Bag and Cartridge Filtration
Dewatering projects and paved, impervious sites can produce water that, while clean to the eye, can fail to meet stringent discharge requirements. Whether solids, metals, or other contaminants, Clear Creek provides a variety of bag and cartridge filtration solutions for facilities that require removal of low concentrations of particulate-phase pollutants. Passive, non-chemical filtration systems have been successfully utilized to eliminate or reduce concentrations of suspended solids and non-dissolved metals on numerous project sites across a variety of industries and environments.
Particulate filtration is a low buy-in, proven technology. Bag and/or cartridge filters capture any particulate matter at or above the micron rating of the filter. When filter inserts have reached the end of their functional life, they are simply replaced with a fresh filter and the spent filter is discarded accordingly. Additionally, particulate filtration is often used as a pretreatment in adsorptive media or ion exchange filtration treatment systems as an affordable method to prolong media life. Available filtration equipment includes single- and multiple-bag filter housings, bag/cartridge series filter skids, and all necessary replacement consumables (1.0 – 100 micron bags, 0.5 – 40 micron cartridges).
Carbon filtration uses a filter with a bed of granulated activated carbon, commonly referred to as GAC. The bed removes contaminants and impurities through chemical adsorption.
In the process of adsorption, the pollutant molecules in the fluid are trapped inside the pore structure of the carbon. In our industry, GAC is commonly used to reduce levels of volatile organic compounds (VOC’s), semi-volatile organic compounds (SVOC’s), oils, polychlorinated biphenyls (PCBs), and hydrogen sulfides.
Pre-filtration is encouraged to extend the life of the carbon and avoid issues with blinding. For cases where significant contaminant levels exist, Organoclay can be placed in the lead position to extend carbon life and reduce overall operating costs.
Depending on the particular treatment method and contaminants, the contact time (amount of time water spends within the carbon bed) will need to be adjusted up or down. Carbon systems are normally set up in a lead-lag vessel configuration. A client should also consider whether the system can be shut down for a carbon change-out; if continual operations are required, redundant vessels are recommended to allow for system operations during replacement of spent media.
Chitosan-Enhanced Sand Filtration
Clear Creek pioneered the regular use of Chitosan-Enhanced Sand Filtration (CESF) for turbidity and TSS abatement in construction and industrial stormwater treatment. In California, CESF systems are referred to as Active Treatment Systems (ATS). Clear Creek uses FlocClear chitosan in our CESF systems, and works closely with the environmental regulators that oversee the proper use of CESF systems and the permitting of chitosan products. Implementing chitosan injection in a media filtration system causes solids to coagulate, leading to larger pollutant particle sizes, better filtration, and increased reductions of pollutants in water discharges.
In a CESF or ATS system, a controlled micro-dose of chitosan is injected inline on raw site waters. These waters are routed to a settling basin and given a site-specific amount of required residence/settling time. Settled waters are delivered to the media filter, often being provided with a polishing dose of chitosan prior to filtration. Settling pretreatment eases filter loading, allowing for a system to operate more reliably over time and ensure in-spec discharge waters. Media filters are outfitted with automated backwash controllers, greatly decreasing system oversight requirements during standard operations. Manual and Automated Supervisory Control and Data Acquisition (SCADA) treatment systems are available for rental or purchase.
CESF is a versatile treatment solution, and has been shown to reduce or eliminate concentrations of a variety of pollutants, including high solids, metals, chemical- and biological oxygen demand, and bacterial colonization. CESF has been implemented on a number of facilities in a variety of industries with great success, becoming a called-out industry standard in the stormwater world.
On rare occasion, certain facilities and industrial sites produce stormwater that does not react well to standard treatment methods. Clear Creek stocks and implements specialized flocculants and coagulants that are purpose-built to eliminate a variety of targeted pollutants, for these cases when chitosan and adsorptive media fail to produce water that meets pollutant targets.
These specialized water treatment polymers have been used in numerous industrial locations, including municipal drinking and wastewater applications. In stormwater treatment, chemical precipitation is often used to target organic tinges, biological/chemical oxygen demand, dissolved metals, and other problem pollutants that do not respond well to other treatment methods. Specialized polymers can be used with mixed-media filtration or with settlement only, depending on site requirements and pollutant concentrations. Often, implementation of chemical precipitation polymers will require post-treatment pH correction to meet discharge requirements.
