Abstract
Pretreatment of feed water to improve membrane flux during filtration of agriculture field water containing substituted phenyl urea pesticide diuron has been reported. Laboratory-made reverse osmosis membrane was used for filtration. Preliminary experiments were conducted with model solution containing natural organic matter extracted from commercial humic acids, divalent ions Ca2+, Mg2+. Membrane fouling was characterized by pure water flux decline, change in membrane hydrophilicity and infrared spectroscopy. Natural organic matter present in field water causes severe membrane fouling. The presence of divalent cations further aggravated fouling. Use of ethylenediaminetetraacetic acid (EDTA) and polyacrylic acids (PAA) in feed resulted in the decrease in membrane fouling. Pretreatment of field water is a must if it is contaminated with micro-organism having membrane fouling potential. Feed water pretreatment and use of PAA restricted membrane fouling to 16 % after 60 h of filtration. Membrane permeate flux decline was maximum at the first 12 h and thereafter remained steady at around 45–46 lm−2h−1 till the end of 60 h. Diuron rejection remained consistently greater than 93 % throughout the experiment. Diuron rejection was found to be unaffected by membrane fouling.
Highlights
Substituted phenyl urea herbicides are most widely used pesticides in agriculture and aquaculture
Since agriculture field water contains Natural organic matters (NOM), divalent ions and pesticides, model solutions were prepared in DI water adding high molecular weight fraction of humic acid as representative NOM, divalent salts either in combination or individually
Pesticides like diuron can be removed from agriculture field water by reverse osmosis membrane with minimum flux decline for economic operation of the filtration process
Summary
Substituted phenyl urea herbicides are most widely used pesticides in agriculture and aquaculture. The maximum permissible concentration of diuron in drinking water in USA is 10 lg/ l, and the norm is even stricter in Europe with maximum permissible limit of total pesticides and related product content in drinking water being 0.5 lg/l (Field et al 1997; Plakas and Karabelas 2012). These are removed from water by activated carbon, ozonation and peroxide treatment (Agbekodo et al 1996; Cyna et al 2002). In a recent publication pesticide removal was reported in the range of 92–98 % by laboratory-made reverse osmosis membrane (Mehta et al 2015) and there is a continuous effort put by the membrane researchers to push this value to even higher level
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