The Biocoil Project - 1995-96

The Students: The Sewage Sisters: Kara Thurston, Dani Gahl, Tessie Gordon, and Stacie Julian

The Teacher: Clinton A. Kennedy

Awards: Awarded $500 Valley County Soil & Water Conservation District Grant, $1,000 Cascade Reservoir Association Grant, $1,500 Lightfoot Foundation Grant, $1,500 Cascade Coordinating Council (IDEQ), $5,000 PEP Grant, $750 Idaho Power Grant, and $700 Pacific Northwest Pollution Control Council for implementation of mobile biocoil project

The Biocoil


Sewage treatment today is based on traditional methods that have been used over the last 50 years. The philosophy behind these methods is best summarized in the Army Corp of Engineers' slogan, "The solution to pollution is dilution." There are three different kinds of sewage treatment in use today: primary, secondary, and tertiary. Essentially, primary treatment is no treatment at all. During primary treatment large organic matter is allowed to settle to the bottom of a sewage pond by coagulation and sedimentation. The next level of treatment is secondary treatment. This stage concentrates on the breakdown of organic matter through the use of coagulation, sedimentation and filtration. The addition of a filtration system allows for higher levels of organic breakdown to occur where all organic matter is converted to inorganic nutrients. It is also possible to add a dissinfection process to destroy pathogens before releasing the effluent. Finally, tertiary treatment is the most sophisticated level of waste water treatment in existence today. Waste water completes primary and secondary treatment before undergoing tertiary treatment. During this stage of treatment, nutrients are removed from the effluent before it is discharged into rivers or lakes. This is traditionally done by chemical means and is cost prohibitive for most communities.

Today's laws require waste water to undergo secondary treatment. However, the discharge of nutrient rich effluent causes eutrophication of our rivers and lakes. This results in unattractive and sometimes lethal algae blooms. Although tertiary treatment is ideal for waste water recycling, most systems are very expensive and use potentially harmful chemicals to purify the effluent. With the new movement towards more environmentally sound treatment methods, biological treatment systems seem to be the most appealing. Unfortunately, the technology used in these systems isn't widespread as of yet. As municipal budgets become tighter and cities continue to feel pressure to clean-up their effluent, now is the optimum time for introducing an inexpensive biological waste water treatment system.


At the beginning of civilization there was no real method for treating waste water. However, as cities began to form it became apparent that it was necessary to device some sort of system for collecting and treating waste. One of the first forms of waste water treatment was a devise commonly known as the outhouse. Outhouses were constructed relatively close to individual houses and consisted of a wooden shack covering a hole in the ground. Most outhouses were equipped with a rough cut seat and several dozen flies. A new outhouse was constructed when waste nearly filled the hole. Dirt was added to fill the remainder of the hole and the waste was forgotten. As cities continued to grow and space became limited, outhouses were forced to move indoors. However, there was a new technology that made the process somewhat more appealing. This technology, the Silent Valveless Water Waste Preventer, is commonly known as the toilet. The patent for the toilet belongs to Albert Giblin although it is believed that Thomas Crapper is the man responsible for marketing the technology. These early toilets discharged directly into nearby rivers and streams. Today waste from toilets is distributed in one of two manners. The first, a septic system, incorporates the basic idea of an outhouse. Septic systems are installed in rural households where there is no larger collection system available. They capture and contain solid waste and allow the liquid waste to be purified by trickling through levels of soil. The second treatment system involves the collection of waste from individual homes. Waste travels from the home, into a series of pipelines, and eventually into a treatment facility where it undergoes primary, secondary, and occasionally tertiary treatment.


Picture this: Nestled in a pristine mountain setting are a series of ponds. Ducks and wildlife live near the tranquil waters. From a distance, you see a faint green glow casting a muted light that reflects off of the glassy surface of the ponds. What is the strange iridescent glow? Have aliens landed or is it just a local tavern's sign? Amazingly, this beautiful glow is being emitted from sewage treatment technology of the future.

The Biocoil, as the technology is called, is a revolutionary photosynthetic Photobioreactor that provides an environment for biological organisms to grow in a controlled manner. A Biocoil consists of several sections of clear, food-grade PVC tubing that is wound horizontally around a vertical, cylindrical wire frame. It is illuminated primarily by sunlight and fluorescent lights located in the center of. the cylinder frame. Liquid is circulated through the tubes at a high velocity using a peristaltic, centrifugal pump that produces compressed air.

In the tubes of a Biocoil, algae is grown to remove nutrients from secondary effluent. The commonly used algae for sewage treatment in this system, Chlorella sp., is maintained in suspensions at a high concentration, which causes the culture to become nutrient deficient. When effluent is added to the nutrient deprived culture, it absorbs nitrates, phosphates, and ammonia in large amounts. The algae culture is passed through the coils of tubing to allow complete nutrient absorption. After 2 hours, the treated effluent can be removed from the system, while the nutrient rich biomass is left behind to continue treatment.

