Electroplating wastewater treatment process using red mud, straw and seawater

Abstract

An electroplating wastewater treatment method includes steps of: (A) crushing the straws into particles, stirring and mixing the crushed straw particles with the electroplating wastewater, and obtaining a mixture, wherein 40-50 g of straw particles are added into each liter of the electroplating wastewater; (B) mixing the seawater with the red mud, adjusting a pH value in a range of 8.5-9.5, filtering after standing, and obtaining a filtrate, wherein: a weight of the red mud which is added into the seawater is 200-300 g per liter seawater; (C) ultrasonically mixing the mixture in step (A) with the filtrate in step (B), standing, and then ultrasonically mixing, and then filtering after standing; and (D) adjusting a pH value of the filtrate obtained in step (C) to 7.

Claims

1. An electroplating wastewater treatment method, which adopts industrial waste red mud, agricultural waste straws and seawater to treat heavy metal ions in electroplating wastewater, the method comprising steps of: (A) mixing the straws with the electroplating wastewater, which comprises crushing the straws into particles, stirring and mixing the crushed straw particles with the electroplating wastewater for 30-50 min, and obtaining a mixture, wherein 40-50 g of straw particles are added into each liter of the electroplating wastewater; (B) mixing the seawater with the red mud, which comprises stirring and mixing the seawater with the red mud for 20-30 min, adjusting a pH value of a mixture of the seawater and the red mud in a range of 8.5-9.5, filtering after standing for 2-3 h, and obtaining a filtrate, wherein: a weight of the red mud which is added into the seawater is 200-300 g per liter seawater; (C) adsorbing metal ions, which comprises ultrasonically mixing the mixture in step (A) with the filtrate in step (B) for 30-50 min, standing for 3-5 h, and then ultrasonically mixing for 20-30 min, and then filtering after standing for 1-2 h, and obtaining a filtrate; and (D) adjusting a pH value of the filtrate obtained in step (C) to 7.

2. The electroplating wastewater treatment method, as recited in claim 1, wherein: in step (C), a volume ratio of the mixture obtained in step (A) and the filtrate obtained in step (B) is in a range of 1:0.8-1.2.

3. The electroplating wastewater treatment method, as recited in claim 1, wherein: in step (A), the crushed straw particles have a particle size in a range of 60-100 meshes.

4. The electroplating wastewater treatment method, as recited in claim 1, wherein: in step (A), before mixing the crushed straw particles with the electroplating wastewater, the crushed straw particles are heated at 250-350 C. for 1.5-3 h in vacuum condition.

5. The electroplating wastewater treatment method, as recited in claim 1, wherein: the electroplating wastewater comprises chromium-containing wastewater, copper-containing wastewater, nickel-containing wastewater, cadmium-containing wastewater, zinc-containing wastewater and silver-containing wastewater.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(1) The present invention is further explained with accompanying embodiments as follows.

(2) Electroplating wastewater comes from Dongguan City Products Co., Ltd., China; through determination, concentrations of main heavy metal ions in the electroplating wastewater are obtained, wherein Cr.sup.6+: 76 mg/L, Cu.sup.2+: 34 mg/L, Zn.sup.2+: 47 mg/L, Ni.sup.2+: 30 mg/L, Ag.sup.+: 22 mg/L and Cd.sup.2+: 52 mg/L; a pH value of the electroplating wastewater is 2.5; red mud comes from a new material in Hebei Province Limited, China, a pH value of the red mud is 13.5.

The First Embodiment

(3) Take 10 L electroplating wastewater for stand-by, crush straws into particles having a particle size of 60 meshes and weigh 400 g straw particles, put the straw particles into the electroplating wastewater, stir and mix for 30 min; take 10 L seawater, add 2000 g red mud into the seawater, stir and mix for 20 min, adjust a value to 8.5, filter after standing for 2 h, and obtain a filtrate; ultrasonically mix a mixture of the straw particles and the electroplating wastewater, with the filtrate for 30 min, stand for 3 h, and then ultrasonically mix for 20 min, filter after standing for 1 h, and adjust a pH value to 7.

The Second Embodiment

(4) Take 10 L electroplating wastewater for stand-by, crush straws into particles having a particle size of 80 meshes and weigh 500 g straw particles, put the straw particles into the electroplating wastewater, stir and mix for 40 min; take 10 L seawater, add 3000 g red mud into the seawater, stir and mix for 20 min, adjust a value to 9, filter after standing for 2 h, and obtain a filtrate; ultrasonically mix a mixture of the straw particles and the electroplating wastewater, with the filtrate for 30 min, stand for 3 h, and then ultrasonically mix for 20 min, filter after standing for 1 h, and adjust a pH value to 7.

