Treatment of dairy wastewater by two-stage membrane operation with ultrafiltration and nanofiltration

Treatment of dairy wastewater by a two-stage membrane process with ultrafiltration (UF) and nanofiltration (NF) was investigated. The results showed that the flux of UF was higher at pH = 4.6 than that at pH = 8 because the resistance of the fouling membrane was lower at the isoelectric point of pro...

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Bibliographic Details
Published in:Water science and technology 2012-01, Vol.65 (5), p.915-919
Main Authors: Gong, Yan-Wen, Zhang, Hong-Xun, Cheng, Xue-Ni
Format: Article
Language:English
Subjects:
Biofouling
Biological Oxygen Demand Analysis
Casein
Chemical oxygen demand
Cleaning
Dairy industry wastewaters
Dairying
Fouling
Hydrogen-Ion Concentration
Industrial Waste - analysis
Lactose
Membrane processes
Membranes
Membranes, Artificial
Nanofiltration
Nanotechnology
Nanotechnology - methods
pH effects
Proteins
Sodium hydroxide
Sodium Hydroxide - chemistry
Solutions
Ultrafiltration
Ultrafiltration - methods
Waste Disposal, Fluid - methods
Wastewater
Wastewater treatment
Water Purification - methods
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Summary:Treatment of dairy wastewater by a two-stage membrane process with ultrafiltration (UF) and nanofiltration (NF) was investigated. The results showed that the flux of UF was higher at pH = 4.6 than that at pH = 8 because the resistance of the fouling membrane was lower at the isoelectric point of protein (pH = 4.6) in UF operation. Protein rejection exceeded 99% by UF + NF operation. Lactose rejections were 98.5 and 54% for UF + NF90 and UF + NF270 respectively. Experiments on membrane cleaning showed that the fouling layer of UF and NF was mainly protein and casein which could be removed by aqueous NaOH with pH = 10. The result of long-term experiments showed that the chemical oxygen demand (COD) of NF90 permeates was below 70 mg/L consistently and the wastewater could be concentrated to 24% by a two-stage membrane process.
ISSN:0273-1223
1996-9732
DOI:10.2166/wst.2012.937