Each section of tubing in the Biocoil contains its own cleaning system to remove any algae build-up which would inhibit the overall productivity of the Biocoil. The cleaning system, like the rest of the Biocoil, is simple. During operation, a scouring pad, similar to an SOS pad, is held motionless in each section of tubing. When the water flow is reversed, the scouring pad travels through the tube, knocking algae from the tubing walls. After the scouring pads have completed the cycle, the pump is returned to the original direction and the tubes are free of algae build-up. The algae can then be settled out in a settling tank where it concentrates and is easily harvested as animal, fertilizer, or fuel. The biomass also be recycled back into the Biocoil system when re-inoculation is necessary.

Biocoils are very simple in design, and because of this, they are inexpensive and easy to assemble and operate. They are small and thus, they have a minimal space requirement, making them even more economical. Many problems are avoided because of simple processes that are incorporated in the design of the Biocoil. Because the effluent in the system is circulated at a high velocity, there is no threat of anoxic conditions developing. At the same time, the turbulence makes it impossible for unwanted toxic algae to grow. Sunlight is the primary source of illumination in a Biocoil, making its energy consumption minimal. The only time that artificial light is used is on cloudy days and during the night. The design of the Biocoil enables maximum photosynthesis to occur and cultures are able to grow because of high turbulence and efficient light usage. Biomass is removed from the Biocoil in a liquid form and can be dried for use as animal feed, fertilizer, and fuel. The sale of the dried algae can help to offset the operating costs thus making the Biocoil even more economical.

Our hope for the future of sewage treatment consists of this inexpensive, biological system. The Biocoil can be used to treat waste water from irrigation, agriculture, feedlots, and municipal sites. It can also be scaled down for private home use in place of the common home septic system. If a technology such as the Biocoil could replace the existing systems, the potential for solving the world's effluent woes would be unlimited. Clean water would be inexpensive and accessible to everyone.


The Biocoil Photobioreactor has seen its initial implementation in those countries where the overall attitude towards biological treatment systems is more progressive. The lab model Biocoil that we have recently constructed is the only operating Biocoil in the United States. For this technology to exist on a national level, there must be a significant change in the negative attitudes of the established municipal engineering associations towards new technologies. In our efforts to expose the Biocoil technology we attended city council meetings and water quality and public testimony hearings. Our experiences have led us to the conclusion that the municipal engineering establishment is forced to choose expensive, traditional waste water systems because their fees are based on the total expense of the project. They have no incentive to look for or try new innovative technologies because they generally do not yield the lucrative fees that the traditional systems allow them to collect. Considering current trends and attitudes of traditional municipal engineering establishments, it is no surprise that there are no full-size operating Biocoils in the United States.

We believe that taxpayers and general public are very responsive to new technologies that are both environmentally sound and cost effective. Although taxpayers express interest in new technology they often lack the incentive, knowledge, and expertise to voice their opinions to the elected officials of their communities. They must take a more active stance in the local governmental system and demand that their tax dollars be spent in a more economical and environmentally sustainable manner. As it is the responsibility of the regulatory agencies and the engineering firms to be accountable to the general public, it is equally important that the taxpayers force these agencies to be more responsive to their ideas and opinions.

In order for the Biocoil Photobioreactor system to be fully implemented in the United States there must be a breakthrough in the attitudes of the regulatory agencies and engineering firms towards innovative technology. It is also necessary for taxpayers to demand accountability from both their elected officials and hired engineering firms.


As treated waste water is commonly discharged into nearby rivers and streams it has become necessary to discharge effluent that contains a very small amount of nutrients in order to ensure that our lakes, reservoirs, and oceans can remain healthy. We have first hand experience about the dangers of excess nutrients in a body of water as our reservoir is suffocating from the contamination of toxic blue green algae. Treated water from the Biocoil system can either be safely released into rivers and streams or used for irrigation purposes. In both situations the water is adequately recycled. The Biocoil technology would bring cleaner water to cities in both the United States and countries throughout the world.

With the present technology, water purification is an expensive endeavor. Biocoil systems allow for water to be effectively purified at approximately 1/4 the cost of conventional systems. This results in substantial savings for the taxpayers of a community. Another benefit of the Biocoil system that saves taxpayers money is the production of a marketable biomass. Dried Chlorella algae can be sold as animal feed, organic fertilizer, and fuel for methane generation. The profit generated from the biomass can be used to offset the operating costs of the system.

The Biocoil also has many alternative uses including the growth of health food algae, production of pharmaceuticals, the purification of feedlot waste water, the treatment of industrial effluent, toxic chemical destruction, the culturing of plant cells, radioactive waste treatment, greenhouse gas conversion, and aqua cultures. The introduction of Biocoils to the United States would not only mean new technology for purifying sewage effluent but would also allow the utilization of the technology for a wide array of applications. This would boost local economies and present several new job opportunities.

The major drawback of Biocoil technology would involve restructuring of the current engineering establishments. Engineering firms whose main objective is to create a higher profit margin by running the cost of production to unreasonable levels would be forced to change their operating guidelines. Biocoils are an inexpensive technology and upon regulatory approval would result in a definite decrease in the profit margin of engineering establishments. Firms specializing in waste water treatment systems would be forced to change the purpose of their institutions. Waste water engineering establishments would be a profession of the past.

We conclude that in order for sewage treatment technology to progress into the 21st century it must move more toward biologically sustainable and economically viable solutions. We believe that the Biocoil Photobioreactor meets sewage treatment requirements for the 21st century.

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