TY - JOUR
T1 - Industrial Wastewater Treatment by Nanofiltration – A Case Study on the Anodizing Industry
AU - Ali, Aamer
AU - Nymann, Maria Christina
AU - Christensen, Morten Lykkegaard
AU - Quist-Jensen, Cejna Anna
PY - 2020
Y1 - 2020
N2 - The anodizing industry generates several alkaline and acidic wastewater streams often with high concentrations of heavy metals. In this study, nanofiltration (NF) was used to treat wastewater from individual baths, i.e., wastewater from color rinse, alkaline pickling rinse, acidic pickling rinse and anodizing rinse, as well as a mixture of all the wastewater streams. The experiments were carried out by using a commercial membrane (NF99HF) exhibiting pure water permeability of 10 L/(m2·h·bar). For all wastewater streams except one, pH was adjusted to bring it within the recommended pH limits of the membrane, whereby part of the heavy metals precipitated and was removed. The NF of the color rinse offered high-quality permeate (heavy metals below detection limit) and high permeability (9 L/(m2·h·bar)), whereas the nano filtration of the alkaline pickling rinse exhibited no permeability. The NF of the acidic pickling rinse showed a permeability of 3.1-4.1 L/(m2·h·bar), but low ion rejection (7%-13%). NF of the neutralized mixed wastewater, after the removal of precipitate, produced high-quality permeate with a stable permeability of 1 L/(m2·h·bar). Treatment of the mixed wastewater is therefore the best option if the water has to be discharged. If the water has to be reused, the permeate conductivity in the color rinse and anodizing rinse baths have been reduced significantly, so the treatment of these streams may then be a better option.
AB - The anodizing industry generates several alkaline and acidic wastewater streams often with high concentrations of heavy metals. In this study, nanofiltration (NF) was used to treat wastewater from individual baths, i.e., wastewater from color rinse, alkaline pickling rinse, acidic pickling rinse and anodizing rinse, as well as a mixture of all the wastewater streams. The experiments were carried out by using a commercial membrane (NF99HF) exhibiting pure water permeability of 10 L/(m2·h·bar). For all wastewater streams except one, pH was adjusted to bring it within the recommended pH limits of the membrane, whereby part of the heavy metals precipitated and was removed. The NF of the color rinse offered high-quality permeate (heavy metals below detection limit) and high permeability (9 L/(m2·h·bar)), whereas the nano filtration of the alkaline pickling rinse exhibited no permeability. The NF of the acidic pickling rinse showed a permeability of 3.1-4.1 L/(m2·h·bar), but low ion rejection (7%-13%). NF of the neutralized mixed wastewater, after the removal of precipitate, produced high-quality permeate with a stable permeability of 1 L/(m2·h·bar). Treatment of the mixed wastewater is therefore the best option if the water has to be discharged. If the water has to be reused, the permeate conductivity in the color rinse and anodizing rinse baths have been reduced significantly, so the treatment of these streams may then be a better option.
KW - Anodizing
KW - Heavy metals
KW - Membranes
KW - Nanofiltration
KW - Wastewater
KW - Water reuse
UR - http://www.scopus.com/inward/record.url?scp=85084376113&partnerID=8YFLogxK
U2 - 10.3390/membranes10050085
DO - 10.3390/membranes10050085
M3 - Journal article
C2 - 32365735
SN - 2077-0375
VL - 10
JO - Membranes
JF - Membranes
IS - 5
M1 - 85
ER -