Pornpan Supawimol. (2002) Treatment of gas station wastewater using palm oil shell ash as adsorbent. Mahidol University,:ม.ป.ท.Pornpan Supawimol. 2002. Treatment of gas station wastewater using palm oil shell ash as adsorbent. ม.ป.ท.:Mahidol University,;Pornpan Supawimol. Treatment of gas station wastewater using palm oil shell ash as adsorbent. ม.ป.ท.:Mahidol University, 2002. Print.