New Zealand Pulp & Paper Mills are World Class
The wastewater discharges from New Zealand's major kraft pulp mills in Kawerau and Kinleith have been the subject of much media attention. It is not, however, well recognised, however, that the discharges from New Zealand's major kraft pulp mills, both owned by Carter Holt Harvey, compare very favourably with mills in other major producing regions around the Pacific Rim and in Europe. Tony Johnson spells out some of the facts to support this conclusion.
Water discharge permits are the major instruments by which countries ensure that effluent discharges from industrial operations do not harm the interests of other users of water bodies or the water bodies themselves. In New Zealand, as in many countries, wastewater discharge limits and other conditions are negotiated between the mills and permitting authorities. The negotiations involve other parties and are conducted through public hearings. The permitting process is open, and the mills have strict reporting requirements to ensure that the limits set are met.
In New Zealand, the environmental policy as applied by the regional councils requires the environmental integrity of each site to be maintained. Individual permit limits are developed on a water quality basis and included in the consent. However, the consent hearings also take into account other factors.
Key parameters
Key effluent discharge parameters typically used in pulp and paper industry comparisons include Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Absorbable Organic Halides (AOX), Total Suspended Solids (TSS) and Dioxin/Furan (TCDD/TCDF). Abatement efforts generally focus on the reduction of solids and oxygen demand. Occasionally colour is important, especially for low-flow water bodies where light penetration is sufficiently affected to have an impact on plant growth in the water system.
Fortunately, typical mill wastes are weakly toxic by conventional measurement and are usually essentially non-toxic following biological treatment. The carcinogenic dioxin compound (TCDD) is below internationally accepted detection limits in New Zealand mill effluents.
In New Zealand the key parameters vary depending on the receiving water body. The regional councils issue permits after public hearings are held to decide content. A water quality approach is followed where effects on the receiving environment are monitored. Hearings consider various factors including environmental, technical, economic, social, etc. Typically, no technology-based regulations are set. The authorities, however, often refer to policies or regulations in other countries where appropriate.
In this short comparison of New Zealand pulp and paper mills with the rest of the world, two key parameters of most significance are compared, namely BOD and AOX.
Biological Oxygen Demand
The oxygen demand of a wastewater stream can be measured in a variety of ways with a five-day BOD test being the most common. The oxygen demand is created from the presence of natural wood components.
Figure 1: BOD
BOD has been a parameter that has seen significant reductions from the pulp and paper industry worldwide in the past 25 years. BOD reductions have been achieved by improvements in wastewater treatment and more recently, process improvements. The average for the New Zealand mills is 1.75 kilograms per tonne (kg/tonne) of product.
Figure 1 ranks New Zealand on a cumulative distribution plot along with mills in the US, Canada, Sweden and Finland. The mill with the lowest discharge in each country is at the left, the highest discharge mill is on the right and all others are ranked in-between. The New Zealand mills are in the best 10 percent of Swedish mills and the best 30 percent of US, Canadian and Finnish mills. This comparison includes both integrated and market kraft mills. Both of the New Zealand mills are integrated operations producing both pulp and paper, and the complexity of the operation makes it more difficult to achieve low BOD discharges. Their excellent performance is therefore all the more creditable. Both New Zealand mills have implemented state-of-the-art technologies in their fibrelines, with modified cooking and elemental chlorine-free (ECF) bleaching. Both New Zealand mills incorporate secondary biological treatment which breaks down organic compounds by forced aeration. This enhances BOD reduction before the wastewater reaches the final receiving water.
Absorbable Organic Halides
AOX is a significant parameter which has seen heavy focus in the last decade. AOX is a standard measurement that quantifies the amount of chlorinated organic material that is discharged from a mill. It is typically measured as the amount of halogenated compound per tonne of pulp.
Figure 2: AOX
With the complete elimination of gaseous chlorine in the New Zealand mills, AOX discharges have been reduced dramatically.
Figure 2 illustrates how the New Zealand mills compare the other four major producing countries. The average with discharge is 0.34 kg/tonne.
The New Zealand mills would be in the best 10 percent of US mills, the best 20 percent of Canadian mills, the best 50 percent of Swedish mills and the best 65 percent of Finnish mills. This is a very creditable performance by the New Zealand mills because this parameter has not been legislated in earlier years as it has in Scandinavia in particular. However, technologies were installed in the early 90s at both New Zealand mills to significantly reduce AOX discharges. These included the installation of oxygen delignification and washing improvements to the fibrelines and more recently extended delignification in pulping. It is significant that up until the recent promulgation of the US Environmental Protection Agency Cluster Rule, only a quarter of US mills had oxygen delignification. Most of the permits and regulations in the other countries have discharge limits for AOX in the order of 0.5-2 kg/tonne. Therefore the New Zealand mills would easily comply in these countries.
New Zealand ranks well
Table 1 compares eight different countries with New Zealand in terms of the four significant parameters typically considered when discussing wastewater quality. These countries produce significant amounts of bleached kraft pulp and paper products. Canada has 41 bleached kraft pulp mills, the US 85, Sweden and Finland 38, Japan 39. The figures in Table 1 for the New Zealand mills reflect typical values under normal operation. The figures used for the other countries are the national permit numbers or typical site permit numbers where national guidelines do not exist. Some countries have different numbers for hardwood (HW) and softwood (SW) In terms of the two parameters discussed earlier, namely BOD and AOX, the New Zealand mills would comply with all regulations except for the very low Swedish AOX limits. This again reflects the excellent world class performance of the New Zealand kraft pulp and paper mills.
| Country | BOD5 | TSS | COD | AOX |
| NZ | 1.75 | 4.0 | 12.2 | 0.34 |
| Canada | 7.5 | 11.25 | - | 1.5 |
| US | 2.73 | 4.41 | 45.6 | 0.623 |
| Indonesia | 8.5 | 8.5 | 29.75 | - |
| Japan | 13.7 | 13.9 | 17.6 | - |
| Sweden | - | - | 10 - 15 | 0.1 - 0.2 |
| Finland | - | - | 65 | 1.0 (HW) 2.0 (SW) |
| France | 3.9 (SW) 2.6 (HW) | 6.5 | 65 (SW) 32.5 (HW) | 1.0 (HW) 2.0 (SW) |
| Brazil | 1.3 - 6.5 | 1.4 - 60 | 4.6 - 45 | 0.2 - 1.0 |
HW = Hardwood SW = softwood All results in kg/tonnes
Table 1: Summary of Key Parameters
The pulp and paper industry worldwide has worked to eliminate harmful substances in the effluent. Unfortunately, the truth about these developments is not widely known and many distortions and claims go unchallenged.
It is hoped these few basic facts on the New Zealand kraft pulp and paper mills will go someway towards giving you an understanding of how we rank - World Class!
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Tony Johnson Principal Beca Simons Tony was recently appointed a principal of Beca Simons in New Zealand. He has 24 years in the industry, of which 9 years were working in the US, Canada and Brazil with AMEC Simons Forest Industry. ajohnson@beca.co.nz |
References
1. Johnson, A.P. and Vice, K. "Trends in World Pulp Mill Guidelines and Standards", Appita Conference, Rotorua, New Zealand, November 1997.
2. Mannisto, H., Mannisto, E. and Krogerus, M. "Current Environmental Performance of the Pulp and Paper Industry", Tappi Minimum Effluent Mills Symposium, Atlanta, GA, US, January 1996.
Contact for Enquiries
Amber Duncalfe
Editor - RM Update
Ministry of Agriculture and Forestry
PO Box 2526
Wellington
NEW ZEALAND
Tel: +64 4 894 0710
Fax: +64 4 894 0745
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