Clearford One System
The foundation of Clearford One is the technology’s proven 25-year track record of decentralized treatment of solids across a specialized network of sealed, small bore, pipes.
Clearford’s system removes solids at the source, performing primary and partial secondary treatment before releasing liquid effluent to ClearConvey, a network of small bore sewer pipes which carries the liquids without any infiltration to an optimized facility for final treatment. Reduced contaminants in the liquid effluent allows for more efficient recovery of clean water using the ClearRecover treatment package. Recovered water can be safely returned to the environment or reused with a distinct network of pipes that return clean water for non-ingestion uses like toilet water.
The solids are held in Clearford’s distributed ClearDigest smart digesters that greatly reduce the volume of organic material, and are pumped out only after decades of normal use. The Clearford system is more efficient, less expensive and longer lasting than conventional systems.
ClearDigest™ smart digesters are buried tanks that receive raw sewage from each connected source. ClearDigest™ tanks retain the solids, decompose the biosolids, modulate the flow, and release solids-free effluent by gravity to the ClearConvey™ pipe network. A proprietary inlet device uses the kinetic energy of the inflow to gently mix sewage in the tank to enhance digestion. A patented outlet device allows the water level in the tank to increase during peak use while restricting the outflow from the tank to a modulated rate.
ClearDigest™ effectively performs all of the primary treatment (settling) and much of the secondary (biological) treatment, reliably removing 75% of suspended solids and 65% of biochemical oxygen demand (BOD) from raw sewage. The liquid effluent from ClearDigest™ is substantially solids-free with consistently lower pollutant levels than raw sewage. This enables the efficient conveyance of liquid effluent in ClearConvey™ small bore sewers, and significantly simplifies treatment operations at the ClearRecover™ treatment plant.
Furthermore, the effect of modulating the flow is significant—it reduces the need to oversize downstream collection and treatment infrastructure by as much as 50% compared to conventional sewage systems. The result is smaller pumps, smaller tankage, and smaller footprint for sanitation infrastructure. Flow modulation also normalizes pollutant loading in the liquid effluent and eliminates shock loading to the treatment plant. This allows the final optimized treatment package to target the specific effluent character for efficient treatment.
While ClearDigest™ is highly efficient at decomposing biosolids in raw sewage, non-biodegradable solids are left to accumulate in the smart digesters. However, the tanks require pumping only after decades of normal use. For this frequency of maintenance, the lifecycle cost for operating the Clearford One™ system is minimized
ClearConvey™ is a small bore sewer tailored specifically for the efficient conveyance of liquid effluent from ClearDigest™ smart digesters. Since the liquid effluent is substantially solids-free, small-bore-sewer pipes are optimized for flow conveyance rather than solids carrying. ClearConvey™ uses small diameter pipes that can be laid with very low and variable slope. The use of flexible plastic pipe allows for streamlined flow in the sewer network, and there is no need for large manholes for maintenance access.
Whereas conventional sewers need large pipes to accommodate sewage solids and peak flow, ClearConvey™ uses substantially smaller pipes—in cases, three times smaller than conventional sewers. This is because ClearDigest™ smart digesters are so effective at removing solids and modulating the flow.
ClearConvey™ relies on gravity to move liquid effluent through the small-bore-sewer pipe network. However, the pipe slope requirement is reduced by up to 50% compared to conventional sewers because ClearConvey™ is not required to move large solids down the sewer pipe. When sewage pumping is required, ClearConvey™ may use only a third of the pump stations required in a conventional system. Furthermore, pumping is simplified by the use of smaller pumps that are only required to handle liquid effluent, not messy sewage solids. This reduces energy use, as well as capital and maintenance requirements.
ClearConvey™ uses flexible, durable high-density polyethylene (HDPE) pipes with fused joints and watertight access points that eliminate extraneous flow to the system. In conventional sewers, leaky joints in pipes and manholes are a significant cause of inflow and infiltration of groundwater that reduce the conveyance capacity of the system and add pumping and treatment costs for downstream infrastructure. Leaky joints may also allow sewage to pollute valuable soil and groundwater resources.
The ClearRecover™ treatment plant is optimized to take full advantage of the unique features of the Clearford One™ system. ClearRecover™ acts as a final polishing step for removing sewage pollutants, leaving clean water that can be reused in the community or released back to the environment. The treatment facility is fully customizable to suit the site requirements for plant configuration, treatment quality and budget. Treatment requirements may be driven by local regulations, as well as the suitability of certain treatment technologies to meet local conditions for equipment supply, construction techniques, and availability of skilled workforce. Deployments of ClearRecover™ range from constructed wetlands to compact state-of-the-art membrane bioreactors.
