Roy, Thomas M; Dr.Benny Mathews, Abraham(Cochin University of Science & Technology, August , 2009)
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Abstract:
The present study focused on the quality of rainwater at various land use
locations and its variations on interaction with various domestic rainwater
harvesting systems.Sampling sites were selected based upon the land use
pattern of the locations and were classified as rural, urban, industrial and
sub urban. Rainwater samples were collected from the south west monsoon of
May 2007 to north east monsoon of October 2008, from four sampling sites namely Kothamangalam, Emakulam, Eloor and Kalamassery, in Ernakulam
district of the State of Kerala, which characterized typical rural, urban,
industrial and suburban locations respectively. Rain water samples at various
stages of harvesting were also collected. The samples were analyzed according
to standard procedures and their physico-chemical and microbiological
parameters were determined. The variations of the chemical composition of the rainwater collected
were studied using statistical methods. It was observed that 17.5%, 30%,
45.8% and 12.1% of rainwater samples collected at rural, urban, industrial and
suburban locations respectively had pH less than 5.6, which is considered as
the pH of cloud water at equilibrium with atmospheric CO,.Nearly 46% of the
rainwater samples were in acidic range in the industrial location while it was
only 17% in the rural location. Multivariate statistical analysls was done using
Principal Component Analysis, and the sources that inf1uence the composition
of rainwater at each locations were identified .which clearly indicated that the
quality of rain water is site specific and represents the atmospheric
characteristics of the free fall The quality of harvested rainwater showed significant variations at
different stages of harvesting due to deposition of dust from the roof
catchment surface, leaching of cement constituents etc. Except the micro
biological quality, the harvested rainwater satisfied the Indian Standard guide
lines for drinking water. Studies conducted on the leaching of cement
constituents in water concluded that tanks made with ordinary portland cement
and portland pozzolana cement could be safely used for storage of rain water.
Description:
School of Engineering, Cochin University of Science and Technology