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Profit from waste
.thmtte t'olhmon B~dlettu, Vol. I¢~.N~ h pp. 2 1 ~ - 2 t 6 , b ~ 5 Printed in Orcal Britain
Profit from Waste Being a conservationist at heart, I find myself feeling good when I see waste eliminated or minimized by improved efficiency in production, or recycling of materials such as scrap iron, newspapers, tin cans and empty bottles. This form of waste recovery and recycling is the most basic approach to conservation of resources. Most of my professional career has been involved in dealing with pollution problems that affect water quality and fisheries habitats in British Columbia. The industry that has been my primary concern is the forest industry, which contributes by far the greatest revenue to this province. My focus has been largely on pulp and paper mills of which we have about two dozen approximately equally divided between the coast and the interior. They are heavy water users in their production process, and therefore, also have large volumes of effluents to dispose of. In some cases at least, they have also been heavy polluters of the aquatic environment, both from the point of view of impairing water quality and degrading habitats. The pulp and paper industry has come a long way in the last three decades in reducing the degree of water pollution in the waters receiving its effluents. This has been costly. But I like to think that pollution control has also been of some benefit to the industry. After all, industry has had to pay in the first place for any material it eventually loses in water. There is a tendency in any industry toward the attitude, however, that it is cheaper to utilize new raw material than to make an effort to prevent loss of product to the sewer, or to recover it before it reaches receiving waters. It only appears to become profitable when an additional incentive is provided, such as prevention of a charge for pollution being laid by a regulatory agency (and this is often more a matter of maintaining good public relations, and a favourable corporate image than avoidance of paying a fine). I should like to point to a number of examples in the pulp and paper industry where there have been tangible revenues to the industry from pollution control. In the mid-1960s we found that oxygen levels in Alberni Harbour on the west coast of Vancouver Island were reaching dangerously low levels in summer and were posing a threat to the valuable salmon runs through Alberni Inlet and up the Somass River system. In examining the sources for this oxygen depression we looked particularly at the kraft pulpmill at Port Alberni. The mill, at that time, discharged its untreated effluent into Alberni Harbour. The liquid effluent was known to have a certain biochemical oxygen demand (BOD) that could depress the dissolved oxygen concentrations of the harbour water. The solid wood wastes, consisting of fibres, chips and bark that settled into the bottom sediments, could also be expected to decay in time and reduce oxygen concentration in both the sediments and overlying water.
I)!125-32,5X "5 53 *~o+IItlO It;'~5 Pergam,~n ['rc-,s Ltd.
In this shallow harbour, it was estimated that 10% of the depletion of the dissolved oxygen in the water could be attributed to the wood solids on the bottom. The short-term remedy to at least partially reduce the uptake from the water was obviously to cut down on the input of wood solids. The Port Alberni pulpmill immediately launched plans for removal of wood wastes from the most obvious source of solid wood material into the harbour. The consultants considered clarifiers for recovery of wood solids from the wood-room effluent, which is usually heavily laden with bark, chips and slivers that come from the debarking operation. The question always has to be raised about what should be done with the solid residues once they are collected. Well, in the pulp and paper industry, hog fuel (wood waste) is used as one of the sources of energy to heat boilers, digesters and other process equipment. Once dried, the solid residues collected from the effluent can contribute to the hog-fuel supply of a pulpmill. The cost analysis for clarifiers at the Port Alberni mill at the time showed that 70% of the clarifier cost could be recovered from the value of the residues being used as hog fuel. And this was long before the energy crisis of the 1970s. Moreover, the cost analysis did not even take into account the savings that could be achieved in not having to dredge the harbour as frequently to maintain a suitable depth for deep-sea ships. A pulpmill installed in the interior of British Columbia during the mid-1960s was experiencing an enormous loss of wood fibres in its effluent during the first 2 years of production. This was not only rapidly clogging the settling basin installed for primary treatment of its effluent but also leading to annual loss of millions of dollars due to lost production of pulp. Even during those highly favourable economic times for the pulp and paper industry, this pulpmill was finding