Pengotoran membran merupakan salah satu masalah utama teknologi membran dalam proses rawatan air. Pengotoran membran menyebabkan penurunan fluks dan menjejaskan kualiti air yang telah dirawat. Tujuan kajian ini adalah untuk menilai sifat pengotoran membran penurasan nano yang dikaitkan dengan proses prarawatan dan menentukan cara terbaik untuk pembersihan membran. Air suapan di kenali sebagai sebelum 3.00 μm, selepas 3.00 μm dan gabungan antara 0.45 dan 3.00 μm prapenapisan. Eksperimen skala bangku telah dijalankan ke atas penapisan aliran silang untuk menilai keberkesanan proses pra-rawatan. Rawatan air dijalankan dengan mengunakan membran penurasan nano yang diperolehi secara komersial (NF90 and NF270) dengan atau tanpa polialuminium klorida (PAC) sebagai dos pengumpal dalam larutan suapan. Didapati bahawa membran NF270 mempunyai rintangan lebih tinggi terhadap pengotoran berbanding dengan NF90 kerana ciri-ciri hidrofilik dengan sudut kenalan 7.18nm sebagai permukaan membrannya yang lebih licin dan kekasaran membranya 18.78nm. Disebaliknya, kadar pengotoran untuk NF90 mencapai 24%, kepada 18% apabila terdapat penurasan gabungan antara 3.00 μm and 0.45 μm prapenapisan. Walau bagaimanapun tanpa penambahan PAC mencapai kadar pengotoran yang rendah sebanyak 12%. Lagipun, NF270 membran proses dengan atau tanpa penambahan PAC memberikan pengurangan fluks yang tidak berkesan tinggi. Kesimpulanya, NF90 membran proses tanpa penambahan PAC dan penurasan yang gabung antara 3.00 dan 0.45 μm prapenapisan mendapati hasilan kualiti air yang tinggi sebanyak 0.5 Mohm resistiviti kerana liang yang kecil. Seterusnya, sistem membran tersebut memerlukan pembersihan kaustik pada 0.5 Mol/L kepekatan untuk menyelesaikan masalah kerak sebanyak 76% di permukaan membran. Air yang dihasilkan melalui proses penapisan tersebut mematuhi kualiti air yang sesuai dijadikan sebagai larutan suapan membrane osmosis terbalik (RO).
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In water treatment processes, membrane fouling is one of the main drawbacks of membrane technology. Membrane fouling causes flux declination and reduces the treated water quality. This study aims to evaluate the fouling behavior of nanofiltration membranes with respect to the pretreatment process and to determine the best practice of membrane cleaning process. The feed water was introduced as solution before and after 3.00 μm pre-filtration and also after combination of 3.00 and 0.45 μm pre-filtration. The bench scale cross flow filtration were conducted to evaluate the efficiency of water pretreatment processes. Water treatment was carried out by using commercially available nanofiltration membrane (NF90 and NF270) with and without polyaluminium chloride as coagulant dosage in feed water. It was found that NF270 is more fouling resistance compared to NF90 due to its hydrophilicity characteristic with contact angle of 7.15 and smoother membrane surface with membrane roughness of 18.78 nm. The fouling rate of NF90 with PAC dosage was reduced from 24% to 18% after 3.00 μm and 0.45 μm pre-filtration. However, without PAC lower fouling rate of 12% can be achieved. NF270 membrane process with or without PAC gave insignificant flux reduction. In overall, NF 90 membrane without PAC with combination of 3.00 and 0.45 μm pre-filtration gave better permeate water quality of 0.5 MΩ due to NF90’s tighter pore size. 0.5 Mol/L of NaOH was required to achieve cleaning efficiency of 76%. The water that is produced during filtration process complies with the standard and is suitable to be used as feed to reverse osmosis (RO) membrane.
Nanofiltration membrane for water purification pretreatment and its fouling phenomena_Geetha Ramanathan_K4_2017_MYMY