NuReSys technology removes orthophosphate from anaerobic sludge streams through a two-tank method that includes an air stripper and a crystallizing reactor. The air stripper uses diffused air to increase and control process pH at optimum conditions and the crystallizing reactor, operating as a CSTR, is where the reagents are added to the sludge stream to precipitate struvite. Controlling the process through two tanks leads to greater process stability and also lends itself to greater design flexibility to solve specific plant issues. Three basic approaches are promoted treating three different process streams: 1) dewatered centrate/filtrate treatment, 2) digestate treatment, or 3) a hybrid operational mode that simultaneously treats both digestate and centrate. Each configuration is aimed at solving different issues directly related to the client’s defined struvite or phosphate issues.
NuReSys has been active in struvite technology for more than a decade. In the past, “peak phosphorus” was the main concern and initiated a growing awareness of the phosphate challenge lying ahead. However, it has become evident that struvite and phosphorus issues within plants allow the technology to be implemented in more applications beyond merely mitigating the peak phosphorus issue. Issues of unwanted scaling, phosphate return loads from sludge processing, struvite accumulation in digesters/holding tanks and equipment, reducing the requirements for iron salts that increase sludge production, and deterioration of dewatering properties after switching from chemical to BNR can all be addressed with the NuReSys technology. As such, NuReSys has shifted focus towards integrated phosphate management, exploiting features and flexibility in its technology to resolve and improve plant operations, even if the recovered struvite were to have no added value at all.
NuReSys technology is offered in North America under license through Schwing Bioset. Schwing Bioset has over 30 years of experience in supplying premier equipment to the wastewater industry offering in addition to the NuReSys technology, dewatering, cake conveyance, storage, and Class A biosolids technologies. www.schwingbioset.com
What are the benefits to implementing your technology?
In addition to a reduction in PO4-P levels within the plant, the following benefits are realized depending on which operational configuration is implemented:
- Reduction in struvite scaling and accumulations.
- Improvement in dewatering characteristics.
- Reduction in polymer consumption.
- Recovery of struvite for beneficial reuse.
- Reduction in sludge volume by reducing or eliminating use of iron salts.
The NuReSys design also affords the use of smaller tanks and shorter HRTs through the process by decoupling the SRT from the hydraulic flow. This decoupling also allows manipulation of the prill growth and recovery by simple adjustments within the process providing greater process flexibility and control.
NuReSys has been at the forefront of struvite technology and was the first to:
- Demonstrate clear growth of struvite crystals in the complex digestate matrix, recognizing the importance of native struvite produced in the digester, and thus demystifying unrealistic gains in dry matter after struvite treatment.
- Implementing online PO4-P measurement to control MgCl2 dosing.
With many years of field experience in general wastewater treatment, we are also capable of evaluating impacts on processes upstream and downstream of the struvite technology. We feel this is an important aspect of any design, as the selected struvite process should benefit the entire plant instead of just focusing on struvite/phosphate alone.
Has the technology been tested, demonstrated, or implemented anywhere to date?
Currently there are eight full-scale installations operating in Europe with a ninth in start-up and a tenth under construction. Pilot units are also available in both Europe and North America.
What are some of the next steps needed to advance the technology?
The technology is proven in Europe in multiple applications and industries. Schwing Bioset has built a demonstration unit that is available for pilot testing at plants throughout the U.S. and Canada to demonstrate the effectiveness of the process.
LIFT can help to introduce the technology within North America to to those looking to solve struvite issues and reduce PO4-P levels within wastewater plants.Chuck WanstromDirector of New Business DevelopmentSchwing Bioset