of waste disposal facilities, and those dealing with disposal options for specific types of waste (Fig. 2). In addition to these directives, Regulation 259/93/EEC establishes a
Waste generation
The main types of solid waste generated in pulp and paper mills are briefly described below (IPPC, 2001, CANMET, 2005):
- –
From pulp mills:
- •
Rejects: The rejects from virgin pulps consist of sand, bark and wood residues from woodhandling, which are undesirable for papermaking. Rejects typically have a relatively low moisture content, significant heating values, are easily dewatered and are, generally, burnt in the mill’s bark boiler for energy recovery.
- •
Green liquor sludge, dregs and lime mud: These
- •
Composition
It is difficult to determine the composition of solid wastes from pulp and paper mills due to its dependence on the process, type and grade of paper products manufactured, methods used for production of pulp from either virgin or recycled fibres, type and efficiency of equipment used both in the main process and in wastewater treatment processes, and specific operating practices. Therefore, the waste composition corresponding to each kind of process may approximately be as follows.
Minimization of waste generation
According to the IPPC, installations must be operated in such a way as to meet six prime objectives:
- –
Application of best available techniques (BAT) to prevent pollution.
- –
No significant pollution.
- –
Waste minimization and the recovery of unavoidable waste.
- –
Efficient use of energy.
- –
Prevention of accidental releases.
- –
Remediation of the plant site back to its original state after plant closure.
An effective waste minimization program can reduce the costs, liabilities and regulatory burdens of hazardous
Waste recovery
Nowadays there are several waste recovery options. These include thermal processes such as incineration with energy recovery, pyrolysis, steam reforming, wet oxidation and supercritical water oxidation; composting; recycling; land reclamation and soil enhancement; production of mineral fillers for building materials and cement; production of insulating and fire-resistant materials and other uses (e.g., pet litter, barrier materials, conversion to fuel components, carriers for artificial
Incineration or combustion
The incineration of residues (both rejects and sludge), combined with power and steam generation, is one of the most commonly applied disposal methods in Europe. This technique can be applied to almost all types of sludge, including secondary or biological sludge. However, due to the high moisture and ash content of most sludges, the incineration process, overall balance can be energy deficient. Fluidized bed boiler technology provides a means for successful thermal oxidation of high ash, high
Utilisation in the cement and brick industry or other building material
In the cement industry both the material and energy content of the paper residues can be recovered. For the use in cement industry, sludges from primary clarifiers (or mixed with sludge from biological treatment) are especially suitable (Ahmadi and Al-Khaja, 2001, Cernec et al., 2005). However, its suitability depends on the amount and type of inorganic compounds present in the residue. The sludge (about 50% moisture content) is dried with waste heat from the pre-dryer of the cement kiln so
Composting
The composting solution consists of letting the wastes or sludges sit until most of the paper fibres and organic materials have been stabilized (odour/chemically) through the action of micro-organisms with minimal carbon loss. Sometimes fertilizers are added to the wastes or sludges in order to increase the nutrient content. This produces a humus-like material that can be used for house plants and in greenhouses. This is one of the lowest cost disposal routes. Excluding the large land
Land application
Due to its CaCO3 content, application of sludge on land has been one of the preferred disposal methods for the deinking industry for many years in the United Kingdom and Northern Europe, areas where the soil is mainly acidic. Before their application to the soil, wastes undergo a dewatering or/and incineration treatment in order to reduce their volume (Carr and Gay, 1997, Van Horn, 1997). Land application itself consists of transporting the sludges or the wastes, in cake form, from the factory
Anaerobic digestion
Historically, in case of solid wastes, this practice has been associated with the treatment of animal manure and sludge from aerobic wastewater treatment plants. At present, anaerobic digestion is applied for the treatment of different kinds of organic solid wastes, for example municipal wastes, agricultural wastes and different industrial wastes (Mata-Alvarez et al., 2000, Mshandete et al., 2005).
By definition, anaerobic digestion requires that the given waste/wastewater contains a substantial
Other options
Other options described in literature are (Kahmark and Unwin, 1996, Christmas, 2002, Kay, 2002, CANMET, 2005, Cernec and Zule, 2005):
- –
Cat litter: Dried sludge can be used as cat litter. This option does not seem to be very promising in terms of costs and volume.
- –
Absorbents: Dried sludge could be used as an absorbent, e.g., for spreading on oil spills. The limitations of this use are the same as those of cat litter production.
- –
Pesticide/fertilizer carrier: The active sludge is dried and the active
Conclusions
The European paper industry generates about 11 million tonnes of waste annually, 70% of which originates from recycled paper production. The waste is very diverse in composition and consists of rejects, different types of sludges and, in case of on-site incineration, ashes. The production of pulp and paper from virgin pulp generates less waste and the waste has the same properties as deinking waste, although with less inorganic content. Within the European Union several already issued and other
Acknowledgement
The authors wish to acknowledge the financial support of the Community of Madrid to the Project PROLIPAPEL-CM (S-0505/AMB/0100).
References (80)
- et al.
Utilization of paper waste sludge in the building construction industry
Resour. Conserv. Rec.
(2001) - et al.
Utilization of kraft pulp production residues in clay brick production
Build. Environ.
(2005) Progress and recent trends in biofuels
Prog. Energ. Combust. Sci.
(2007)- et al.
Utilization of sewage sludge in EU application of old and new methods – a review
Renew. Sustain. Energy Rev.
(2008) - et al.
Composting of deinking sludge from the recycled paper manufacturing industry
Bioresource Technol.
(2005) - et al.
Composting of pulp and paper mill fly ash with wastewater treatment sludge
Bioresource Technol.
(1999) - et al.
Aerobic composting and anaerobic digestion of pulp and paper mill sludges
Water Sci. Technol.
(1997) - et al.
Mineral phases of green liquor dregs, slaker grits, lime mud and word ash of a kraft pulp and paper mill
J. Hazard. Mater.
(2007) - et al.
Anaerobic digestion of organic solid wastes. An overview of research achievements and perspectives
Bioresource Technol.
(2000) - et al.
Enhancement of anaerobic batch digestion of sisal pulp waste by mesophilic aerobic pre-treatment
Water Res.
(2005)
Processing of waste from pulp and paper plant
J. Cleaner Production
Why energy from waste incineration is an essential component of environmentally responsible waste management
Waste Manag.
The treatment of pulp and paper mill effluent: a review
Bioresource Technol.
The challenges of sustainable papermaking
Environ. Sci. Technol.
Chemical and microbiological stability of waste sludge from paper industry intended for brick production
Waste Manage. Res.
Indirect steam gasification of paper mill sludge waste
TAPPI J.
Survey benchmarks generation, management of solid residues
Pulp Pap.
Cited by (490)
Smart materials for light absorptive rewritable paper: Chromic mechanisms and structural design
2024, Materials Science and Engineering R: ReportsCo-valorization of discarded wood pinchips and sludge from the pulp and paper industry for production of advanced biofuels
2024, Industrial Crops and ProductsPulp-paper industry sludge waste biorefinery for sustainable energy and value-added products development: A systematic valorization towards waste management
2024, Journal of Environmental ManagementLightweight composite materials made of paper sludge and corn starch
2024, Industrial Crops and Products