Possibilities For Reducing Aeration Through Carbon Diversion Technologies

Process intensification is a standard term used in engineering that can be applied broadly. For instance, wastewater treatment intensification could be defined as any system that significantly outperforms conventional designs. New approaches are needed to intensify treatment of wastewater within existing infrastructure, because sustainable increases to wastewater treatment capacity and capability are necessary.

In 2015, a group of scientists, engineers, entrepreneurs, and other wastewater professionals gathered to accelerate, develop, demonstrate, and further implement innovative technologies to enhance recovery of water, nutrients, energy, heat, and other valuable products at water resource recovery facilities (WRRFs) at reduced costs. Over 30 new technology developers shared their innovations with nearly 150 leading experts and practitioners from utilities, consulting firms, universities, regulators, and other areas of the industry. Among the technologies examined was carbon diversion — using enhanced primary treatment, filtration, or high-rate systems to increase carbon resource recovery.

Recently, several carbon diversion technologies discussed during that gathering have been accepted to the Leaders Innovation Forum for Technology (LIFT) Technology Scan process. LIFT Technology Scans identify and evaluate innovative technologies to inform water facility owners, funders, advisors, and end users in order to promote early adoption of the technologies. They offer technology providers an optimal platform to introduce their emerging, precommercial, and newly commercialized technologies.

Diverting organics from the biological oxidation process, which demands large amounts of energy for aeration, and redirecting them to anaerobic digestion, where these organics can actually help produce energy, could significantly alter treatment facilities. In fact, studies in A Guide to Net-Zero Energy Solutions for WRRFs (WE&RF ENER1C12) indicate that carbon diversion using chemically enhanced primary treatment or A-stage processes could help plants achieve energy neutrality.

However, the specific impact of carbon-diversion technologies will depend on a number of factors, including a plant’s configuration and its current level of energy efficiency — and because carbon is required for biological nutrient removal (BNR), there is also the lingering issue of meeting nutrient discharge limits. If mainstream shortcut nitrogen removal processes can be developed, the demand for carbon would decrease drastically, paving the way for carbon diversion to reach its full potential.

A recently completed Water Environment & Reuse Foundation research report, State of Knowledge and Workshop Report: Intensification of Resource Recovery Forum (TIRR1R15), summarizes a suite of carbon diversion technologies and their apparent technology readiness levels. In that report, the technologies are divided into three types: primary effluent filtration, biologically enhanced primary treatment, and anaerobic treatment alternatives.

Primary effluent filtration technologies under consideration include ones by Schreiber, BKT, Trojan Technologies, and ClearCove Systems. Schreiber has taken its Fuzzy Filter, a compressed media filtration technology that is well-established for use in tertiary treatment and wet weather management, and adapted it for use in primary effluent filtration. Full-scale piloting and demonstrations are under way at the Dry Creek and Linda County treatment plants in California. Schreiber reports that primary filtration yields a 37 percent increase in digester gas production, a 25 percent decrease in blower power requirement, and a 34 percent increase in secondary process capacity. BKT’s biofiltration system (BBF™), an upflow process system that has previously been used for wet weather treatment, is now being applied to primary filtration. The BBF unit uses expanded polypropylene as a floating media layer for filtration. A BBF pilot plant has been operating for primary and wet weather treatment for 12 months using a small coagulant dose to enhance filtration. Two full-scale BBF systems (320 MGD total) have been designed for wet weather treatment in Seoul, Korea. Trojan Technologies Salsnes Filter is a rotating belt filter that removes suspended solids and provides thickening and dewatering up to 30 percent dry weight. Trojan estimates that the filter requires 10 percent of the land of a primary clarifier and that existing clarifiers could be transformed into extra secondary tank capacity with the addition of the filter. The company offers a demonstration unit for site evaluation. ClearCove Systems’ enhanced primary treatment (EPT) technology performs screening, grit removal, primary clarification, and equalization in one single step. This proprietary technology would completely replace headworks in order to divert nearly all organics to the digester. ClearCove’s findings indicate that the EPT system yields three times more biogas than a thickened sludge sample and produces an energy savings of 52 percent for aeration. In order to meet carbon demands for BNR, ClearCove suggests that online control could divert effluent from EPT to secondary treatment. The New York State Energy Research and Development Authority (NYSERDA) conducted a technology demonstration project in Ithaca, NY.

