Water & Wastewater Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/983816
www.wwtonline.co.uk | WWT | JUNE 2017 | 35 Reactor (Microvi design or existing) Microvi's proprietary Biocatalysts man consumption. The disadvantages of conventional nitrate-removal technologies paint a bleak— and costly—picture for the millions of people in need of nitrate treatment. A disruptive new paradigm for nitrate degradation For the past several years, Microvi, a global greentech pioneer based in the San Francisco Bay Area, has been working on an innovative approach to overcome the challenges of treating nitrate and other water pollutants. This new approach is called the MicroNiche Engineering (MNE) platform, where materi- als science is used to control natural organism populations in a way that has never been possible before. As a result, the Denitrovi technology was born: using natural degraders to convert nitrate into harm- less nitrogen gas in a matter of a few minutes all without generating a biological waste. Denitrovi represents a paradigm shi€ from conven- tional nitrate degradation. In conventional fixed-film or suspended growth processes, non-specific organisms are repeatedly grown and removed as sludge. Any attempt to artificially favour a particular species of organism requires complex and delicate control systems which can be notori- ously unreliable and limits process flexibility. In contrast, Denitrovi uses specially- targeted, high performance natural microorganisms that are completely incorporated at very high density within the Denitrovi composites. These natural nitrate-degrading organisms never leave the reactor, as they are protected from washout, overgrowth, toxicity, and abrupt changes in operation. In this sense, Microvi have overcome the intrinsic issues with conventional biological treatment, and not just for nitrate removal but for any biological system. A key motivation behind the Denitrovi technology was to meet the urgent need of com- munities around the world who require a simple, effective and waste-free solution for high nitrate. The first instal- lation of this new technology took place in Aboriginal com- munities in Western Australia in 2012. The installation is con- tinuing to remove nitrate from groundwater in the last five years with the same biocata- lysts. The biocatalysts are still very effective with no signs of deterioration in performance over five years. In this case, with such a remote site, no conventional technology could have been simple enough to be effective. In January 2017, the first full-scale installation of the Denitrovi technology began operation at the Sunny Slope Water Company in Pasadena, California. In the preceding years, the Denitrovi technolo- gy was evaluated according to strict standards and protocols set by the California Division of Drinking Water (DDW). This included the evaluation of a number of parameters, includ- ing dissolved oxygen, nitrate, turbidity, total coliform, and specific microbiological tests. During this project, steady state nitrate removal was achieved in a short period of time, days as opposed to the weeks that are o€en required for conventional biological technologies. The short start- up period was an indicator of the high biocatalytic density available for nitrate degra- dation from the first day of operation. Advantages of the new approach This new nitrate removal system is extraordinarily efficient. Less water is lost or needs costly recovery process- ing, with a water recovery of over 98%. It is also flexible. The system can be retrofitted into existing tanks or installed simply into new systems. The start-up and recovery time is quick, providing a good solu- tion for both continuous and intermittent use. Microvi's nitrate removal technology can offer cost sav- ing compared to a traditional nitrate removal system. It has lower energy and chemicals requirements and requires no reactor backwashing. Economic analysis performed by a third-party engineering firm found that the Denitrovi nitrate removal system offers whole of life cost savings on the order of 35% as compared to ion exchange systems for a specific application. For the plant designer and owner, removing the need to find, secure and then maintain a disposal route for the undesirable concen- trated brine waste is hugely significant. The minor mass and volume of waste gener- ated along with its inert nature make it much easier to dispose reducing the requirement for costly treatment. The end user can be assured that they are not reliant on a third party or changing legislation to accept their waste and therefore have total control of long term com- mercial and operating costs. For the plant operator, this new process is easier and faster than traditional biologi- cal treatment. With treatment rates of just minutes, there can be smaller tanks where the biocatalytic composites convert nitrate more efficiently. Short treatment times reduce the plant's footprint and allows for modular/standard systems built and tested off site. The simple reactor has minimal internal components, straightforward control, and Clean Water Polluted Water GOAL 3 DRINKING WATER QUALITY