Pulping pollution control

Pollution Control in the Bleachery. The quantity of water necessary for bleaching, and consequently the volume of effluents, has been decreased significantly by various schemes for recycle of Hquors, eg, pulp washing using dilute spent Hquors and countercurrent flow. Effort is underway to close bleach plants and further reduce water consumption. 

Properties Commercial grades Uses Manufacture White to grayish-white solid. Reacts with water to form calcium hydroxide. Commercial lime is available in lump, pebble, ground, and pulverized forms. One of the oldest commercial chemicals. Used in hundreds of applications. The most important uses are for making steel and chemicals, water treatment, pollution control, pulp and paper, and construction. Limestone (calcium carbonate, CaCOj) from mines or quarries is heated in a kiln (calcined). 

Other plant-scale applications to pollution control include the flotation of suspended sewage particles by depressurizing so as to release dissolved air [Jenkins, Scherfig, and Eckhoff, Applications of Adsorptive Bubble Separation Techniques to Wastewater Treatment, in Lemlich (ed.). Adsorptive Bubble Separation Techniques, Academic, New York, 1972, chap. 14 and Richter, Internat. Chem. Eng, 16,614 (1976)]. Dissolved-air flotation is also employed in treating waste-water from pulp and paper mills [Coertze, Prog. Water TechnoL, 10, 449(1978) and Severeid, TAPPl 62(2), 61, 1979]. In addition, there is the flotation, with electrolytically released bubbles [Chambers and Cottrell, Chem. Eng, 83(16), 95 (1976)], of oily iron dust [Ellwood, Chem. Eng, 75(16), 82 (1968)] and of a variety of wastes from surface-treatment processes at the maintenance and overhaul base of an airline [Roth and Ferguson, Desalination, 23, 49 (1977)]. 

STRATEGIES FOR POLLUTION CONTROL IN PULP AND PAPER INDUSTRIES... 

Jackson, John E., and Leone, Robert A., "The Political Economy of Federal Regulatory Activity A Case Study of Water Pollution Controls in the Pulp and Paper Industry," preliminary version. 

Ozone is used in the treatment of drinking water and in industries where high purity water is required (e.g., breweries, pharmaceuticals, and electronics). Ozone is also used in industrial wastewater pollution control, wastewater disinfection, and odor control in the treatment of process water, such as cooling tower water in the treatment of swimming pools and spas in pulp bleaching and in organic synthesis, as a selective oxidant. 

Environmental Pollution Control. The importance of chemical oxidation of reduced sulfur compounds lies in its application to treatment of wastes-treams from municipal sewage systems, acid mine drainage and industrial plants such as tanneries, paper and pulp mills, oil refineries and textile mills. 

Claussen P (1978) Membrane filtration of SSL for byproduct recovery and pollution control. Pulp Pap Can 79(3) 41-45... 

Zaidi A, Buisson H, Sourirajan S, and Wood H. Ultra- and nano-filtration in advanced effluent treatment schemes for pollution control in the pulp and paper industry. Wat. Sci. Tech. 1992 25(10) 263-276. 

Georgia Kraft Company, Foam Separation of Kraft Pulping Wastes, Water Pollution Control Research Series, DAST-3, U.S. Department of the Interior, Federal Water Pollution Control Administration (1969). 

Each of the pulping methods—mechanical, chemimechanical (presoak), semichemical, and the kraft and sulfite chemical processes—produce different types of wastes, so that emission control measures for each should be considered separately. Since the mechanical and kraft chemically based pulping methods dominate the world markets (Table 15.1), the discussion will focus on these two processes. Resource use and pollution control problems of the... 

Reverse osmosis, although originally developed for water desalination ( ), has been applied to numerous pollution control and concentration problems, including industrial (2 and municipal O) wastewaters, pulp and paper waste streams ( ), food processing liquids ( 5), and dairy wastes ( ). 

Contents indude regulations, air pollution control, water pollution control, solid waste disposal, iron and steel manufacturing, foundries, nonferrous metal production, metal finishing, cement manufacture, glass manufacture, pulp and paper, food processing, brewing industry, tanning, and chemical manufacture. 

In the pulping industry, sulfur oxides emissions represent loss of pulping chemical, but the economic loss is apparently not regarded as very serious, at least in this period of relatively abundant and cheap sulfur. In current practice, much sulfur is evidently lost to become either a water or air pollutant (16, 53, 102), but pollution control regulations are forcing increased recovery and recycling of sulfur and other pulping chemicals. The need to increase heat recovery and use should also influence emission controls. 

The requirements for water pollution control have been forcing a shift to concentrating spent sulfite pulping liquor by evaporation, followed by incineration with heat recovery (102). When calcium-base liquor is burned, the sulfur emerges as calcium sulfate and is not available for recycle to the pulping process. The flue gas from such furnaces in Sweden is reported to contain 0.2—0.3% sulfur dioxide, and in one Swedish mill a Bahco wet limestone scrubber is used to treat the gases (115). 

Uses Emulsifier, pigment wetting agent/dispersant for agric. pesticides, paper pulp mfg., water treatment, oil recovery and pollution control, textile auxiliaries, cleaning materials, antimist compds., emulsion polymerization... 

---