Groundwater is one of the major water source available on our planet. But with the presence of many contaminants, the percentage of pure groundwater availability is decreasing day by day.
Arsenic is such a toxic pollutant present in natural waters like surface and sub subsurface water sources. The presence of arsenic is becoming a greater threat to the survival of human beings and other useful micro-organisms. There are various technologies are available to remove arsenic from groundwater. Like coagulation, lime softening, ion exchange, reverse osmosis and membrane techniques. Coagulation is one such technology, which is a more effective treatment technique to remove arsenic from groundwater.
World Health Organization (WHO) reduce the permissible limit of arsenic from 0.05mg/l to 0.01mg/l. The serious health effects caused by the presence of arsenic led the WHO to take this precautionary measure. Coagulation is a common process to treat industrial and domestic wastewater in order to remove the suspended particles from the water.
Coagulation is a chemical water treatment technique typically applied between sedimentation and filtration stages to improve the efficiency of the treatment process. Coagulation is a process used to neutralize the pollutant charges by forming the floc (gelatinous mass). The floc trap all the particles thus forms a mass large enough to settle or trapped in the filter. Aluminum chloride, ferric chloride, aluminum sulfate, bentonite clay are few coagulants used in the coagulation process.
Jar test apparatus
Ferric Chloride (FeCl3)
Use the conventional jar test apparatus for this experiment.
Collect the groundwater sample and find the initial arsenic concentration (mg/l) present in the sample.
Fill each beaker with the groundwater sample (1 litre) and place them in the jar test apparatus assembly.
Add 60mg coagulant (Ferric Chloride) in each beaker.
Now, turn on the jar test apparatus and the sample should be rapidly mixed at 100 rpm for the first 1 minute.
After that reduce speed to 40rpm for the next 20 minutes and turn off equipment.
Allow the sample to settle down for the 30minutes.
Now, take out the 100ml sample from each beaker and find the remaining arsenic concentration in the sample.
Compare the initial and final values of arsenic concentration to know the reduction in arsenic concentration.
Repeat the above procedure with different values of ferric chloride (70mg/l, 80mg/l, 50mg/l and 40mg/l) to find the optimum dosage of coagulant.
Simple in operation.
Best treatment process to remove many kinds of pollutants.
Enhances the filtration process.
With this wide range of applications coagulation technique proven to be the effective treatment process for the removal of arsenic from groundwater.Kit required to develop Arsenic Removal from Groundwater by Coagulation Process: