A method of purifying a recycled or renewable organic material, wherein the recycled or renewable organic material comprises more than 1 ppm silicon as silicon compounds and/or more than 10 ppm phosphorous as phosphorous compounds, comprising the steps of (a) providing a feed of the recycled or renewable organic material, wherein the recycled or renewable organic material is selected from a group consisting of plant based fats and oils, animal based fats and oils, fossil waste-based oils, waste oils, algal oils and microbial oils; (b) optionally pre heat treating the recycled or renewable organic material at 180 to 325°C and optionally adding acid before or after the heat treatment process and optionally filtering the pre heat treated recycled or renewable organic material; (c) heat treating the recycled or renewable organic material in the presence of an adsorbent selected from silica-based adsorbents at 180 to 325°C and filtering the heat treated recycled or renewable organic material, and optionally adding acid before or after the heat treatment process; (d) optionally blending the heat treated recycled or renewable organic material with a hydrocarbon or lipid-based stream; (e) optionally evaporating the volatile silicon compounds from the heat treated recycled or renewable organic material; and (f) hydrotreating the heat treated recycled or renewable organic material in a presence of a hydrotreating catalyst; to obtain purified hydrotreated recycled or renewable organic material comprising less than 20%, preferably less than 10%, more preferably less than 5%, of the original silicon content of the recycled or renewable organic material provided in step (a) and/or less than 30% of the original phosphorous content of the recycled or renewable organic material provided in step (a). comprising the steps of (a) providing a feed of the recycled or renewable organic material, wherein the recycled or renewable organic material is selected from a group consisting of plant based fats and oils, animal based fats and oils, fossil waste-based oils, waste oils, algal oils and microbial oils; (b) optionally pre heat treating the recycled or renewable organic material at 180 to 325°C and optionally adding acid before or after the heat treatment process and optionally filtering the pre heat treated recycled or renewable organic material; (c) heat treating the recycled or renewable organic material in the presence of an adsorbent selected from silica-based adsorbents at 180 to 325°C and filtering the heat treated recycled or renewable organic material, and optionally adding acid before or after the heat treatment process; (d) optionally blending the heat treated recycled or renewable organic material with a hydrocarbon or lipid-based stream; (e) optionally evaporating the volatile silicon compounds from the heat treated recycled or renewable organic material; and (f) hydrotreating the heat treated recycled or renewable organic material in a presence of a hydrotreating catalyst; (a) providing a feed of the recycled or renewable organic material, wherein the recycled or renewable organic material is selected from a group consisting of plant based fats and oils, animal based fats and oils, fossil waste-based oils, waste oils, algal oils and microbial oils; (b) optionally pre heat treating the recycled or renewable organic material at 180 to 325°C and optionally adding acid before or after the heat treatment process and optionally filtering the pre heat treated recycled or renewable organic material; (c) heat treating the recycled or renewable organic material in the presence of an adsorbent selected from silica-based adsorbents at 180 to 325°C and filtering the heat treated recycled or renewable organic material, and optionally adding acid before or after the heat treatment process; (d) optionally blending the heat treated recycled or renewable organic material with a hydrocarbon or lipid-based stream; (e) optionally evaporating the volatile silicon compounds from the heat treated recycled or renewable organic material; and (f) hydrotreating the heat treated recycled or renewable organic material in a presence of a hydrotreating catalyst; to obtain purified hydrotreated recycled or renewable organic material comprising less than 20%, preferably less than 10%, more preferably less than 5%, of the original silicon content of the recycled or renewable organic material provided in step (a) and/or less than 30% of the original phosphorous content of the recycled or renewable organic material provided in step (a).