Waste products from industrial processes

Thermal power plant is more commonly associated with very large central power stations. The capital cost for thermal power plant, in terms of cost per installed kilowatt of electrical generating capacity, rises sharply for outputs of less than some 15 MW. It is for this reason that thermal power plant is not usually considered for industrial applications unless it is the combined cycle or combined heat and power modes. However, for cases where the fuel is of very low cost (for example, a waste product from a process such as wood waste), then the thermal power plant, depending on output, can offer an excellent choice, as its higher initial capital cost can be offset against lower running costs. This section introduces the thermal power cycle for electrical generation only. 

In the contiguous United States, the main emphasis is on miscible CO2 flooding. Carbon dioxide is relatively inexpensive since it has no value as a fuel and is available in large amounts from natural deposits or as a waste product of industrial processes. Table I shows major natural deposits of CO2, their approximate amounts, and their locations with respect to oil fields ( 1). With (or even without) partial recycling of CO2, there is no foreseeable shortage of this injection fluid. 

Biomass is an environmental benign source of energy and a COj-neutral fuel for heat and power generation. Wood can be used either directly from forestry or also as waste product from wood processing industry, e.g. saw dust. The advantage of gasification... 

As highlighted in previous reviews of nitrile hydratase, nitriles from both natural and industrial sources are a prevalent chemical functionality in our environment (i-5). In industry, nitriles find use in the production of fine chemicals, as pesticides, and as feedstock for the production of polyacrylamide and other polymers. Historically, waste products from these processes were dumped into open waterways or pumped into deep pressure wells, leading to deleterious environmental effects. Naturally occuring nitriles include... 

Transfer as a raw material to another process a substance that is a waste product from one process may serve as a raw material for another, sometimes in an entirely different industry... 

Carbon dioxide and water are the major waste products from most natural and industrial processes and hence are found in large quantities in the environment. If an efficient and cheap means could be found, the reduction of C02 could provide a potentially rich source of carbon for utilisation in the production of, for example, synthetic hydrocarbon fuels to replace petroleum, formic and oxalic acids for the chemical industries and foodstuffs such as glucose. 

Heterotrophic and autotrophic bacteria are important participants in the restoration industry. Both types are indigenous to almost every site. The subsurface environment includes many thousands of species of microbes, which act in harmony to support each other. Waste products from one group become nutrients for another. When free oxygen is depleted, anaerobic activity increases. Thus, it is often convenient to consider microbiological activity as a series of processes resulting from bacterially mediated oxidation-reduction reactions. 

Bauer S, Wolff I, Werner N, et al. 1992. Toxicological investigations in the semiconductor industry I. Studies on the acute oral toxicity of a complex mixture of waste products from the aluminium plasma etching process. Toxicology and Industrial Health 8 141-156. 

Other brines and mud suspensions from industrial processes that are currently being considered for carbonation include aqueous red mud flows [27] and mixtures of bauxite and saline waste water [115] from aluminum production. Here, the C02 fixation capacities are of the order of 5-10 g per 100 g red mud as a result of 15wt% Na20 + CaO (dry), while a 90%/10% (v/v) bauxite waste/brine mixture can take up more than 9.5 g C02 per liter of liquid. Worldwide, a total of 200 Mt bauxite residues are stored, mainly in ponds. 

Fly ash, as it is a large-volume industrial waste, is both cheap and abundant, so that there is an economic incentive to use fly-ash-modified cements. In addition, C02 is also produced as a waste by-product of industrial processes (power generation, cement manufacture, etc.), and its permanent sequestration into cement is an added environmental benefit. A fully carbonated Portland cement permanently sequesters about 130 L of C02 per kilogram of cement. Figure 15.8 shows the structural and chemical modifications produced in cemented fly ash microspheres as a result of the supercritical C02 treatment. As is the case with fly ash, kiln dusts are primarily siliceous, so that the same benefits can be derived from their use as modifiers in immobilization and S/S matrices. 

Other plants such as potatoes, cauliflower, cherries, and soybeans and several fungi may also be used as sources of peroxidase enzymes. Soybeans, in particular, may represent a valuable source of peroxidase because the enzyme is found in the seed coat, which is a waste product from soybean-based industries [90]. In this case, it may be possible to use the solid waste from the soybean industry to treat the wastewaters of various chemical industries. In fact, the direct use of raw soybean hulls to accomplish the removal of phenol and 2-chlorophenol has been demonstrated [105]. However, it should be noted that this type of approach would result in an increase in the amount of solid residues that must be disposed following treatment. Peroxidases extracted from tomato and water hyacinth plants were also used to polymerize phenolic substrates [106], Actual plant roots were also used for in vivo experiments of pollutant removal. The peroxidases studied accomplished good removal of the test substrate guaiacol and the plant roots precipitated the phenolic pollutants at the roots surface. It was suggested that plant roots be used as natural immobilized enzyme systems to remove phenolic compounds from aquatic systems and soils. The direct use of plant material as an enzyme source represents a very interesting alternative to the use of purified enzymes due to its potentially lower cost. However, further studies are needed to confirm the feasibility of such a process. 

The list of potentially hazardous materials includes drugs, food additives, preservatives, ores, pesticides, dyes, detergents, lubricants, soaps, plastics, extracts from plant and animal sources, plants and animals that are toxic by contact or consumption, and industrial intermediates and waste products from production processes. Some of the information refers to materials of undefined composition. The chemicals included are assumed to exhibit the reported toxic effect in their pure state unless otherwise noted. However, even in the case of a supposedly pure chemical, there is usually some degree of uncertainty as to its exact composition and the impurities that may be present. This possibility must be considered in attempting to interpret the data presented because the toxic effects observed could in some cases be caused by a contaminant. Some radioactive materials are included but the effect reported is the chemically produced effect rather than the radiation effect. 

Waste products from many industrial processes contain at times significant concentrations of metals which are objectionable on environmental grounds and yet constitute an appreciable economic asset. The presence of toxic metals in such wastes constitutes an environmental hazard, particularly because the ever-decreasing pH of the rainwater makes their leachability and contamination of the ground water more likely. Careful and costly waste-disposal procedures are thus mandatory so as to prevent this from occurring. A preferred alternative is the cost-effective conversion of such waste into useful products. This provides an optimal solution to the waste-disposal problem because (a) it eliminates the need for a safe and costly disposal of the hazardous waste (b) it maximizes resource utilization and conservation through recycling, and (c) it derives an economic benefit from the sale of the obtained products. 

Cadmium, a waste product from several industrial processes, is the cause of itai-itai ( ouch-ouch ) disease, which is characterized by osteomalacia with painful fractures of affected, bones and by nephropathy with an excretory pattern similar to that seen in Fanconi s syndrome. In... 

Waste products from our industrial processes constitute the largest source of pollution. While they differ in nature from domestic wastes, industrial wastes in some respects have a greater detrimental effect... 

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