Waste process for

Whey hydrolysis and dairy waste processing for production of food ingredients [116] production of glucose, galactose, substrates for alcohol and ascorbic acid production [64] Solubilization of fish, meat, and leather remains, production of protein hydrolysates [64,65]... 

The disposal of municipal and industrial wastes has become an important problem because the traditional means of disposal, landfill, has become environmentally much less acceptable than previously. In addition, special incinerator systems are required to meet environmental standards for disposal by incineration. Disposal of wastes by landfill or incineration also includes a potential loss of energy sources and, in some cases, valuable mineral resources. New, much stricter regulation of these disposal methods will make the economics of waste processing for resource recovery much more favorable. 

On the other end of the scale of sophistication are agglomeration methods needed for low cost applications in the field of recovery of small amounts of valuable materials by leaching and waste processing for disposal. Many finely divided particulate wastes cannot be deposited in landfills or similar open storage facilities because of the danger of recontamination by wind and water. Because, in this case, agglomeration is only an additional cost, the cheapest possible method must be selected. 

From the outsrt of resewch the use of oiganic anhydrides as dehydrating ag its Ci.e., acetic anhydnde) was investigated with the idea of a no waste process for the generation of isocyanates via dehydration of carbamates (see Scheme I). 

In Chap. 10, modification of the process for reducing process waste was considered in detail. It also was concluded that to minimize utility waste, the single most effective measure would be improved heat recovery. The energy-targeting methods presented in Chaps. 6 and 7 maximize heat recovery for a given set of process conditions. However, the process conditions can be changed to improve the heat recovery further. 

Recrystallisation. The process of purification by recrystallisation is undoubtedly the most frequent operation in practical organic chemistry, and it is one which, when cleanly and efficiently performed, should give great pleasure to the chemist, particularly if the original crude material is in a very impure and filthy condition. Yet no operation is carried out so badly, wastefully (and thoughtlessly) by students in general, not only by elementary students, but often by research students of several years experience. The student who intends later to do advanced work must master the process, for unless he can choose a suitable solvent and then successfully recrystallise often minute quantities of material, he will frequently find his work completely arrested. 

R. E. Hiachee, G. D. Sayles, and R. S. Keen, eds.. Biological Unit Processes for Hazardous Waste Treatment, BatteUe Press, Columbus, Ohio, 1995. 

In 1987, Toray Industries, Inc., announced the development of a new process for making aromatic nitriles which reportedly halved the production cost, reduced waste treatment requirements, and reduced production time by more than two-thirds, compared with the vapor-phase process used by most producers. The process iavolves the reaction of ben2oic acid (or substituted ben2oic acid) with urea at 220—240°C ia the presence of a metallic catalyst (78). 

Some beehive ovens, having various improvements and additions of waste heat boilers, thereby allowing heat recovery from the combustion products, may stiU be in operation. Generally, however, the beehive oven has been replaced by waH-heated, horizontal chamber, ie, slot, ovens in which higher temperatures can be achieved as well as a better control over the quality of the coke. Modem slot-type coke ovens are approximately 15 m long, approximately 6 m high, and the width is chosen to suit the carbonization behavior of the coal to be processed. For example, the most common widths are ca 0.5 m, but some ovens may be as narrow as 0.3 m, or as wide as 0.6 m. 

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. 

Hydrothermal Synthesis Systems. Of the unit operations depicted in Figure 1, the pressurized sections from reactor inlet to pressure letdown ate key to hydrothermal process design. In consideration of scale-up of a hydrothermal process for high performance materials, several criteria must be considered. First, the mode of operation, which can be either continuous, semicontinuous, or batch, must be determined. Factors to consider ate the operating conditions, the manufacturing demand, the composition of the product mix (single or multiple products), the amount of waste that can be tolerated, and the materials of constmction requirements. Criteria for the selection of hydrothermal reactor design maybe summarized as... 

In a rotary kiln, the burner can produce both thermal and fuel NO, if the fuel contains nitrogen. Many soHd waste streams also contain nitrogen, typically as much as 20 wt %, which contributes to the fuel NO pathway. Key sources of soHd waste fuel nitrogen include plastics, nylons, dyes, and other process wastes. Nylon, for example, is 33 wt % nitrogen. 

Water formed in the reaction as well as some undesirable by-products must be removed from the acetic acid solvent. Therefore, mother Hquor from the filter is purified in a residue still to remove heavies, and in a dehydration tower to remove water. The purified acetic acid from the bottom of the dehydration tower is recycled to the reactor. The water overhead is sent to waste treatment, and the residue still bottoms can be processed for catalyst recovery. Alternatively, some mother Hquor from the filter can be recycled directiy to the reactor. 

To avoid generation of waste brines and the associated serious problem of brine disposal, the potash industry in the former FRG began converting some operations to electrostatic separation, a dry process for separating potassium salts from other soluble salts (24,25). 

Commercially, a small amount of the 4,4 -MDA is isolated by distillation from PMDA. Depending on the process employed, the removal of MDA can be partial (as is done with the isocyanates) or total. Partial removal of MDA gives some processiag latitude but yields of 4,4 -MDA are reduced. Distillation residues from PMDA manufacture that contain less than 1% MDA pose a disposal problem. Processes for the regeneration of MDA by heating these residues ia the presence of aniline and an acid catalyst have been patented (33—35). Waste disposal of PMDA is expensive and reclamation processes could become commercially viable. The versatility of the isocyanate process, however, can be used to avoid the formation of low MDA content distillation residues. 

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