Zero Discharge Manufacturing

Zero discharge manufacturing encompasses all the methods that various industries use to eliminate the wastes—at least all hazardous wastes—they produce. Though each industry differs on how it does this, zero discharge manufacturing always has these things in common:

1. wastewater solid-liquid separation and reuse
2. minimized rinsing or cooling operations to reduce water use
3. nonhazardous solid waste cleanup and reuse
4. hazardous chemical elimination
5. advanced filtration systems to collect hazardous organic compounds or metals
6. heat energy capture and reuse
7. scrubber, afterburner, or electrostatic precipitator for gas emissions

Zero discharge manufacturing is a method of making the industrial process much more sustainable than current practices. Zero discharge procedures usually center on biological methods of production that eliminate hazardous emissions and contaminated soil and water. Zero discharge emphasizes the reuse of materials, energy, and heat.

 Even the dairy industry has attempted zero discharge operations, which represents an important breakthrough because agriculture of almost all types is a major producer of wastes. Zero discharge dairy farms may become more common as more farms adapt to the following practices: (1) capturing wastewaters and mixing with manure wastes; (2) collecting manure and treating in energy-producing on-site digesters; (3) directing rain runoff away from animal areas; (4) fixing all waste transport and feed storage leaks; and (5) building a secondary containment berm around animal and waste areas to hold wastes from accidental spills. Zero discharge agriculture is very difficult to achieve, but, if agriculture can make important headway toward sustainable methods, it will provide an important example for other industries to follow.

 Current zero discharge operations usually begin with wastewater management for two reasons: water is a natural resource that is becoming increasingly scarce, and water carries waste chemicals produced by many different types of manufacturing. Zero discharge facilities have now incorporated one or more of the technologies described in the following table for controlling water pollution.

 Zero discharge has been achieved in wastewater recovery and certain aspects within manufacturing such as production wastes, chemical wastes, and emissions. Manufacturers have found it difficult, however, to incorporate all three methods within one manufacturing plant. Any zero discharge method must consume less energy than the previous waste disposal method, or companies will be reluctant to accept it.