Moosi Rani Sagar receives rainwater runoff through an open channel and wide hilly catchment, which makes the inflow water an organic-rich solution. The majority of the inflow receives in 2 months of monsoon which stays in the stepwell throughout the year. Further rituals performed and putting a huge amount of grains for fishes and leftovers from food stalls add to the organic content, which over a period of time degrades in anaerobic conditions to produce thick sludge in the bottom bed of the Sagar.
To clean this water it was recommended to dewater the whole stepwell in a non-rainy period, scraping the sludge from the bottom which was observed around 9 ft thick and cleaning of catchment at the canal which was full of non-biodegradable plastic and excreta of animals. But having large archaeological importance and minute possibilities of discharge which could fill the downstream residential area with stinking water, the permissions for dewatering was not given, hence came the solution of in-situ aeration and filtration system.
A total of four aerators with one filtration unit was installed in October month to remove the algae and reduce the anaerobic conditions by mixing oxygen-rich air. The detailed mechanism of both the systems is as follows-
Aeration and Filteration Unit- 2 floating aeration units and one external filtration system was installed for oxygenation and removal of algae in the first phase of cleaning. While floating aerators work as sprinkler/fountain, throws the water to a height of 25 fts, mix Oxygen-rich air in the dirty water, at the same time adding beautifully to the aesthetics of this heritage site. Each aeration unit aerates 100 cubic meters of water per hour.
The external filter unit also has the same filtration capacity of 100 cubic meters per hour but works on a different mechanism. It was taking inlet from two pumps of 12.5HP and 15HP passing it from metal mesh/sieve and putting filtered water back in the Sagar with cascading from stairs which again mixes air in the filters water and also looks beautiful. Every 2 hours it generates a backwash to clean its sieve which is 0.05% of total filtered water. The backwash is rich in nutrients which will be used as manure in plantation patches. At every 3 day interval, samples of inlet and outlet water were being observed, based on that one pump of 12.5 HP was shifted to the opposite side of the filtration system to rotate the water inside the stepwell hence improving the efficiency of filtration.
