Wastewater Treatment and Reuse
gswcircleIn Developing Cities throughout the world, over 1 billion people are living without access to safe drinking water.  In addition, they do not have access to water for irrigation and small industrial uses that could provide economic solutions and a path out of poverty. 
untreated waste water dumped in open lots
Waste Water Dumped in Slums and Open Lots in Developing Cities
Even in the affluent areas of developing cities where water use can be 50 times greater, public infrastructure has not kept up with growth; therefore waste water collection  and treatment is inadequate and waste water is dumped in open lots near slums or used directly to irrigate vegetables.  In November 2002, countries throughout the world met in Hyderabad, India and signed the Hyderabad Declaration on Wastewater Reuse in Agriculture.  With this declaration, countries agreed to find simple solutions to treating waste water for reuse in agriculture.

waste water treated by aquatic plantsNature's Voice Our Choice has developed a Wastewater Treatment system that treats water for reuse in the irrigation of agriculture, building, and small industry processes.  This system is built using simple, locally available materials and uses local aquatic plant species to treat the waste water.

 How the system works:  In a conventional Waste Water Treatment Plant there are 3 phases: Primary, Secondary, and Advanced treatment.  The same is true with natural systems.  However, the plants and micro-organisms (bacteria) that thrive in the roots of aquatic plants are performing all the work.  

Arial View of Waste Water Treatment System
Arial View of Waste Water Treatment System in Nouakchott, Mauritania, West Africa
Aquatic Plants and Constructed Wetlands:  The aquatic plants consisting of water hyacinths and water lettuce multiply asexually doubling there mass every 3 to 4 days.  Thus to maintain the system, it is necessary to harvest the plants, removing a third of the mass, in each basin once to twice a week.  Once dried, the plants may be processed into compost to be used as a high nutrient fertilizer.  A local maintenance team is trained in the technique of harvesting, drying, and processing the plants to create an income generating activity from the by-products of the treatment plant.

Aeration Requirements:  The primary working component of this system is Aerobic (beneficial) bacteria.  As described above these bacteria thrive in aerobic (high oxygen) environments.  During the day, through photosynthesis, plants provide dissolved oxygen in water, however, at night they use oxygen.  Therefore to maintain an oxygen rich environment where bacteria can thrive; it is necessary to aerate the ponds twice a day.  Once in the evening for 2 hours to provide needed oxygen throughout the night and once in the morning to replenish depleted oxygen supplies.

System 3Recycle Flow Requirements:  Bacteria is the only living organism that has the ability to continuously naturally genetically modify itself to operate at maximum performance in its environment.  In nature, the bacteria’s environment is constantly changing and this ‘Chaos’ is what forces the bacteria to stay active and effective.  In a constructed controlled system with the same influent, bacteria can become stagnant, resistant, and less effective overtime.  Therefore, by varying the recycle flow from the final basin to the other basins, we can continuously ‘change’ the environment and ensure that the bacteria remain active.  This also adds some aeration to the system.

Energy Needs:  The system is designed so that water flows by gravity between the basins.  The minimal energy needed for aeration and recycle flow can be achieved with solar panels or simple wind turbines.

Mosquito Control:  Frogs, Mosquito Fish, and or catfish are introduced into the system to eliminate the mosquito problem associated with standing water and help to create a balanced ecosystem.