Journal of Scientific & Industrial Research Vol. 74, April 2015, pp. 245-249 Effect of excess air on polycyclic aromatic hydrocarbons removal from petroleum sludge using thermal treatment with additives E N Pakpahan 1 , M H Isa 2 *, S R M Kutty 2 , S Chantara 3, 4 , W Wiriya 4 and I H Farooqi 5 1 Division on Hazardous & Toxic Substances Registration & Notification,Deputy Minister for Hazardous & Toxic Substances, Hazardous & Toxic Wastes and Garbage Management - Ministry of Environment,Republic of Indonesia 2 Civil Engineering Department, Universiti Teknologi PETRONAS, 31750 Tronoh, Perak, Malaysia 3 Environmental Chemistry Research Laboratory, Chemistry Department, Faculty of Science, Chiang Mai University, 50200, Thailand 4 Environmental Science Program and Centre for Environmental Health, Toxicology and Management of Chemicals (ETM), Faculty of Science, Chiang Mai University, 50200, Thailand 5 Department of Civil Engineering, Aligarh Muslim University, Aligarh, 202002, Uttar Pradesh, India Received 18 June 2013; revised 26 November 2014; accepted 2 February 2015 Petroleum sludge contains polycyclic aromatic hydrocarbons (PAH) which are hazardous compounds due to their toxic and carcinogenic-mutagenic characteristics. The United States Environmental Protection Agency has identified 16 of these compounds as priority pollutants. This study evaluates the effectiveness of excess air addition in thermal removal of priority PAH from petroleum sludge treated in a rotary-drum electric heater at 650°C with Ca(OH) 2 (1 mole) + NaHCO 3 (1 mole) (1:1) additives. The concentrations of PAH in flue gas and residue phases were determined using Gas Chromatography-Mass Spectrometry (GC-MS). The samples were extracted with acetonitrile by ultra-sonication prior to GC-MS analysis. The concentrations of 2-3 ring PAH, 4-6 ring PAH, suspect carcinogenic PAH, ΣPAH and ΣTEF were also determined. Excess air addition was found to be instrumental in PAH removal. Keywords: Thermal treatment, Excess air, Additives, Polycyclic aromatic hydrocarbons (PAH), Petroleum sludge cake. Introduction Petroleum sludge is a major waste produced from the petroleum refining industry. Oil production and petroleum refining processes generate considerable amount of petroleum sludge worldwide as wastes; an estimated 230,000 million tonnes each year. Typically, the sludge contains 10-30% total petroleum hydrocarbons (TPH), 5-20% solids and 50-85% water. The polycyclic aromatic hydrocarbons (PAH) content of the sludge is about 550 mg/kg TPH 1 . The sludge is a major hazardous petroleum waste due to the presence of harmful organic compounds such as PAH which have toxic and carcinogenic-mutagenic characteristics 2,3 . Out of the known more than 10,000 PAHs, with about 200 tested as possible carcinogens, the United States Environmental Protection Agency (USEPA) has identified 16 as priority compounds 4 . The 16 priority PAH are: Naphthalene (Nap; 2-rings, C 10 H 8 ), Acenaphtylene (Acy; 3-rings, C 10 H 8 ), Acenaphthene (Ace; 3-rings, C 10 H 10 ), Fluorene (Flu; 3- rings, C 13 H 10 ), Phenanthrene (Phe; 3-rings, C 13 H 10 ), Anthracene (Ant; 3-rings, C 13 H 10 ), Fluoroanthene (Fla; 4-rings, C 16 H 10 ), Pyrene (Pyr; 4-rings, C 16 H 10 ), Benzo[a]Anthracene (BaA; 4-rings, C 18 H 12 ), Chrysene (Chr; 4-rings, C 18 H 12 ), Benzo[b]Fluoranthene (BbF; 5-rings, C 20 H 12 ), Benzo[k]Fluoranthrene (BkF; 5-rings, C 20 H 12 ), Benzo[a]Pyrene (BaP; 5-rings, C 20 H 12 ), Indeno[1,2,3-cd]Pyrene (Ind; 6-rings, C 22 H 12 ), Dibenzo[a,h]Anthracene (DbA; 6-rings, C 22 H 14 ), and Benzo[g,h,i]Perylene (BPer; 6-rings, C 22 H 12 ). Toxicity equivalence factor (TEF) of the priority PAH reflects their relative carcinogenic potential as a quantitative cancer risk estimate with reference to the specific compound benzo[a]pyrene or BaP 2,3 . TEF of the priority PAH are: Nap 0.001, Acy 0.001, Ace 0.001, Flu 0.001, Phe 0.001, Ant 0.01, Fla 0.001, Pyr 0.001, BaA 0.1, Chr 0.01, BbF 0.1, BkF 0.1, BaP 1.0, Ind 0.1, DbA 5.0, and BPer 0.01. Thermal treatment, especially kiln incineration (typical temperature of 820 to 1600°C), can completely degrade all priority PAH. The high energy requirement and operational cost, however, are of concern. Some studies on thermal removal of PAH conducted by employing additives such as lime, sodium, metal and metal oxides with or without excess air supply are summarised in Table 1 5-11 . Recently, Pakpahan et al 12 —————— * Author for correspondence E-mail: hasnain_isa@petronas.com.my