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The Arcata Marsh and Wildlife Sanctuary
Read more about the community of Arcata, California, and its artificial marsh sewage treatment plant.

Possible Solutions for Sewage

Seeking a more natural and less expensive approach to sewage treatment, the city of Arcata, California has implemented an effective low-tech alternative: an artificial wetlands waste treatment plant. Currently, more than 150 cities and towns in the United States use natural and artificial wetlands to treat sewage.

In the first stage of Arcata's system, sewage is held in sedimentation tanks where the solids settle out as a sludge that is removed and processed for use as fertilizer. The remaining wastewater is pumped into oxidation ponds; here, as in conventional treatment plants, bacteria break down the waste. About one month later, the water is released into a series of artificial marshes, where it is further filtered and cleansed by reeds, cattails, and bacteria. The purity of the water increases as it is subjected to the wide range of acidities that result naturally from daily cycles of photosynthesis.

Although the water is clean enough at the end of this process to be discharged directly into the bay, California state law requires it to be chlorinated, to ensure that all pathogens have been destroyed. So Arcata chlorinates the water and then dechlorinates it before sending it into the bay. In some communities in states that don't require chlorination, the water is diverted at this point to fish hatcheries. The remaining nutrients in the water provide food for the fish, thus contributing to a source of food for people.

As an additional bonus, the Arcata marshes and lagoons serve a wildlife sanctuary and city park, providing habitats for otters, seabirds, and other marine animals and attracting many tourists.

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