it difficult to show a profit on its balance sheet. Needless to say, mill management acted quickly to correct this loss to the great advantage of both the annual profit-and-loss statement and the aquatic environment. The loss of fibres in some of our coastal mills has led to seriously degraded benthic habitats and impoverished benthos in the coastal waters receiving the effluents. One aspect of pollution control in the pulp and paper industry of British Columbia in which I have been totally unsuccesful in convincing engineers and technical people on what I considered as sound corrective action is in foam control. Foam is aesthetically undesirable and it can have undesirable ecological consequences if it accumulates on shorelines where oysters and other shellfish grow naturally or are cultured. Foam can create problems in mill operations as well. I recall one plant manager in Ontario informing me that they once had lost from their inventory a railroad tank car of chlorine dioxide used in bleaching pulp. It turned out later to be buried in a *sea of foam' which had covered their plant grounds. The pulpmill at Port Alberni, referred to earlier, had such a vast foam problem following one of its expansions that it was impossible on one occasion to enter one of their buildings because the doorway was blocked by a thick blanket of foam. It is common in pulpmills to suppress foam by use of anti-foaming agents at considerable cost. In a partial- or full-bleach kraft (sulphate) pulpmill most 215
Marine Pollution Bulletin
of the foam is caused by mixing of the different streams of alkaline and acidic bleach plant effluents. Some 20 years ago, when I did a bit of work on foams in kraft mill effluents (Waldichuk, M., 1964, Can. Pulp Paper Ind. 17, 40-51), I discovered that 1 part per million of green liquor dregs (residue from dissolution of salts from the black liquor recovery) could effectively suppress the foam created when mixing the alkaline and acid bleach effluents. The green liquor dregs are normally discharged intermittently with the total effluent from a plant. They could be used for suppressing foam. Most of the newer kraft pulpmills discharging into the marine environment in British Columbia have a foam tank at some point before the effluent passes through a pipeline to the outfall. This is provided mainly for foam collection to prevent blockage by foam of effluent through the pipeline. At one mill on Vancouver Island, the foam tank appeared to continually overflow, to the dismay of oyster growers who had oyster culture leases nearby. They were particularly concerned, deservedly so, that the brown fluid formed from condensation of the foam could be harmful to their oysters. The plant engineers and technical workers did everything possible, including spraying of the foam with water and applying ultrasonic sound, to condense the foam in the tank. The condensate from the foam would then be introduced into the pipeline only to reappear as foam again above the outfall. The wind would then blow the foam onshore, and there it could create unpleasant conditions for the oysters. The suggestion that the foam be skimmed off in the foam tank, then condensed in a separate vessel and piped to the black liquor recovery boilers was never acceptable to the plant operators (I suspect mainly because it would involve more working parts that would require maintenance). It never made sense to me to beat the foam, containing a considerable amount of toxic organic material, back into the effluent, when it could have been evaporated and burned with some recovery of energy. After all, the economy of the kraft process is in part based on recovery of the organic material for energy and of the inorganic constituents for the digestion liquor used for cooking the chips. Fortunately, this recovery also renders kraft pulpmills far lighter water polluters than they would be otherwise. The heavy polluters among the pulp and paper industry in the past have always been the sulphite pulpmills. This has been so because effluents from the sulphite process, using calcium bisulphite as the base for the cooking liquor, have not been amenable to recovery. Evaporation of spent sulphite liquor (SSL) leads to various problems, scaling (calcium precipitates at high temperatures) being a major one. When discharged into either fresh or marine waters the SSL, which is rich in
216
