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Byproduct recovery from reclaimed water reverse osmosis concentrate using lime and soda-ash treatment
Lime and soda-ash treatment of reclaimed water reverse osmosis concentrate was studied as a pretreatment step for the secondary seawater reverse osmosis desalination. Removal of calcium, magnesium, and silica foulant minerals and recovery of byproducts were investigated. The key results were as follows: (1) The traditional lime-soda process produced mixtures of calcium carbonate and magnesium hydroxide that have little commercial value. (2) Modification of lime-soda softening with pre-acidification to remove carbonate has the primary advantage of producing calcite with potential commercial value. (3) During the modified lime-soda treatment, a high magnesium and calcium removal (approximately 98%), high silica removal (approximately 95%), and trace elements removal (approximately 50 to 98%) may be possible. (4) Pre-acidification also reduced the dose of lime required to remove magnesium efficiently. (5) Treatment of high-sulfate concentrates with a modified limesoda process will produce products contaminated with calcium sulfate. (6) The addition of a calcium sulfate crystallization step to selectively precipitate calcium sulfate before the precipitation of magnesium hydroxide and calcium carbonate may lead to the production of calcium sulfate as a 92% pure byproduct and decrease the calcium sulfate contamination of the magnesium hydroxide and calcite byproducts. (7) The successful reduction of foulant concentrations may allow for seawater desalination with an estimated water recovery efficiency of 80 to 90%. Although water recovery is desirable, the major savings will be in the reduction of concentrate volume and minerals recovery. Because almost all waters have the same major ions of calcium, magnesium, sodium, potassium, chloride, sulfate, and carbonate, the ability to produce byproducts will depend on the specific ionic composition, but the methods outlined in this paper should be generally applicable. The recovery of byproducts can lower the costs of chemicals consumption and sludge disposal; however, further work is needed to characterize the economics of the salt production.
Byproduct recovery from reclaimed water reverse osmosis concentrate using lime and soda-ash treatment
Lime and soda-ash treatment of reclaimed water reverse osmosis concentrate was studied as a pretreatment step for the secondary seawater reverse osmosis desalination. Removal of calcium, magnesium, and silica foulant minerals and recovery of byproducts were investigated. The key results were as follows: (1) The traditional lime-soda process produced mixtures of calcium carbonate and magnesium hydroxide that have little commercial value. (2) Modification of lime-soda softening with pre-acidification to remove carbonate has the primary advantage of producing calcite with potential commercial value. (3) During the modified lime-soda treatment, a high magnesium and calcium removal (approximately 98%), high silica removal (approximately 95%), and trace elements removal (approximately 50 to 98%) may be possible. (4) Pre-acidification also reduced the dose of lime required to remove magnesium efficiently. (5) Treatment of high-sulfate concentrates with a modified limesoda process will produce products contaminated with calcium sulfate. (6) The addition of a calcium sulfate crystallization step to selectively precipitate calcium sulfate before the precipitation of magnesium hydroxide and calcium carbonate may lead to the production of calcium sulfate as a 92% pure byproduct and decrease the calcium sulfate contamination of the magnesium hydroxide and calcite byproducts. (7) The successful reduction of foulant concentrations may allow for seawater desalination with an estimated water recovery efficiency of 80 to 90%. Although water recovery is desirable, the major savings will be in the reduction of concentrate volume and minerals recovery. Because almost all waters have the same major ions of calcium, magnesium, sodium, potassium, chloride, sulfate, and carbonate, the ability to produce byproducts will depend on the specific ionic composition, but the methods outlined in this paper should be generally applicable. The recovery of byproducts can lower the costs of chemicals consumption and sludge disposal; however, further work is needed to characterize the economics of the salt production.
Byproduct recovery from reclaimed water reverse osmosis concentrate using lime and soda-ash treatment
Nebenproduktgewinnung aus dem Umkehrosmosekonzentrat der Wasseraufbereitung durch modifiziertes Verfahren mit Kalk und Sodaasche
Mohammadesmaeili, Farah (author) / Kabiri Badr, Mostafa (author) / Abbaszadegan, Morteza (author) / Fox, Peter (author)
Water Environment Research ; 82 ; 342-350
2010
9 Seiten, 7 Bilder, 7 Tabellen, 13 Quellen
Article (Journal)
English
Improved concentrate recovery for reverse osmosis treatment of brackish groundwater
| Tema Archive | 2010