In my project area, we use bore wells as a water source, but recently the water is contaminated by nitrates.
Could you please let me know which low-cost technology can be used to removes nitrates in borehole water in rural areas of a developing country?
Conventional processes for nitrate removal - ion exchange, reverse osmosis and electro dialysis - are quite expensive and pose a question of subsequent disposal of generated nitrate waste brine.
By the Zambian Drinking Water Standard (ZDWS), recommended nitrate levels are 10 mg/l NO3-N equaling 44.3 mg/l NO3. We would like to reach these levels so any advice is helpful.
Nitrate is the indication of microbiological in the water, the best way is disinfection by using chlorine. Abstracting water from borehole to the reservoir/tank and disinfect water into the tank/reservoir with chlorine. This is the first option and the second option is iron exchange, reverse osmosis, and package plant.
i think that you should try to treat the water by passing the water on a film of a Seaweed mounted on cement base then the water influent treat it by activated carbon to adsorpe any unwanted taste
in that way you are going to elimenat all Nitrogen and phosphate from water beside the COD and BOD are going to be decrease
Hmmmm .... i wuld instal a natural garden with many diferent water cleaning and nitrat's infiltrating cultures ... what is with solar energy preheatig water systems ?
Hmm. Reverse osmosis requires costly, energy intensive and requires skilled labour. Biology process requires carbon source for denitrification, not to mention that it also have to have a basin, technology elements, and a little bit more skilled staff. I would try to use some wetland-like technology, or deal with the source.
I agree with Mr. Mann and Mr. Lauenstein. I would recommend a shallow, watertight pool which is populated by duckweed or water hyacint ( Lemnoidae and Eichhornia crassipes -take care, the second is considered to be highly invasive and dangerous, especially in Africa). If possible use local surface or underwater floating water plant species, the ones growing the fastest. Let the water flow through slowly the pool. The size/volume of the pool, the flow and harvest intensity should be tested first with a pilot. I would start with 15-20 cm depth, a few square meters, 2 day contact time (flow/volume) and a biweekly harvest of 25%. I would measure effluent NO2 daily, starting from the seventh day, and I would set the parameters (flow, depth) based on the result. Temperature might influence plantal growth, if the water is cold, they grow slower. If this works: it is cheap but requires labour to harvest the yield intermittently. Also, the pool have to be cleaned regularly to produce adequate water. Pumping needs at least a windmill wheel, so this one could be installed without electricity.
The easy method it will be blending, just pump water from different borehole and blend it. Make sure that the pumping took place at night in order for reaction to take place.
The easy method it will be blending, just pump water from different borehole and blend it. Make sure that the pumping took place at night in order for reaction to take place.
You can use aquaponics; the plants in an aquaponics system will see your nitrates as "fertilizer", and clean them out of the water. You'll then have to put the water through a secondary process to get any bacterial contamination out, but this will solve your first problem.
For more, see http://www.friendlyaquaponics.com/ for tons of free information about what aquaponics is, what it does, and what it costs.
Aloha, Tim............
Published
by Tim Mann, President and Owner at Island CAD Services, Inc
1 Comment
@ Tim, thank you,, for the information and the link!
Biological treatment can help in not generating waste brine but needs more control in the disinfection process after treatment. Depending on the flow rate of the well biological treatment may be or may not be more cost effective than IX, RO or EDR.
Have you considered looking for and dealing with the source of the nitrate? Would it be possible to use trees or plants to take up the nitrate before it gets into the groundwater?
Nitrate is a compound that is formed naturally when nitrogen combines with oxygen or ozone. Nitrogen is essential for all living things, but high levels of nitrate in drinking water can be dangerous to health, especially for infants and pregnant women. Nitrate contamination of ground water resources has increased in Asia, Europe, United States, and various other parts of the world. This trend has raised concern as nitrates cause methemoglobinemia and cancer. Several treatment processes can remove nitrates from water with varying degrees of efficiency, cost, and ease of operation.
Safe & Economical Process
Biological denitrification exploits the ability of certain naturally-occurring bacteria to use nitrate for respiration under anoxic conditions (absence of oxygen). The overall process is the reduction of nitrate to nitrogen gas and proceeds as follows:
NO3 - → NO2 - → NO → N2O → N2
Denitrification can be achieved using both heterotrophic and autotrophic bacteria. In heterotrophic denitrification an organic carbon substrate, such as methanol, ethanol or acetic acid, is required as a food source for the bacteria. In autotrophic denitrification an inorganic energy source such as sulphur, reduced sulphur species (e.g. thiosulphate) or hydrogen is required; the carbon needed for bacterial growth is obtained from bicarbonate in the water.
Trickling filter followed by flash aeration may do the trick.
Nitrate is a compound that is formed naturally when nitrogen combines with oxygen or ozone. Nitrogen is essential for all living things, but high levels of nitrate in drinking water can be dangerous to health, especially for infants and pregnant women. Nitrate contamination of ground water resources has increased in Asia, Europe, United States, and various other parts of the world. This trend has raised concern as nitrates cause methemoglobinemia and cancer. Several treatment processes can remove nitrates from water with varying degrees of efficiency, cost, and ease of operation.
Safe & Economical Process
Biological denitrification exploits the ability of certain naturally-occurring bacteria to use nitrate for respiration under anoxic conditions (absence of oxygen). The overall process is the reduction of nitrate to nitrogen gas and proceeds as follows:
NO3 - → NO2 - → NO → N2O → N2
Denitrification can be achieved using both heterotrophic and autotrophic bacteria. In heterotrophic denitrification an organic carbon substrate, such as methanol, ethanol or acetic acid, is required as a food source for the bacteria. In autotrophic denitrification an inorganic energy source such as sulphur, reduced sulphur species (e.g. thiosulphate) or hydrogen is required; the carbon needed for bacterial growth is obtained from bicarbonate in the water.
Trickling filter followed by flash aeration may do the trick.
You have covered all of the typical ways to reduce nitrate in drinking water. Another way requires some chemistry and biology. I have seen some biological processes that reduces nitrate to nitrate and eventually de-nitrification. I think there is some research published on the microbiological reduction of nitrate. I hope this leads your research to find a low cost and SIMPLE solution.
You have covered all of the typical ways to reduce nitrate in drinking water. Another way requires some chemistry and biology. I have seen some biological processes that reduces nitrate to nitrate and eventually de-nitrification. I think there is some research published on the microbiological reduction of nitrate. I hope this leads your research to find a low cost and SIMPLE solution.