|Frost & Sullivan Market Insight||Published: 4 Feb 2002|
By K.Ravi, Research Analyst, Water Group, Chennai, India.
It is also one of the largest producers of wastewater. The paper and water industries have worked closely for years to achieve enormous reductions in both fresh water use and the contaminants in wastewater. Meanwhile, factors such as growing water scarcity, increased pressure to cut costs, and tightening environmental regulations have once again brought the issue of water use and treatment in the pulp and paper industry to the center stage.
Water in the Paper Manufacturing Process
Water is intricately associated with all the three stages of paper production namely, pulp making, pulp processing, and paper/paper board manufacturing, and their associated activities of cooking, bleaching, and washing. About 85 percent of the water consumed in the pulp and paper industry is used only for processing, thus, leading to the generation of large volumes of contaminated wastewater.
While screening, cleaning, and paper making operations are the primary sources of effluents, cooling water used in various machineries and stormwater runoff also contribute significantly. Typical water pollution concerns for the wastewater from paper mills are effluent solids, toxicity, color, and biological oxygen demand (BOD) (See table for details). Apart from removing these impurities, the primary and secondary water treatment plants, which are normally a part of any standard paper-manufacturing unit, also treat the wastewater for adsorbable organic halides (AOX) and chemical oxygen demand (COD).
Water Use Trends
Even though the pulp and paper industry is still highly dependent on fresh water, there have been some remarkable achievements with regard to the water-use patterns. For instance:
Despite these developments, the amount of water recycled in the paper industry, at 11.8 percent is still the lowest amongst water-intensive industries. Will closed-loop manufacturing process help further water recycling?
Closed-loop Process and Zero Liquid Discharge
The principle of closed-loop manufacturing aims to eliminate discharges to the external environment, by recycling and reusing most of the solid and liquid wastes, while reducing air exhausts to bare minimum, both in quantity and toxicity. While reuse of solid wastes was found to be easier (by burning them for energy production), recycling of water within the system had inherent problems. Closed water circuits created a favorable environment for the growth of micro-organisms, which lead to increased build-up of slime deposits that caused severe operational problems. Moreover, the accumulation of contaminants from the paper additives deteriorated the quality of the end product over a period. Hence, the closed system needed to be reopened and cleaned at regular intervals.
Sensing the need to overcome this bottleneck, the European Union (EU) has funded a three-year ‘Paper Kidney Project’ to explore the possibility of using technologies such as membrane separation, aerobic biotechnological treatment, and polishing to achieve trouble-free water recycling. The group, comprising representatives from the paper industry, water treatment companies, and research institutes, has a target of attaining zero liquid discharge.
Apart from the EU project, industry and research institutions across both sides of the Atlantic are working on numerous technologies for achieving cost-effective and most efficient wastewater treatment. A few of them are:
The pulp and paper manufacturers themselves are taking the lead and implementing several practices that are becoming trendsetters for water use and treatment.
Trendsetting by Paper Mills
International Paper Company, U.S.A. has improved the performance of the wastewater plant at its Lock Haven mill by increasing the loading on its aerated stabilization basin, without changing the effluent discharge limits. For this purpose, existing static tube mixers in the basin have been upgraded and replaced with a new fine bubble diffused air aeration system.
The white water coming out of the paper machinery in the Shan Ying Pulp and Paper Mill in China is led to a common flotation unit and a good proportion of the clarified water is recycled. Moreover, the plant has set stringent targets of reducing water consumption by 33 percent and reducing COD in wastewater by 60 percent.
Kuan Yuan paper mill in Taiwan has installed numerous self-aspirating submersible aerators for wastewater and water treatment. Due to the optimum aeration, no chemical treatment is required after bio-treatment. These aerators give the optimum COD and BOD levels to the pre-treated effluent.
Frost & Sullivan believes that the challenges posed for water treatment in the pulp and paper sector offer significant opportunities for the water and wastewater industry. A recent market study by Frost & Sullivan projects an annual growth rate of 3.7 percent for water and wastewater treatment equipment in the pulp and paper sector in Europe.
Development of effective water treatment technologies for achieving the closed-loop manufacturing system will be one of the immediate priorities for the industry.
The issue of nutrient reduction in pulp and paper effluents is likely to gain attention. This would create demand for new technologies for nutrient balance and reduction.
More stringent regulations on water use and recycling in the paper industry would necessitate special systems for metal management, chloride control, balancing chemicals, solid-waste handling, etc. This would mean new developments in system closure and non-process element control technologies.
More environmental awareness among the paper industries will also lead to innovative research and development in areas such as process control electronics, process modeling and automation, biotechnological treatment of effluents, membrane separation, and chlorine-free bleaching.
Frost & Sullivan’s report "W&WW Treatment Equipment: Customer Analysis of the Pulp & Paper Industry" is available now.
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