The Third Embodiment

(5) Take 10 L electroplating wastewater for stand-by, crush straws into particles having a particle size of 100 meshes and weigh 500 g straw particles, put the straw particles into the electroplating wastewater, stir and mix for 40 min; take 10 L seawater, add 3000 g red mud into the seawater, stir and mix for 25 min, adjust a value to 9, filter after standing for 2.5 h, and obtain a filtrate; ultrasonically mix a mixture of the straw particles and the electroplating wastewater, with the filtrate for 40 min, stand for 3 h, and then ultrasonically mix for 25 min, filter after standing for 1.5 h, and adjust a pH value to 7.

The Fourth Embodiment

(6) Take 10 L electroplating wastewater for stand-by, crush straws into particles having a particle size of 100 meshes and weigh 500 g straw particles, put the straw particles into the electroplating wastewater, stir and mix for 50 min; take 10 L seawater, add 3000 g red mud into the seawater, stir and mix for 30 min, adjust a value to 9.5, filter after standing for 3 h, and obtain a filtrate; ultrasonically mix a mixture of the straw particles and the electroplating wastewater, with the filtrate for 50 min, stand for 3 h, and then ultrasonically mix for 30 min, filter after standing for 2 h, and adjust a pH value to 7.

The Fifth Embodiment

(7) Take 10 L electroplating wastewater for stand-by, crush straws into particles having a particle size of 60 meshes and weigh 500 g straw particles, heat the crushed straw particles at 250 C. in vacuum condition for 1.5 h, obtain carbonized straw particles, put the carbonized straw particles into the electroplating wastewater, stir and mix for 50 min; take 10 L seawater, add 3000 g red mud into the seawater, stir and mix for 30 min, adjust a value to 9.5, filter after standing for 3 h, and obtain a filtrate; ultrasonically mix a mixture of the carbonized straw particles and the electroplating wastewater, with the filtrate for 50 min, stand for 3 h, and then ultrasonically mix for 30 min, filter after standing for 2 h, and adjust a pH value to 7.

The Sixth Embodiment

(8) Take 10 L electroplating wastewater for stand-by, crush straws into particles having a particle size of 100 meshes and weigh 500 g straw particles, heat the crushed straw particles at 300 C. in vacuum condition for 2 h, obtain carbonized straw particles, put the carbonized straw particles into the electroplating wastewater, stir and mix for 50 min; take 10 L seawater, add 3000 g red mud into the seawater, stir and mix for 30 min, adjust a value to 9.5, filter after standing for 3 h, and obtain a filtrate; ultrasonically mix a mixture of the carbonized straw particles and the electroplating wastewater, with the filtrate for 50 min, stand for 3 h, and then ultrasonically mix for 30 min, filter after standing for 2 h, and adjust a pH value to 7.

(9) Concentrations of chromium ions, copper ions, nickel ions, cadmium ions, zinc ions and silver ions in the treated electroplating wastewater of the first embodiment to the sixth embodiment are tested and test results are compared with Electroplating Pollutant Discharge Standard (GB21900-2008). Accordingly, comparing results are shown in Table 1.

(10) TABLE-US-00001 TABLE 1 Cr.sup.6+ Cu.sup.2+ Zn.sup.2+ Ni.sup.2+ Ag.sup.+ Cd.sup.2+ Project (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) Wastewater 76 34 47 30 22 52 Sample First 0.191 0.483 1.428 0.458 0.282 0.048 Embodiment Second 0.180 0.460 1.401 0.431 0.268 0.046 Embodiment Third 0.167 0.442 1.377 0.407 0.244 0.044 Embodiment Fourth 0.159 0.424 1.354 0.387 0.226 0.038 Embodiment Fifth 0.132 0.321 1.232 0.275 0.123 0.026 Embodiment Sixth 0.121 0.357 1.112 0.242 0.101 0.025 Embodiment National 0.2 0.5 1.5 0.5 0.3 0.05 Standard

(11) It can be seen from Table 1, the first embodiment to the sixth embodiment are in accordance with requirements of the Electroplating Pollutant Discharge Standard (GB21900-2008). Therefore, it shows that the present invention has good treatment effect, low cost, high efficiency and environmental protection, and is suitable for all small and medium enterprises including electroplating process to promote the application.

(12) The above embodiments are merely illustrative of preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and variations of the technical solutions of the present invention, made by those skilled in the art without departing from the spirit of the present invention, shall be within the scope of protection as set forth in the claims of the present invention.