Ion exchange is an exchange of ions between two electrolytes or between an electrolyte solution and a complex. In most cases the term is used to denote the processes of purification, separation, and decontamination of aqueous and other ion-containing solutions with solid polymeric or mineralic ‘ion exchangers’.
Typical ion exchangers are ion exchange resins (functionalized porous or gel polymer), zeolites, montmorillonite, clay, and soil humus. Ion exchangers are either cation exchangers that exchange positively charged ions (cations) or anion exchangers that exchange negatively charged ions (anions). There are also amphoteric exchangers that are able to exchange both cations and anions simultaneously. However, the simultaneous exchange of cations and anions can be more efficiently performed in mixed beds that contain a mixture of anion and cation exchange resins, or passing the treated solution through several different ion exchange materials.
Along with absorption and adsorption, ion exchange is a form of sorption. Ion exchange is a reversible process and the ion exchanger can be regenerated or loaded with desirable ions by washing with an excess of these ions. Due to the nature of construction sites, on-site regeneration is limited due to waste disposal costs and concerns for all but the largest and longest duration jobs.
Water containing trace contaminants, such as PFAS and selenium, becomes expensive to treat with non-selective media, such as GAC. Selective treatment media, such as ion exchange resins with a binding preference for a specific contaminant, are a cost-effective treatment option for the removal of trace contaminants such as PFAS and selenium.
Mechanical Media Filtration
Non-chemical mechanical media filtration is a functional step above standard bag and cartridge filtration, and is available for facilities with higher concentrations of particulate-phase pollutants. Waters with higher pollutant loads can quickly mask bag and cartridge filtration systems, leading to frequent filter insert replacements, increased consumable costs, and treatment system downtime.
Mechanical media filtration systems are more economical and reliable when these increased pollutant loads are found. Deep-bed sand or mixed-media equipment (generally stacked gravel, garnet, and anthracite) can be used to filter particulate-phase pollutants with particle sizes down to 5-micron, providing much of the efficacy of a bag or cartridge filter unit. Mechanical media filtration systems are outfitted with automated backwash controllers, eliminating the consumable and labor costs incurred while replacing spent bag and cartridge filter inserts. Occasionally, an additional backwash waste settling tank is required for reliable system operations.
Sites with high concentrations of zinc, copper, and other metals in their stormwater will often have difficulties meeting pollutant requirements with standard BMPs and sweeping schedules. Metals Coprecipitation is a particularly robust treatment solution, and is often used in municipal drinking and wastewater systems. This technology is available for implementation in industrial facilities, and has been proven highly effective in numerous laboratory and in-field testing procedures.
In Metals Coprecipitation, a proprietary metal salt targets a number of differing site water pollutants. Settlement, pH-correction (when necessary), and filtration take place after dosing, leaving waters with impressive clarity and purity. Clear Creek has mobilized systems that dose water with these proprietary metal salts, allowing sites to have discharge flows that reliably meet pollutant benchmarks, regardless of raw water pollutant concentrations. Galvanizing facilities and metal scrapyards often will fail to meet pollutant requirements with most other treatment techniques, and are good candidates for metals coprecipitation treatment techniques.
Whether it is naturally occurring hydrocarbons in the Los Angeles basin, equipment hydraulic failure, or leaking underground storage tanks, emulsified oil in water is a difficult problem. Because activated carbon (GAC) has an affinity for small molecule adsorption and organoclay has an affinity for large particle adsorption, these technologies complement each other effectively. We recommend organoclay treatment leading GAC treatment to extend carbon life and to save on cost and downtime.
There are also specialty organoclays, some using polyamines, anthracite or other unique components to enhance the adsorption for a specific range of contaminant. In our lab, we continually test various blends for our pilot tests to find the right mix for our clients.
With mine closures, landfill leachate systems, abandoned factories, superfund sites, et cetera, heavy metals seem to increasingly crop up in urban areas. Organoclay effectively removes heavy metals and maintains efficacy even as organics are present. Metals that are not heavy metals are generally treated with Ion Exchange, which tackles some of the most difficult metal pollutants.
