Pulp industry

Gaseous Effluents. Twenty percent of the carbon disulfide used in xanthation is converted into hydrogen sulfide (or equivalents) by the regeneration reactions. Ninety to 95% of this hydrogen sulfide is recoverable by scmbbers that yield sodium hydrogen sulfide for the tanning or pulp industries, or for conversion back to sulfur. Up to 60% of the carbon disulfide is recyclable by condensation from rich streams, but costly carbon-bed... 

R. Smith and T. Norris, eds., TAPPI Proceedings 1988 Paper Preservation Symposium, Technical Association of the Paper and Pulp Industry, Washington, D.C., 1988. 

Bulk Enzymes. Enzymes such as proteases, amylases, glucose isomerases, and rennin are used in food processing. Similarly proteases and Hpases are used in detergents. CeUulases and xylanases are used in the paper pulp industry. The genes for most of the enzymes used in the various commercial processes have been cloned and overexpressed. Rennin (chymosin) produced from E. coli and A. nigerhas been approved by FDA for use in the dairy industry. 

Uses. The dominant use of sulfur dioxide is as a captive intermediate for production of sulfuric acid. There is also substantial captive production in the pulp and paper industry for sulfite pulping, and it is used as an intermediate for on-site production of bleaches, eg, chlorine dioxide or sodium hydrosulfite (see Bleaching agents). There is a substantial merchant market for sulfur dioxide in the paper and pulp industry. Sulfur dioxide is used for the production of chlorine dioxide at the paper (qv) mill site by reduction of sodium chlorate in sulfuric acid solution and also for production of sodium dithionite by the reaction of sodium borohydride with sulfur dioxide (315). This last appHcation was growing rapidly in North America as of the late 1990s. 

Sulfite waste Hquor from the pulping industry contains a large amount of hydrolyzed sugars. Some sulfite waste Hquors are now being fermented to give both ethanol (qv) and single-cell protein in the form of yeast (see Foods, non-CONVENTIONAL Yeasts). 

Due to the direct contact of water with various species, the aqueous streams are laden with various compounds including methanol, non-process elements NPEs, and organic and inorganic species. In this problem, we focus on methanol as the pimary species in water. Methanol is classified as a high priority pollutant for the pulping industry. In addition, it may provide a source of revenue if properly recovered. 

The paper and pulp industries consume taif/e quantities of Ca(OH)2 and precipitated (as distinct from naturally occurring) CaCOs. The largest application of lime in pulp manufacture is as a causlicizing agent in sulfate (kraft) plants (p. 89). Here the waste NajC solution is reacted with lime to regenerate the caustic soda used in the process ... 

Because these variables have a very pronounced effect on the current density required to produce and also maintain passivity, it is necessary to know the exact operating conditions of the electrolyte before designing a system of anodic protection. In the paper and pulp industry a current of 4(KX) A was required for 3 min to passivate the steel surfaces after passivation with thiosulphates etc. in the black liquor the current was reduced to 2 7(X) A for 12 min and then only 600 A was necessary for the remainder of the process . From an economic aspect, it is normal, in the first instance, to consider anodically protecting a cheap metal or alloy, such as mild steel. If this is not satisfactory, the alloying of mild steel with a small percentage of a more passive metal, such as chromium, molybdenum or nickel, may decrease both the critical and passivation current densities to a sufficiently low value. It is fortunate that the effect of these alloying additions can be determined by laboratory experiments before application on an industrial scale is undertaken. 

Most metals and many refractory compounds can be thermal-sprayed. Applications include coating of gas-turbine components for aircraft and industrial use, components of steam turbines and diesel engines, components for the oil and gas industry, paper and pulp industry, and chemical processing industry. 

The pulp industry is broken down into predominantly two types of fibre types ... 

Table 1 Biocides used within the pulp industry...

Krofta, M. and Wang, L.K., Pollution Abatement Using Advanced flotation Technology in the Paper and Pulp Industry, Powder and Bulk Solids Conference, Rosemont, Chicago, IL, May 1985. 

Kangas J, Jappinen P, Savolainen H. 1984. Exposure to hydrogen sulfide, mercaptans and sulfur dioxide in pulp industry. Am Ind Hyg Assoc J 45(12) 787-790. 

Applications of Peroxidise Application in the Paper Pulp Industry... 

Synthetic organic chemists have simplified many processes, using catalysts to make useful chemicals in one step from basic raw materials such as propane. The gigantic paper and pulp industry has devised many new bleaching processes to replace traditional chlorine bleaching. 

Landfors J (1993) Alternative on-site caustic soda production in the paper and pulp industry, Electrochem Processing, Innovations and Progress, April 21-23, Glasgow Sunblad B (1992, Eka Nobel) Can CA 2,071,810 Chem Abstr 118 194663f... 

Environmental issues are discussed below. It is worth pointing out now that the industry has had to adapt to chlorine demand changes in this sector such as CFCs, pulp and paper and solvents. In Europe no chlorine is used in the pulp industry and it is being run-down elsewhere. Many of the plants which supplied chlorine into the pulp sector are situated a long way from other chlorine end-users and there have been closures of chlorine units, mainly in Scandinavia, Canada and the West Coast of the USA. 

The second option involves the use of a CIO2 scrubber. This is a technique presently used in the paper and pulp industry. In the scrubber, the chlorine dioxide reacts with another chemical, such as a sulphite, DMSO, white spirit or an alkaline hydrogen peroxide solution. The hydrogen peroxide solution is most suited to the process described in this chapter as there are no waste streams. The reaction of chlorine dioxide with the alkaline hydrogen peroxide solution is rapid [10]. The reaction equation is as follows ... 

Biomass can generate energy in many different forms. Refuse derived fuels (MSW) can produce steam or electric power. They can also be converted to other fuels using chemical or biological processes producing ethanol or methanol. The wood and pulp industries use their wastes to provide a significant part of their heat, steam, and electricity needs. 

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