Treatment method for indigo-containing wastewater by combined adsorption and regeneration process
An integrative approach combines a process of adsorption and ozonation which are used for removing the indigo dye from textile wastewater and the regeneration of adsorbent materials. Metal oxide modified adsorbents are efficient dye adsorbent materials for indigo dye wastewater and are used have been developed for adsorption process and regenerated by ozonation process. Upon the regeneration process, the adsorption capacity has been recovered. The synergistic effect of adsorption and ozonation benefit for the efficient dye removal from wastewater and the adsorbent regeneration achieved in an environmentally friendly and cost effective way.
1 . A method of treating indigo-containing wastewater to remove indigo from said wastewater, comprising:
providing a column filled with an adsorbent capable of adsorbing the indigo;
pumping the wastewater comprising the indigo into the column, thereby exposing the wastewater to the adsorbent for a sufficient period of time for the indigo to be adsorbed and generating indigo-saturated adsorbent and a column effluent;
destroying residual gaseous ozone from the effluent:
stopping the pumping of the wastewater into the column; and
regenerating the indigo-saturated adsorbent by:
(a) generating ozone in water with an ozone generator,
(b) generating micro-nano-bubbles (MNBs) with a micro-nanobubbler in the water,
(c) mixing the ozone and the MNBs in the water, and
(d) directing the ozone mixed with the MNBs into the column, thereby decomposing the indigo;
wherein the adsorbent is Fe(NO 3 ) 3 created by an impregnation-calcination procedure with Al 2 O 3 , and
wherein no sludge comprising metal ions is generated upon completion of the method.
2 . The method for according to claim 1 , wherein the adsorbent has an average particle size of 1 mm to 10 mm, and wherein the adsorbent has a micro-mesoporous structure with an adsorption capacity average of 30 mg/g to 100 mg/g.
3 . The method according to claim 1 , wherein the adsorbent retains at least 80% indigo adsorption capacity after 10 adsorption and regeneration cycles.
4 . The method according to claim 1 , wherein the adsorbent retains at least 90% indigo adsorption capacity after 10 adsorption and regeneration cycles.
5 . The method according to claim 1 , wherein the ozone generated has a concentration of 10 g/m 3 to 20 g/m 3 in the water.