Avaliação quali-quantitativa de águas cinza para uso em um condomínio residencial

Abstract

The qualitative and quantitative analysis of effluents for home use is essential for the proper elaboration of reuse projects. With population growth and the expansion of arid regions, it is necessary to look for ways to reduce the consumption of drinking water. Among the solutions is the reuse of water for non-potable domestic uses, such as watering gardens and flushing toilets. The treatment and storage of adequate volumes for the demands of these uses is essential, since it makes the system more attractive, reducing the costs involved. This work characterized the effluent from the washbasins and baths of 544 apartments in a residential building considered being of a lofty standard in the city of Fortaleza, Ceará. In the work, it proposed Limits for several quality parameters for greywater. Using a distance sensor installed inside the reservoirs, capable of providing the instantaneous volume, it was possible to quantify the greywater consumptions. Based on the volumes and resident population, it was possible to determine the volumes consumed in irrigation and discharge, besides the per capita consumption of greywater. The treatment system, composed of physical and chemical processes, can significantly reduce the physical, chemical, and biological parameters, ensuring compliance with the legislation. The basic characteristics of the untreated greywater are turbidity of 15.8 UC, a content of suspended solids of 223 mg / L, slightly acidic pH, and 5 logarithmic units of thermotolerant coliforms. After treatment, the effluent reduced turbidity by 87.26% and almost 75% of the total suspended solids. It separated the average per capita consumption of greywater determined according to usage, with 25.3 Lpcd for discharges and 13.05 Lpcd for irrigation. With these values, it was possible to determine optimal storage volumes up to 10 times lower than those performed. It also presented appropriate criteria were also for calculating the flow rates of the treatment systems and the ideal reservoir volumes. The characteristics of the effluent under study differ from those got by other authors, showing that the local environmental conditions and the habits of the population influence the results. The treated effluent could meet most of the less restrictive parameters proposed, except for total suspended solids.