wood sugars, rapidly degrades and depletes the dissolved oxygen present in the water. Fish kills in waters receiving pulpmill effluents have been largely due to anoxic conditions created by effluents from sulphite pulpmills. New mills being installed now are usually kraft mills, because of the easy recovery of the spent kraft liquor (black liquor) that is possible. If the type of product required demands a sulphite mill. the plant is designed for one of the more soluble bases, e.g. magnesium, ammonium or sodium bisulphite. It is noteworthy that in some existing sulphite pulpmills efforts have been made to utilize the SSL to produce by-products. Ethyl alcohol can be produced from the sugar-rich SSL, and there are plants in existence (e.g., Bellingham, Washington, U.S.A.) that make such a by-product. Lignin sulphonates are used in drilling muds for oil-well drilling and originate as a byproduct from SSL. Vanillin can be produced from SSL, but one mill could probably supply the world demand for this product. Road binders and adhesives can also be produced from SSL. It might be interesting to note that some years ago one small sulphite pulpmill in the northeastern U.S.A. was producing an adhesive for floor tiling as a by-product from its SSL. Long after the mill was no longer profitable for production of sulphite pulp, it continued to operate because the adhesive it produced as a by-product was of such high quality and in such great demand that it actually made it profitable for the mill to continue. There are other instances that can be cited as examples of recovery of products from waste. One that I often use involves the atmosphere and not the aquatic environment. When the Trail smelter in south-central British Columbia went into operation early in this century, its emissions of sulphur dioxide were destroying vegetation not only in the vicinity of Trail but also in eastern Washington State south of the international border. The prevailing winds transported the atmospheric pollutants in that direction. The American farmers were incensed, and rightly so. This atmospheric pollution destroying a neighbouring state's crops led eventually to an international court case where it was decreed that no state is entitled to pollute another's atmosphere. The Trail smelter was required to limit its emissions. It installed scrubbers in its stacks to remove the sulphur dioxide. In order to utilize the sulphuric acid that it produced from its emissions, the plant decided to extract nitrogen from the atmosphere to produce ammonium sulphate, some of which it eventually sold as fertilizer to the American farmers for growing crops that it formerly had polluted. Sometimes a little coercion is needed to achieve the kind of action needed to recover our wastes or to reduce their production.
MICHAEL WALDICHUK
Profit from Waste Being a conservationist at heart, I find myself feeling good when I see waste eliminated or minimized by improved efficiency in production, or recycling of materials such as scrap iron, newspapers, tin cans and empty bottles. This form of waste recovery and recycling is the most basic approach to conservation of resources. Most of my professional career has been involved in dealing with pollution problems that affect water quality and fisheries habitats in British Columbia. The industry that has been my primary concern is the forest industry, which contributes by far the greatest revenue to this province. My focus has been largely on pulp and paper mills of which we have about two dozen approximately equally divided between the coast and the interior. They are heavy water users in their production process, and therefore, also have large volumes of effluents to dispose of. In some cases at least, they have also been heavy polluters of the aquatic environment, both from the point of view of impairing water quality and degrading habitats. The pulp and paper industry has come a long way in the last three decades in reducing the degree of water pollution in the waters receiving its effluents. This has been costly. But I like to think that pollution control has also been of some benefit to the industry. After all, industry has had to pay in the first place for any material it eventually loses in water. There is a tendency in any industry toward the attitude, however, that it is cheaper to utilize new raw material than to make an effort to prevent loss of product to the sewer, or to recover it before it reaches receiving waters. It only appears to become profitable when an additional incentive is provided, such as prevention of a charge for pollution being laid by a regulatory agency (and this is often more a matter of maintaining good public relations, and a favourable corporate image than avoidance of paying a fine). I should like to point to a number of examples in the pulp and paper industry where there have been tangible revenues to the industry from pollution control. In the mid-1960s we found that oxygen levels in Alberni Harbour on the west coast of Vancouver Island were reaching dangerously low levels in summer and were posing a threat to the valuable salmon runs through Alberni Inlet and up the Somass River system. In examining the sources for this oxygen depression we looked particularly at the kraft pulpmill at Port Alberni. The mill, at that time, discharged its untreated effluent into Alberni Harbour. The liquid effluent was known to have a certain biochemical oxygen demand (BOD) that could depress the dissolved oxygen concentrations of the harbour water. The solid wood wastes, consisting of fibres, chips and bark that settled into the bottom sediments, could also be expected to decay in time and reduce oxygen concentration in both the sediments and overlying water.
