Zero-discharge

Water Quality. AH commercial oil shale operations require substantial quantities of water. AH product water is treated for use and operations are permitted as zero-discharge facHities. In the Unocal operation, no accidental releases of surface water have occurred during the last four years of sustained operations from 1986 to 1990. The Unocal Parachute Creek Project compliance monitoring program of ground water, surface water, and process water streams have indicated no adverse water quaHty impacts and no violations of the Colorado Department of Health standards (62). 

It is not currently feasible to achieve a zero discharge of chemical pollutants from metal finishing operations. However, substantial reductions in the type and volume of hazardous chemicals wasted from most metal finishing operations are possible.8 Because end-of-pipe waste detoxification is costly for small- and medium-sized metal finishers, and the cost and liability of residuals disposal have increased for all metal finishers, management and production personnel may be more willing to consider production process modifications to reduce the amount of chemicals lost to waste. 

Option 3 All of Option 2 plus ultrafiltration and carbon adsorption for oily waste, zero discharge of any processes using either cadmium or lead by using an evaporative system. 

The CWA21 imposes pollutant limitations for all discharges of wastewater from identifiable ( point ) sources into the nation s waterways. These discharges are defined as either direct discharges, indirect discharges, or zero discharges. 

The waste from this treatment scheme should be suitable for discharge or reuse with a possible need for removal of inorganic dissolved solids if a "zero discharge" system is used. 

Figure 5.22 Solids conveying rate as a function of barrel and screw temperature for the shallow screw (8.89 mm) at a screw speed of 50 rpm and at zero discharge pressure...

The effect of channel depth on solids conveying rate is shown in Fig. 5.26 for screw and barrel temperatures of 75 and 125 °C, respectively, and at a screw speed of 50 rpm. At zero discharge pressure, the solids conveying rates were nearly proportional to the depth of the screw channel (or cross-sectional area perpendicular to the flight). For example, the conveying rates were 91 and 125 kg/h for the 8.89 and 11.1 mm deep screws, respectively. For these screws, the cross-sectional areas perpendicular to the flights were calculated at 420 and 530 mm an area increase of... 

These principles are embodied in the concepts of zero discharge and sustainable technology. 

ZERO EMISSION, ZERO DISCHARGE, CLEANER PRODUCTION,... 

The terms of zero emission, zero discharge, cleaner production, waste minimization, pollution prevention, design for environment, material substitution, and dematerialization are all closely related, and each is self-explanatory. The U.S. Environmental Protection Agency (USEPA), the United Nations Industrial Development Organization (UNIDO), and other national and international organizations at different periods of time have promoted each [8,19,23,30-34,39-46]. 

The use of flotation clarifiers and fiber recovery facilities in paper mills may achieve near total water and fiber recycle and, in turn, accomplish the task of zero discharge [16]. 

Diepolder, P. Is Zero Discharge Realistic Hydrocarbon Proc. 1992, October. 

This practice is undesirable because the addition of makeup water often results in the discharge of phossy water, unless an auxiliary tank collects phossy water overflows from the storage tanks, thus ensuring zero discharge. A closed-loop system is then possible if the phossy water from the auxiliary tank is reused as makeup for the main phosphorus tank. 

Point-of-Source Recovery - in certain circumstances, it is possible to utilize reverse osmosis to effect a "zero discharge" electroplating rinse water recovery system. The rinse water from the first rinse is pumped to a reverse osmosis system that concentrates the salts and directs them back to the plating bath. The purified rinse water (permeate) is directed to the last rinse, and neither solute nor solvent is lost. in the united States there are approximately 150 reverse osmosis systems operating in this manner on nickel baths and 12 on acid copper. There are also a few installations operating on copper cyanide, hexavalant chrome, and acid zinc. 

---