Tratamento anaeróbio da água residuária proveniente da lavagem de garrafas PET destinadas à reciclagem

Abstract

In view of the worldwide context of encouraging recycling, the need to treat the effluent generated in the washing of PET bottles, which contains a large amount of organic matter and surfactants, is notorious. The surfactants are in the so-called emerging class of pollutants, recently identified, and difficult to treat. To this end, advanced biological treatment technologies have been studied, such as bioreactors with granulation and biomass immobilization. The present work had as objective the treatment of the waste water in question, using an Anaerobic Fluidized Bed Reactor (AFBR). The AFBR was inoculated with sludge from the poultry slaughterhouse DACAR and immobilized in sand with a mean diameter between 1.18 mm and 2.0 mm. The hydraulic detention time applied was 24h and the reactor was fed with recycled PET wastewater (RPW) diluted in nutritional medium. Physical and chemical analyzes of COD, anionic surfactants, alkalinity, volatile acids, pH, flow and total solids were performed for control and monitoring. Six phases of operation were determined, gradually increasing the concentration of organic matter and surfactants in each of them, and simultaneously. The phases were divided into: Phase I- Inoculation using glucose as carbon source and COD of 1000 mg / L; Phase II- Adaptation of the biomass to the RPW with COD progressively increased from 100 mg / L to 500 mg / L; Phase III- 1000 mg / L of COD and 6 mg / L of anionic surfactants (AS); Phase IV- 2000 mg / L of COD and 15 mg / L of AS; Phase V- 3000 mg / L of COD and 30 mg / L of AS and Phase VI- 4000 mg / L of COD and 45 mg / L of AS. The removal rates obtained for the operational phases were respectively: Phase II: 74.69 ± 8% COD, Phase III: 85.23 ± 7 COD and 51.13 ± 13% AS, Phase IV: 84.78 ± 4% of COD and 45.51 ± 5% of AS, Phase V 74.06 ± 6% of COD and 19.01 ± 19% of AS, and finally, Phase VI that presented 64.04 ± 8.46% for COD removal and 18.08 ± 20% for AS. The results obtained showed a certain independence of COD removal and AS removal parameters, since a good rate of removal of organic load did not imply good AS removal and vice versa. In general, the AFBR obtained a good performance in the treatment of wastewater according to the proposed conditions.