Showing posts from December, 2019

Risk of Contamination in Rooftop Rainwater Harvesting

There has been a growing interest, especially in developing nations like India, in rooftop rainwater harvesting as an alternative source of freshwater.  Rooftop rainwater harvesting involves the collection and storage of water from rooftops. Generally, rainwater is free from impurities except those picked up by rain from the atmosphere, but the quality of rainwater may deteriorate during harvesting, storage and reuse. Microbiological Contamination Microbial contamination of collected rainwater indicated by E. coli (or thermotolerant coliforms) is quite common, particularly in samples collected shortly after rainfall.  Many research publications from different regions reported 24- 92% of harvested rainwater samples positive for microbial contamination. Higher microbial concentrations are generally found in the first flush of rainwater, and the level of contamination reduces as the rain continues. Heavy Metals Rainwater is slightly acidic in nature and

Harvest Water from Air

The depletion of freshwater sources and rising water scarcity across the world, companies are now looking to tap the atmosphere that holds  around six times as much water as all the world’s rivers. Estimates of atmospheric water (when liquified) in India is 1,360 BCM which is closed to utilizable water resource of 1,123 BCM (Groundwater - 433 BCM and Surface water -690 BCM). India's current population estimated requirement of 2 BCM safe drinking water annually.  The solar-powered atmospheric water generator (Image Source: Sciencemag) An atmospheric water generator (AWG)s are machines that extract water from humid ambient air. Water vapour in the air is condensed by cooling the air below its dew point, exposing the air to desiccants, or pressurizing the air.  The contaminants in atmosphere water could be high but it can be removed with the integrated water filtration system. To date, an industrial AWG of 1,000  litres/day  capacity could cost upwards of Rs. 1.0