Caracterização e tratamento de águas cinzas visando reúso doméstico

Abstract

The production and dissemination of knowledge on environmental issues, considering the social and economic aspects, including the reuse of water used for non-potable purposes meets the assumptions of sustainable planet. As, when properly handled, greywater can be used for non-potable consumption in buildings, for example, discharge of toilets, washing floors, washing sidewalks, watering gardens, ornamental uses such as water features and fountains, since that does not provide health risks to users. In this study was evaluated in laboratory scale the potential treatment of greywater coming from the washing machine, and the possibility of reuse of this water for non-potable purposes in popular residences. The methodology was based on the experimental research, using research strategy involving data collection and analysis parameters, quantifying the production of drinking water, greywater demand, analysis of physical, chemical and microbiological parameters, evaluating the performance of synthetic greywater and chemical process by using coagulation, flocculation, fluctuation and flotation, filtration through granular media and post-treatment by adsorption on activated charcoal. A preliminary step of qualitative characterization of greywater collected from the washing machine, from the point physicochemical and microbiological was carried out in a single-family residence. It were collected 43 samples in the period of six months and carried out at laboratory scale, greywater showed electrical conductivity of 364 ± 196 μScm-1; apparent color of 362±201uC; true color of 157 ± 102uC; total solids of 391 ± 215mgL-l; suspended solids of 40 ± 29 mgL-l; dissolved solids of 347 ± 201 mg L-l; settling solids of 1.0 ± 0.8; temperature of 25 ± 3.5°C; turbidity of 49 ± 36 NTU; pH of 7.4 ± 1.2, COD of 300 ± 142 mg/L, BOD of 101 ± 142 mg/L; surfactants of 0.6 ± 0.5 mg/L; coliforms ranged from ND to 9,6x105 and tolerant coliforms term ranged from ND to 1.8x 105. Treatability tests carried out with jar tests, the best conditions of coagulation are defined concentrations of 160 mg/L of aluminum sulfate (Al2(SO4)3), resulting pH coagulation of 5.0 and turbidity of 14.1 NTU, optimization of rapid mixing, Gf of 1200s-1, time of 8s and optimization of flocculation with better performance Gf 40s-1 and the ti me 6 to 10 min. For the above defined conditions were passed by several granular media, selecting the best material, which was the sand grains 0.42mm (effective size). The results indicate that the system of chemical pretreatment by coagulation, flocculation and flotation with subsequent passage through sand and activated carbon adsorption filter, have been successful for the removal of the evaluated parameters. Comparing the initial parameters of the sample and the results improved efficiency of the treatment, we have respective indexes, remove turbidity, 37 NTU to 0.04 NTU; apparent color 276uC to 20uC; COD 228mg/L to 34mg/L and surfactants 1.09mg/L 0.20mg/L. Results showed the potential of the application of this treatment for greywater reuse in residences.