Wastewater Treatment

REMOTOX® precipitates dissolved metals as metal sulfides, which exhibit lower solubility than the corresponding metal hydroxides.

Product Features:

Relatively inexpensive.
Its residues are inert and non-toxic.
REMOTOX does not contain dithiocarbamate or its related salts.
No need to dissolve prior to use as compared to solid material.
Has a very low crystallization (salt-out) temperature.
NSF approved for drinking water treatment.
Not regulated by the DOT.
Compared to other sulfides, such as sodium hydrosulfide, it provides more stability in acidic medium.
REMOTOX has been tested to maintain its effectiveness for a minimum of one year.

REMOTOX® Calcium Polysulfide for removing copper, zinc, lead, chromium, cadmium, cyanide and other metals from process wastewater.

Many industries, including metal finishing, printed circuit board manufacturing, pulp and paper, food processing, and mining operations produce wastewater streams containing significant amounts of metals. REMOTOX has been proven effective in removing a broad range of heavy metal ions and other inorganic compounds.

Heavy Metal Precipitation by Calcium Polysulfide, Remotox.

Calcium Polysulfide dosage guidelines available upon request.

Application Advantages:

High reactivity with heavy metal ions and extremely low solubility of resulting metal sulfides over a wide pH range. See Solubility of Metal Hydroxides and Sulfides as a Function of pH.
Removes chromates and dichromates without preliminary reduction of the chromium to its trivalent state. See Overall Effectiveness of Water Treatment Process for Hexavalent Chromium (CrVI) and Trivalent Chromium (CrIII).
Can break and precipitate chelated and/or complexed heavy metals, typically without pretreatment.
Converts waste cyanides into less toxic thiocyanates and precipitates metals to levels generally within sewer use ordinances. See study on Cyanide Treatment with Polysulfides.
Dissolved calcium ions form a coagulant aid (Ca(OH)2).
Better settling and dewatering aspects of the metal sulfides, resulting in a more compact solid sludge. See excerpt from Source Reduction Technology Report in Circuit Board Manufacture.
REMOTOX can be adapted to enhance any existing treatment system.

When mixed with water, REMOTOX decomposes to form bisulfide, aqueous hydrogen sulfide and other sulfur compounds. Most heavy metal ions are precipitated as metal sulfides by these breakdown products. See Calcium Polysulfide Chemical Reactions.

Metal sulfides are much less soluble than metal hydroxides. Metal hydroxides change solubility with changes in pH. Metal sulfides remain insoluble within a wide pH range. In the case of chromium, REMOTOX reduces hexavalent chromium to trivalent state which then precipitates as chromium hydroxide in a one-step reaction; therefore, no need for bisulfite, metabisulfite, sulfur dioxide or sulfuric acid.

While effective treatment can be achieved over a wide pH range, best results are typically obtained within water system pH 7-10. See pH Guidelines for Treatment of Soluble Metal Streams. Ensuring adequate contact time and thorough mixing is critical to successful treatment. Dewatering the resulting precipitate can be expedited by employing an anionic flocculant.

REMOTOX® is used in applications where metals need to be removed to meet discharge permits. The product can either be poured directly into a batch treatment system or fed with a chemical metering pump.

Calcium Polysulfide for heavy metal precipitation

Municipal Wastewater Treatment

REMOTOX® is increasing in popularity among sewage and wastewater plant operators due to its effective removal of zinc and copper.

For additional information, heavy-metal removal studies, samples or assistance, please don't hesitate to contact us.