Waste materials

Incineration. Incinerators were discussed in Sec. 11.1. When incinerators are used to treat gaseous pollutants in relatively low concentration, auxiliary firing from fuel or other waste material normally will be necessary. The capital and operating costs may be high. In addition, long duct lines are often necessary. 

Reverse osmosis is a high-pressure membrane separation process (20 to 100 bar) which can be used to reject dissolved inorganic salt or heavy metals. The concentrated waste material produced by membrane process should be recycled if possible but might require further treatment or disposal. 

Z. Evaporation. If the wastewater is in low volume and the waste material involatile, then evaporation can be used to concentrate the waste. The relatively pure evaporated water might still require biological treatment after condensation. The concentrated waste can then be recycled or sent for further treatment or disposal. The cost of such operations can be prohibitively expensive unless the heat available in the evaporated water can be recovered. 

When viewing effluent treatment methods, it is clear that the basic problem of disposing of waste material safety is, in many cases, not so much solved but moved from one place to another. The fundamental problem is that once waste has been created, it cannot be destroyed. The waste can be concentrated or diluted, its physical or chemical form can be changed, but it cannot be destroyed. 

The oil and gas industry produces much waste material, such as scrap metal, human waste, unspent chemicals, oily sludges and radiation. All of the incoming streams to a facility such as a production platform end up somewhere, and only few of the outgoing streams are useful product. It is one of the responsibilities of the engineer to try to limit the amount of incoming material which will finally become waste material. 

Another important example of redox titrimetry that finds applications in both public health and environmental analyses is the determination of dissolved oxygen. In natural waters the level of dissolved O2 is important for two reasons it is the most readily available oxidant for the biological oxidation of inorganic and organic pollutants and it is necessary for the support of aquatic life. In wastewater treatment plants, the control of dissolved O2 is essential for the aerobic oxidation of waste materials. If the level of dissolved O2 falls below a critical value, aerobic bacteria are replaced by anaerobic bacteria, and the oxidation of organic waste produces undesirable gases such as CH4 and H2S. 

Multicompartment dmm filters range in size from about 1 m to over 100 m they are widely used in mineral and chemical processing, in the pulp and paper industry, and in sewage and waste materials treatment. 

If either dry powders or inverse emulsions are not properly mixed with water, large lumps of polymer form that do not dissolve. This not only wastes material, but can also cause downstream problems. This is especially tme for paper where visible defects may be formed. Specialized equipment for dissolving both dry polymers and inverse emulsions on a continuous basis is available (22,23). Some care must be taken with regard to water quaUty when dissolving polyacrylamides. Anionic polymers can degrade rapidly in the presence of ferrous ion sometimes present in well water (24). Some cationic polymers can lose charge by hydrolysis at high pH (25). 

Significant amounts of cryoHte are also recovered from waste material ia the manufacture of aluminum. The carbon lining of the electrolysis ceUs, which may contain 10—30% by weight of cryoHte, is extracted with sodium hydroxide or sodium carbonate solution and the cryoHte precipitated with carbon dioxide (28). Gases from operating ceUs containing HF, CO2, and fluorine-containing dusts may be used for the carbonation (29). 

Specific gravity is the most critical of the characteristics in Table 3. It is governed by ash content of the material, is the primary deterrninant of bulk density, along with particle size and shape, and is related to specific heat and other thermal properties. Specific gravity governs the porosity or fractional void volume of the waste material, ie. 

Biomass. Biomass is simply defined for these purposes as any organic waste material, such as agricultural residues, animal manure, forestry residues, municipal waste, and sewage, which originated from a living organism (70—74). 

In separation, the primary function of the geotextde is to prevent intmsion of one material into another in order to prevent contamination of either material by the other. In the case of an aggregate being placed over a firm foundation sod, the purpose is to maintain the drainage integrity of the aggregate wad apphcation is similar. In landfdl appHcation, the purpose is to prevent intmsion of waste material into the leachette codector system. 

Miscellaneous. Hydrochloric acid is used for the recovery of semiprecious metals from used catalysts, as a catalyst in synthesis, for catalyst regeneration (see Catalysts, regeneration), and for pH control (see Hydrogen-ION activity), regeneration of ion-exchange (qv) resins used in wastewater treatment, electric utiUties, and for neutralization of alkaline products or waste materials. In addition, hydrochloric acid is also utilized in many production processes for organic and inorganic chemicals. 

