Outputs, waste

Material intensity is given by the mass of waste per unit of output. Waste is calculated by subtracting the mass of products and saleable subproducts from the raw materials. Water and air are not included unless incorporated in the product. 

Is there a scope to redirect any output waste streams back to the reactor feed to reduce waste Can the recycle to reactor be fed directly to the reactor or is a... 

The removal of heavy metals on fixed-bed columns was performed primarily with lead and zinc in a concentration of 5 ppm as this proved to be most critical in the practical realization of large scale operations. The metal content of input and output waste waters was determined by atomic absorption spectrophotometry. In the series of experiments the appropriately treated columns were kept in operation only for a certain period of time (3-400 hours), when denitrification capacity suddenly dropped in a few hours from 90-95% to 0, indicating that the microbes accumulated a lethal dose of the toxic heavy metal (pH = 7.5, at 25 C, with continuous feedings at the 5 ppm level). Cell death was also verified by the lack of TTC reduction. 

The process tree consists of inputs, outputs, waste and emissions of the set of economic and physical processes which contribute to the service provided by the previously-determined functional unit. It is drawn up based on the functional unit itself and the scope of the study. There is agreement at large on applying a "cradle-to-grave" approach, to cover the steps from the extraction of natural resources to waste management, including reuse, recycling, incineration, and disposal. 

The waste pretreatment frequendy (and sometimes dramatically) reduces the output of a process, which is not considered in this cost breakdown. 

Fig. 5. Equipment foi surface treating plastic components. Parts ate loaded into one of the two lower chambers which is then evacuated to remove most of the air. This chamber is then flooded with a dilute mixture of fluorine and nitrogen which is made and stored in the upper chamber. After the treatment is completed, the fluorine mixture is pumped back up to the upper chamber for storage and the lower chamber repeatedly flooded with air and evacuated to remove any traces of fluorine gas. Two treatment chambers are cycled between the loading/unloading operation and the treatment step to increase equipment output. The fluorine—nitrogen blend may be used several times before by-products from the treatment process begin to interfere. AH waste...

Uniform, rehable flow of bulk soflds can allow the production of quaUty products with a minimum of waste, control dust and noise, and extend the hfe of a plant and maximi2e its productivity and output. By conducting laboratory tests and utili2ing experts with experience in applying soflds flow data, plant start-up delays that can impact schedule and cost can be eliminated. 

The traveling-grate furnace requires less labor, increases the output per unit of grate area, and produces more uniform product than the WetheriU. furnaces. The traveling grate is an endless chain of cast-iron bars, driven by sprockets, which traverses a firebrick chamber. Anthracite briquettes are fed to a depth of ca 15 cm. After ignition by the previous charge, the coal briquettes are covered by 15—16.5 cm of ore/coal briquettes. The latter are dried with waste heat from the furnace. Zinc vapor evolves and bums in a combustion chamber and the spent clinker faUs into containers for removal (24,25). 

Other types of selective systems employ multiple final control elements or multiple controllers. In some applications, several manipulated variables are used to control a single process variable (also called split-range control). Typical examples include the adjustment of both inflow and outflow from a chemic reactor in order to control reactor pressure or the use of both acid and base to control pH in waste-water treatment. In this approach, the selector chooses from several controller outputs which final control element should be adjusted (Marlin, Process Control, McGraw-Hill, New York, 1995). 

Life-Cycle Analysis The aforementioned multimedia approach to evaluating a product s waste stream(s) aims to ensure that the treatment of one waste stream does not result in the generation or increase in an additional waste output. Clearly, impac ts resulting during the... 

TABLE 25-68 Energy Output and Efficiency for 1000 Metric Ton of Waste/Day Steam-Boiler Turbine-Generator Energy-Recovery Plant Using Unprocessed Industrial Solid Wastes with Energy Content of 12,000 kJ/kg... 

Figure 2-21 show the effect of 5% by weight of steam injection at a turbine inlet temperature of 2400 °F (1316 °C) on the system. With about 5% injection at 2400°F (1316 °C) and a pressure ratio of 17 1, an 8.3% increase in work output is noted with an increase of about 19% in cycle efficiency over that experienced in the simple cycle. The assumption here is that steam is injected at a pressure of about 60 psi (4 Bar) above the air from the compressor discharge and that all the steam is created by heat from the turbine exhaust. Calculations indicate that there is more than enough waste heat to achieve these goals. 

Although, the input line is low enough to draw all the bias eurrent to run the eontrol IC and the MOSFET, doing so would waste approximately 1.2 W, or a 4.2 pereent effieieney loss. A start-up eireuit that provides eurrent from the input only during start-up or overeurrent foldbaek is best. The IC and MOSFET ean reeeive power from the -I-12V output during normal operation. Refer to sehematie in Figure 3-59 ... 

The reuse or recycling of wastes can reduce the amount of freshwater and raw materials required for a process. While looking at the inputs to unit operations, think about the opportunities for reusing and recycling outputs from other operations. Note that if reused wastes are not properly documented, double-counting may occur in the material balance, particularly at the process or complete plant level that is, a waste will be quantified as an output from one process and as an input to another. 

Step 6 Write the Component Material Balances. The Phase II auditing steps define the pollutants and wastes that are among the team s focus. Its objective has always been to identify specific wastes or pollutants that the enterprise can reduce these are the components the team needs to assess in the material balances. It is important to note that once the material balance for each unit operation has been completed for raw-material inputs and waste outputs, it is necessary to repeat the procedure for each contaminant of concern. 

Now you can reconsider the material balance equations by adding those additional factors identified in the previous step. If necessary, estimates of unaccountable losses will have to be calculated. Note that, in the case of a relatively simple manufacturing plant, preparation of a preliminary material-balance system and its refinement (Steps 14 and 15) can usefully be combined. For more-complex P2 assessments, however, two separate steps are likely to be more appropriate. An important rule to remember is that the inputs should ideally equal the outputs - but in practice this will rarely be the case. Some judgment will be required to determine what level of accuracy is acceptable, and we should have an idea as to what the unlikely sources of errors are (e.g., evaporative losses from outside holding ponds may be a materials loss we cannot accurately account for). In the case of high concentrations of hazardous wastes, accurate measurements are needed to develop cost-effective waste-reduction options. It is possible that the material balance for a number of unit operations will need to be repeated. Again, continue to review, refine, and, where necessary, expand your database. The compilation of accurate and comprehensive data is essential for a successful P2 audit and subsequent waste-reduction action plan. Remember - you can t reduce what you don t know is therel... 

Records and prints waste disposal manifests on official forms and outputs reports by waste category, transporter, and disposal site. Also records MSDSs. Requires 256K memory. 

Determine the destination of the outputs (including waste) and how they will be transmitted to the next workstation or be disposed of. 

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