Tratamento de água cinza em processos (anaeróbio + aeróbio) de alta taxa visando o reúso predial

Resumen

One of the ways of saving water in households is the use of alternative supply sources. The reuse of gray waters for non‐potable purposes, such as washing of cars, watering of gardens and flushing of toilets, is just an example. This study made a preliminary physicochemical and microbiological qualitative characterization of gray waters collected in several sources (lavatories, showers, kitchen sinks, washtubs and washing machines). Gray waters presented a significant concentration of fast biodegradable organic matter and sulphates, showing their great potential for producing H2S, if stored without treatment. The nutrient concentrations (N and P) were lower than those found in the conventional wastewater, because the majority of them originate from excrements (urine and feces). The presence of E. coli showed the need of disinfection before reuse, especially if reuse standards for flushing toilets are very stringent. Another phase studied the monitoring of a reuse system in a building located at the Federal University of the State of Espírito Santo. In this particular building two professors’ offices are located, with women and men’s individual and collective bathrooms, totaling six sinks, two showers, six toilets and two urinals. The building’s gray waters (shower and lavatory’s effluents) are sent separately to a Gray Water Treatment Plant (GWTP), whose process is based on the association of an Anaerobic Baffled Reactor (ABR), a Biological Aerated Filter (BAF), a Tertiary Filter (TF) and chlorine‐based disinfection. The treatment adopted showed a high efficiency to remove turbidity, color, BOD5, COD and E. coli and characteristics that are compatible with several established standards for non‐potable reuse.