FAO SECRETARIAT
In recent years the problem of water pollution has been receiving increased attention, and articles concerning pollution have frequently been published in the daily press and in trade magazines. In many countries water pollution has increased to such an extent that public health authorities have declared water in certain areas unfit for human consumption, and in some cases have even prohibited swimming in such waters. Water pollution has also destroyed or driven away underwater life in many waterways.
Effluents from communities and from many industries cause water pollution and some effluents even contaminate the water with poisonous chemicals. This is not normally the case with effluents from the pulp and paper industry but, because of the size of this industry and the fact that it uses large quantities of process water, pollution is an important consideration in this connection.
The present installed capacity of the world pulp and paper industry is about 100 million metric tons of pulp and 120 million metric tons of paper and paperboard per year. Assuming that the average amount of effluent from pulp and paper mills is 200 cubic meters per ton of pulp and paper, the total of effluent discharged from the world pulp and paper industry would be about 40,000 million cubic meters per year. Before external treatment the effluents may be estimated to contain a total of 40 to 50 million tons of suspended solids. This very large figure serves to underline the importance of external effluent treatment. Such treatment can substantially reduce the amount of suspended solids which would otherwise pollute the waters in the vicinity of pulp and paper mills.
In order to limit damage and to improve the quality of the inland water, some countries have refused to permit the establishment of new pulp and paper mills in certain locations. Regulations which compel the existing industry to purify effluents before they are discharged into lakes or rivers have also been introduced or made more exacting.
The problem of water pollution and effluent treatment in the field of pulp and paper was discussed at the seventh session of the Advisory Committee on Pulp and Paper in November 1966. The seriousness of the problem was stressed, particularly by members from densely populated, developed countries where pulp and paper mills discharge their effluents into inland lakes and rivers.
Soon afterward there were two meetings dealing with water pollution and the pulp and paper industry - the Canadian National Conference on Pollution and Our Environment held in Montreal and, in Geneva, the Economic Commission for Europe (ECE) held an Ad Hoc Meeting of Experts for the Study of Economic Aspects of Water Pollution Control Problems. One year later, in October 1967, the third Paper and Pulp Industry Air and Stream Improvement Conference was held in Vancouver. Effluent disposal problems were also discussed at the International Conference on Water Pollution held in New York in November 1967.
The report of the ECE meeting contains information on the investment and operating costs of effluent treatment in several European countries. Unfortunately all the data are not on a comparable basis, some showing the cost per cubic meter of daily effluents, some per year or daily ton of products, and others a lump sum of total mill investment or total annual operating costs. This makes it impossible to use all the data to arrive at a picture of the cost in different countries and mills. The reported investment requirements for effluent treatment vary from a moderate U.S. $20 to the very high figure of $500 per daily cubic meter of effluents, and the operating costs from $0.02 to $0.08 per daily cubic meter; the high figures refer to small mills Another document fixes the cost as follows:
Calcium bisulfite pulp:
Investment 15 percent of total mill investment
Operating cost $3 per ton of pulp
Other sulfite and sulfate pulp
Investment 5 percent of the total mill investment
Operating cost $2 per ton of pulp
Paper
Investment 3 percent of total mill investment
Operating cost $0.80 per ton of paper
The cost, of course, depends very much on local conditions, the amount of effluent, disposal of mud and also on the degree of purification. One example, where the quantity of purified effluent is 10,000 cubic meters per 24 hours, shows that if the reduction of BOD¹ has to be raised to 97 instead of 70 percent, the investment and operating cost will be nearly double.
¹ BOD = biochemical oxygen demand.
In the Report on primary and secondary treatment for Ontario mills - capital costs, H.D. Paavila gives a summary of the estimated cost of effluent treatment of the pulp and paper industry in the Province of Ontario if the objective of reducing suspended solids to 50 parts per million (ppm) and the BOD value by 85 percent has to be met. It is stressed that the data on investments required are only to be considered preliminary since in most cases no engineering studies have been made.