The biologically enhanced primary treatment technologies reviewed thus far include A-stage processes, alternating activated adsorption and an Evoqua system. A-stage processes have been used since the 1970s. A high-rate activated sludge process using adsorption to maximize carbon capture (the A-stage) is followed by secondary treatment that can perform BNR (the B-stage). The A-stage uses an aeration tank with a high surface-loading rate, aeration for a short hydraulic retention time (~ 0.5 hr), and a sludge retention time of 0.1 to 0.5 day. The A/B process is compatible with nitrogen removal, especially if shortcut pathways are used, which have a lower carbon demand. Although the process was designed to reduce overall volume of treatment, today it is mainly used to improve the energy balance or increase plant capacity. There are more than 20 full-scale installations in Europe and a few in the United States. Alternating activated adsorption (AAA) is a new configuration of the A-stage process consisting of two alternating sequencing batch reactors that can be retrofitted into rectangular basins. The Captivator System® blends waste-activated sludge with incoming wastewater in an aerated contact tank prior to dissolved air flotation. This system uses biosorption to capture soluble biochemical oxygen demand not captured in primary treatment, along with particulate biochemical oxygen demand. Evoqua claims the system reduces aeration energy requirements by 40 percent while increasing biogas production by 40 percent and has a footprint that is one-fifth that of conventional primary treatment. A 32-MGD installation has been operating since 2013 in Pima County, AZ. An example from Philadelphia was also presented in which two out of five existing primary clarifiers would be transformed to the Captivator, and the remaining three would be converted to secondary aeration to meet a pending nitrification requirement. A 300,000-GPD pilot plant is also available for on-site evaluations.

There is a growing interest in anaerobic treatment of domestic wastewater due to the potential to reduce energy demand and increase energy recovery. Anaerobic systems also have low overall sludge production, which can save capital and operational costs. Anaerobic treatment has been studied for more than four decades, and the upflow anaerobic sludge blanket (UASB) reactor is widely applied in South America. More recent interest is on the development of anaerobic membrane bioreactors. The major disadvantages of anaerobic treatment are the reduction of sulfur and production of H2S (a corrosive and odorous gas), the production of supersaturated dissolved methane (a potent greenhouse gas), and the presence of residual organics. Anaerobic treatment is also less efficient at low temperatures, which may limit application. If anaerobic treatment were realized, nutrient removal would be integrated as a downstream treatment process. Traditional BNR is challenging with anaerobic effluents, and new denitrification processes are being developed that use H2S and methane as reducing equivalents (in lieu of carbon). Nitrite shunt and deammonification are also promising processes when used downstream of anaerobic mainstream treatment.

While there are technologies that show promise for energy savings, there still is a need for additional research into the full potential of carbon diversion technologies that would have the most benefit to WRRFs. WE&RF’s research will advance our knowledge and promote early adoption of technologies. For more information on carbon diversion technologies accepted by LIFT, visit the WE&RF website for available research reports at www.werf.org.


Water Environment Research Foundation (WERF) notified BKT that its BBF system has officially been accepted into the general technology scan of the LIFT program based on additional technical review of its innovative capacity to facilitate carbon diversion.

This announcement follows BKT’s presentation at the WEF/WERF Forum on Intensification of Resource Recovery (IR^2) about the benefits of BBF’s application prior to secondary treatment of wastewater. Integration of the BBF increases carbon capture, enhancing the production of energy through digestion gas as well as reducing the amount of energy demanded by the blower to oxidize carbon during secondary treatment. This carbon diversion becomes essential in the future configuration of energy‐neutral water resource recovery facilities such as mainstream deammonification, where the resulting low COD/N ratio of BBF effluent will be highly beneficial to such downstream application performances.

As part of this recognition by WERF as an innovative technologies for carbon diversion, BBF will be featured in the LIFT Technology Database, accessible to all WERF Subscribers as a clearinghouse of promising technologies and processes reviewed by leading experts in the water industry. Additional details, will be available to Water Environment Federation (WEF) members and the broader water quality community through the LIFT pages of the WERF website.

In the near future, BBF will be included in the inaugural edition of LIFT Link, anticipated to be available in the first half of 2016. An online platform intended to support collaboration and innovation in the water sector, LIFT Link will accelerate BKT’s ability to forge collaborations with municipal utilities, environmental consultants, and other industry experts.


