No abstract

No abstract

Nanofiltration (NF) membrane fouling by DOM remains a major and poorly understood issue. To acquire a better insight we studied the fouling of the DOM fractions humic acids (HAs) and fulvic acids (FAs), with and without Ca(2+), on native and grafted ceramic NF membranes. Grafting with two methods and three different grafting groups allowed to create a range of membranes with a variety of surface chemistries, and a wide range of surface polarity, much broader than ever used in previous studies. A typical polymer (polyamide) NF membrane was included for comparison. All obtained results reveal that membrane fouling is not determined by membrane hydrophilicity/hydrophobicity as a general and sole criterion, but rather on the whole of the surface chemistry determining the amount and strength of the possible foulant-membrane interactions. As a consequence the effect of inorganic ions on the fouling is also dependent on the surface chemistry. Important new insight in the DOM fouling mechanism was acquired, shedding new light on the state-of-the-art knowledge.

No abstract

Compared to traditional separation and purification techniques, membrane filtration is particularly beneficial for the treatment of wastewater streams such as pulp and paper mill effluents (PPME), olive oil wastewater (OOWW) and oil/gas produced water (PW). However, severe membrane fouling can be a major issue. In this work, the use of ceramic membranes and the potential for the broad applicability of a recently developed antifouling grafting was evaluated to tackle this issue. To this end, the fouling behavior of native and grafted membranes was tested in the selected difficult wastewater streams, both in dead-end and in cross-flow mode. In addition, the quality of the produced permeate water was determined to assess the overall performance of the investigated membranes for reuse or recycling of the treated wastewater. The obtained results show that grafting significantly enhances the antifouling tendency of the ceramic membranes. Particularly, the membrane grafted with methyl groups using the Grignard technique (MGR), showed in all cases no or negligible fouling as compared to the native membrane. As a consequence, the process flux or filtration capacity of the MGR membrane in cross-flow is always higher and more stable than the native membrane, even though the grafting lowers the pure water flux. Hence, the inert character of the MGR membrane is repeatedly proven and shown to be broadly applicable and generic for anti-fouling, without loss in permeate quality. Moreover, in case of OOWW, the quality of the MGR permeate is even better than that of the native membrane due to its lower fouling. All results can be explained taking into account the physico-chemical properties of foulants and membranes, as shown in previous work. In conclusion, the use of MGR membranes could provide an optimum economical solution for the treatment of the selected challenging wastewaters.

No abstract

No abstract

No abstract