The combination of ClearDigest™ smart digesters and ClearConvey™ small-bore-sewer pipe network significantly reduces the hydraulic and pollutant loading to the ClearRecover™ treatment plant. The modulation of flow from ClearDigest™ greatly reduces peak hydraulic loading to the treatment plant, resulting in as much as 50% smaller equipment and tankage compared to conventional plants. Sizing is further reduced by the elimination of extraneous flow to the ClearConvey™ pipe network. ClearRecover™ fits into half the footprint of conventional treatment plants, requiring less land and reduced maintenance costs.
ClearRecover™ treatment operations are simplified compared to conventional plants. The sewage needing treatment contains 75% fewer suspended solids and 65% less biochemical oxygen demand (BOD) than raw sewage, thanks to pre-treatment in ClearDigest™ smart digesters. Pollutant loading is normalized to a consistent effluent character that is targeted for efficient final treatment at the ClearRecover™ plant. ClearRecover™ does not require extensive headworks and primary treatment—there are substantial capital and operating cost savings associated with elimination of screening, grit removal and primary settling. Sludge production is reduced compared with conventional plants because most of the pollutants are captured in ClearDigest™ smart digesters. Furthermore, biological treatment is targeted to specific pollutants such as nutrients (nitrogen, phosphorus) for more efficient use of treatment infrastructure and greater environmental protection.
ClearRecover™ achieves the highest quality when paired with UV Pure’s patented Crossfire Technology®. Treated effluent can be sterilized to non-detect pathogen levels using this highly efficient ultraviolet (UV) disinfection technology, making the effluent safe for reuse in non-potable applications like toilets and irrigation.
- Easier Installation
ClearConvey uses flexible HDPE pipes and can be installed by local, unskilled labor, using simple cut-and-cover and/or horizontal drilling. The ClearDigest units are lightweight reinforced plastic and come in two pieces that are easily attached together and lifted into place by two workers without the need for heavy equipment. The sealed system does not leak and allows potable water pipes and other services to be laid in the same channel as the ClearConvey pipe network, significantly reducing installation costs.
- Unconstrained Deployment
The Clearford One pipes allow more flexible community design or adaptation. Grade changes are easier to manage and communities are no longer constrained to rigid grid patterns or clear cutting. This also makes Clearford ideal for retrofitting sanitation systems in existing communities that developed without the rigid constraints of conventional sewers or septic systems.
- More Affordable
Clearford One is less expensive to purchase and install than conventional water and sanitation systems. But the largest savings will come through lower operating and maintenance costs.
- Longer Lasting
ClearDigest and ClearConvey are rated to last for over 75 years—almost twice as long as conventional sewer systems.
- Prosperity Enabling
Clean water and sanitation are basic needs. They are essential to achieving the Millennium Development Goals, and are a key first step towards a healthy and prosperous society. The Clearford system is recognized by the World Bank as uniquely suited to deliver affordable modern sanitation to the water scarce and less prosperous regions of the world.
- Low Water Operation
The Clearford One requires 90% less water to operate than conventional sewers. This is extremely valuable for water-scarce regions where conventional sewers can’t even be contemplated.
- More Sustainable
Clearford One unifies sanitation to lower water consumption and energy use. With no infiltration of ground water into the ClearConvey network, less water requires treatment. With only liquid flowing through ClearConvey no minimum flow or velocity is required for the system to operate. Clearford One enables potable water pipes to be laid in the same channel as ClearConvey and efficient recycling of treated recovered water through a distinct pipe network back to sewage sources for non-ingestions uses like toilets or irrigation.
Clearford has designed, patented and implemented a truly revolutionary sewage conveyance and conversion system. This has been done through the application of a distributed capture, digestion and flow attenuation architecture.
The Clearford design establishes a series of distributed underground smart digesters adjacent to the buildings which are serviced by the SBS, these smart digesters intercept the sewage and allow for at-source settling of sewage solids so that only the decanted liquids flow through the SBS pipe network.
The Clearford system operates efficiently with any range of daily water usage dramatically reducing the cost of operations.