We will help our clients find the right sized vessel and contact time needed to get the reduction they need to stay compliant.
Many projects and facilities have issues with elevated or depressed pH values in their site water discharges. These sites often fail to reliably meet required pH values without some form of active treatment technology. Testing at timber facilities, concrete construction, and other project sites may reveal out of balance pH values that can be amplified when polymers or other chemical treatment techniques are implemented. Clear Creek is capable of providing automated pH adjustment for any project, correcting any elevated or depressed pH issues that your facility may have.
Constant automated monitoring and chemical micro-dosing is performed by a programmable logic controller and a chemical metering pump, allowing site water pH values to be fine-tuned to meet discharge requirements. Treatment with strong acids or strong bases are available, depending on requirements. Clear Creek can implement automated pH correction into any of its treatment systems, or standalone in the event that no other on-site pollutant issues exist.
Proprietary Adsorptive Media
It is rare for a facility or jobsite to have a single targeted pollutant; quite often, a variety of differing pollutants will need to be removed within a single water flow. Because of this, Clear Creek is always working with our lead vendors to supply our customers with proprietary adsorptive media blends to allow for lower cost, more efficient treatment methods.
Our media blends utilize both industry-proven and emerging technologies. Blends are created off-site and pilot-tested with a facility’s stormwater discharge to ensure performance prior to on-site implementation. Often, a variety of blends are tested side-by-side at differing contact times (amount of time water spends within the media bed). Information found in these tests is used to determine media type and level of treatment required to meet discharge requirements.
The development and implementation of emerging technologies sets Clear Creek apart as an industry leader. The efficacy of each blend varies site-to-site, so please contact one of our representatives to begin a pilot test and find the media technology that best suits your site stormwater pollutant loads.
Reverse Osmosis (RO)
Reverse osmosis (RO) is a water purification technology that uses a semi-permeable membrane to remove ions, molecules, and larger particles from drinking water. In reverse osmosis, an applied pressure is used to overcome osmotic pressure, a colligative property, that is driven by chemical potential differences of the solvent, a thermodynamic parameter. Reverse osmosis can remove many types of dissolved and suspended species from water, including bacteria, and is used in both industrial processes and the production of potable water. The result is that the solute is retained on the pressurized side of the membrane and the pure solvent is allowed to pass to the other side. To be “selective”, this membrane should not allow large molecules or ions through the pores (holes), but should allow smaller components of the solution (such as solvent molecules) to pass freely.
In the normal osmosis process, the solvent naturally moves from an area of low solute concentration (high water potential), through a membrane, to an area of high solute concentration (low water potential). The driving force for the movement of the solvent is the reduction in the free energy of the system when the difference in solvent concentration on either side of a membrane is reduced, generating osmotic pressure due to the solvent moving into the more concentrated solution. Applying an external pressure to reverse the natural flow of pure solvent, thus, is reverse osmosis. The process is similar to other membrane technology applications. However, key differences are found between reverse osmosis and filtration. The predominant removal mechanism in membrane filtration is straining, or size exclusion, so the process can theoretically achieve perfect efficiency regardless of parameters such as the solution’s pressure and concentration. Reverse osmosis also involves diffusion, making the process dependent on pressure, flow rate, and other conditions.
Ultra Violet (UV)
Ultraviolet (UV) disinfection is a water treatment method that is utilized to reduce or eliminate bacterial and viral colonies in site waters. This treatment uses short-wavelength ultraviolet light from lamps to destroy or inactivate microorganisms by destroying nucleic acids and disrupting their DNA, leaving them unable to perform vital cellular functions. UV is commonly used in water purification after other filtration processes are completed. Water clarity has a large impact on the efficacy of UV, so it should not be used without prior filtration methods.
UV devices can produce strong UV light in circulating water systems to make them inhospitable environments to microorganisms such as bacteria, viruses, molds and other pathogens. UV is commonly used in place of chlorination due to a lower cost, easy operation, and elimination of potential residual chemical post-treatment. The key for a successful UV project is ensuring water clarity, implementing proper treatment contact times and correctly sized bulbs, and performing redundant treatments when necessary.