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Valuation of water quality in a system of rainwater collection. Case study: Laboratory of Isotope Ecology/CENA/USP

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Author(s):
Jean Carvalho
Total Authors: 1
Document type: Master's Dissertation
Press: Piracicaba.
Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
Defense date:
Examining board members:
Plinio Barbosa de Camargo; Marcos Vinicius Folegatti; Rodrigo Braga Moruzzi
Advisor: Plinio Barbosa de Camargo
Abstract

Due to increasing industrial and agricultural activities, coupled with the extensive urban growth and the exponential increase in population in the last century, the pressure on water resources has intensified dramatically. Thus, there is a need to seek new sources of public water supply. The collection of rainwater goes back thousands of years, however, because it is an area where the studies are recent, many questions permeate on the method to be adopted for the implementation of rainwater harvesting systems, as well as ensure health of its users. Thus, seeking to add scientifically and analyze new possibilities for harnessing rainwater systems, this project aims to analyze and characterize water quality at various points in a system of capture, store and use rainwater, at the Laboratory of Isotope Ecology CENA / USP in Piracicaba, SP. A system has been built in real scale with five drums of 100 L for discarding of first waters, totaling approximately 3.3 mm discarted water, with two cisterns of 5000 liters each to store the collected water. Were seven sampling points totaling 36 analyzes per rainfall event. Parameters of pH, electrical conductivity (CE), total nitrogen (TN), dissolved inorganic carbon (DIC), dissolved organic carbon (DOC) and dissolved oxygen (OD) were analyzed. Analyses of OD were discontinued after the realization that the OD, in the different stages of the system, showed no statistical differences due to the layout of the system. The analyzed pH always showed a higher values than the precipitation and has tended to decrease as the collected water was discarded. Showing an average pH of 6.1 when the water reaches the cistern. The values of EC and NT were higher than the values found in precipitation and tended to decrease gradually in each stage of disposal system of the first water, as also showed a correlated pattern with the rainfall intensity and with the interval between rainfall events. The CE standard deviation tend to decrease at each step of the disposal system of the first water, demonstrating that the disposal system of the first water serves as a homogenizer of water captured, regardless of the rainfall characteristics. The parameters of DIC also showed higher values than those found in rain water, and showed a gradual decrease in each stage of disposal system of the first water. The parameters of DOC showed no correlation with the amount of discarted water or with the rainfall parameters. It was concluded that the disposal system of the first waters has a key role in the final quality of water abstracted. As well as the recommendation of ABNT, of discarding the first 2 mm of rain, matches exactly the point where you can get the best quality water with minimal loss. It was found that the drought period and the rainfall intensity directly influence the quality of water that will be collected. (AU)

FAPESP's process: 11/04325-6 - Valuation of water quality in a system of rain water collection. Case study: Laboratory of Isotope Ecology/CENA/USP
Grantee:Jean Carvalho
Support Opportunities: Scholarships in Brazil - Master