Patent DE-102008054142-A1 (DE)
Title: Method for processing industrial wastewater during the production of solar cells with a relative high portion of hydrogen fluoride and/or fluorides, comprises mixing soda lye or potash with wastewater in a pre-treatment zone
Inventor: BILLENKAMP ELMAR
IPC: C02F1/04
Filed: 2008-10-31
Abstract: The method for processing industrial wastewater such as rinsing water and concentrates during the production of solar cells with a relative high portion of hydrogen fluoride and/or fluorides, comprises mixing soda lye or potash as chemical neutralization agent (12) to the wastewater in a pre-treatment zone until it adjusts a pH-value of 7.5-8.5 to neutralized waste water that is subjected to a pre-filtration- and activated carbon adsorption zone (5, 6) in the pre-treatment step in which the suspended solid materials and organic pollutants are separated and/or adsorbed. The method for processing industrial wastewater such as rinsing water and concentrates during the production of solar cells with a relative high portion of hydrogen fluoride and/or fluorides, comprises mixing soda lye or potash as chemical neutralization agent (12) to the wastewater in a pre-treatment zone until it adjusts a pH-value of 7.5-8.5 to neutralized waste water that is subjected to a pre-filtration- and activated carbon adsorption zone (5, 6) in the pre-treatment step in which the suspended solid materials and organic pollutants are separated and/or adsorbed. The neutralized and filtered waste water is subsequently supplied to a reverse osmosis zone (7) that forms 60-80 vol.% of permeate and 20-40 vol.% of retentate by a water permeable membrane and a predetermined process pressure from the pre-filtered neutralized waste water. The industrial waste water is controllably supplied in a common pre-neutralization zone (4) of the pre-treatment step and is mixed with potash to adjust the pH value of 8 in the neutralized waste water. The neutralized waste water in the pre-treatment zone is supplied to the pre-filtration zone and subsequently to the activated carbon adsorption zone through which the solid material portion and residues of hydrogen peroxide contained in the neutralized waste water are mechanically separated and/or adsorbed from the chemical process and organic components. The neutralized and subsequently pre-filtered waste water is supplied to a special reverse osmosis zone that forms a portion of 80 vol.% of clear, low mineral, slight electric conductive, fluoride-free water as permeate, and a portion of 20 vol.% of residue-containing waste water concentrate as retentate. The retentate of the first treatment zone in the pre-neutralization zone is mixed with potash or soda lye in a second treatment zone to adjust a pH value of 8-9.5 and the neutralized retentate is distilled in a special vacuum distillation zone under heating by which 85-95 vol.% of clear, low mineral, slight electric conductive fluoride-free water is formed as distillate and a portion of 5-20 vol.% of residue-containing remnant is separated. The permeate from the reverse osmosis zone and the distillate from the vacuum distillation zone are supplied to the industrial production process as pure water or to the public sewage system.