Studying and Investigating the Removal of Benzene and Phenol From Waste Water of Petrochemical Industries. Case Study: Olefin Plant of Ilam Petrochemical Company

Mono-aromatic hydrocarbons like benzene and phenol are the most water soluble hydrocarbons processed by a typical refinery and olefin plants. Consequently, they are to be found in refineries and olefin plants wastewater.As far as environment is concerned, presence of benzene and phenol and other VOCs (Volatile Organic Compounds) in wastewater is led to release in rivers and streams, to groundwater sources, as well as to the atmosphere. The negative health impacts that result from the consumption of these compounds include cancer, liver lesions, drowsiness and irritation of organs. Human exposure to benzene and phenol compounds over a long period of time results in skin and sensory irritation, adverse respiratory health effects and central nervous system irritation.In current paper, applicable methods of removal or degradation of benzene and phenol has been inspected. The most common methods are Steam and air stripping, adsorption by activated carbon or carbon nanotube, oxidation, biological degradation and photo catalytic oxidation. Olefin unit of Ilam Petrochemical Company (ILPC) has been considered as a case study. By investigation of ILPC olefin waste water, it was concluded that the flow rate of waste water is 6747 kg/hr and concentrations of benzene and phenol are 1 and 10-70 mg/l respectively. Economical and environmental aspects of mentioned methods have been discussed and a comparison between methods has been performed. It was resulted the stripping method is not a qualified method to remove phenol because of high solubility of phenol in water. Adsorption by activated carbon or carbon nanotube is a total removal method, but regeneration of activated and nano-tube carbons is very expensive.Oxidation is an effective method to destruct these harmful compounds with 75% heat recovery, entails considerable fuel costs but high amount of effluent water decrease the efficiency of oxidation. Since the process is continuous and it isn’t possible to have high residence time, the biological oxidation cannot be a suitable way to remove benzene and phenol. TiO2 photo catalyst has 90 % degradation efficiency but it is a batch process with high operating cost.

Keywords:

Olefin , wastewater , degradation , stripping , benzene , phenol.