(Perma)Culture and Sanity
Only 3% of the Earth's water is 'fresh' water (as opposed to saltwater). As populations increase and unpolluted water sources shrink, the issue of how we treat our water during and after use is rapidly gaining critical importance.
Groundwater often contains a sobering array of pollutants, and water taken from rivers for city drinking supplies can have problems with turbidity (cloudiness due to suspended particles), high acidity/low pH, microbial infestations by E. coli and other organisms, metals, biocides, fertilizer, road runoff and other residues.
These problems build on and exacerbate each other—metals are more absorbable by humans when water is acidic (in alkaline water, metals precipitate out and fall to the bottom where mud can absorb them and keep them out of biological cycles). Microbes in acidic waters also more readily incorporate metals into their tissues, making them available for ingestion and bioconcentration by phyto- and zoo-planktons, minnows, larger fish and—ultimately—humans.
Keeping our ground and surface waters clean means protecting watersheds from human and livestock wastes, metals, household and industrial chemicals and biocides... places where watersheds are thusly protected are rare. For these reasons and for the foreseeable future, roof water will likely remain the cleanest source of water for human use.
The question of how to clean wastewater should ideally follow the question of why we add pollutants to clean water in the first place. Complicated methods for cleaning human wastes from water, for example, ignore simple systems like composting toilets which avoid introducing those wastes into water in the first place.
By recognizing that human wastes can be a resource instead of just a disposal problem, the question moves from,"How can we fix this pollution problem?" to "How shall we productively use this new resource?" Given the perpective of the second approach, we can create very different systems that produce yields instead of consuming and/or dissipating resources.
3 of the 4 most harmful chemicals in California waterways (soap, detergent, bleach and used motor oil) come from residential wastewater streams.
Alternative Agriculture, 1989
A number of methods are conventionally used for cleaning wastewater, the most common being treatment in sewage ponds (where some 30 - 40 chemicals may be added before the resulting 'clean' water is returned to city plumbing systems or local waterways). In extreme cases, reverse osmosis and other energy-intensive technological fixes may be employed. These conventional methods of wastewater treatment require elaborate systems with high ongoing energy and maintenance requirements.
In Nature, wastewater is treated at no cost and is actually made much cleaner than is practical using technological means. Happily, we can mimic natural cleansing systems to produce very pure water from highly polluted water and receive a yield or yields in the process. This is a creative and wealth-producing solution, as opposed to treating wastes as a 'disposal problem'... first throwing money at the 'problem,' and then creating new problems because of the fact that nothing is ever actually, truly 'disposed' of.
How natural and constructed wetland systems work to clean polluted or waste water; pros and cons of constructed wetlands as compared with conventional systems.
Removing metals and other persistent pollutants from wastewater streams using constructed wetlands.
A description of the working parts of a constructed wetland wastewater treatment system, describing their biological functions and variations.
Reprinted from (Perma) Culture and Sanity Website