Answers to a questionnaire from 25 mills indicate that, at the beginning of 1968, the total amount of effluent requiring treatment was about one million cubic meters (267.5 million gallons) per day. The total of suspended solids to be removed from this amount of effluent is estimated to be about 400 metric tons. The total reported investment required for primary treatment at these 25 mills is estimated at approximately $25 million, corresponding to an average investment of about $53,000 per daily ton of suspended solids removed, or about $25 per cubic meter per day of effluent requiring treatment.
The total investment required for the secondary treatment to reduce the BOD by 85 percent is estimated to exceed $50 million, corresponding to more than $50 per daily cubic meter of effluent.
In a paper entitled "Results of NCSI² industry survey of investment and cost of effluent treatment" by Russel O. Blosser, presented at the third Paper and Pulp Industry Air and Stream Improvement Conference held at Vancouver, Canada in October 1967, and published in the 2 February 1968 issue of the Pulp and Paper Magazine of Canada, recent data are given from the United States of America.
² NCSI = National Council of Stream Improvement Inc. Canada.
On the basis of data received from 415 pulp and paper mills, accounting for 82 percent of the United States pulp and paper industry, an estimate was made of the total capital expenditure and charges of the pulp and paper industry by 1965 and of the expected increase up to 1969. It shows that the industry had spent on effluent treatment and disposal facilities a total of $168 million up to 1965 which represented an increase in only two years of 45 percent over the 1963 total. Annual capital expenditure is expected to rise to 80 million by 1968, and total capital expenditure, calculated as a replacement cost, to $500 million by 1969.
The total annual operating cost to the industry rose from $15 million in 1959 to $27 million in 1965, and is estimated to exceed $50 million by 1968, meaning that the cost per metric ton of paper, which was $0.69 in 1965, may be as high as $1.10 by 1968.
Expenditure and annual charges calculated per metric ton of pulp and paper produced by various types of mills were given as follows
|
|
Capital expenditure |
Operating charges |
|
U.S.$/metric ton of capacity |
U.S. cents/metric ton produced |
|
|
Paper from waste paper |
800-1100 |
45-75 |
|
Nonintegrated paper |
1100-2800 |
45-100 |
|
Integrated kraft pulp/paper |
400-2800 |
17-150 |
|
Sulfite pulp/paper |
2200-5500 |
90-165 |
|
Integrated semichemical (NSSC) pulp/paper |
5500 |
90 |
From this table it can be seen that both the expenditures and charges are highest for the sulfite mills.
Capital expenditure and operating charges have also been listed for the different external treatment procedures, as follows:
|
|
Capital expenditure |
Operating charges |
|
U.S.$/metric ton of daily capacity tan |
U.S. cents/metric ton |
|
|
Primary - earthen basins |
500 |
25-30 |
|
Primary-mechanical |
1000-1500 |
45-75 |
|
Primary - mechanical and dewatering |
1500-1750 |
55-130 |
|
Secondary - oxidation basins |
1000-2000 |
25-35 |
|
Secondary - activated sludge |
5000 |
245 |
|
Secondary - irrigation |
2000 |
50 |
As might be expected, primary treatment using earthen basins represents the lowest cost of treatment, while the costs rise progressively as the treatment becomes more mechanized.
According to these data primary treatment by earthen basins followed by secondary treatment by irrigation make stream improvement least expensive. However, this kind of effluent treatment is not always possible because of the quantity of water involved, which requires very large irrigation areas and earthen basins. For example, assuming that a 200 ton/day pulp and paper mill has, as an average, 200 cubic meters of effluent per ton of paper, the daily amount is 40,000 cubic meters, which requires 40 hectares of 1 meter deep basins, provided that a settling time of 24 hours is sufficient.
If the need for effluent treatment and disposal facilities is not taken into consideration in time, pulp and paper mills are often not in a position to use the least expensive solution and are therefore obliged to use more mechanized, and thus more expensive, systems. Consequently it is essential that, when feasibility studies for pulp and paper industry are made, they include effluent treatment facilities even in eases where there is no legislation on stream pollution at the time. Later regulations may otherwise make the establishment and operation of an effluent treatment plant more expensive than would have been necessary or may even force a shutdown of the mill, as has already happened in several cases.
No doubt there will be further technical developments in the field of effluent treatment and new methods, more effective and possibly less expensive, will be discovered. FAO would very much appreciate it if information could be obtained as to new developments in the various countries.
J.P.B.
