The reuse of lyes: an alternative to reduce pollution wastewater obtained in the preparation of green olives

M. B. MALDONADO; BARBERO M. A.; BARBERO M. N.; GATTO E.; CALLEJÓN D.; POLENTA G; GABRIELA DENOYA; CRESPO D.

San Juan

Simposio; International Symposium On Olive Growing; 2012

varios

The present work was carried out with the aim to study the potential reuse of residual lyes originated in the production of green table olives, which constitutes an suitable alternative to decrease the water pollution. An experiment was mounted, which included ten reuses, each one with three replicates. Olive fruit used in the assay belong to the variety Arauco, and was harvested at the recommended maturity (index 2). Cans used for the fermentations were filled up to the top with harvested fruit, and lye was then added for debittering (2,25% NaOH) until the olives were entirely covered. This process took approximately 8 hs for the lye to penetrate ¾ of distance from the epidermis to the pit .With the purpose of recycling, the bleach was then filtered with fabric of boile, and stored for subsequent tests.  The debittered fruit were washed with water 2 times, for 4 and 12 hours respectively.  After the washes, the olives were placed in brine acidified with HCl (0.2%) and acetic acid for the lactic fermentation to proceed. Once used, the lye was filtered with boile fabric, and the remaining OH concentration determined by titration with ClH 1N. Solid NaOH was then added to the solution to restore the original concentration (2,25 %), before using it in the subsequent debittering process. Samples of the solution were taken throughout the different steps of the process, and frozen at ±18 ºC until analysis. The accomplished analyses included: DBO5, DQO, conductivity, polyphenols, settleable solids. The main physicochemical parameters (pH, acidity, chlorides, residual bleach and microbiological) were also determined at several times during the course of the ten fermentations. Results were highly promising, since it was found that lye could be re-use up to 7 times without affecting the organoleptics characteristics of the product. On the other hand, all parameters determined in the final residual solution was considered as normal, all of them complying with the local regulations. The information obtained in the experiments can be potentially applied at the industrial level, leading to a significant decrease in the volume of effluents generated in the manufacturing of this kind of product.