Avaliação de um filtro plantado com macrófitas (Cyperus giganteus) utilizado para o tratamento e reuso domiciliar de água cinza

Abstract

The wastewater are produced in different amounts and, when kept separate, have different properties. The separation of flows of different types of effluents, according to their characteristics, facilitating treatment and reuse. Phytoremediation is an efficient and low cost system that uses plants and their photosynthetic microbes in order to detoxify polluted or degraded environments. One of the ways to conserve water in homes is by using alternative sources of supply. The reuse of gray water for non-potable purposes such as washing cars, watering gardens and discharge of toilets is just one example. The goal is to write a feasibility study technical, economic and environmental impact of a treatment system for gray water through a sand filter planted with giant papyrus (Cyperus giganteus) for reuse in flushing the toilet. The study was conducted in a bathroom of a residence in a condominium in Brasilia, inhabited by one person. The system of water supply condo is uniquely designed for six wells. The preliminary stage of the process was to characterize the amount of water needed to supply the bathroom (sink, shower and toilet), and qualitative characterization of ash produced water (mixed with sink shower). The average consumption of water in the bathroom was 81.6 L / person / day. It took, on average, 4.5, 36.5, 40.6 liters of water to supply the sink, shower and toilet, respectively. The demand of the toilet was at least 50% of the total consumption of water in the bathroom, showing that gray water can meet the demands required of the device. The gray water showed a significant concentration of solids and fecal coliform bacteria similar to other studies. Concentrations of nutrients (N and P) were lower than in conventional sewage, since most of them comes from the droppings (urine and feces). The second step was the construction of the filter planted with papyrus and reuse system for discharge into the toilet. The system cost $ 374.5 (three hundred and seventy 4 dollars and fifty cents) and had a payback period of investment (payback) of 7 years. The filter showed good removal efficiency of fecal coliform (91%) and reduction of turbidity (88%). Nitrogen and phosphorus had a large increase in concentration after passing through the filter, due to the presence of these nutrients in the soil which was also used as filter material. If extrapolássemos water savings generated by the reuse (41L per person) for the whole building, the 2350 residents were saving in 2987 m3 of water every month and per year would be saved 29,868 m3. This represents 15% of all consumption neighborhood.