Treating chemical wastewater
The EnViro-cell process allows the electrochemical oxidation and reduction of dissolved substances in industrial wastewater solutions, as Dr Mueller explains.The central component of classic packed bed electrolysis is one or more packed bed (granulated graphite) electrodes with a high efficiency surface area.
These make it possible to economically treat even extremely low concentration solutions, such as wastewater containing small amounts of heavy metals.
The basic packed bed electrolysis unit can be configured to meet the demands of four large applications areas:
- Recovery of precious metals such as gold and silver;
- Removal of metal ions (copper, lead, tin, mercury, cadmium) from wastewater;
- Anodic oxidation of cyanide, nitrites and similar substances without the use of environmentally hazardous chemical additives;
- Renewal of process solutions in galvanic rinsing and related applications.
Classic packed bed units are capable of meeting or surpassing all of today's mandated wastewater emission levels for heavy metals.
Packed bed units are available for a wide range of metal concentrations ranging from 10ppb to 250000ppb and can be used individually or in series as concentrations demand.
Operating costs are so low that total expense estimates for a packed bed installation need only reflect investment expenditures.
The modular cell concept allows easy maintenance - individual modules can be placed off-line without disrupting overall operation.
In the chemical industry for many processes copper in ionic form is used as a catalyst. This is the case in the following productions:
- Production of copper-phthalo cyanine;
- Oxychlorination of acetylene, ethylene, benzene, toluene, xylene;
- Dimerisation of acetylene (chloroprene production);
- Production of acrylic acid derivatives;
- Production of polyamides (copper and cyanide).
For the purification of wastewater produced during the manufacture of vinyl chloride, a continuously operating electrolysis plant consisting of packed bed cells is used. The plant comprises two stages of packed bed cells, each of them consisting of four cells, type EP4/50.
After the two stages, the copper concentration of 6mg/l is reduced to <0.5mg/l. By cathodic reduction the copper ions are reduced to metallic copper on the surface of the graphite granules. Thus the packed bed of graphite granules is loaded with copper.
While the plant is continuously operating, the metal loaded graphite is sucked out of the cells, regenerated and refilled into the cells. Each stage is equipped with a rectifier supplying the cells with direct current.
The main advantages of this electrolysis process are:
- Waste-free process;
- No addition of chemicals;
- No increase in the salt content;
- Low energy consumption.
All EnViro-cell modular cell types and standard system solutions are characterised by high environmental compatibility, using only electrochemical technologies and no potentially hazardous chemicals for treating industrial wastewater.
The systems produce wastewater concentrations of heavy metals and other substances which meet or surpass all mandated environmental levels.
The technology also allows the recovery and recycling of precious and other economically valuable metals without high-volume production of industrial sludge which must be expensively processed before disposal.
The systems amortise quickly and are highly cost-efficient. EnViro-cell offers its system in a variety of sizes, ranging from compact units to large-scale industrial processors.
Customised, client-specific designs and treatment solutions are also available from engineers, who are also involved in wide-ranging R&D programs involving international companies in the chemical, electro-plating and related industries.
These include feasibility studies in which EnViro-cell technology is integrated in extended processing systems using other disposal and recovery systems.