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Arsenic Remediation with Dried Plant

Remediation Prototype I

After proven successful in arsenic contamination adsorption with dried plants, we want to build a low cost remediation prototype. Our goal is it must be little to no cost, widely available, easily assemble and use.

We started with a common PVC pipe . Begin at the bottom, we filled approximately 5cm of sand as a filter for any loose adsorbent and follow with 50gr of adsorbent. Bamboo would be another ideal tube in certain area.

Water hyacinth and duckweed was selected as the adsorbent for the experiment. Once the assembly is completed, 4 liters of Arsenic contaminated water was pour through at a flow rate of 1 liter per 5 minutes as we analyzed each passed liter for remaining arsenic. The results for each adsorbent are as follow:

Water Hyacinth (Eichhornia Crassipes)

After the first liter (20ppb), the following 3 liters was consistent at 10ppb.

Duckweed (Azolla Caroliniana)

The duckweed results was better than the water hyacinth with the consistency at 5ppb.

Initial Conclusion

We were surprised that right out of the gate, our prototype was very successful in arsenic removal. One quick reaction is that with an abundant (50gr) of adsorbent, the level was quickly reduced below WHO level in 5 minutes. Another is that in the previous lab experiment, the adsorbent was added to the water in a glass beaker where 1/3 of the adsorbent is floating instead of submerging. In this experiment, the water passed through all the adsorbent.

Although happy with the results, the experiment also bring up a few questions. We only pour in 4 liters of contaminated water, how much more can the adsorbent continue to be effective and what is the optimum flow rate (time vs quantity of adsorbent).
Another concern is the color of egress water is slightly brown due to the dried adsorbent. We experimented with a small layer of carbon, it removed all color as well as unwanted taste. Again, more experiments are needed such as pipe diameter, length and flow rate.