I)!125-32,5X "5 53 *~o+IItlO It;'~5 Pergam,~n ['rc-,s Ltd.
In this shallow harbour, it was estimated that 10% of the depletion of the dissolved oxygen in the water could be attributed to the wood solids on the bottom. The short-term remedy to at least partially reduce the uptake from the water was obviously to cut down on the input of wood solids. The Port Alberni pulpmill immediately launched plans for removal of wood wastes from the most obvious source of solid wood material into the harbour. The consultants considered clarifiers for recovery of wood solids from the wood-room effluent, which is usually heavily laden with bark, chips and slivers that come from the debarking operation. The question always has to be raised about what should be done with the solid residues once they are collected. Well, in the pulp and paper industry, hog fuel (wood waste) is used as one of the sources of energy to heat boilers, digesters and other process equipment. Once dried, the solid residues collected from the effluent can contribute to the hog-fuel supply of a pulpmill. The cost analysis for clarifiers at the Port Alberni mill at the time showed that 70% of the clarifier cost could be recovered from the value of the residues being used as hog fuel. And this was long before the energy crisis of the 1970s. Moreover, the cost analysis did not even take into account the savings that could be achieved in not having to dredge the harbour as frequently to maintain a suitable depth for deep-sea ships. A pulpmill installed in the interior of British Columbia during the mid-1960s was experiencing an enormous loss of wood fibres in its effluent during the first 2 years of production. This was not only rapidly clogging the settling basin installed for primary treatment of its effluent but also leading to annual loss of millions of dollars due to lost production of pulp. Even during those highly favourable economic times for the pulp and paper industry, this pulpmill was finding it difficult to show a profit on its balance sheet. Needless to say, mill management acted quickly to correct this loss to the great advantage of both the annual profit-and-loss statement and the aquatic environment. The loss of fibres in some of our coastal mills has led to seriously degraded benthic habitats and impoverished benthos in the coastal waters receiving the effluents. One aspect of pollution control in the pulp and paper industry of British Columbia in which I have been totally unsuccesful in convincing engineers and technical people on what I considered as sound corrective action is in foam control. Foam is aesthetically undesirable and it can have undesirable ecological consequences if it accumulates on shorelines where oysters and other shellfish grow naturally or are cultured. Foam can create problems in mill operations as well. I recall one plant manager in Ontario informing me that they once had lost from their inventory a railroad tank car of chlorine dioxide used in bleaching pulp. It turned out later to be buried in a *sea of foam' which had covered their plant grounds. The pulpmill at Port Alberni, referred to earlier, had such a vast foam problem following one of its expansions that it was impossible on one occasion to enter one of their buildings because the doorway was blocked by a thick blanket of foam. It is common in pulpmills to suppress foam by use of anti-foaming agents at considerable cost. In a partial- or full-bleach kraft (sulphate) pulpmill most 215
Marine Pollution Bulletin
of the foam is caused by mixing of the different streams of alkaline and acidic bleach plant effluents. Some 20 years ago, when I did a bit of work on foams in kraft mill effluents (Waldichuk, M., 1964, Can. Pulp Paper Ind. 17, 40-51), I discovered that 1 part per million of green liquor dregs (residue from dissolution of salts from the black liquor recovery) could effectively suppress the foam created when mixing the alkaline and acid bleach effluents. The green liquor dregs are normally discharged intermittently with the total effluent from a plant. They could be used for suppressing foam. Most of the newer kraft pulpmills discharging into the marine environment in British Columbia have a foam tank at some point before the effluent passes through a pipeline to the outfall. This is provided mainly for foam collection to prevent blockage by foam of effluent through the pipeline. At one mill on Vancouver Island, the foam tank appeared to continually overflow, to the dismay of oyster growers who had oyster culture leases nearby. They were particularly concerned, deservedly