Tanks, waste reduction

Waste Reduction Processes can be redesigned to reduce the amount of waste generated. For example, transfer hnes between processes can be Blown clear pneumaticaUy to drive liquid into the Batch mix tank. 

Closed-loop recycling. To further promote waste reduction and recycling, spent materials that are reclaimed and returned to the original process in an enclosed system of pipes and tanks are excluded from the definition of solid waste, provided that the following conditions are met ... 

Biological destrnction of tank waste (BDTW) is a separation and volume-reduction technology designed to treat snpematant and slniced salt cake waste from nnderground storage tanks. These... 

J.4.1 Use of Mechanical Devices Such As Rubber Wipers. In order to reduce the amount of paint left clinging to the walls of a mix tank, rubber wipers are used to scrape the side of the tank. This operation requires manual labor and hence the percentage of waste reduction is a function of the operator. Since the benefits will be offset by increased labor, mechanization/automation should be considered. Many new mixers are available that are designed with automatic wall scrapers (Weismantel 1985). These mixers can be used with either flat or conical bottom cylindrical mix tanks. 

The importance of waste reduction through the use of a chemical catalyst can be exemplified by the use of yV-methylimidazole as a catalyst in the leaching step of gold extraction from ores in the mining industry. Cyanide, a toxic substance that poses a major health threat, has traditionally been used for these processes. A sample case is the 1999 leak in a Rumanian facility from a cyanide storage tank into the Rhine River that killed thousands of fish. 

Perhaps the most significant impediment to comprehensive waste reduction in laboratories is the element of scale. Techniques that are practical and cost-effective on a 55-gallon or tank car quantity of mataial may be highly unrealistic when applied to a 50-gram (or milligram) quantity. Evaluating the costs of both equipment and time becomes especially important when dealing with very small quantities. 

As is normally the case with efforts of this kind, substantial waste reductions were aehieved by simple measures. One of these was the reduetion by 15,500 kg/year of organoehlorine eompound emissions from the manufaeture of Saran plastie by transferring produet to a storage tank twice a day instead of only once. When only one transfer per day was performed, the tank was filled to capacity with liquid and vaporized organoehlorine compound emissions had to be vented to waste. Retaining these materials for reeycle from the half-filled tanks saved the company an estimated 34,000 per year. 

Even though the floating roof achieved a 90% reduction of toluene emissions from the tank, the overall facility-wide change in toluene waste generation is negative 40% - this is the figure that should be reported in the or percent change" part of Section 8 of Form R. 

Waste associated with equipment cleaning represents the largest source of waste in a paint facility. Methods that reduce the need or frequency of tank cleaning or allow for reuse of the cleaning solutions are the most effective. Source reduction methods include ... 

Suggestions for reducing tank cleaning wastes include the following source reduction strategies ... 

This refers to the amount of time a work piece is actually in a tank being rinsed. Its effect on rinsing efficiency, and therefore its potential for source reduction, can be nearly as great as that of the previous two options.[21] Taken together, these three options provide a set of rinsing procedures which, when done well, can reduce dragout, and therefore waste requiring treatment by over 50%. 

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