BKT Korea has recently completed development of the FMX‐C, a new model of BKT’s innovative FMX anti‐fouling membrane filtration system. Joining FMX’s four existing models, the FMX‐C customizes the current FMX system for use with a ceramic membrane to expand the product line’s versatility of application and range of capacity.

While the traditional FMX system already promises higher concentration than other filtration methods equipped with conventional polymeric membranes, introduction of the ceramic membrane in the FMX‐C can shift these concentration targets even higher.

Not only can the new FMX‐C provide effective filtration of high‐temperature or highly corrosive influent but it can also operate in severe conditions would corrode or degrade conventional polymeric membranes. Because ceramic membranes can tolerate elevated temperatures and withstand extreme pH and high operating pressures, the FMX‐C is suitable for many applications where polymeric membranes cannot be used, especially in handling acid liquid materials for the chemical industry.

Furthermore, the durability of the ceramic membrane material, coupled with the FMX’s inherent anti‐fouling features, lowers the frequency of replacement demanded and makes the FMX‐C ideal for in‐place chemical cleaning (CIP) with caustic inorganic compounds or steam sterilization at high temperatures.


BKT’s biological filtration (BBF) system has been approved by the California State Water Resources Control Board as an alternative filtration technology for achieving the minimum turbidity level required under Title 22 of the California Water Recycling Criteria.

Over the last six months, BKT has tested its BBF technology extensively at a pilot plant located at Los Angeles County Sanitation District’s Joint Water Pollution Control Plant in Carson, CA. During this time, BBF has consistently met Title 22 guidelines in normal operation, meeting the turbidity requirement of 2NTU while achieving 93% removal of total nitrogen from non‐nitrified secondary effluent.

 A vast majority of wastewater treatment facilities in the United States, most of which were built decades ago, are not able to meet low nitrogen discharge limits. Pollution resulting from the operation of these plants has therefore led to severe environmental problems. The limitations of these existing facilities present a serious technological hindrance for water reuse applications requiring nitrogen removal, including groundwater replenishment.

Now proven to function effectively in filtration, BBF is capable of simultaneously removing nitrogen while occupying equal or less space compared to traditional tertiary filtration options such as sand filters. This compact footprint makes BBF an ideal choice for retrofitting outdated wastewater facilities looking to update their technology with nitrogen removal processes under space limitations.

Worldwide, BBF has over 100 reference sites from small, decentralized wastewater treatment packages to installations up to 190 MGD in capacity. Recently, the City of Barstow, CA selected BBF for use in an ongoing groundwater remediation project to remove nitrates. BBF technology has successfully been applied to municipal wastewater treatment, groundwater remediation, and combined sewer overflow (CSO) control.


Anaheim, CA — FMX technology — The South Korean Ministry of Trade Industry & Energy has granted a significant Research & Development project to environmental services company BKT. Over the next three years, the South Korean government will budget $6 million, matched by a contribution of $1.5 million from BKT, to facilitate the joint development of an environmentally conscious processing system for efficient reuse of shale gas fracking water.

The design of this new system is intended to incorporate BKT’s unique FMX membrane filtration technology, specialized in high solids, high density, and high viscosity liquid‐solid separation. The features of this easily mobilized FMX unit are particularly crucial to ensuring adaptability to the high fluctuations in the Total Suspended Solids (TSS) content of shale gas produced water.

Founded in 1995, BKT offers a wide range of customized water and energy solutions designed to promote a mission of innovation beyond waste. Since 2011, BKT has been investigating shale gas water reuse extensively, both through internal resources and in collaboration with the US Department of Energy (DOE).

The two‐year DOE project, initiated in 2012 with partner group Southern Research Institute (SRI), is focused on developing advanced technologies that address issues related to processes and methods for handling large volumes of hydraulic fracturing flow‐back water, as well as water produced during the longer term production phase. The program will optimize hydraulic fracturing water treatment and disposal of residues (high‐solid slurry and membrane concentrate) using BKT’s anti‐fouling FMX membrane system.

Thus, BKT now enters this new R&D project equipped with significant prior on‐site test experience, ample research data, and extensive partner network. With this additional funding, BKT is expected to move forward more aggressively in the shale gas industry.

“The technical team at BKT is extremely excited to further our existing knowledge,” said Dr. Joon H. Min, President at BKT, “We believe that our tradition of innovation will prove key to advancing technology in contributing a viable solution for environment friendly shale gas water management.”