so, that the brown fluid formed from condensation of the foam could be harmful to their oysters. The plant engineers and technical workers did everything possible, including spraying of the foam with water and applying ultrasonic sound, to condense the foam in the tank. The condensate from the foam would then be introduced into the pipeline only to reappear as foam again above the outfall. The wind would then blow the foam onshore, and there it could create unpleasant conditions for the oysters. The suggestion that the foam be skimmed off in the foam tank, then condensed in a separate vessel and piped to the black liquor recovery boilers was never acceptable to the plant operators (I suspect mainly because it would involve more working parts that would require maintenance). It never made sense to me to beat the foam, containing a considerable amount of toxic organic material, back into the effluent, when it could have been evaporated and burned with some recovery of energy. After all, the economy of the kraft process is in part based on recovery of the organic material for energy and of the inorganic constituents for the digestion liquor used for cooking the chips. Fortunately, this recovery also renders kraft pulpmills far lighter water polluters than they would be otherwise. The heavy polluters among the pulp and paper industry in the past have always been the sulphite pulpmills. This has been so because effluents from the sulphite process, using calcium bisulphite as the base for the cooking liquor, have not been amenable to recovery. Evaporation of spent sulphite liquor (SSL) leads to various problems, scaling (calcium precipitates at high temperatures) being a major one. When discharged into either fresh or marine waters the SSL, which is rich in
216
wood sugars, rapidly degrades and depletes the dissolved oxygen present in the water. Fish kills in waters receiving pulpmill effluents have been largely due to anoxic conditions created by effluents from sulphite pulpmills. New mills being installed now are usually kraft mills, because of the easy recovery of the spent kraft liquor (black liquor) that is possible. If the type of product required demands a sulphite mill. the plant is designed for one of the more soluble bases, e.g. magnesium, ammonium or sodium bisulphite. It is noteworthy that in some existing sulphite pulpmills efforts have been made to utilize the SSL to produce by-products. Ethyl alcohol can be produced from the sugar-rich SSL, and there are plants in existence (e.g., Bellingham, Washington, U.S.A.) that make such a by-product. Lignin sulphonates are used in drilling muds for oil-well drilling and originate as a byproduct from SSL. Vanillin can be produced from SSL, but one mill could probably supply the world demand for this product. Road binders and adhesives can also be produced from SSL. It might be interesting to note that some years ago one small sulphite pulpmill in the northeastern U.S.A. was producing an adhesive for floor tiling as a by-product from its SSL. Long after the mill was no longer profitable for production of sulphite pulp, it continued to operate because the adhesive it produced as a by-product was of such high quality and in such great demand that it actually made it profitable for the mill to continue. There are other instances that can be cited as examples of recovery of products from waste. One that I often use involves the atmosphere and not the aquatic environment. When the Trail smelter in south-central British Columbia went into operation early in this century, its emissions of sulphur dioxide were destroying vegetation not only in the vicinity of Trail but also in eastern Washington State south of the international border. The prevailing winds transported the atmospheric pollutants in that direction. The American farmers were incensed, and rightly so. This atmospheric pollution destroying a neighbouring state's crops led eventually to an international court case where it was decreed that no state is entitled to pollute another's atmosphere. The Trail smelter was required to limit its emissions. It installed scrubbers in its stacks to remove the sulphur dioxide. In order to utilize the sulphuric acid that it produced from its emissions, the plant decided to extract nitrogen from the atmosphere to produce ammonium sulphate, some of which it eventually sold as fertilizer to the American farmers for growing crops that it formerly had polluted. Sometimes a little coercion is needed to achieve the kind of action needed to recover our wastes or to reduce their production.
MICHAEL WALDICHUK