Historic gravity systems conveying whole sewage must ensure that the solids move within all sections of the pipe network with sufficient velocity so as not to have those solids fall out of suspension, causing sewage solids to become lodged in the piping. High sewage flows in historic systems can achieve these velocities but cannot be expected and relied upon in low water usage rate areas where sewage obstructions in historic gravity sewer systems are frequent and costly to dislodge. The SBS effluent system works continuously, without blockages, regardless of the daily sewage volume generated from each building.
The Clearford at-source gravity separation system enables the SBS pipe network to be installed at nearly flat gradients without the risk of blockage since the constraint for a minimum velocity to be met in historic gravity systems is irrelevant for solids-free SBS effluent.
As the trench depth for pipe installation increases, the excavation volume increases exponentially since a wider trench at the ground surface is formed to ensure sufficient excavation wall slopes for worker safety; an increase in excavation volume for deeper trenches translates into higher installation costs for steeply sloped pipe networks.
The near-flat piping installation of the SBS system provides for shallow pipe trenching which can be constructed entirely with hand labour and light equipment resulting in significant capital cost savings.
Anaerobic bacteria become more efficient at consuming sludge as they mature and as such, the patented hydraulic mixer in the Clearford smart digester generates a current that gently mixes the sewage allowing for efficient anaerobic bacteria to come into contact with solid waste.
The best sludge digestion performance by bacteria occurs during long extended periods of anaerobic digestion. The patented attenuation device in the Clearford smart digester enables longer contact between anaerobic bacteria and solid waste.
At-source separation of sewage solids provides not only for decentralized or satellite digestion of sewage solids but provides for compete anaerobic digestion of sludge. Unlike the sludge storage capacities at treatment plants which are generally limited to a few days or weeks, provided there isn’t heavy rainfall, the Clearford smart digester furnishes sufficient sludge retention times to optimize the consumption capabilities of mature anaerobes effectively eliminating nearly all readily available organics. This means that the effluent flowing towards any treatment facility will be of superior quality and will require less treatment to reach potable standards.
Diurnal sewage surge flows are buffered within the Clearford smart digester providing for attenuated effluent flow to the downstream treatment plant.
Traditional peaking factor values applied to average daily flows for design flow calculations can be reduced to 2.0 with the inclusion of the Clearford smart digester. The proprietary attenuation devices enhance the overall buffering abilities.
The reduction in the design flow allows for smaller receiving infrastructure at the treatment plant and capital cost savings for a smaller treatment plant footprint and equipment reductions, and lower operational costs for less power consumption during equipment operation.
Manhole versus System Access Point (SAP) Installation Separation Distances:
The sealed SBS pipe network system can be accessed by System Access Points (SAPs) at 150 to 180 meter intervals, with no requirement for more SAPs within shorter spans.
Unlike historic gravity sewer systems that require manholes to be placed at all changes in horizontal alignments, which would be frequent in non-linear road layouts, the flexible HDPE piping material used in the SBS sanitary system installations can be serviced by small diameter SAPs for extended separation distances, even in curvilinear piping layouts. As HDPE pipe can bend at a radius of 25 times its diameter, it allows for bends, inflections or abrupt changes in alignment without specialized connectors, and the solids free effluent can pass through these variances without risk of depositing solids to block these sections of the piping. The SAPs provide access to the sealed SBS network and provide for air flow to avoid hydraulic locks in the system; since the maintenance practice of simple flushing of the system is not necessary, worker access to the piping is not necessary and as such, access is limited to the flushing hoses and closed circuit camera systems.
The robust load bearing SAPs are smaller in diameter, faster to install and more economical to construct than leak-prone manholes. Additionally, the increase in the spacing of the SAPs allows for fewer SAPs to be installed for the same servicing line and thus a more economical capital expenditure than the shorter separation span of historic gravity systems’ manholes.
The small Bore Sewer (SBS) piping, appurtenances and System Access Points (SAPs) are all assembled from high density polyethylene (HDPE) components, which are thermally fused to create a sealed network.
The HDPE material is the same material relied upon worldwide in the natural gas industry for providing truly sealed pipe networks. Robust HDPE piping has a long (75 + years) design life, is resistant to corrosive or biological attack and is non-reactive / inert in the environment.
No groundwater inflow enters into the sealed piping at typical culprit points: from open manholes or gasket connections and / or couplings of rigid pipe. At the same time, waste water from the system will not be allowed out to contaminate the environment.
Sealed sewers guarantee that the collected flow received at the downstream treatment plant is the absolute sum of all sewage leaving each building with no seasonal storm influences necessitating overdesign of the wastewater collection and treatment system.