Utilização de biossurfactante no scale-up de uma torre de pré-saturação induzida para separação água-óleo

Abstract

The concern with the quality of the water that leaves industrial facilities contaminated by oil results in extremely strict quality control standards for the discharge of this oily industrial effluent into springs or for its reuse. In the environment of a Thermoelectric Plant (TP), the installations must be maintained in accordance with the standards imposed by environmental agencies, to ensure conditions of service to the National Electric System Operator (NESO). In this research, a biosurfactant was used as an auxiliary flotation collector to support a scale-up criterion in the construction of an induced presaturation tower (IPST) in a semi-industrial scale. The semi-industrial IPST was developed to separate water-oil by flotation using 03 stages arranged vertically, in series. When feeding each stage, the effluent is pre-saturated with the aid of air microbubbles generated by modified multistage centrifugal pumps. Obtaining the results of the bench prototype led to equipment with a nominal treatment capacity of 1200 L.h-1, which occupied a space of 4 meters high by 2 meters wide and 5 meters long, made of stainless steel and a high degree of automation. IPST was set up in the industrial facilities of Centrais Elétricas da Paraíba SA – EPASA – João Pessoa - PB - Brazil. Correlations between operating parameters and efficiency were indicated by Principal Component Analysis (PCA). The definition of the most relevant statistical factors was obtained with the aid of a fractional factorial design. The search for optimized operating conditions was investigated by a Central Composite Rotational Design (CCRD). The application of the “desirability function” tool defined the independent variables as globais optimization conditions of 95%: Recycle flow (Qrec) – 450 L.h-1, Average speed of the oily foam scrapers (Vrasp) – 80 rpm, Average pressure microbubble pumps (PMB) – 11 bar and effluent feed temperature (TA) – 38 ºC. The results obtained validated the use of a biosurfactant as an auxiliary collector of positive environmental impact and Damköhler correlation as a scale-up tool for municipal flotation chambers with pre-saturation, arranged in series.