The oily wastewater treatment using the nanofiltration process
The objective of this work was to investigate the possibility of oily wastewater treatment using the nanofiltration (NF) process. The NF studies were carried out with a permeate obtained from ultrafiltration (UF) (used for the treatment of the oily wastewater from metal industry). The influence of transmembrane pressure on a permeate flux, the degree of the rejection of oil and inorganic compounds was investigated. The studies on the NF treatment of oily wastewater demonstrated a high effectiveness of the rejection of oil and inorganic compounds. The permeate obtained from the treatment was free of oil. Moreover, the retention coefficient of the inorganic compounds was higher than 75% for all the cations examined (Na+, K+, Mg2+, Ca2+, Zn2+, Cu2+) and higher than 95% for sulphates. Therefore, the permeate obtained in the NF process can be reused for fresh emulsion preparation.