Greywater Treatment Using Modified Pvdf Membrane
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Date
2022-07-01
Authors
Goh, Jian Loon
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Lignin is a sustainable substance which can be extracted from a wide range of lignocellulosic biowastes in Malaysia. It can be blended into PVDF membranes to enhance the membrane morphology for oil-water filtration. PVDF polymeric matrix membrane is superb in terms of chemical and thermal stabilities, which make it very promising to be utilised as a membrane matrix for water separation. However, poor hydrophilic property of the PVDF has led to the severe fouling during operation.
Thus, current work is performed to increase the surface hydrophilicity and change surface roughness of the membrane which could reduce membrane fouling and reduce the extent of permeate flux decline. Lignin dissolved in sodium hydroxide solution can be coated with calcium carbonate to improve the surface hydrophilicity which correlate the membrane fouling and change the surface roughness of the membrane which correlate the flux decline.
In this work, the polyvinylidene fluoride (PVDF) membrane was coated with lignin and calcium carbonate to improve the filtration of oil water emulsion. 0.75wt. % lignin dissolved in 0.5wt. % sodium hydroxide solution with varied calcium carbonate concentration (1wt. %, 3wt. % and 5wt. %). Surface modification permits the enhancement of membrane properties without affecting the existing membrane formulation. Membrane characterizations were performed using contact angle goniometer, RS Weight and UV-vis spectrophotometer to determine the water contact angle, permeate flux and percent of oil rejection respectively. In conclusion, the lignin-CaCO3 modified membrane rejected up to 99.50% of oil, the lignin modified membrane rejected up to 94.5% of oil and the neat PVDF membrane only rejected 83.30% of oil. The water contact angle as measure by the water angle goniometer of the lignin-CaCO3 modified membrane is much lesser than that of lignin modified membrane. The water contact angle is less than 90 degree. This implies that the membrane is hydrophilic.
Modified PVDF membrane is capable of rejecting up to 99.5% of oil which implies that it could be an ideal solution to remove the oil particulates from the greywater which comes mainly from baths, showers, hand basins, washing machines, dishwashers and kitchen sinks. Oil removal from greywater is a must before discharging as it can interfere with biological life in surface water and create unsightly films. Oil enter the drainage system and mix with other sanitary waste, congeal and harden in the pipe. Also, oil can cause unpleasant odors when mix with other substances in the water and can result in sewer overflows due to reduced capacity or burst drain,