One problem I am facing right now is that the harvested rainwater has a bad odour. Hence, the system (used for toilet flushing only) has been temporarily suspended.
On water testing, it is observed that apart from odour the water has above limit colour and turbidity.
I am planning to erect a filter cum dozing unit on the delivery pumping mains.
Can someone suggest the type of filter cum dozing unit for a flow of 10 m3/day?
Dear Mr D'Souza we are using Aerobic Bacteria which is multi strain for treatment of Fecal Waste in the Bio toilets . I think for your treatment of Rain water to get rid of obnoxious odour you can try out Bio Leach LLMO it comes in liquid form . Based on the size of your storage tank the dosage needs to be decided
Stabilised hydrogen peroxide will give you a short term or repeat application solution. Long term, clean the storage tank of detritus and instal first flush diverted on the feed to the tanks.
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Hi Lenin, it seems that if you are able to supply 10 m3/day from your rainwater collection system, you must have a large collection area and a large storage tank/reservoir - not a standard household roof collection system. In this case it is probably quite difficult to manage your catchment area to prevent leaves and bird/animal droppings getting into your water storage. It then seems you will have to consider treatment of the water rather than prevention of organics getting into your storage. I agree with Chetan that a zeolite - activated carbon - chlorine dioxide system would be optimal for removing odours. However if you are needing a more low cost and low operational requirement solution, you may want to test out the option of aeration over a charcoal filter (a trickling filter packed with charcoal), or just an activated carbon filter on its own. I also agree with Louri that chlorine is usually not ideal for addressing odours - rather ozone, bromine or chlorine dioxide if the filtration system is inadequate. Would be great if you can let us know the outcome and option you choose. Regards Ian
You should explore a first flush system for your rainwater system. These are normally sized to divert the first 1-2 mm of rain from the rainfall event into a separate tank before your main holding tank. There are commercially available units or I have constructed them of pipe or 200 liter drums. You should be able to find the information if you search for "first flush". If you have a particularly heave load of dust, bird dropping you may need to oversize the first flush containers. If you have several relatively small rainfalls you can collect more water if you install drain taps on your first flush. This will save water and the water from the first flush maybe able to be used for floor mopping or such. If you have relatively large rainfall events then you can install a small drain hole in the first flush container and the system will be automatic,
If needed then you can follow up with additional treatment as recommended previously.
Rain water must be stored in closed tanks away from sunlight and atmosphere, leave small vents just to air the tanks, the problem seems to be primarily linked to biofilm formation, this is a frequent issue if the rainwater is stored without pretreatment, surface runoffs do collect some biomass and pathogens, generally originating from avian faecal matter and other organic entrapments in the gutters, You may use bioswale based filtration methods using Rigofill-ST based tanks as receptacles or use Sedipipe/Sedipoint flow separation technology to prevent the fine particles from entering the storage tanks. In some parts of western India, people use rainwater for several months for drinking after storage in beri, khoe and tanka systems.
Hi Lenin, the high color and turbidity in your rainwater might be due to organic matter (leaves from trees?) collecting in the tank and decomposing when left to sit there for a pro -longed period of time without the air (anaerobic decomposition). If you can combat this and prevent the organics getting into the tank - that would be the easiest and cheapest solution. How you do it - depends on the set out of your collection system. If these preventative measures do not fully eliminate the odour issue - then activated carbon filter might help prior to supply to the toilets. The chlorine will not work well is high level of organics is present. Regards, Iouri
Lenin, what is causing the odour? Is it hydrogen sulphide (H2S) or something else? If H2S, simple aeration of the stored water should eliminate it, as sulphur reducing bacteria require anaerobic conditions.
As there is a requirement for filtration and disinfection and the water is going to be used for toilet flushing a low cost approach would be a bag filter as it can be changed easily.
Rainwater Harvesting, if collected from rooftop is ideally meant for drinking purposes and if you do decide to use the water form drinking purposes then it would be a better idea to go in for a zeolite cartridge that will eradicate the turbidity, followed with an activated carbon filter.
For disinfection the best choice would be chlorine dioxide as very little is required to get a well disinfected end water quality that would take care of all pathogens as well as eradicate any foul odour.
I would have thought a simple in line cartridge filter system that facilitates periodic replacement might be best. Similarly a simple in line chlorination system designed for a small pool might work. However, the easiest solution would be to periodically treat the holding tank with some chlorox (liquid bleach) as if it is only for toilet flushing the concentration levels do not have to be too precise.
Dr. Blake has the most simplistic remedy. We have some low producing wells here in Colorado 1-3 gpm, and this is often the solution we recommend. And yes you also want the storage sealed with a vent (ideally a 2"x 10"x 5 micron sediment filter cartridge works well), and the tanks kept out of sunlight unless they are non-light transmitting.