Quantification and elimination of substituted synthetic phenols and volatile organic compounds in the wastewater treatment plant during the production of industrial scale polypropylene.

Substituted synthetic phenols and VOC as industrial waste in water and gases from a polypropylene (PP) production plant were the focus of this research. The scope of the study included two levels of the process which were: extrusion and desorber. A total of 264 samples were taken of the liquid and gas affluent and effluent. Waste water and residual gases were collected during the processing of 6 grades of PP with melt flow index of 25, 20, 15, 10, 2 and 1. The monitoring programs were carried out over the course of a year and the samples were taken at different times in order to evaluate the stability and magnitude of a possible environmental impact of the process. Five phenols were identified in the wastewater and a total of 41 VOCs were found in the gas sample. The selection of these phenols was based principally on their high consumption given the need to improve the thermo-oxidative properties of the PP. For the study of the VOC, a new methodology was developed permitting simultaneous analysis by GC-MS/PDHID/FID combining 7 valves, 8 columns and 3 detectors. In the past the wastewaters were treated with solid phase extraction cartridges and the substituted phenols were analyzed by HPLC with DAD. In the VOCs 7 alkanes, 8 alkenes, 2 alkynes, 7 alcohols, 4 ketones, 2 carboxylic acids, 4 permanent gases, 4 sulfides and 3 thiols were detected. The 5 phenols identified were Irganox 1076, DTF, Etanox 330, Irganox 1010 and Cyanox 1790, and the highest concentrations of each one of these were identified in wastewater from the cutting of pellets with values of 380, 366, 396, 331 y 330 ppm respectively. The wastewater from the desorber showed the highest values for Irganox 1076 and DTF with maximum levels of 250 and 213 ppm respectively. These maximum values were obtained after processing the PP with a melt flow index of 25. The grades with fluidity of 1 and 2 generated the least migration of these phenols to the wastewater. The two industrial wastewater samples were transported to the wastewater treatment plant where the Irganox 1076 and the DTF were completely eliminated in the treatment process. The concentrations of Irganox 1010, Cyanox 1790 and Ethanox 330 were reduced over 90%.