A low-cost water and wastewater treatment system having several embodiments achieves efficient contaminant removal in an environmentally "friendly" manner. The technology couples biological and passive chemical unit processes, and relies largely on pH changes to remove contaminants. A first embodiment...http://www.google.com.au/patents/US5993649?utm_source=gb-gplus-sharePatent US5993649 - Sequential biological-chemical water treatment system
