Bio-domes are a sustainable low cost water treatment technology that uses just one third the energy of traditional mechanical aeration systems and is also suitable for rural and other communities that currently rely on essentially unimproved treatment lagoons. They work by providing an optimal environment that promotes flourishing communities of beneficial bacterial biofilms that naturally process the dissolved and suspended pollutants in order to cleanse the water.
by Chris de Morsella, Green Economy Post Follow Chris on Twitter @greeneconpost
One of the biggest and most persistent problems that it is critical to solve in our time and solve in a sustainable manner is the issue of fresh water availability. We need to find ways to ensure the future of supply and to do so in a manner that does not itself build in fatal and non-sustainable dependencies into the proposed solution itself! This is a problem of such urgency and import; it is perhaps the biggest problem humanity is facing in our time. The growing lack of clean fresh water, already out of reach for far too many people and becoming at risk for billions more, is a tinder box that has the capacity to set off armed conflict on practically every continent. Many military thinkers fear that water wars may soon begin to break out in various places in the world including in the Middle East. The Arabs have a saying… “without water there is no life”; far too many people are already discovering first hand what water scarcity entails and how hard life is when it is lacking or of poor quality.
One of the major ways that humans reduce the availability of fresh water is by causing it to become dirty and laden with pathogens; sewage and similarly polluted bodies of water are no longer suitable for use untreated. Urban sewage is not the only source of waste water, agricultural runoff and aquaculture systems as well create their own water quality issues. All of these activities: urban & periurban water usage producing polluted runoff and sewage; aquaculture and agricultural uses that also pollute water and of course industrial usage, which often pollutes water with various toxics – all of these activities effectively diminish the available fresh water supply and make the problem worse.
Wastewater Compliance Systems, Inc has developed an interesting and very simple technology to help treat sewage waste water and other waste stream water returning it to the level of purity and quality that is fit to return for re-use or input back into the natural hydrological systems. They had been calling their invention the “Poo-Gloos” because of their igloo like shape, but now, wisely, prefer the less eccentric name Bio-Dome.
These systems, consist of several concentrically nested domes filled with loose plastic packing, providing a very large surface area on which sewage-eating bacterial biofilms can flourish. They sit on the floor of a treatment lagoon, in which they are completely submerged and they are infused with low pressure air to optimize the growth of naturally occurring biofilms. As water flows through the system, bottom-to-top, beneficial bacteria effectively reduce biochemical oxygen demand (BOD), total suspended solids (TSS), and ammonia-nitrogen (NH3/NH4+) in waste water lagoons prior to discharge.
The company also offers a similar bio-shell product; it utilizes the same underlying principles and was developed as an alternative to bio-domes to be utilized in applications where space is limited and/or lagoon depths are too shallow to accommodate a bio-dome. The half pipe design of the bio-shells can be installed end-to-end, which allows for a more dense installation.
Bio Domes Work by Combining Aeration With Very Large Surface Area for Beneficial Biofilms to Grow On
Lagoon efficiency can be dramatically improved by promoting the growth and development of beneficial microbial colonies. Diverse bacterial colonies consume water‐borne contaminants, but such colonies can only exist within a thin biofilm attached to submerged surfaces. Beneficial biofilms thrive when they are protected from sunlight, and exposed to optimal degrees of aeration and nutrient mixing.
The domes have a 6ft diameter, are 5ft high, and weigh 850 lbs. They are economical, and require much less energy to operate than the capital and energy intensive mechanical aeration systems used by many large scale sewage treatment plants. Because of their small scale they can be incrementally installed to match the specific needs of a community; whether it is to increase lagoon capacity, extend the useful life of the lagoon, or to help lagoon operators meet regulatory requirements.
In order to significantly enhance the biological activity in a wastewater lagoon, there are two core needs: aeration and lots of surface area for biofilm development. Bio-domes simply and effectively introduce the needed air and the requisite surface area into existing water bodies without exorbitant capital costs. Additionally the unique design of the bio-domes results in a high Oxygen Transfer Efficiency (OTE) with a minimum of energy input. Their systems typically require just one third the amount of energy as most aeration systems for the same performance. This much lower recurring energy cost is an important factor in the sustainability of waste water treatment systems and it will become an ever more important factor as energy itself becomes more expensive.
Biofilm is crucial in establishing robust biological activity in a wastewater lagoon. Suspended growth bacteria are not always able to develop in sufficient quantities in a typical wastewater lagoon, nor are they capable of surviving in cold weather environments. Biofilm allows a variety of beneficial bacteria to develop in higher concentrations than is possible in suspended growth. Biofilm growth is limited though by the amount of available surface area in the lagoon. To overcome this, the patented design of bio-domes creates an additional 2800 square feet of surface area inside each unit. This increase in surface area correlates directly to increased biological activity once the biofilm has had a chance to develop.
This is the kind of simple elegant solution that we need. It increases sustainability not only because it cleans water, but because it does so using much less energy than other mechanical aeration systems. It is also simple to install and can be installed incrementally, an important sustainability factor in itself. I also like how this treatment option is eminently suited to a distributed water treatment philosophy that relies less on big monolithic, centralized, energy and capital intensive sewage treatment plants and increasingly instead on a distributed network of more locally scaled treatment facilities that operate with less energy and capital.
