Application of a high-performance compact reactor (HCR) in the treatment of polluting hydrocarbon loads

The objective of this study was the application of a high-performance compact reactor (HCR) in the treatment by activated sludge of a load polluted by hydrocarbons. The tests were carried out in the laboratory with synthetic water containing fuel oil as the principal source of carbon. A solution riched in nutrients was added continuously. At a first stage, the effectiveness of the process and its capacity to support high loads were highlighted. We regard the reactor as a perfectly agitated continuous reactor (PACR) with recycling of sludges. A simple mathematical model, based on the kinetics of the microbial growth of Monod and also on the kinetics of Michaelis-Menten for the use of the substrate, was used in order to evaluate the constant kinetics. The values of the kinetic parameters resulting from this study were compared with the data of the literature. The performance of the HCR system was confirmed by the high values of the specific speed of use of the substrate. The influence of the residence time of the cells on the quality of the effluent and the characteristics of sludges was discussed, and its importance as the control parameter of the process was examined. The HCR is distinguished from conventional systems with activated sludge by its compactness and its aptitude to treat significant organic loads, with very short hydraulic times of retention to produce an effluent of quality and activated sludge of good characteristics of decantability.

The HCR system made it possible to treat a strongly charged effluent contrary to the traditional processes with activated sludge. Indeed, the performances of the biological treatment are often limited when it is a question of treating hydrocarbon effluents. The phenomena of transfer and the decantability of the activated sludge generally constitute the factors limiting this type of treatment. HCR system has the advantage of exceeding these limitations, even with this type of pollution. This process made it possible to reach a raised level of depollution, and the effectiveness of treatment was higher than 90%. It also allows the production of activated sludge having almost constant characteristics of decantability, the measured Mohlman indices in the range between 43 to 148 mL/g. The treated loads can reach 12 kg BOD 5 /kg MES.j –1 o f mass load and 17 kg BOD5/m3 j–1 of space loading. These values are much higher than those applied in more conventional processes, which makes it possible to carry out profits in energy. We have characterized the kinetics of biodegradation of the pollutant by the activated sludge using the Monod model. The kinetic parameters obtained constitute a good tool of study and extrapolation on a large scale. The HCR process therefore presents several advantages: its compactness allows a profit of space and its performance in the treatment of loads rose with a weak production of sludges.