The processing of hides and skins into leather results in a large quantity of waste materials (9). The hide in the salt-cured condition contains salt in a crystalline form, water as salt solution, and as hide Hquid components, flesh, blood, manure, and surface dirt from the animal. 

Includes other graded coarse aggregate, dam constmction, drain fields, building products, pipe bedding, and waste material. 

Weapons materials from production reactors were accumulated during the Cold War period as a part of the U.S. defense program. Prominent were tritium, ie, hydrogen-3, having a of 12.3 yr, and plutonium-239, 1/2 = 2.4 X lO" yr. The latter constitutes a waste both as a by-product of weapons fabrication in a waste material called transuranic waste (TRU), and as an excess fissionable material if not used for power production in a reactor. 

A considerable quantity of oil can be extracted from waste material from shelling and processing plants, eg, the inedible kernels rejected during shelling and fragments of kernels recovered from shells. About 300 t of pecan oil and 300—600 t of English walnut oil are produced aimuaHy from such sources. The oil is refined and used for edible purposes or for the production of soap the cake is used in animal feeds (see Feeds and feed additives). Fmit-pit oils, which closely resemble and are often substituted for almond oil, are produced on a large scale for cosmetic and pharmaceutical purposes (143). For instance, leaves, bark, and pericarp of walnut may be used to manufacture vitamin C, medicines, dyes and tannin materials (144). 

Due to environmental considerations, many phenol plants are equipped with a special water treatment faciUty where acetone and phenol are recovered from the wastewater stream. Also, recovered heavy residue is considered a K-022 waste material by the U.S. EPA and must be properly disposed of by incineration or other means (12). 

Contract disposal agencies offer their services to reheve the chemical industry of unwanted materials however, the cost of such disposal (primarily incineration) is high. The manufacturer should ascertain that the disposal agency employees are adequately aware of chemical ha2ards and can responsibly handle and dispose of the waste materials (see Wastes, industrial). 

Sewer Disposal. Photoprocessing and printing wastes tend to be aqueous solutions that ate combined with other plant effluents and sent to the local sewer plant for treatment. The parameters of concern include silver, pH, and biological oxygen demand (BOD). BOD is a measure of how well a waste material degrades in the environment. Lower values ate preferred. Silver-bearing waste streams ate typically treated on-site, and the treated effluent is released to the drain. The printer usually receives a small cash credit for silver recovered. 

Collins, Ramaswamy, Ahmed, and Blumenthal, in Inyang and Bergeson, eds.. Utilisation of Waste Materials in Civil Engineering Construction. 

High density tungsten alloy machine chips are recovered by oxidation at about 850°C, foUowed by reduction in hydrogen at 700—900°C. Typically, the resultant powders are about 3-p.m grain size and resinter readily. There can be some pickup of refractory materials used in furnace constmction, which must be controUed. This process is important commercially. Eor materials that may be contaminated with other metals or impurities, the preferred recovery process is the wet chemical conversion process used for recovery of tungsten from ores and process wastes. Materials can always be considered for use as additions in alloy steel melting. 

Thermal degradation of isocyanates occurs on heating above 100—120°C. This reaction is exothermic, and a mnaway reaction can occur at temperatures >175° C. In view of the heat sensitivity of isocyanates, it is necessary to melt MDl with caution and to foUow suppHers recommendation. Disposal of empty containers, isocyanate waste materials, and decontamination of spilled isocyanates are best conducted using water or alcohols containing small amounts of ammonia or detergent. Eor example, a mixture of 50% ethanol, 2-propanol, or butanol 45% water, and 5% ammonia can be used to neutrali2e isocyanate waste and spills. Spills and leaks of isocyanates should be contained immediately, ie, by dyking with an absorbent material, such as saw dust. 

Shipping vitamin D in crystalline or resin form should be done in containers marked appropriately to indicate the material is toxic by DOT standards. Its proper DOT labeling is DOT Hazard Class 6.1, poisonous. Waste material should be burned or placed in an appropriate landfill. 

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