Clearford’s SBS™ system continues to function where historic sewers fail: 50L/capita/day
Clearford’s technology is the Small Bore Sewer™ (SBS™) system, a watertight small diameter wastewater collection system that provides servicing with superior operational and environmental performance at a significantly lower cost when compared to historic gravity sewers. With the SBS™ as the enabling technology, Clearford delivers, on a global basis, turnkey, fixed-price wastewater collection, treatment, and energy generation solutions.
Clearford Process
The easiest visual and concept that represents the significant difference in the Clearford process when compared to the historic gravity sewer, is in the comparison between historic mainframe computers and the modern concept of distributed computing.
Mainframe computing was structured so that each and every monitor was connected to a network that sent requests for processing to a single centralized source. Surges of demand took place at the beginning and end of the day when the monitors were powered on and off. Eventually, as the processes and requests to the mainframe became too complex, and the networks too vast, the mainframe would fail; this lead to the innovation of the personal computer processor.
Personal computing which is now the norm, involves microprocessors in each computer, allowing each modular unit to process its own simple requests, without the need to be attached and plugged into a mainframe.
The SBS™ system operates on the model of distributed processing of solids, allowing for a simple and cost effective solution to treat the liquid. This is in contrast where historic gravity sewers collect and send all solids and liquids to a centralized location, where the combination of peak flows, rainwater inflow and groundwater infiltration cause repeated failure and environmental damage.
Components
Over the 20+ year life of the Company, Clearford has invested millions of dollars into Research and development. This has led to 26 issued or pending patents on material components of the Clearford SBS™, as well as the processes and design format of the overall system.
Inlet Device
In order to accelerate anaerobic digestion, increase bio-gas production rate, and cause the accessible organic mass to be eliminated, Clearford has developed a non-mechanical method of increasing hydraulic mixing within the Clearford Vessel vessel.
Historically, the inlet device for septic tanks has the purpose of dissipating the energy of sewage as it enters into the vessel. By slowing down incoming sewage, it is able to stratify much easier and thus prevents solids from mixing within the tank; in septic tanks, the purpose is simply to separate solids and liquids, and ensure that minimal solids are discharged into the subsequent tile field, typically only 20% suspended solids. Stratification and maximum solids removal serves the purpose of protecting the tile field; Clearford can support a higher fraction of suspended solids. Without the hydraulic mixing and accelerated anaerobic digestion that Clearford accomplishes, septic tanks must be pumped out every 2-5 years.
The Clearford vessel has a patented inlet device that allows the incoming sewage to harness the energy to effectively create gentle hydraulic mixing of the sludge blanket within the Vessel. The inlet device has an increase in velocity at the entrance of the tank.
Bacteria that have aged in the bottom stratum of the septic tank are excellent at consuming available organics in the sewage; however, these bacteria become enclosed in layers of sludge and cannot access the organic materials in new sewage. Allowing the energy of the incoming sewage to be harnessed to mix the sludge blanket within the tank, the bacteria colonies that develop and mature over the life of the vessel have access to the new sewage.
In the picture above, the left drawing illustrates a septic tank’s flow pattern, and the picture on the right illustrates the expected flow pattern in a Clearford vessel. Green is zero velocity or “dead zones”, the dark red and blue coloration shows high velocity in opposite directions and hydraulic mixing in the vessel as a spinning motion on the diagram. As can be seen, within the Clearford vessel, there is a substantial increase in movement and velocity in the tank.
Attenuation Device
The inlet that creates the passive hydraulic mixing is one aspect of the Vessel that differentiates it from a septic tank; another is the patented attenuation device, which allows for a hydraulic retention time of up to 3 hours of flow retardation.
The graph above shows the various attenuation devices tested during research, and their hydraulic retention time. The blue Control Test was without an attenuation device, which would represent a similar retention as a historic gravity sewer or septic tank. The test run #4 represents the attenuation device selected and which is now used by Clearford. Historic Sewers cannot store flow and must be able to pass the highest expected flow on any day. Attenuation, or peak shaving, of a flow translates into lower peak/design flows, smaller pipes, and installation slopes and smaller receiving infrastructure. This attenuation within the vessel translates to a reduced peaking factor for system sizing. This is illustrated below:
In order to ensure that the sewer piping network and wastewater treatment plants are large enough to handle the regular working flows of a community, they must be designed to service the community peak flow. For historic sewer systems the peaking factor are designed for between 2 and 4 depending on the community population. Actual peaking factor can be much higher; illustrated above is the peaking factor of 3. The Clearford Small Bore Sewer system with the patented attenuation device achieves hydraulic retention to design for a peaking factor of approximately 1.4. This translates into direct cost savings as the treatment plant and pipes can be reduced by approximately 50%.
Materials
High Density Polyethylene Pipe
Economic advantages of using HDPE pipe material:
- Flexible high density polyethylene (HDPE) pipe can be installed in a bent or curvilinear alignment around subsurface obstructions, such as foundations or historic trees, without importing expensive elbows and couplings required by conventional piping. The HDPE pipe can be bent into a radius of 25 times its diameter – for example a 4” diameter pipe can be bent into a radius of 8.2 feet.
- The expected lifecycle of HDPE pipe is over 100 years. This robust plastic material is resistant to acid and biological attack while lacking the rigidity that causes other plastic pipe materials to crack.
- The fusion equipment is small and equipment to fuse 3” to 10” diameter pipe can be as small as the size of a (carry-on) piece of luggage so transportation is simple.
- Training local workers to use the heating plates can be performed within an hour, so local laborers can be used. Additionally, no chemical glues are used in the connection of the SBS™ system and so there is no requirement for specialized hazardous material storage and container disposal.
Vessel constructed of best priced local materials:
- The vessel design is specialized in its configuration but not dependent on the materials used. Best priced local materials (concrete, brick, fiberglass, polyethylene, etc.) can be employed in the construction of the exoskeleton structure depending on the regional conditions. Proprietary hydraulic mixing and attenuation devices installed in the vessel as supplied by Clearford to be installed at local manufacturing facilities.
